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Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.4 by dl, Mon Jan 12 17:16:18 2009 UTC vs.
Revision 1.137 by dl, Tue Oct 30 14:23:11 2012 UTC

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1		/*
2		* Written by Doug Lea with assistance from members of JCP JSR-166
3		* Expert Group and released to the public domain, as explained at
4	<	* http://creativecommons.org/licenses/publicdomain
4	>	* http://creativecommons.org/publicdomain/zero/1.0/
5		*/
6
7		package jsr166y;
8	<	import java.util.*;
9	<	import java.util.concurrent.*;
10	<	import java.util.concurrent.locks.*;
11	<	import java.util.concurrent.atomic.*;
12	<	import sun.misc.Unsafe;
13	<	import java.lang.reflect.*;
8	>
9	>	import java.util.ArrayList;
10	>	import java.util.Arrays;
11	>	import java.util.Collection;
12	>	import java.util.Collections;
13	>	import java.util.List;
14	>	import java.util.Random;
15	>	import java.util.concurrent.AbstractExecutorService;
16	>	import java.util.concurrent.Callable;
17	>	import java.util.concurrent.ExecutorService;
18	>	import java.util.concurrent.Future;
19	>	import java.util.concurrent.RejectedExecutionException;
20	>	import java.util.concurrent.RunnableFuture;
21	>	import java.util.concurrent.TimeUnit;
22	>	import java.util.concurrent.atomic.AtomicInteger;
23	>	import java.util.concurrent.atomic.AtomicLong;
24	>	import java.util.concurrent.locks.AbstractQueuedSynchronizer;
25	>	import java.util.concurrent.locks.Condition;
26
27		/**
28	<	* An {@link ExecutorService} for running {@link ForkJoinTask}s.  A
29	<	* ForkJoinPool provides the entry point for submissions from
30	<	* non-ForkJoinTasks, as well as management and monitoring operations.
31	<	* Normally a single ForkJoinPool is used for a large number of
32	<	* submitted tasks. Otherwise, use would not usually outweigh the
33	<	* construction and bookkeeping overhead of creating a large set of
34	<	* threads.
28	>	* An {@link ExecutorService} for running {@link ForkJoinTask}s.
29	>	* A {@code ForkJoinPool} provides the entry point for submissions
30	>	* from non-{@code ForkJoinTask} clients, as well as management and
31	>	* monitoring operations.
32	>	*
33	>	* <p>A {@code ForkJoinPool} differs from other kinds of {@link
34	>	* ExecutorService} mainly by virtue of employing
35	>	* <em>work-stealing</em>: all threads in the pool attempt to find and
36	>	* execute tasks submitted to the pool and/or created by other active
37	>	* tasks (eventually blocking waiting for work if none exist). This
38	>	* enables efficient processing when most tasks spawn other subtasks
39	>	* (as do most {@code ForkJoinTask}s), as well as when many small
40	>	* tasks are submitted to the pool from external clients.  Especially
41	>	* when setting <em>asyncMode</em> to true in constructors, {@code
42	>	* ForkJoinPool}s may also be appropriate for use with event-style
43	>	* tasks that are never joined.
44		*
45	<	* <p>ForkJoinPools differ from other kinds of Executors mainly in
46	<	* that they provide <em>work-stealing</em>: all threads in the pool
47	<	* attempt to find and execute subtasks created by other active tasks
48	<	* (eventually blocking if none exist). This makes them efficient when
49	<	* most tasks spawn other subtasks (as do most ForkJoinTasks), as well
50	<	* as the mixed execution of some plain Runnable- or Callable- based
51	<	* activities along with ForkJoinTasks. Otherwise, other
52	<	* ExecutorService implementations are typically more appropriate
53	<	* choices.
45	>	* <p>A static {@link #commonPool} is available and appropriate for
46	>	* most applications. The common pool is used by any ForkJoinTask that
47	>	* is not explicitly submitted to a specified pool. Using the common
48	>	* pool normally reduces resource usage (its threads are slowly
49	>	* reclaimed during periods of non-use, and reinstated upon subsequent
50	>	* use).  The common pool is by default constructed with default
51	>	* parameters, but these may be controlled by setting any or all of
52	>	* the three properties {@code
53	>	* java.util.concurrent.ForkJoinPool.common.{parallelism,
54	>	* threadFactory, exceptionHandler}}.
55		*
56	<	* <p>A ForkJoinPool may be constructed with a given parallelism level
57	<	* (target pool size), which it attempts to maintain by dynamically
58	<	* adding, suspending, or resuming threads, even if some tasks are
59	<	* waiting to join others. However, no such adjustments are performed
60	<	* in the face of blocked IO or other unmanaged synchronization. The
61	<	* nested <code>ManagedBlocker</code> interface enables extension of
62	<	* the kinds of synchronization accommodated.  The target parallelism
63	<	* level may also be changed dynamically (<code>setParallelism</code>)
64	<	* and dynamically thread construction can be limited using methods
65	<	* <code>setMaximumPoolSize</code> and/or
44	<	* <code>setMaintainsParallelism</code>.
56	>	* <p>For applications that require separate or custom pools, a {@code
57	>	* ForkJoinPool} may be constructed with a given target parallelism
58	>	* level; by default, equal to the number of available processors. The
59	>	* pool attempts to maintain enough active (or available) threads by
60	>	* dynamically adding, suspending, or resuming internal worker
61	>	* threads, even if some tasks are stalled waiting to join
62	>	* others. However, no such adjustments are guaranteed in the face of
63	>	* blocked IO or other unmanaged synchronization. The nested {@link
64	>	* ManagedBlocker} interface enables extension of the kinds of
65	>	* synchronization accommodated.
66		*
67		* <p>In addition to execution and lifecycle control methods, this
68		* class provides status check methods (for example
69	<	* <code>getStealCount</code>) that are intended to aid in developing,
69	>	* {@link #getStealCount}) that are intended to aid in developing,
70		* tuning, and monitoring fork/join applications. Also, method
71	<	* <code>toString</code> returns indications of pool state in a
71	>	* {@link #toString} returns indications of pool state in a
72		* convenient form for informal monitoring.
73		*
74	+	* <p> As is the case with other ExecutorServices, there are three
75	+	* main task execution methods summarized in the following table.
76	+	* These are designed to be used primarily by clients not already
77	+	* engaged in fork/join computations in the current pool.  The main
78	+	* forms of these methods accept instances of {@code ForkJoinTask},
79	+	* but overloaded forms also allow mixed execution of plain {@code
80	+	* Runnable}- or {@code Callable}- based activities as well.  However,
81	+	* tasks that are already executing in a pool should normally instead
82	+	* use the within-computation forms listed in the table unless using
83	+	* async event-style tasks that are not usually joined, in which case
84	+	* there is little difference among choice of methods.
85	+	*
86	+	* <table BORDER CELLPADDING=3 CELLSPACING=1>
87	+	*  <tr>
88	+	*    <td></td>
89	+	*    <td ALIGN=CENTER> <b>Call from non-fork/join clients</b></td>
90	+	*    <td ALIGN=CENTER> <b>Call from within fork/join computations</b></td>
91	+	*  </tr>
92	+	*  <tr>
93	+	*    <td> <b>Arrange async execution</td>
94	+	*    <td> {@link #execute(ForkJoinTask)}</td>
95	+	*    <td> {@link ForkJoinTask#fork}</td>
96	+	*  </tr>
97	+	*  <tr>
98	+	*    <td> <b>Await and obtain result</td>
99	+	*    <td> {@link #invoke(ForkJoinTask)}</td>
100	+	*    <td> {@link ForkJoinTask#invoke}</td>
101	+	*  </tr>
102	+	*  <tr>
103	+	*    <td> <b>Arrange exec and obtain Future</td>
104	+	*    <td> {@link #submit(ForkJoinTask)}</td>
105	+	*    <td> {@link ForkJoinTask#fork} (ForkJoinTasks <em>are</em> Futures)</td>
106	+	*  </tr>
107	+	* </table>
108	+	*
109		* <p><b>Implementation notes</b>: This implementation restricts the
110		* maximum number of running threads to 32767. Attempts to create
111	<	* pools with greater than the maximum result in
112	<	* IllegalArgumentExceptions.
111	>	* pools with greater than the maximum number result in
112	>	* {@code IllegalArgumentException}.
113	>	*
114	>	* <p>This implementation rejects submitted tasks (that is, by throwing
115	>	* {@link RejectedExecutionException}) only when the pool is shut down
116	>	* or internal resources have been exhausted.
117	>	*
118	>	* @since 1.7
119	>	* @author Doug Lea
120		*/
121		public class ForkJoinPool extends AbstractExecutorService {
122
123		/*
124	<	* See the extended comments interspersed below for design,
125	<	* rationale, and walkthroughs.
124	>	* Implementation Overview
125	>	*
126	>	* This class and its nested classes provide the main
127	>	* functionality and control for a set of worker threads:
128	>	* Submissions from non-FJ threads enter into submission queues.
129	>	* Workers take these tasks and typically split them into subtasks
130	>	* that may be stolen by other workers.  Preference rules give
131	>	* first priority to processing tasks from their own queues (LIFO
132	>	* or FIFO, depending on mode), then to randomized FIFO steals of
133	>	* tasks in other queues.
134	>	*
135	>	* WorkQueues
136	>	* ==========
137	>	*
138	>	* Most operations occur within work-stealing queues (in nested
139	>	* class WorkQueue).  These are special forms of Deques that
140	>	* support only three of the four possible end-operations -- push,
141	>	* pop, and poll (aka steal), under the further constraints that
142	>	* push and pop are called only from the owning thread (or, as
143	>	* extended here, under a lock), while poll may be called from
144	>	* other threads.  (If you are unfamiliar with them, you probably
145	>	* want to read Herlihy and Shavit's book "The Art of
146	>	* Multiprocessor programming", chapter 16 describing these in
147	>	* more detail before proceeding.)  The main work-stealing queue
148	>	* design is roughly similar to those in the papers "Dynamic
149	>	* Circular Work-Stealing Deque" by Chase and Lev, SPAA 2005
150	>	* (http://research.sun.com/scalable/pubs/index.html) and
151	>	* "Idempotent work stealing" by Michael, Saraswat, and Vechev,
152	>	* PPoPP 2009 (http://portal.acm.org/citation.cfm?id=1504186).
153	>	* The main differences ultimately stem from GC requirements that
154	>	* we null out taken slots as soon as we can, to maintain as small
155	>	* a footprint as possible even in programs generating huge
156	>	* numbers of tasks. To accomplish this, we shift the CAS
157	>	* arbitrating pop vs poll (steal) from being on the indices
158	>	* ("base" and "top") to the slots themselves.  So, both a
159	>	* successful pop and poll mainly entail a CAS of a slot from
160	>	* non-null to null.  Because we rely on CASes of references, we
161	>	* do not need tag bits on base or top.  They are simple ints as
162	>	* used in any circular array-based queue (see for example
163	>	* ArrayDeque).  Updates to the indices must still be ordered in a
164	>	* way that guarantees that top == base means the queue is empty,
165	>	* but otherwise may err on the side of possibly making the queue
166	>	* appear nonempty when a push, pop, or poll have not fully
167	>	* committed. Note that this means that the poll operation,
168	>	* considered individually, is not wait-free. One thief cannot
169	>	* successfully continue until another in-progress one (or, if
170	>	* previously empty, a push) completes.  However, in the
171	>	* aggregate, we ensure at least probabilistic non-blockingness.
172	>	* If an attempted steal fails, a thief always chooses a different
173	>	* random victim target to try next. So, in order for one thief to
174	>	* progress, it suffices for any in-progress poll or new push on
175	>	* any empty queue to complete. (This is why we normally use
176	>	* method pollAt and its variants that try once at the apparent
177	>	* base index, else consider alternative actions, rather than
178	>	* method poll.)
179	>	*
180	>	* This approach also enables support of a user mode in which local
181	>	* task processing is in FIFO, not LIFO order, simply by using
182	>	* poll rather than pop.  This can be useful in message-passing
183	>	* frameworks in which tasks are never joined.  However neither
184	>	* mode considers affinities, loads, cache localities, etc, so
185	>	* rarely provide the best possible performance on a given
186	>	* machine, but portably provide good throughput by averaging over
187	>	* these factors.  (Further, even if we did try to use such
188	>	* information, we do not usually have a basis for exploiting it.
189	>	* For example, some sets of tasks profit from cache affinities,
190	>	* but others are harmed by cache pollution effects.)
191	>	*
192	>	* WorkQueues are also used in a similar way for tasks submitted
193	>	* to the pool. We cannot mix these tasks in the same queues used
194	>	* for work-stealing (this would contaminate lifo/fifo
195	>	* processing). Instead, we loosely associate submission queues
196	>	* with submitting threads, using a form of hashing.  The
197	>	* ThreadLocal Submitter class contains a value initially used as
198	>	* a hash code for choosing existing queues, but may be randomly
199	>	* repositioned upon contention with other submitters.  In
200	>	* essence, submitters act like workers except that they never
201	>	* take tasks, and they are multiplexed on to a finite number of
202	>	* shared work queues. However, classes are set up so that future
203	>	* extensions could allow submitters to optionally help perform
204	>	* tasks as well. Insertion of tasks in shared mode requires a
205	>	* lock (mainly to protect in the case of resizing) but we use
206	>	* only a simple spinlock (using bits in field runState), because
207	>	* submitters encountering a busy queue move on to try or create
208	>	* other queues -- they block only when creating and registering
209	>	* new queues.
210	>	*
211	>	* Management
212	>	* ==========
213	>	*
214	>	* The main throughput advantages of work-stealing stem from
215	>	* decentralized control -- workers mostly take tasks from
216	>	* themselves or each other. We cannot negate this in the
217	>	* implementation of other management responsibilities. The main
218	>	* tactic for avoiding bottlenecks is packing nearly all
219	>	* essentially atomic control state into two volatile variables
220	>	* that are by far most often read (not written) as status and
221	>	* consistency checks.
222	>	*
223	>	* Field "ctl" contains 64 bits holding all the information needed
224	>	* to atomically decide to add, inactivate, enqueue (on an event
225	>	* queue), dequeue, and/or re-activate workers.  To enable this
226	>	* packing, we restrict maximum parallelism to (1<<15)-1 (which is
227	>	* far in excess of normal operating range) to allow ids, counts,
228	>	* and their negations (used for thresholding) to fit into 16bit
229	>	* fields.
230	>	*
231	>	* Field "runState" contains 32 bits needed to register and
232	>	* deregister WorkQueues, as well as to enable shutdown. It is
233	>	* only modified under a lock (normally briefly held, but
234	>	* occasionally protecting allocations and resizings) but even
235	>	* when locked remains available to check consistency.
236	>	*
237	>	* Recording WorkQueues.  WorkQueues are recorded in the
238	>	* "workQueues" array that is created upon first use and expanded
239	>	* if necessary.  Updates to the array while recording new workers
240	>	* and unrecording terminated ones are protected from each other
241	>	* by a lock but the array is otherwise concurrently readable, and
242	>	* accessed directly.  To simplify index-based operations, the
243	>	* array size is always a power of two, and all readers must
244	>	* tolerate null slots. Shared (submission) queues are at even
245	>	* indices, worker queues at odd indices. Grouping them together
246	>	* in this way simplifies and speeds up task scanning.
247	>	*
248	>	* All worker thread creation is on-demand, triggered by task
249	>	* submissions, replacement of terminated workers, and/or
250	>	* compensation for blocked workers. However, all other support
251	>	* code is set up to work with other policies.  To ensure that we
252	>	* do not hold on to worker references that would prevent GC, ALL
253	>	* accesses to workQueues are via indices into the workQueues
254	>	* array (which is one source of some of the messy code
255	>	* constructions here). In essence, the workQueues array serves as
256	>	* a weak reference mechanism. Thus for example the wait queue
257	>	* field of ctl stores indices, not references.  Access to the
258	>	* workQueues in associated methods (for example signalWork) must
259	>	* both index-check and null-check the IDs. All such accesses
260	>	* ignore bad IDs by returning out early from what they are doing,
261	>	* since this can only be associated with termination, in which
262	>	* case it is OK to give up.  All uses of the workQueues array
263	>	* also check that it is non-null (even if previously
264	>	* non-null). This allows nulling during termination, which is
265	>	* currently not necessary, but remains an option for
266	>	* resource-revocation-based shutdown schemes. It also helps
267	>	* reduce JIT issuance of uncommon-trap code, which tends to
268	>	* unnecessarily complicate control flow in some methods.
269	>	*
270	>	* Event Queuing. Unlike HPC work-stealing frameworks, we cannot
271	>	* let workers spin indefinitely scanning for tasks when none can
272	>	* be found immediately, and we cannot start/resume workers unless
273	>	* there appear to be tasks available.  On the other hand, we must
274	>	* quickly prod them into action when new tasks are submitted or
275	>	* generated. In many usages, ramp-up time to activate workers is
276	>	* the main limiting factor in overall performance (this is
277	>	* compounded at program start-up by JIT compilation and
278	>	* allocation). So we try to streamline this as much as possible.
279	>	* We park/unpark workers after placing in an event wait queue
280	>	* when they cannot find work. This "queue" is actually a simple
281	>	* Treiber stack, headed by the "id" field of ctl, plus a 15bit
282	>	* counter value (that reflects the number of times a worker has
283	>	* been inactivated) to avoid ABA effects (we need only as many
284	>	* version numbers as worker threads). Successors are held in
285	>	* field WorkQueue.nextWait.  Queuing deals with several intrinsic
286	>	* races, mainly that a task-producing thread can miss seeing (and
287	>	* signalling) another thread that gave up looking for work but
288	>	* has not yet entered the wait queue. We solve this by requiring
289	>	* a full sweep of all workers (via repeated calls to method
290	>	* scan()) both before and after a newly waiting worker is added
291	>	* to the wait queue. During a rescan, the worker might release
292	>	* some other queued worker rather than itself, which has the same
293	>	* net effect. Because enqueued workers may actually be rescanning
294	>	* rather than waiting, we set and clear the "parker" field of
295	>	* WorkQueues to reduce unnecessary calls to unpark.  (This
296	>	* requires a secondary recheck to avoid missed signals.)  Note
297	>	* the unusual conventions about Thread.interrupts surrounding
298	>	* parking and other blocking: Because interrupts are used solely
299	>	* to alert threads to check termination, which is checked anyway
300	>	* upon blocking, we clear status (using Thread.interrupted)
301	>	* before any call to park, so that park does not immediately
302	>	* return due to status being set via some other unrelated call to
303	>	* interrupt in user code.
304	>	*
305	>	* Signalling.  We create or wake up workers only when there
306	>	* appears to be at least one task they might be able to find and
307	>	* execute.  When a submission is added or another worker adds a
308	>	* task to a queue that previously had fewer than two tasks, they
309	>	* signal waiting workers (or trigger creation of new ones if
310	>	* fewer than the given parallelism level -- see signalWork).
311	>	* These primary signals are buttressed by signals during rescans;
312	>	* together these cover the signals needed in cases when more
313	>	* tasks are pushed but untaken, and improve performance compared
314	>	* to having one thread wake up all workers.
315	>	*
316	>	* Trimming workers. To release resources after periods of lack of
317	>	* use, a worker starting to wait when the pool is quiescent will
318	>	* time out and terminate if the pool has remained quiescent for a
319	>	* given period -- a short period if there are more threads than
320	>	* parallelism, longer as the number of threads decreases. This
321	>	* will slowly propagate, eventually terminating all workers after
322	>	* periods of non-use.
323	>	*
324	>	* Shutdown and Termination. A call to shutdownNow atomically sets
325	>	* a runState bit and then (non-atomically) sets each worker's
326	>	* runState status, cancels all unprocessed tasks, and wakes up
327	>	* all waiting workers.  Detecting whether termination should
328	>	* commence after a non-abrupt shutdown() call requires more work
329	>	* and bookkeeping. We need consensus about quiescence (i.e., that
330	>	* there is no more work). The active count provides a primary
331	>	* indication but non-abrupt shutdown still requires a rechecking
332	>	* scan for any workers that are inactive but not queued.
333	>	*
334	>	* Joining Tasks
335	>	* =============
336	>	*
337	>	* Any of several actions may be taken when one worker is waiting
338	>	* to join a task stolen (or always held) by another.  Because we
339	>	* are multiplexing many tasks on to a pool of workers, we can't
340	>	* just let them block (as in Thread.join).  We also cannot just
341	>	* reassign the joiner's run-time stack with another and replace
342	>	* it later, which would be a form of "continuation", that even if
343	>	* possible is not necessarily a good idea since we sometimes need
344	>	* both an unblocked task and its continuation to progress.
345	>	* Instead we combine two tactics:
346	>	*
347	>	*   Helping: Arranging for the joiner to execute some task that it
348	>	*      would be running if the steal had not occurred.
349	>	*
350	>	*   Compensating: Unless there are already enough live threads,
351	>	*      method tryCompensate() may create or re-activate a spare
352	>	*      thread to compensate for blocked joiners until they unblock.
353	>	*
354	>	* A third form (implemented in tryRemoveAndExec and
355	>	* tryPollForAndExec) amounts to helping a hypothetical
356	>	* compensator: If we can readily tell that a possible action of a
357	>	* compensator is to steal and execute the task being joined, the
358	>	* joining thread can do so directly, without the need for a
359	>	* compensation thread (although at the expense of larger run-time
360	>	* stacks, but the tradeoff is typically worthwhile).
361	>	*
362	>	* The ManagedBlocker extension API can't use helping so relies
363	>	* only on compensation in method awaitBlocker.
364	>	*
365	>	* The algorithm in tryHelpStealer entails a form of "linear"
366	>	* helping: Each worker records (in field currentSteal) the most
367	>	* recent task it stole from some other worker. Plus, it records
368	>	* (in field currentJoin) the task it is currently actively
369	>	* joining. Method tryHelpStealer uses these markers to try to
370	>	* find a worker to help (i.e., steal back a task from and execute
371	>	* it) that could hasten completion of the actively joined task.
372	>	* In essence, the joiner executes a task that would be on its own
373	>	* local deque had the to-be-joined task not been stolen. This may
374	>	* be seen as a conservative variant of the approach in Wagner &
375	>	* Calder "Leapfrogging: a portable technique for implementing
376	>	* efficient futures" SIGPLAN Notices, 1993
377	>	* (http://portal.acm.org/citation.cfm?id=155354). It differs in
378	>	* that: (1) We only maintain dependency links across workers upon
379	>	* steals, rather than use per-task bookkeeping.  This sometimes
380	>	* requires a linear scan of workQueues array to locate stealers,
381	>	* but often doesn't because stealers leave hints (that may become
382	>	* stale/wrong) of where to locate them.  A stealHint is only a
383	>	* hint because a worker might have had multiple steals and the
384	>	* hint records only one of them (usually the most current).
385	>	* Hinting isolates cost to when it is needed, rather than adding
386	>	* to per-task overhead.  (2) It is "shallow", ignoring nesting
387	>	* and potentially cyclic mutual steals.  (3) It is intentionally
388	>	* racy: field currentJoin is updated only while actively joining,
389	>	* which means that we miss links in the chain during long-lived
390	>	* tasks, GC stalls etc (which is OK since blocking in such cases
391	>	* is usually a good idea).  (4) We bound the number of attempts
392	>	* to find work (see MAX_HELP) and fall back to suspending the
393	>	* worker and if necessary replacing it with another.
394	>	*
395	>	* It is impossible to keep exactly the target parallelism number
396	>	* of threads running at any given time.  Determining the
397	>	* existence of conservatively safe helping targets, the
398	>	* availability of already-created spares, and the apparent need
399	>	* to create new spares are all racy, so we rely on multiple
400	>	* retries of each.  Compensation in the apparent absence of
401	>	* helping opportunities is challenging to control on JVMs, where
402	>	* GC and other activities can stall progress of tasks that in
403	>	* turn stall out many other dependent tasks, without us being
404	>	* able to determine whether they will ever require compensation.
405	>	* Even though work-stealing otherwise encounters little
406	>	* degradation in the presence of more threads than cores,
407	>	* aggressively adding new threads in such cases entails risk of
408	>	* unwanted positive feedback control loops in which more threads
409	>	* cause more dependent stalls (as well as delayed progress of
410	>	* unblocked threads to the point that we know they are available)
411	>	* leading to more situations requiring more threads, and so
412	>	* on. This aspect of control can be seen as an (analytically
413	>	* intractable) game with an opponent that may choose the worst
414	>	* (for us) active thread to stall at any time.  We take several
415	>	* precautions to bound losses (and thus bound gains), mainly in
416	>	* methods tryCompensate and awaitJoin: (1) We only try
417	>	* compensation after attempting enough helping steps (measured
418	>	* via counting and timing) that we have already consumed the
419	>	* estimated cost of creating and activating a new thread.  (2) We
420	>	* allow up to 50% of threads to be blocked before initially
421	>	* adding any others, and unless completely saturated, check that
422	>	* some work is available for a new worker before adding. Also, we
423	>	* create up to only 50% more threads until entering a mode that
424	>	* only adds a thread if all others are possibly blocked.  All
425	>	* together, this means that we might be half as fast to react,
426	>	* and create half as many threads as possible in the ideal case,
427	>	* but present vastly fewer anomalies in all other cases compared
428	>	* to both more aggressive and more conservative alternatives.
429	>	*
430	>	* Style notes: There is a lot of representation-level coupling
431	>	* among classes ForkJoinPool, ForkJoinWorkerThread, and
432	>	* ForkJoinTask.  The fields of WorkQueue maintain data structures
433	>	* managed by ForkJoinPool, so are directly accessed.  There is
434	>	* little point trying to reduce this, since any associated future
435	>	* changes in representations will need to be accompanied by
436	>	* algorithmic changes anyway. Several methods intrinsically
437	>	* sprawl because they must accumulate sets of consistent reads of
438	>	* volatiles held in local variables.  Methods signalWork() and
439	>	* scan() are the main bottlenecks, so are especially heavily
440	>	* micro-optimized/mangled.  There are lots of inline assignments
441	>	* (of form "while ((local = field) != 0)") which are usually the
442	>	* simplest way to ensure the required read orderings (which are
443	>	* sometimes critical). This leads to a "C"-like style of listing
444	>	* declarations of these locals at the heads of methods or blocks.
445	>	* There are several occurrences of the unusual "do {} while
446	>	* (!cas...)"  which is the simplest way to force an update of a
447	>	* CAS'ed variable. There are also other coding oddities that help
448	>	* some methods perform reasonably even when interpreted (not
449	>	* compiled).
450	>	*
451	>	* The order of declarations in this file is:
452	>	* (1) Static utility functions
453	>	* (2) Nested (static) classes
454	>	* (3) Static fields
455	>	* (4) Fields, along with constants used when unpacking some of them
456	>	* (5) Internal control methods
457	>	* (6) Callbacks and other support for ForkJoinTask methods
458	>	* (7) Exported methods
459	>	* (8) Static block initializing statics in minimally dependent order
460		*/
461
462	<	/** Mask for packing and unpacking shorts */
463	<	private static final int  shortMask = 0xffff;
462	>	// Static utilities
463	>
464	>	/**
465	>	* If there is a security manager, makes sure caller has
466	>	* permission to modify threads.
467	>	*/
468	>	private static void checkPermission() {
469	>	SecurityManager security = System.getSecurityManager();
470	>	if (security != null)
471	>	security.checkPermission(modifyThreadPermission);
472	>	}
473
474	<	/** Max pool size -- must be a power of two minus 1 */
69	<	private static final int MAX_THREADS =  0x7FFF;
474	>	// Nested classes
475
476		/**
477	<	* Factory for creating new ForkJoinWorkerThreads.  A
478	<	* ForkJoinWorkerThreadFactory must be defined and used for
479	<	* ForkJoinWorkerThread subclasses that extend base functionality
480	<	* or initialize threads with different contexts.
477	>	* Factory for creating new {@link ForkJoinWorkerThread}s.
478	>	* A {@code ForkJoinWorkerThreadFactory} must be defined and used
479	>	* for {@code ForkJoinWorkerThread} subclasses that extend base
480	>	* functionality or initialize threads with different contexts.
481		*/
482		public static interface ForkJoinWorkerThreadFactory {
483		/**
484		* Returns a new worker thread operating in the given pool.
485		*
486		* @param pool the pool this thread works in
487	<	* @throws NullPointerException if pool is null;
487	>	* @throws NullPointerException if the pool is null
488		*/
489		public ForkJoinWorkerThread newThread(ForkJoinPool pool);
490		}
491
492		/**
493	<	* Default ForkJoinWorkerThreadFactory implementation, creates a
493	>	* Default ForkJoinWorkerThreadFactory implementation; creates a
494		* new ForkJoinWorkerThread.
495		*/
496	<	static class  DefaultForkJoinWorkerThreadFactory
496	>	static class DefaultForkJoinWorkerThreadFactory
497		implements ForkJoinWorkerThreadFactory {
498		public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
499	<	try {
500	<	return new ForkJoinWorkerThread(pool);
501	<	} catch (OutOfMemoryError oom)  {
499	>	return new ForkJoinWorkerThread(pool);
500	>	}
501	>	}
502	>
503	>	/**
504	>	* Class for artificial tasks that are used to replace the target
505	>	* of local joins if they are removed from an interior queue slot
506	>	* in WorkQueue.tryRemoveAndExec. We don't need the proxy to
507	>	* actually do anything beyond having a unique identity.
508	>	*/
509	>	static final class EmptyTask extends ForkJoinTask<Void> {
510	>	EmptyTask() { status = ForkJoinTask.NORMAL; } // force done
511	>	public final Void getRawResult() { return null; }
512	>	public final void setRawResult(Void x) {}
513	>	public final boolean exec() { return true; }
514	>	}
515	>
516	>	/**
517	>	* Queues supporting work-stealing as well as external task
518	>	* submission. See above for main rationale and algorithms.
519	>	* Implementation relies heavily on "Unsafe" intrinsics
520	>	* and selective use of "volatile":
521	>	*
522	>	* Field "base" is the index (mod array.length) of the least valid
523	>	* queue slot, which is always the next position to steal (poll)
524	>	* from if nonempty. Reads and writes require volatile orderings
525	>	* but not CAS, because updates are only performed after slot
526	>	* CASes.
527	>	*
528	>	* Field "top" is the index (mod array.length) of the next queue
529	>	* slot to push to or pop from. It is written only by owner thread
530	>	* for push, or under lock for trySharedPush, and accessed by
531	>	* other threads only after reading (volatile) base.  Both top and
532	>	* base are allowed to wrap around on overflow, but (top - base)
533	>	* (or more commonly -(base - top) to force volatile read of base
534	>	* before top) still estimates size.
535	>	*
536	>	* The array slots are read and written using the emulation of
537	>	* volatiles/atomics provided by Unsafe. Insertions must in
538	>	* general use putOrderedObject as a form of releasing store to
539	>	* ensure that all writes to the task object are ordered before
540	>	* its publication in the queue. (Although we can avoid one case
541	>	* of this when locked in trySharedPush.) All removals entail a
542	>	* CAS to null.  The array is always a power of two. To ensure
543	>	* safety of Unsafe array operations, all accesses perform
544	>	* explicit null checks and implicit bounds checks via
545	>	* power-of-two masking.
546	>	*
547	>	* In addition to basic queuing support, this class contains
548	>	* fields described elsewhere to control execution. It turns out
549	>	* to work better memory-layout-wise to include them in this
550	>	* class rather than a separate class.
551	>	*
552	>	* Performance on most platforms is very sensitive to placement of
553	>	* instances of both WorkQueues and their arrays -- we absolutely
554	>	* do not want multiple WorkQueue instances or multiple queue
555	>	* arrays sharing cache lines. (It would be best for queue objects
556	>	* and their arrays to share, but there is nothing available to
557	>	* help arrange that).  Unfortunately, because they are recorded
558	>	* in a common array, WorkQueue instances are often moved to be
559	>	* adjacent by garbage collectors. To reduce impact, we use field
560	>	* padding that works OK on common platforms; this effectively
561	>	* trades off slightly slower average field access for the sake of
562	>	* avoiding really bad worst-case access. (Until better JVM
563	>	* support is in place, this padding is dependent on transient
564	>	* properties of JVM field layout rules.)  We also take care in
565	>	* allocating, sizing and resizing the array. Non-shared queue
566	>	* arrays are initialized (via method growArray) by workers before
567	>	* use. Others are allocated on first use.
568	>	*/
569	>	static final class WorkQueue {
570	>	/**
571	>	* Capacity of work-stealing queue array upon initialization.
572	>	* Must be a power of two; at least 4, but should be larger to
573	>	* reduce or eliminate cacheline sharing among queues.
574	>	* Currently, it is much larger, as a partial workaround for
575	>	* the fact that JVMs often place arrays in locations that
576	>	* share GC bookkeeping (especially cardmarks) such that
577	>	* per-write accesses encounter serious memory contention.
578	>	*/
579	>	static final int INITIAL_QUEUE_CAPACITY = 1 << 13;
580	>
581	>	/**
582	>	* Maximum size for queue arrays. Must be a power of two less
583	>	* than or equal to 1 << (31 - width of array entry) to ensure
584	>	* lack of wraparound of index calculations, but defined to a
585	>	* value a bit less than this to help users trap runaway
586	>	* programs before saturating systems.
587	>	*/
588	>	static final int MAXIMUM_QUEUE_CAPACITY = 1 << 26; // 64M
589	>
590	>	volatile long totalSteals; // cumulative number of steals
591	>	int seed;                  // for random scanning; initialize nonzero
592	>	volatile int eventCount;   // encoded inactivation count; < 0 if inactive
593	>	int nextWait;              // encoded record of next event waiter
594	>	int rescans;               // remaining scans until block
595	>	int nsteals;               // top-level task executions since last idle
596	>	final int mode;            // lifo, fifo, or shared
597	>	int poolIndex;             // index of this queue in pool (or 0)
598	>	int stealHint;             // index of most recent known stealer
599	>	volatile int runState;     // 1: locked, -1: terminate; else 0
600	>	volatile int base;         // index of next slot for poll
601	>	int top;                   // index of next slot for push
602	>	ForkJoinTask<?>[] array;   // the elements (initially unallocated)
603	>	final ForkJoinPool pool;   // the containing pool (may be null)
604	>	final ForkJoinWorkerThread owner; // owning thread or null if shared
605	>	volatile Thread parker;    // == owner during call to park; else null
606	>	volatile ForkJoinTask<?> currentJoin;  // task being joined in awaitJoin
607	>	ForkJoinTask<?> currentSteal; // current non-local task being executed
608	>	// Heuristic padding to ameliorate unfortunate memory placements
609	>	Object p00, p01, p02, p03, p04, p05, p06, p07;
610	>	Object p08, p09, p0a, p0b, p0c, p0d, p0e;
611	>
612	>	WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode) {
613	>	this.mode = mode;
614	>	this.pool = pool;
615	>	this.owner = owner;
616	>	// Place indices in the center of array (that is not yet allocated)
617	>	base = top = INITIAL_QUEUE_CAPACITY >>> 1;
618	>	}
619	>
620	>	/**
621	>	* Returns the approximate number of tasks in the queue.
622	>	*/
623	>	final int queueSize() {
624	>	int n = base - top;       // non-owner callers must read base first
625	>	return (n >= 0) ? 0 : -n; // ignore transient negative
626	>	}
627	>
628	>	/**
629	>	* Provides a more accurate estimate of whether this queue has
630	>	* any tasks than does queueSize, by checking whether a
631	>	* near-empty queue has at least one unclaimed task.
632	>	*/
633	>	final boolean isEmpty() {
634	>	ForkJoinTask<?>[] a; int m, s;
635	>	int n = base - (s = top);
636	>	return (n >= 0 ||
637	>	(n == -1 &&
638	>	((a = array) == null ||
639	>	(m = a.length - 1) < 0 ||
640	>	U.getObjectVolatile
641	>	(a, ((m & (s - 1)) << ASHIFT) + ABASE) == null)));
642	>	}
643	>
644	>	/**
645	>	* Pushes a task. Call only by owner in unshared queues.
646	>	*
647	>	* @param task the task. Caller must ensure non-null.
648	>	* @throw RejectedExecutionException if array cannot be resized
649	>	*/
650	>	final void push(ForkJoinTask<?> task) {
651	>	ForkJoinTask<?>[] a; ForkJoinPool p;
652	>	int s = top, m, n;
653	>	if ((a = array) != null) {    // ignore if queue removed
654	>	U.putOrderedObject
655	>	(a, (((m = a.length - 1) & s) << ASHIFT) + ABASE, task);
656	>	if ((n = (top = s + 1) - base) <= 2) {
657	>	if ((p = pool) != null)
658	>	p.signalWork();
659	>	}
660	>	else if (n >= m)
661	>	growArray(true);
662	>	}
663	>	}
664	>
665	>	/**
666	>	* Pushes a task if lock is free and array is either big
667	>	* enough or can be resized to be big enough.
668	>	*
669	>	* @param task the task. Caller must ensure non-null.
670	>	* @return true if submitted
671	>	*/
672	>	final boolean trySharedPush(ForkJoinTask<?> task) {
673	>	boolean submitted = false;
674	>	if (runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
675	>	ForkJoinTask<?>[] a = array;
676	>	int s = top;
677	>	try {
678	>	if ((a != null && a.length > s + 1 - base) ||
679	>	(a = growArray(false)) != null) { // must presize
680	>	int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
681	>	U.putObject(a, (long)j, task);    // don't need "ordered"
682	>	top = s + 1;
683	>	submitted = true;
684	>	}
685	>	} finally {
686	>	runState = 0;                         // unlock
687	>	}
688	>	}
689	>	return submitted;
690	>	}
691	>
692	>	/**
693	>	* Takes next task, if one exists, in LIFO order.  Call only
694	>	* by owner in unshared queues.
695	>	*/
696	>	final ForkJoinTask<?> pop() {
697	>	ForkJoinTask<?>[] a; ForkJoinTask<?> t; int m;
698	>	if ((a = array) != null && (m = a.length - 1) >= 0) {
699	>	for (int s; (s = top - 1) - base >= 0;) {
700	>	long j = ((m & s) << ASHIFT) + ABASE;
701	>	if ((t = (ForkJoinTask<?>)U.getObject(a, j)) == null)
702	>	break;
703	>	if (U.compareAndSwapObject(a, j, t, null)) {
704	>	top = s;
705	>	return t;
706	>	}
707	>	}
708	>	}
709	>	return null;
710	>	}
711	>
712	>	final ForkJoinTask<?> sharedPop() {
713	>	ForkJoinTask<?> task = null;
714	>	if (runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
715	>	try {
716	>	ForkJoinTask<?>[] a; int m;
717	>	if ((a = array) != null && (m = a.length - 1) >= 0) {
718	>	for (int s; (s = top - 1) - base >= 0;) {
719	>	long j = ((m & s) << ASHIFT) + ABASE;
720	>	ForkJoinTask<?> t =
721	>	(ForkJoinTask<?>)U.getObject(a, j);
722	>	if (t == null)
723	>	break;
724	>	if (U.compareAndSwapObject(a, j, t, null)) {
725	>	top = s;
726	>	task = t;
727	>	break;
728	>	}
729	>	}
730	>	}
731	>	} finally {
732	>	runState = 0;
733	>	}
734	>	}
735	>	return task;
736	>	}
737	>
738	>	/**
739	>	* Version of pop that takes top element only if it
740	>	* its root is the given CountedCompleter.
741	>	*/
742	>	final ForkJoinTask<?> popCC(CountedCompleter<?> root) {
743	>	ForkJoinTask<?>[] a; int m;
744	>	if (root != null && (a = array) != null && (m = a.length - 1) >= 0) {
745	>	for (int s; (s = top - 1) - base >= 0;) {
746	>	long j = ((m & s) << ASHIFT) + ABASE;
747	>	ForkJoinTask<?> t =
748	>	(ForkJoinTask<?>)U.getObject(a, j);
749	>	if (t == null || !(t instanceof CountedCompleter) ||
750	>	((CountedCompleter<?>)t).getRoot() != root)
751	>	break;
752	>	if (U.compareAndSwapObject(a, j, t, null)) {
753	>	top = s;
754	>	return t;
755	>	}
756	>	if (root.status < 0)
757	>	break;
758	>	}
759	>	}
760	>	return null;
761	>	}
762	>
763	>	/**
764	>	* Shared version of popCC
765	>	*/
766	>	final ForkJoinTask<?> sharedPopCC(CountedCompleter<?> root) {
767	>	ForkJoinTask<?> task = null;
768	>	if (root != null &&
769	>	runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
770	>	try {
771	>	ForkJoinTask<?>[] a; int m;
772	>	if ((a = array) != null && (m = a.length - 1) >= 0) {
773	>	for (int s; (s = top - 1) - base >= 0;) {
774	>	long j = ((m & s) << ASHIFT) + ABASE;
775	>	ForkJoinTask<?> t =
776	>	(ForkJoinTask<?>)U.getObject(a, j);
777	>	if (t == null || !(t instanceof CountedCompleter) ||
778	>	((CountedCompleter<?>)t).getRoot() != root)
779	>	break;
780	>	if (U.compareAndSwapObject(a, j, t, null)) {
781	>	top = s;
782	>	task = t;
783	>	break;
784	>	}
785	>	if (root.status < 0)
786	>	break;
787	>	}
788	>	}
789	>	} finally {
790	>	runState = 0;
791	>	}
792	>	}
793	>	return task;
794	>	}
795	>
796	>	/**
797	>	* Takes a task in FIFO order if b is base of queue and a task
798	>	* can be claimed without contention. Specialized versions
799	>	* appear in ForkJoinPool methods scan and tryHelpStealer.
800	>	*/
801	>	final ForkJoinTask<?> pollAt(int b) {
802	>	ForkJoinTask<?> t; ForkJoinTask<?>[] a;
803	>	if ((a = array) != null) {
804	>	int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
805	>	if ((t = (ForkJoinTask<?>)U.getObjectVolatile(a, j)) != null &&
806	>	base == b &&
807	>	U.compareAndSwapObject(a, j, t, null)) {
808	>	base = b + 1;
809	>	return t;
810	>	}
811	>	}
812	>	return null;
813	>	}
814	>
815	>	/**
816	>	* Takes next task, if one exists, in FIFO order.
817	>	*/
818	>	final ForkJoinTask<?> poll() {
819	>	ForkJoinTask<?>[] a; int b; ForkJoinTask<?> t;
820	>	while ((b = base) - top < 0 && (a = array) != null) {
821	>	int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
822	>	t = (ForkJoinTask<?>)U.getObjectVolatile(a, j);
823	>	if (t != null) {
824	>	if (base == b &&
825	>	U.compareAndSwapObject(a, j, t, null)) {
826	>	base = b + 1;
827	>	return t;
828	>	}
829	>	}
830	>	else if (base == b) {
831	>	if (b + 1 == top)
832	>	break;
833	>	Thread.yield(); // wait for lagging update
834	>	}
835	>	}
836	>	return null;
837	>	}
838	>
839	>	/**
840	>	* Takes next task, if one exists, in order specified by mode.
841	>	*/
842	>	final ForkJoinTask<?> nextLocalTask() {
843	>	return mode == 0 ? pop() : poll();
844	>	}
845	>
846	>	/**
847	>	* Returns next task, if one exists, in order specified by mode.
848	>	*/
849	>	final ForkJoinTask<?> peek() {
850	>	ForkJoinTask<?>[] a = array; int m;
851	>	if (a == null || (m = a.length - 1) < 0)
852		return null;
853	+	int i = mode == 0 ? top - 1 : base;
854	+	int j = ((i & m) << ASHIFT) + ABASE;
855	+	return (ForkJoinTask<?>)U.getObjectVolatile(a, j);
856	+	}
857	+
858	+	/**
859	+	* Pops the given task only if it is at the current top.
860	+	*/
861	+	final boolean tryUnpush(ForkJoinTask<?> t) {
862	+	ForkJoinTask<?>[] a; int s;
863	+	if ((a = array) != null && (s = top) != base &&
864	+	U.compareAndSwapObject
865	+	(a, (((a.length - 1) & --s) << ASHIFT) + ABASE, t, null)) {
866	+	top = s;
867	+	return true;
868	+	}
869	+	return false;
870	+	}
871	+
872	+	/**
873	+	* Version of tryUnpush for shared queues; called by non-FJ
874	+	* submitters after prechecking that task probably exists.
875	+	*/
876	+	final boolean trySharedUnpush(ForkJoinTask<?> t) {
877	+	boolean success = false;
878	+	if (runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
879	+	try {
880	+	ForkJoinTask<?>[] a; int s;
881	+	if ((a = array) != null && (s = top) != base &&
882	+	U.compareAndSwapObject
883	+	(a, (((a.length - 1) & --s) << ASHIFT) + ABASE, t, null)) {
884	+	top = s;
885	+	success = true;
886	+	}
887	+	} finally {
888	+	runState = 0;                         // unlock
889	+	}
890		}
891	+	return success;
892	+	}
893	+
894	+	/**
895	+	* Polls the given task only if it is at the current base.
896	+	*/
897	+	final boolean pollFor(ForkJoinTask<?> task) {
898	+	ForkJoinTask<?>[] a; int b;
899	+	if ((b = base) - top < 0 && (a = array) != null) {
900	+	int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
901	+	if (U.getObjectVolatile(a, j) == task && base == b &&
902	+	U.compareAndSwapObject(a, j, task, null)) {
903	+	base = b + 1;
904	+	return true;
905	+	}
906	+	}
907	+	return false;
908	+	}
909	+
910	+	/**
911	+	* Initializes or doubles the capacity of array. Call either
912	+	* by owner or with lock held -- it is OK for base, but not
913	+	* top, to move while resizings are in progress.
914	+	*
915	+	* @param rejectOnFailure if true, throw exception if capacity
916	+	* exceeded (relayed ultimately to user); else return null.
917	+	*/
918	+	final ForkJoinTask<?>[] growArray(boolean rejectOnFailure) {
919	+	ForkJoinTask<?>[] oldA = array;
920	+	int size = oldA != null ? oldA.length << 1 : INITIAL_QUEUE_CAPACITY;
921	+	if (size <= MAXIMUM_QUEUE_CAPACITY) {
922	+	int oldMask, t, b;
923	+	ForkJoinTask<?>[] a = array = new ForkJoinTask<?>[size];
924	+	if (oldA != null && (oldMask = oldA.length - 1) >= 0 &&
925	+	(t = top) - (b = base) > 0) {
926	+	int mask = size - 1;
927	+	do {
928	+	ForkJoinTask<?> x;
929	+	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
930	+	int j    = ((b &    mask) << ASHIFT) + ABASE;
931	+	x = (ForkJoinTask<?>)U.getObjectVolatile(oldA, oldj);
932	+	if (x != null &&
933	+	U.compareAndSwapObject(oldA, oldj, x, null))
934	+	U.putObjectVolatile(a, j, x);
935	+	} while (++b != t);
936	+	}
937	+	return a;
938	+	}
939	+	else if (!rejectOnFailure)
940	+	return null;
941	+	else
942	+	throw new RejectedExecutionException("Queue capacity exceeded");
943	+	}
944	+
945	+	/**
946	+	* Removes and cancels all known tasks, ignoring any exceptions.
947	+	*/
948	+	final void cancelAll() {
949	+	ForkJoinTask.cancelIgnoringExceptions(currentJoin);
950	+	ForkJoinTask.cancelIgnoringExceptions(currentSteal);
951	+	for (ForkJoinTask<?> t; (t = poll()) != null; )
952	+	ForkJoinTask.cancelIgnoringExceptions(t);
953	+	}
954	+
955	+	/**
956	+	* Computes next value for random probes.  Scans don't require
957	+	* a very high quality generator, but also not a crummy one.
958	+	* Marsaglia xor-shift is cheap and works well enough.  Note:
959	+	* This is manually inlined in its usages in ForkJoinPool to
960	+	* avoid writes inside busy scan loops.
961	+	*/
962	+	final int nextSeed() {
963	+	int r = seed;
964	+	r ^= r << 13;
965	+	r ^= r >>> 17;
966	+	return seed = r ^= r << 5;
967	+	}
968	+
969	+	// Execution methods
970	+
971	+	/**
972	+	* Pops and runs tasks until empty.
973	+	*/
974	+	private void popAndExecAll() {
975	+	// A bit faster than repeated pop calls
976	+	ForkJoinTask<?>[] a; int m, s; long j; ForkJoinTask<?> t;
977	+	while ((a = array) != null && (m = a.length - 1) >= 0 &&
978	+	(s = top - 1) - base >= 0 &&
979	+	(t = ((ForkJoinTask<?>)
980	+	U.getObject(a, j = ((m & s) << ASHIFT) + ABASE)))
981	+	!= null) {
982	+	if (U.compareAndSwapObject(a, j, t, null)) {
983	+	top = s;
984	+	t.doExec();
985	+	}
986	+	}
987	+	}
988	+
989	+	/**
990	+	* Polls and runs tasks until empty.
991	+	*/
992	+	private void pollAndExecAll() {
993	+	for (ForkJoinTask<?> t; (t = poll()) != null;)
994	+	t.doExec();
995	+	}
996	+
997	+	/**
998	+	* If present, removes from queue and executes the given task, or
999	+	* any other cancelled task. Returns (true) immediately on any CAS
1000	+	* or consistency check failure so caller can retry.
1001	+	*
1002	+	* @return 0 if no progress can be made, else positive
1003	+	* (this unusual convention simplifies use with tryHelpStealer.)
1004	+	*/
1005	+	final int tryRemoveAndExec(ForkJoinTask<?> task) {
1006	+	int stat = 1;
1007	+	boolean removed = false, empty = true;
1008	+	ForkJoinTask<?>[] a; int m, s, b, n;
1009	+	if ((a = array) != null && (m = a.length - 1) >= 0 &&
1010	+	(n = (s = top) - (b = base)) > 0) {
1011	+	for (ForkJoinTask<?> t;;) {           // traverse from s to b
1012	+	int j = ((--s & m) << ASHIFT) + ABASE;
1013	+	t = (ForkJoinTask<?>)U.getObjectVolatile(a, j);
1014	+	if (t == null)                    // inconsistent length
1015	+	break;
1016	+	else if (t == task) {
1017	+	if (s + 1 == top) {           // pop
1018	+	if (!U.compareAndSwapObject(a, j, task, null))
1019	+	break;
1020	+	top = s;
1021	+	removed = true;
1022	+	}
1023	+	else if (base == b)           // replace with proxy
1024	+	removed = U.compareAndSwapObject(a, j, task,
1025	+	new EmptyTask());
1026	+	break;
1027	+	}
1028	+	else if (t.status >= 0)
1029	+	empty = false;
1030	+	else if (s + 1 == top) {          // pop and throw away
1031	+	if (U.compareAndSwapObject(a, j, t, null))
1032	+	top = s;
1033	+	break;
1034	+	}
1035	+	if (--n == 0) {
1036	+	if (!empty && base == b)
1037	+	stat = 0;
1038	+	break;
1039	+	}
1040	+	}
1041	+	}
1042	+	if (removed)
1043	+	task.doExec();
1044	+	return stat;
1045	+	}
1046	+
1047	+	/**
1048	+	* Executes a top-level task and any local tasks remaining
1049	+	* after execution.
1050	+	*/
1051	+	final void runTask(ForkJoinTask<?> t) {
1052	+	if (t != null) {
1053	+	currentSteal = t;
1054	+	t.doExec();
1055	+	if (top != base) {       // process remaining local tasks
1056	+	if (mode == 0)
1057	+	popAndExecAll();
1058	+	else
1059	+	pollAndExecAll();
1060	+	}
1061	+	++nsteals;
1062	+	currentSteal = null;
1063	+	}
1064	+	}
1065	+
1066	+	/**
1067	+	* Executes a non-top-level (stolen) task.
1068	+	*/
1069	+	final void runSubtask(ForkJoinTask<?> t) {
1070	+	if (t != null) {
1071	+	ForkJoinTask<?> ps = currentSteal;
1072	+	currentSteal = t;
1073	+	t.doExec();
1074	+	currentSteal = ps;
1075	+	}
1076	+	}
1077	+
1078	+	/**
1079	+	* Returns true if owned and not known to be blocked.
1080	+	*/
1081	+	final boolean isApparentlyUnblocked() {
1082	+	Thread wt; Thread.State s;
1083	+	return (eventCount >= 0 &&
1084	+	(wt = owner) != null &&
1085	+	(s = wt.getState()) != Thread.State.BLOCKED &&
1086	+	s != Thread.State.WAITING &&
1087	+	s != Thread.State.TIMED_WAITING);
1088	+	}
1089	+
1090	+	/**
1091	+	* If this owned and is not already interrupted, try to
1092	+	* interrupt and/or unpark, ignoring exceptions.
1093	+	*/
1094	+	final void interruptOwner() {
1095	+	Thread wt, p;
1096	+	if ((wt = owner) != null && !wt.isInterrupted()) {
1097	+	try {
1098	+	wt.interrupt();
1099	+	} catch (SecurityException ignore) {
1100	+	}
1101	+	}
1102	+	if ((p = parker) != null)
1103	+	U.unpark(p);
1104	+	}
1105	+
1106	+	// Unsafe mechanics
1107	+	private static final sun.misc.Unsafe U;
1108	+	private static final long RUNSTATE;
1109	+	private static final int ABASE;
1110	+	private static final int ASHIFT;
1111	+	static {
1112	+	int s;
1113	+	try {
1114	+	U = getUnsafe();
1115	+	Class<?> k = WorkQueue.class;
1116	+	Class<?> ak = ForkJoinTask[].class;
1117	+	RUNSTATE = U.objectFieldOffset
1118	+	(k.getDeclaredField("runState"));
1119	+	ABASE = U.arrayBaseOffset(ak);
1120	+	s = U.arrayIndexScale(ak);
1121	+	} catch (Exception e) {
1122	+	throw new Error(e);
1123	+	}
1124	+	if ((s & (s-1)) != 0)
1125	+	throw new Error("data type scale not a power of two");
1126	+	ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
1127	+	}
1128	+	}
1129	+
1130	+	/**
1131	+	* Per-thread records for threads that submit to pools. Currently
1132	+	* holds only pseudo-random seed / index that is used to choose
1133	+	* submission queues in method doSubmit. In the future, this may
1134	+	* also incorporate a means to implement different task rejection
1135	+	* and resubmission policies.
1136	+	*
1137	+	* Seeds for submitters and workers/workQueues work in basically
1138	+	* the same way but are initialized and updated using slightly
1139	+	* different mechanics. Both are initialized using the same
1140	+	* approach as in class ThreadLocal, where successive values are
1141	+	* unlikely to collide with previous values. This is done during
1142	+	* registration for workers, but requires a separate AtomicInteger
1143	+	* for submitters. Seeds are then randomly modified upon
1144	+	* collisions using xorshifts, which requires a non-zero seed.
1145	+	*/
1146	+	static final class Submitter {
1147	+	int seed;
1148	+	Submitter() {
1149	+	int s = nextSubmitterSeed.getAndAdd(SEED_INCREMENT);
1150	+	seed = (s == 0) ? 1 : s; // ensure non-zero
1151		}
1152		}
1153
1154	+	/** ThreadLocal class for Submitters */
1155	+	static final class ThreadSubmitter extends ThreadLocal<Submitter> {
1156	+	public Submitter initialValue() { return new Submitter(); }
1157	+	}
1158	+
1159	+	// static fields (initialized in static initializer below)
1160	+
1161		/**
1162		* Creates a new ForkJoinWorkerThread. This factory is used unless
1163		* overridden in ForkJoinPool constructors.
1164		*/
1165		public static final ForkJoinWorkerThreadFactory
1166	<	defaultForkJoinWorkerThreadFactory =
1167	<	new DefaultForkJoinWorkerThreadFactory();
1166	>	defaultForkJoinWorkerThreadFactory;
1167	>
1168	>
1169	>	/** Property prefix for constructing common pool */
1170	>	private static final String propPrefix =
1171	>	"java.util.concurrent.ForkJoinPool.common.";
1172
1173		/**
1174	<	* Permission required for callers of methods that may start or
1175	<	* kill threads.
1174	>	* Common (static) pool. Non-null for public use unless a static
1175	>	* construction exception, but internal usages must null-check on
1176	>	* use.
1177		*/
1178	<	private static final RuntimePermission modifyThreadPermission =
115	<	new RuntimePermission("modifyThread");
1178	>	static final ForkJoinPool commonPool;
1179
1180		/**
1181	<	* If there is a security manager, makes sure caller has
119	<	* permission to modify threads.
1181	>	* Common pool parallelism. Must equal commonPool.parallelism.
1182		*/
1183	<	private static void checkPermission() {
122	<	SecurityManager security = System.getSecurityManager();
123	<	if (security != null)
124	<	security.checkPermission(modifyThreadPermission);
125	<	}
1183	>	static final int commonPoolParallelism;
1184
1185		/**
1186		* Generator for assigning sequence numbers as pool names.
1187		*/
1188	<	private static final AtomicInteger poolNumberGenerator =
131	<	new AtomicInteger();
1188	>	private static final AtomicInteger poolNumberGenerator;
1189
1190		/**
1191	<	* Array holding all worker threads in the pool. Array size must
1192	<	* be a power of two.  Updates and replacements are protected by
136	<	* workerLock, but it is always kept in a consistent enough state
137	<	* to be randomly accessed without locking by workers performing
138	<	* work-stealing.
1191	>	* Generator for initial hashes/seeds for submitters. Accessed by
1192	>	* Submitter class constructor.
1193		*/
1194	<	volatile ForkJoinWorkerThread[] workers;
1194	>	static final AtomicInteger nextSubmitterSeed;
1195
1196		/**
1197	<	* Lock protecting access to workers.
1197	>	* Permission required for callers of methods that may start or
1198	>	* kill threads.
1199		*/
1200	<	private final ReentrantLock workerLock;
1200	>	private static final RuntimePermission modifyThreadPermission;
1201
1202		/**
1203	<	* Condition for awaitTermination.
1203	>	* Per-thread submission bookkeeping. Shared across all pools
1204	>	* to reduce ThreadLocal pollution and because random motion
1205	>	* to avoid contention in one pool is likely to hold for others.
1206		*/
1207	<	private final Condition termination;
1207	>	private static final ThreadSubmitter submitters;
1208	>
1209	>	// static constants
1210
1211		/**
1212	<	* The uncaught exception handler used when any worker
1213	<	* abrupty terminates
1212	>	* Initial timeout value (in nanoseconds) for the thread triggering
1213	>	* quiescence to park waiting for new work. On timeout, the thread
1214	>	* will instead try to shrink the number of workers.
1215		*/
1216	<	private Thread.UncaughtExceptionHandler ueh;
1216	>	private static final long IDLE_TIMEOUT      = 1000L * 1000L * 1000L; // 1sec
1217
1218		/**
1219	<	* Creation factory for worker threads.
1219	>	* Timeout value when there are more threads than parallelism level
1220		*/
1221	<	private final ForkJoinWorkerThreadFactory factory;
1221	>	private static final long FAST_IDLE_TIMEOUT =  100L * 1000L * 1000L;
1222
1223		/**
1224	<	* Head of stack of threads that were created to maintain
1225	<	* parallelism when other threads blocked, but have since
1226	<	* suspended when the parallelism level rose.
1224	>	* The maximum stolen->joining link depth allowed in method
1225	>	* tryHelpStealer.  Must be a power of two. This value also
1226	>	* controls the maximum number of times to try to help join a task
1227	>	* without any apparent progress or change in pool state before
1228	>	* giving up and blocking (see awaitJoin).  Depths for legitimate
1229	>	* chains are unbounded, but we use a fixed constant to avoid
1230	>	* (otherwise unchecked) cycles and to bound staleness of
1231	>	* traversal parameters at the expense of sometimes blocking when
1232	>	* we could be helping.
1233		*/
1234	<	private volatile WaitQueueNode spareStack;
1234	>	private static final int MAX_HELP = 64;
1235
1236		/**
1237	<	* Sum of per-thread steal counts, updated only when threads are
1238	<	* idle or terminating.
1237	>	* Secondary time-based bound (in nanosecs) for helping attempts
1238	>	* before trying compensated blocking in awaitJoin. Used in
1239	>	* conjunction with MAX_HELP to reduce variance due to different
1240	>	* polling rates associated with different helping options. The
1241	>	* value should roughly approximate the time required to create
1242	>	* and/or activate a worker thread.
1243		*/
1244	<	private final AtomicLong stealCount;
1244	>	private static final long COMPENSATION_DELAY = 1L << 18; // ~0.25 millisec
1245
1246		/**
1247	<	* Queue for external submissions.
1247	>	* Increment for seed generators. See class ThreadLocal for
1248	>	* explanation.
1249		*/
1250	<	private final LinkedTransferQueue<ForkJoinTask<?>> submissionQueue;
1250	>	private static final int SEED_INCREMENT = 0x61c88647;
1251
1252		/**
1253	<	* Head of Treiber stack for barrier sync. See below for explanation
1254	<	*/
1255	<	private volatile WaitQueueNode syncStack;
1253	>	* Bits and masks for control variables
1254	>	*
1255	>	* Field ctl is a long packed with:
1256	>	* AC: Number of active running workers minus target parallelism (16 bits)
1257	>	* TC: Number of total workers minus target parallelism (16 bits)
1258	>	* ST: true if pool is terminating (1 bit)
1259	>	* EC: the wait count of top waiting thread (15 bits)
1260	>	* ID: poolIndex of top of Treiber stack of waiters (16 bits)
1261	>	*
1262	>	* When convenient, we can extract the upper 32 bits of counts and
1263	>	* the lower 32 bits of queue state, u = (int)(ctl >>> 32) and e =
1264	>	* (int)ctl.  The ec field is never accessed alone, but always
1265	>	* together with id and st. The offsets of counts by the target
1266	>	* parallelism and the positionings of fields makes it possible to
1267	>	* perform the most common checks via sign tests of fields: When
1268	>	* ac is negative, there are not enough active workers, when tc is
1269	>	* negative, there are not enough total workers, and when e is
1270	>	* negative, the pool is terminating.  To deal with these possibly
1271	>	* negative fields, we use casts in and out of "short" and/or
1272	>	* signed shifts to maintain signedness.
1273	>	*
1274	>	* When a thread is queued (inactivated), its eventCount field is
1275	>	* set negative, which is the only way to tell if a worker is
1276	>	* prevented from executing tasks, even though it must continue to
1277	>	* scan for them to avoid queuing races. Note however that
1278	>	* eventCount updates lag releases so usage requires care.
1279	>	*
1280	>	* Field runState is an int packed with:
1281	>	* SHUTDOWN: true if shutdown is enabled (1 bit)
1282	>	* SEQ:  a sequence number updated upon (de)registering workers (30 bits)
1283	>	* INIT: set true after workQueues array construction (1 bit)
1284	>	*
1285	>	* The sequence number enables simple consistency checks:
1286	>	* Staleness of read-only operations on the workQueues array can
1287	>	* be checked by comparing runState before vs after the reads.
1288	>	*/
1289	>
1290	>	// bit positions/shifts for fields
1291	>	private static final int  AC_SHIFT   = 48;
1292	>	private static final int  TC_SHIFT   = 32;
1293	>	private static final int  ST_SHIFT   = 31;
1294	>	private static final int  EC_SHIFT   = 16;
1295	>
1296	>	// bounds
1297	>	private static final int  SMASK      = 0xffff;  // short bits
1298	>	private static final int  MAX_CAP    = 0x7fff;  // max #workers - 1
1299	>	private static final int  SQMASK     = 0xfffe;  // even short bits
1300	>	private static final int  SHORT_SIGN = 1 << 15;
1301	>	private static final int  INT_SIGN   = 1 << 31;
1302	>
1303	>	// masks
1304	>	private static final long STOP_BIT   = 0x0001L << ST_SHIFT;
1305	>	private static final long AC_MASK    = ((long)SMASK) << AC_SHIFT;
1306	>	private static final long TC_MASK    = ((long)SMASK) << TC_SHIFT;
1307	>
1308	>	// units for incrementing and decrementing
1309	>	private static final long TC_UNIT    = 1L << TC_SHIFT;
1310	>	private static final long AC_UNIT    = 1L << AC_SHIFT;
1311	>
1312	>	// masks and units for dealing with u = (int)(ctl >>> 32)
1313	>	private static final int  UAC_SHIFT  = AC_SHIFT - 32;
1314	>	private static final int  UTC_SHIFT  = TC_SHIFT - 32;
1315	>	private static final int  UAC_MASK   = SMASK << UAC_SHIFT;
1316	>	private static final int  UTC_MASK   = SMASK << UTC_SHIFT;
1317	>	private static final int  UAC_UNIT   = 1 << UAC_SHIFT;
1318	>	private static final int  UTC_UNIT   = 1 << UTC_SHIFT;
1319	>
1320	>	// masks and units for dealing with e = (int)ctl
1321	>	private static final int E_MASK      = 0x7fffffff; // no STOP_BIT
1322	>	private static final int E_SEQ       = 1 << EC_SHIFT;
1323	>
1324	>	// runState bits
1325	>	private static final int SHUTDOWN    = 1 << 31;
1326	>
1327	>	// access mode for WorkQueue
1328	>	static final int LIFO_QUEUE          =  0;
1329	>	static final int FIFO_QUEUE          =  1;
1330	>	static final int SHARED_QUEUE        = -1;
1331	>
1332	>	// Instance fields
1333	>
1334	>	/*
1335	>	* Field layout order in this class tends to matter more than one
1336	>	* would like. Runtime layout order is only loosely related to
1337	>	* declaration order and may differ across JVMs, but the following
1338	>	* empirically works OK on current JVMs.
1339	>	*/
1340	>
1341	>	volatile long stealCount;                  // collects worker counts
1342	>	volatile long ctl;                         // main pool control
1343	>	final int parallelism;                     // parallelism level
1344	>	final int localMode;                       // per-worker scheduling mode
1345	>	volatile int nextWorkerNumber;             // to create worker name string
1346	>	final int submitMask;                      // submit queue index bound
1347	>	int nextSeed;                              // for initializing worker seeds
1348	>	volatile int mainLock;                     // spinlock for array updates
1349	>	volatile int runState;                     // shutdown status and seq
1350	>	WorkQueue[] workQueues;                    // main registry
1351	>	final ForkJoinWorkerThreadFactory factory; // factory for new workers
1352	>	final Thread.UncaughtExceptionHandler ueh; // per-worker UEH
1353	>	final String workerNamePrefix;             // to create worker name string
1354	>
1355	>	/*
1356	>	* Mechanics for main lock protecting worker array updates.  Uses
1357	>	* the same strategy as ConcurrentHashMap bins -- a spinLock for
1358	>	* normal cases, but falling back to builtin lock when (rarely)
1359	>	* needed.  See internal ConcurrentHashMap documentation for
1360	>	* explanation.
1361	>	*/
1362	>
1363	>	static final int LOCK_WAITING = 2; // bit to indicate need for signal
1364	>	static final int MAX_LOCK_SPINS = 1 << 8;
1365	>
1366	>	private void tryAwaitMainLock() {
1367	>	int spins = MAX_LOCK_SPINS, r = 0, h;
1368	>	while (((h = mainLock) & 1) != 0) {
1369	>	if (r == 0)
1370	>	r = ThreadLocalRandom.current().nextInt(); // randomize spins
1371	>	else if (spins >= 0) {
1372	>	r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
1373	>	if (r >= 0)
1374	>	--spins;
1375	>	}
1376	>	else if (U.compareAndSwapInt(this, MAINLOCK, h, h | LOCK_WAITING)) {
1377	>	synchronized (this) {
1378	>	if ((mainLock & LOCK_WAITING) != 0) {
1379	>	try {
1380	>	wait();
1381	>	} catch (InterruptedException ie) {
1382	>	Thread.currentThread().interrupt();
1383	>	}
1384	>	}
1385	>	else
1386	>	notifyAll(); // possibly won race vs signaller
1387	>	}
1388	>	break;
1389	>	}
1390	>	}
1391	>	}
1392	>
1393	>	//  Creating, registering, and deregistering workers
1394
1395		/**
1396	<	* The count for event barrier
1396	>	* Tries to create and start a worker
1397		*/
1398	<	private volatile long eventCount;
1398	>	private void addWorker() {
1399	>	Throwable ex = null;
1400	>	ForkJoinWorkerThread wt = null;
1401	>	try {
1402	>	if ((wt = factory.newThread(this)) != null) {
1403	>	wt.start();
1404	>	return;
1405	>	}
1406	>	} catch (Throwable e) {
1407	>	ex = e;
1408	>	}
1409	>	deregisterWorker(wt, ex); // adjust counts etc on failure
1410	>	}
1411
1412		/**
1413	<	* Pool number, just for assigning useful names to worker threads
1413	>	* Callback from ForkJoinWorkerThread constructor to assign a
1414	>	* public name. This must be separate from registerWorker because
1415	>	* it is called during the "super" constructor call in
1416	>	* ForkJoinWorkerThread.
1417		*/
1418	<	private final int poolNumber;
1418	>	final String nextWorkerName() {
1419	>	int n;
1420	>	do {} while(!U.compareAndSwapInt(this, NEXTWORKERNUMBER,
1421	>	n = nextWorkerNumber, ++n));
1422	>	return workerNamePrefix.concat(Integer.toString(n));
1423	>	}
1424
1425		/**
1426	<	* The maximum allowed pool size
1426	>	* Callback from ForkJoinWorkerThread constructor to establish its
1427	>	* poolIndex and record its WorkQueue. To avoid scanning bias due
1428	>	* to packing entries in front of the workQueues array, we treat
1429	>	* the array as a simple power-of-two hash table using per-thread
1430	>	* seed as hash, expanding as needed.
1431	>	*
1432	>	* @param w the worker's queue
1433		*/
1434	<	private volatile int maxPoolSize;
1434	>	final void registerWorker(WorkQueue w) {
1435	>	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1436	>	tryAwaitMainLock();
1437	>	try {
1438	>	WorkQueue[] ws;
1439	>	if ((ws = workQueues) == null)
1440	>	ws = workQueues = new WorkQueue[submitMask + 1];
1441	>	if (w != null) {
1442	>	int rs, n =  ws.length, m = n - 1;
1443	>	int s = nextSeed += SEED_INCREMENT; // rarely-colliding sequence
1444	>	w.seed = (s == 0) ? 1 : s;          // ensure non-zero seed
1445	>	int r = (s << 1) | 1;               // use odd-numbered indices
1446	>	if (ws[r &= m] != null) {           // collision
1447	>	int probes = 0;                 // step by approx half size
1448	>	int step = (n <= 4) ? 2 : ((n >>> 1) & SQMASK) + 2;
1449	>	while (ws[r = (r + step) & m] != null) {
1450	>	if (++probes >= n) {
1451	>	workQueues = ws = Arrays.copyOf(ws, n <<= 1);
1452	>	m = n - 1;
1453	>	probes = 0;
1454	>	}
1455	>	}
1456	>	}
1457	>	w.eventCount = w.poolIndex = r;     // establish before recording
1458	>	ws[r] = w;                          // also update seq
1459	>	runState = ((rs = runState) & SHUTDOWN) | ((rs + 2) & ~SHUTDOWN);
1460	>	}
1461	>	} finally {
1462	>	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1463	>	mainLock = 0;
1464	>	synchronized (this) { notifyAll(); };
1465	>	}
1466	>	}
1467	>
1468	>	}
1469
1470		/**
1471	<	* The desired parallelism level, updated only under workerLock.
1471	>	* Final callback from terminating worker, as well as upon failure
1472	>	* to construct or start a worker in addWorker.  Removes record of
1473	>	* worker from array, and adjusts counts. If pool is shutting
1474	>	* down, tries to complete termination.
1475	>	*
1476	>	* @param wt the worker thread or null if addWorker failed
1477	>	* @param ex the exception causing failure, or null if none
1478		*/
1479	<	private volatile int parallelism;
1479	>	final void deregisterWorker(ForkJoinWorkerThread wt, Throwable ex) {
1480	>	WorkQueue w = null;
1481	>	if (wt != null && (w = wt.workQueue) != null) {
1482	>	w.runState = -1;                // ensure runState is set
1483	>	long steals = w.totalSteals + w.nsteals, sc;
1484	>	do {} while(!U.compareAndSwapLong(this, STEALCOUNT,
1485	>	sc = stealCount, sc + steals));
1486	>	int idx = w.poolIndex;
1487	>	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1488	>	tryAwaitMainLock();
1489	>	try {
1490	>	WorkQueue[] ws = workQueues;
1491	>	if (ws != null && idx >= 0 && idx < ws.length && ws[idx] == w)
1492	>	ws[idx] = null;
1493	>	} finally {
1494	>	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1495	>	mainLock = 0;
1496	>	synchronized (this) { notifyAll(); };
1497	>	}
1498	>	}
1499	>	}
1500	>
1501	>	long c;                             // adjust ctl counts
1502	>	do {} while (!U.compareAndSwapLong
1503	>	(this, CTL, c = ctl, (((c - AC_UNIT) & AC_MASK) |
1504	>	((c - TC_UNIT) & TC_MASK) |
1505	>	(c & ~(AC_MASK|TC_MASK)))));
1506	>
1507	>	if (!tryTerminate(false, false) && w != null) {
1508	>	w.cancelAll();                  // cancel remaining tasks
1509	>	if (w.array != null)            // suppress signal if never ran
1510	>	signalWork();               // wake up or create replacement
1511	>	if (ex == null)                 // help clean refs on way out
1512	>	ForkJoinTask.helpExpungeStaleExceptions();
1513	>	}
1514	>
1515	>	if (ex != null)                     // rethrow
1516	>	U.throwException(ex);
1517	>	}
1518	>
1519	>	// Submissions
1520
1521		/**
1522	<	* Holds number of total (i.e., created and not yet terminated)
1523	<	* and running (i.e., not blocked on joins or other managed sync)
1524	<	* threads, packed into one int to ensure consistent snapshot when
1525	<	* making decisions about creating and suspending spare
1526	<	* threads. Updated only by CAS.  Note: CASes in
1527	<	* updateRunningCount and preJoin running active count is in low
1528	<	* word, so need to be modified if this changes
1522	>	* Unless shutting down, adds the given task to a submission queue
1523	>	* at submitter's current queue index (modulo submission
1524	>	* range). If no queue exists at the index, one is created.  If
1525	>	* the queue is busy, another index is randomly chosen. The
1526	>	* submitMask bounds the effective number of queues to the
1527	>	* (nearest power of two for) parallelism level.
1528	>	*
1529	>	* @param task the task. Caller must ensure non-null.
1530		*/
1531	<	private volatile int workerCounts;
1532	<
1533	<	private static int totalCountOf(int s)           { return s >>> 16;  }
1534	<	private static int runningCountOf(int s)         { return s & shortMask; }
1535	<	private static int workerCountsFor(int t, int r) { return (t << 16) + r; }
1531	>	private void doSubmit(ForkJoinTask<?> task) {
1532	>	Submitter s = submitters.get();
1533	>	for (int r = s.seed, m = submitMask;;) {
1534	>	WorkQueue[] ws; WorkQueue q;
1535	>	int k = r & m & SQMASK;          // use only even indices
1536	>	if (runState < 0)
1537	>	throw new RejectedExecutionException(); // shutting down
1538	>	else if ((ws = workQueues) == null || ws.length <= k) {
1539	>	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1540	>	tryAwaitMainLock();
1541	>	try {
1542	>	if (workQueues == null)
1543	>	workQueues = new WorkQueue[submitMask + 1];
1544	>	} finally {
1545	>	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1546	>	mainLock = 0;
1547	>	synchronized (this) { notifyAll(); };
1548	>	}
1549	>	}
1550	>	}
1551	>	else if ((q = ws[k]) == null) {  // create new queue
1552	>	WorkQueue nq = new WorkQueue(this, null, SHARED_QUEUE);
1553	>	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1554	>	tryAwaitMainLock();
1555	>	try {
1556	>	int rs = runState;       // to update seq
1557	>	if (ws == workQueues && ws[k] == null) {
1558	>	ws[k] = nq;
1559	>	runState = ((rs & SHUTDOWN) | ((rs + 2) & ~SHUTDOWN));
1560	>	}
1561	>	} finally {
1562	>	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1563	>	mainLock = 0;
1564	>	synchronized (this) { notifyAll(); };
1565	>	}
1566	>	}
1567	>	}
1568	>	else if (q.trySharedPush(task)) {
1569	>	signalWork();
1570	>	return;
1571	>	}
1572	>	else if (m > 1) {                // move to a different index
1573	>	r ^= r << 13;                // same xorshift as WorkQueues
1574	>	r ^= r >>> 17;
1575	>	s.seed = r ^= r << 5;
1576	>	}
1577	>	else
1578	>	Thread.yield();              // yield if no alternatives
1579	>	}
1580	>	}
1581
1582		/**
1583	<	* Add delta (which may be negative) to running count.  This must
223	<	* be called before (with negative arg) and after (with positive)
224	<	* any managed synchronization (i.e., mainly, joins)
225	<	* @param delta the number to add
1583	>	* Submits the given (non-null) task to the common pool, if possible.
1584		*/
1585	<	final void updateRunningCount(int delta) {
1586	<	int s;
1587	<	do;while (!casWorkerCounts(s = workerCounts, s + delta));
1585	>	static void submitToCommonPool(ForkJoinTask<?> task) {
1586	>	ForkJoinPool p;
1587	>	if ((p = commonPool) == null)
1588	>	throw new RejectedExecutionException("Common Pool Unavailable");
1589	>	p.doSubmit(task);
1590		}
1591
1592		/**
1593	<	* Add delta (which may be negative) to both total and running
1594	<	* count.  This must be called upon creation and termination of
1595	<	* worker threads.
236	<	* @param delta the number to add
1593	>	* Returns true if caller is (or may be) submitter to the common
1594	>	* pool, and not all workers are active, and there appear to be
1595	>	* tasks in the associated submission queue.
1596		*/
1597	<	private void updateWorkerCount(int delta) {
1598	<	int d = delta + (delta << 16); // add to both lo and hi parts
1599	<	int s;
1600	<	do;while (!casWorkerCounts(s = workerCounts, s + d));
1597	>	static boolean canHelpCommonPool() {
1598	>	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
1599	>	int k = submitters.get().seed & SQMASK;
1600	>	return ((p = commonPool) != null &&
1601	>	(int)(p.ctl >> AC_SHIFT) < 0 &&
1602	>	(ws = p.workQueues) != null &&
1603	>	ws.length > (k &= p.submitMask) &&
1604	>	(q = ws[k]) != null &&
1605	>	q.top - q.base > 0);
1606		}
1607
1608		/**
1609	<	* Lifecycle control. High word contains runState, low word
1610	<	* contains the number of workers that are (probably) executing
1611	<	* tasks. This value is atomically incremented before a worker
1612	<	* gets a task to run, and decremented when worker has no tasks
1613	<	* and cannot find any. These two fields are bundled together to
1614	<	* support correct termination triggering.  Note: activeCount
1615	<	* CAS'es cheat by assuming active count is in low word, so need
252	<	* to be modified if this changes
1609	>	* Returns true if the given task was submitted to common pool
1610	>	* and has not yet commenced execution, and is available for
1611	>	* removal according to execution policies; if so removing the
1612	>	* submission from the pool.
1613	>	*
1614	>	* @param task the task
1615	>	* @return true if successful
1616		*/
1617	<	private volatile int runControl;
1617	>	static boolean tryUnsubmitFromCommonPool(ForkJoinTask<?> task) {
1618	>	// Peek, looking for task and eligibility before
1619	>	// using trySharedUnpush to actually take it under lock
1620	>	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
1621	>	ForkJoinTask<?>[] a; int s;
1622	>	int k = submitters.get().seed & SQMASK;
1623	>	return ((p = commonPool) != null &&
1624	>	(int)(p.ctl >> AC_SHIFT) < 0 &&
1625	>	(ws = p.workQueues) != null &&
1626	>	ws.length > (k &= p.submitMask) &&
1627	>	(q = ws[k]) != null &&
1628	>	(a = q.array) != null &&
1629	>	(s = q.top - 1) - q.base >= 0 &&
1630	>	s >= 0 && s < a.length &&
1631	>	a[s] == task &&
1632	>	q.trySharedUnpush(task));
1633	>	}
1634	>
1635	>	/**
1636	>	* Tries to pop a task from common pool with given root
1637	>	*/
1638	>	static ForkJoinTask<?> popCCFromCommonPool(CountedCompleter<?> root) {
1639	>	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
1640	>	ForkJoinTask<?> t;
1641	>	int k = submitters.get().seed & SQMASK;
1642	>	if (root != null &&
1643	>	(p = commonPool) != null &&
1644	>	(int)(p.ctl >> AC_SHIFT) < 0 &&
1645	>	(ws = p.workQueues) != null &&
1646	>	ws.length > (k &= p.submitMask) &&
1647	>	(q = ws[k]) != null && q.top - q.base > 0 &&
1648	>	root.status < 0 &&
1649	>	(t = q.sharedPopCC(root)) != null)
1650	>	return t;
1651	>	return null;
1652	>	}
1653
256	–	// RunState values. Order among values matters
257	–	private static final int RUNNING     = 0;
258	–	private static final int SHUTDOWN    = 1;
259	–	private static final int TERMINATING = 2;
260	–	private static final int TERMINATED  = 3;
1654
1655	<	private static int runStateOf(int c)             { return c >>> 16; }
263	<	private static int activeCountOf(int c)          { return c & shortMask; }
264	<	private static int runControlFor(int r, int a)   { return (r << 16) + a; }
1655	>	// Maintaining ctl counts
1656
1657		/**
1658	<	* Try incrementing active count; fail on contention. Called by
268	<	* workers before/during executing tasks.
269	<	* @return true on success;
1658	>	* Increments active count; mainly called upon return from blocking.
1659		*/
1660	<	final boolean tryIncrementActiveCount() {
1661	<	int c = runControl;
1662	<	return casRunControl(c, c+1);
1660	>	final void incrementActiveCount() {
1661	>	long c;
1662	>	do {} while (!U.compareAndSwapLong(this, CTL, c = ctl, c + AC_UNIT));
1663		}
1664
1665		/**
1666	<	* Try decrementing active count; fail on contention.
278	<	* Possibly trigger termination on success
279	<	* Called by workers when they can't find tasks.
280	<	* @return true on success
1666	>	* Tries to create one or activate one or more workers if too few are active.
1667		*/
1668	<	final boolean tryDecrementActiveCount() {
1669	<	int c = runControl;
1670	<	int nextc = c - 1;
1671	<	if (!casRunControl(c, nextc))
1672	<	return false;
1673	<	if (canTerminateOnShutdown(nextc))
1674	<	terminateOnShutdown();
1675	<	return true;
1668	>	final void signalWork() {
1669	>	long c; int u;
1670	>	while ((u = (int)((c = ctl) >>> 32)) < 0) {     // too few active
1671	>	WorkQueue[] ws = workQueues; int e, i; WorkQueue w; Thread p;
1672	>	if ((e = (int)c) > 0) {                     // at least one waiting
1673	>	if (ws != null && (i = e & SMASK) < ws.length &&
1674	>	(w = ws[i]) != null && w.eventCount == (e | INT_SIGN)) {
1675	>	long nc = (((long)(w.nextWait & E_MASK)) |
1676	>	((long)(u + UAC_UNIT) << 32));
1677	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1678	>	w.eventCount = (e + E_SEQ) & E_MASK;
1679	>	if ((p = w.parker) != null)
1680	>	U.unpark(p);                // activate and release
1681	>	break;
1682	>	}
1683	>	}
1684	>	else
1685	>	break;
1686	>	}
1687	>	else if (e == 0 && (u & SHORT_SIGN) != 0) { // too few total
1688	>	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
1689	>	((u + UAC_UNIT) & UAC_MASK)) << 32;
1690	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1691	>	addWorker();
1692	>	break;
1693	>	}
1694	>	}
1695	>	else
1696	>	break;
1697	>	}
1698		}
1699
1700	+	// Scanning for tasks
1701	+
1702		/**
1703	<	* Return true if argument represents zero active count and
294	<	* nonzero runstate, which is the triggering condition for
295	<	* terminating on shutdown.
1703	>	* Top-level runloop for workers, called by ForkJoinWorkerThread.run.
1704		*/
1705	<	private static boolean canTerminateOnShutdown(int c) {
1706	<	return ((c & -c) >>> 16) != 0; // i.e. least bit is nonzero runState bit
1705	>	final void runWorker(WorkQueue w) {
1706	>	w.growArray(false);         // initialize queue array in this thread
1707	>	do { w.runTask(scan(w)); } while (w.runState >= 0);
1708		}
1709
1710		/**
1711	<	* Transition run state to at least the given state. Return true
1712	<	* if not already at least given state.
1711	>	* Scans for and, if found, returns one task, else possibly
1712	>	* inactivates the worker. This method operates on single reads of
1713	>	* volatile state and is designed to be re-invoked continuously,
1714	>	* in part because it returns upon detecting inconsistencies,
1715	>	* contention, or state changes that indicate possible success on
1716	>	* re-invocation.
1717	>	*
1718	>	* The scan searches for tasks across a random permutation of
1719	>	* queues (starting at a random index and stepping by a random
1720	>	* relative prime, checking each at least once).  The scan
1721	>	* terminates upon either finding a non-empty queue, or completing
1722	>	* the sweep. If the worker is not inactivated, it takes and
1723	>	* returns a task from this queue.  On failure to find a task, we
1724	>	* take one of the following actions, after which the caller will
1725	>	* retry calling this method unless terminated.
1726	>	*
1727	>	* * If pool is terminating, terminate the worker.
1728	>	*
1729	>	* * If not a complete sweep, try to release a waiting worker.  If
1730	>	* the scan terminated because the worker is inactivated, then the
1731	>	* released worker will often be the calling worker, and it can
1732	>	* succeed obtaining a task on the next call. Or maybe it is
1733	>	* another worker, but with same net effect. Releasing in other
1734	>	* cases as well ensures that we have enough workers running.
1735	>	*
1736	>	* * If not already enqueued, try to inactivate and enqueue the
1737	>	* worker on wait queue. Or, if inactivating has caused the pool
1738	>	* to be quiescent, relay to idleAwaitWork to check for
1739	>	* termination and possibly shrink pool.
1740	>	*
1741	>	* * If already inactive, and the caller has run a task since the
1742	>	* last empty scan, return (to allow rescan) unless others are
1743	>	* also inactivated.  Field WorkQueue.rescans counts down on each
1744	>	* scan to ensure eventual inactivation and blocking.
1745	>	*
1746	>	* * If already enqueued and none of the above apply, park
1747	>	* awaiting signal,
1748	>	*
1749	>	* @param w the worker (via its WorkQueue)
1750	>	* @return a task or null if none found
1751		*/
1752	<	private boolean transitionRunStateTo(int state) {
1753	<	for (;;) {
1754	<	int c = runControl;
1755	<	if (runStateOf(c) >= state)
1756	<	return false;
1757	<	if (casRunControl(c, runControlFor(state, activeCountOf(c))))
1758	<	return true;
1752	>	private final ForkJoinTask<?> scan(WorkQueue w) {
1753	>	WorkQueue[] ws;                       // first update random seed
1754	>	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1755	>	int rs = runState, m;                 // volatile read order matters
1756	>	if ((ws = workQueues) != null && (m = ws.length - 1) > 0) {
1757	>	int ec = w.eventCount;            // ec is negative if inactive
1758	>	int step = (r >>> 16) | 1;        // relative prime
1759	>	for (int j = (m + 1) << 2; ; r += step) {
1760	>	WorkQueue q; ForkJoinTask<?> t; ForkJoinTask<?>[] a; int b;
1761	>	if ((q = ws[r & m]) != null && (b = q.base) - q.top < 0 &&
1762	>	(a = q.array) != null) {  // probably nonempty
1763	>	int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1764	>	t = (ForkJoinTask<?>)U.getObjectVolatile(a, i);
1765	>	if (q.base == b && ec >= 0 && t != null &&
1766	>	U.compareAndSwapObject(a, i, t, null)) {
1767	>	if (q.top - (q.base = b + 1) > 0)
1768	>	signalWork();    // help pushes signal
1769	>	return t;
1770	>	}
1771	>	else if (ec < 0 || j <= m) {
1772	>	rs = 0;               // mark scan as imcomplete
1773	>	break;                // caller can retry after release
1774	>	}
1775	>	}
1776	>	if (--j < 0)
1777	>	break;
1778	>	}
1779	>
1780	>	long c = ctl; int e = (int)c, a = (int)(c >> AC_SHIFT), nr, ns;
1781	>	if (e < 0)                        // decode ctl on empty scan
1782	>	w.runState = -1;              // pool is terminating
1783	>	else if (rs == 0 || rs != runState) { // incomplete scan
1784	>	WorkQueue v; Thread p;        // try to release a waiter
1785	>	if (e > 0 && a < 0 && w.eventCount == ec &&
1786	>	(v = ws[e & m]) != null && v.eventCount == (e | INT_SIGN)) {
1787	>	long nc = ((long)(v.nextWait & E_MASK) |
1788	>	((c + AC_UNIT) & (AC_MASK|TC_MASK)));
1789	>	if (ctl == c && U.compareAndSwapLong(this, CTL, c, nc)) {
1790	>	v.eventCount = (e + E_SEQ) & E_MASK;
1791	>	if ((p = v.parker) != null)
1792	>	U.unpark(p);
1793	>	}
1794	>	}
1795	>	}
1796	>	else if (ec >= 0) {               // try to enqueue/inactivate
1797	>	long nc = (long)ec | ((c - AC_UNIT) & (AC_MASK|TC_MASK));
1798	>	w.nextWait = e;
1799	>	w.eventCount = ec | INT_SIGN; // mark as inactive
1800	>	if (ctl != c || !U.compareAndSwapLong(this, CTL, c, nc))
1801	>	w.eventCount = ec;        // unmark on CAS failure
1802	>	else {
1803	>	if ((ns = w.nsteals) != 0) {
1804	>	w.nsteals = 0;        // set rescans if ran task
1805	>	w.rescans = (a > 0) ? 0 : a + parallelism;
1806	>	w.totalSteals += ns;
1807	>	}
1808	>	if (a == 1 - parallelism) // quiescent
1809	>	idleAwaitWork(w, nc, c);
1810	>	}
1811	>	}
1812	>	else if (w.eventCount < 0) {      // already queued
1813	>	int ac = a + parallelism;
1814	>	if ((nr = w.rescans) > 0)     // continue rescanning
1815	>	w.rescans = (ac < nr) ? ac : nr - 1;
1816	>	else if (((w.seed >>> 16) & ac) == 0) { // randomize park
1817	>	Thread.interrupted();     // clear status
1818	>	Thread wt = Thread.currentThread();
1819	>	U.putObject(wt, PARKBLOCKER, this);
1820	>	w.parker = wt;            // emulate LockSupport.park
1821	>	if (w.eventCount < 0)     // recheck
1822	>	U.park(false, 0L);
1823	>	w.parker = null;
1824	>	U.putObject(wt, PARKBLOCKER, null);
1825	>	}
1826	>	}
1827		}
1828	+	return null;
1829		}
1830
1831		/**
1832	<	* Controls whether to add spares to maintain parallelism
1833	<	*/
1834	<	private volatile boolean maintainsParallelism;
1832	>	* If inactivating worker w has caused the pool to become
1833	>	* quiescent, checks for pool termination, and, so long as this is
1834	>	* not the only worker, waits for event for up to a given
1835	>	* duration.  On timeout, if ctl has not changed, terminates the
1836	>	* worker, which will in turn wake up another worker to possibly
1837	>	* repeat this process.
1838	>	*
1839	>	* @param w the calling worker
1840	>	* @param currentCtl the ctl value triggering possible quiescence
1841	>	* @param prevCtl the ctl value to restore if thread is terminated
1842	>	*/
1843	>	private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) {
1844	>	if (w.eventCount < 0 && !tryTerminate(false, false) &&
1845	>	(int)prevCtl != 0 && !hasQueuedSubmissions() && ctl == currentCtl) {
1846	>	int dc = -(short)(currentCtl >>> TC_SHIFT);
1847	>	long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT;
1848	>	long deadline = System.nanoTime() + parkTime - 100000L; // 1ms slop
1849	>	Thread wt = Thread.currentThread();
1850	>	while (ctl == currentCtl) {
1851	>	Thread.interrupted();  // timed variant of version in scan()
1852	>	U.putObject(wt, PARKBLOCKER, this);
1853	>	w.parker = wt;
1854	>	if (ctl == currentCtl)
1855	>	U.park(false, parkTime);
1856	>	w.parker = null;
1857	>	U.putObject(wt, PARKBLOCKER, null);
1858	>	if (ctl != currentCtl)
1859	>	break;
1860	>	if (deadline - System.nanoTime() <= 0L &&
1861	>	U.compareAndSwapLong(this, CTL, currentCtl, prevCtl)) {
1862	>	w.eventCount = (w.eventCount + E_SEQ) | E_MASK;
1863	>	w.runState = -1;   // shrink
1864	>	break;
1865	>	}
1866	>	}
1867	>	}
1868	>	}
1869
1870	<	// Constructors
1870	>	/**
1871	>	* Tries to locate and execute tasks for a stealer of the given
1872	>	* task, or in turn one of its stealers, Traces currentSteal ->
1873	>	* currentJoin links looking for a thread working on a descendant
1874	>	* of the given task and with a non-empty queue to steal back and
1875	>	* execute tasks from. The first call to this method upon a
1876	>	* waiting join will often entail scanning/search, (which is OK
1877	>	* because the joiner has nothing better to do), but this method
1878	>	* leaves hints in workers to speed up subsequent calls. The
1879	>	* implementation is very branchy to cope with potential
1880	>	* inconsistencies or loops encountering chains that are stale,
1881	>	* unknown, or so long that they are likely cyclic.
1882	>	*
1883	>	* @param joiner the joining worker
1884	>	* @param task the task to join
1885	>	* @return 0 if no progress can be made, negative if task
1886	>	* known complete, else positive
1887	>	*/
1888	>	private int tryHelpStealer(WorkQueue joiner, ForkJoinTask<?> task) {
1889	>	int stat = 0, steps = 0;                    // bound to avoid cycles
1890	>	if (joiner != null && task != null) {       // hoist null checks
1891	>	restart: for (;;) {
1892	>	ForkJoinTask<?> subtask = task;     // current target
1893	>	for (WorkQueue j = joiner, v;;) {   // v is stealer of subtask
1894	>	WorkQueue[] ws; int m, s, h;
1895	>	if ((s = task.status) < 0) {
1896	>	stat = s;
1897	>	break restart;
1898	>	}
1899	>	if ((ws = workQueues) == null || (m = ws.length - 1) <= 0)
1900	>	break restart;              // shutting down
1901	>	if ((v = ws[h = (j.stealHint | 1) & m]) == null ||
1902	>	v.currentSteal != subtask) {
1903	>	for (int origin = h;;) {    // find stealer
1904	>	if (((h = (h + 2) & m) & 15) == 1 &&
1905	>	(subtask.status < 0 || j.currentJoin != subtask))
1906	>	continue restart;   // occasional staleness check
1907	>	if ((v = ws[h]) != null &&
1908	>	v.currentSteal == subtask) {
1909	>	j.stealHint = h;    // save hint
1910	>	break;
1911	>	}
1912	>	if (h == origin)
1913	>	break restart;      // cannot find stealer
1914	>	}
1915	>	}
1916	>	for (;;) { // help stealer or descend to its stealer
1917	>	ForkJoinTask[] a;  int b;
1918	>	if (subtask.status < 0)     // surround probes with
1919	>	continue restart;       //   consistency checks
1920	>	if ((b = v.base) - v.top < 0 && (a = v.array) != null) {
1921	>	int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1922	>	ForkJoinTask<?> t =
1923	>	(ForkJoinTask<?>)U.getObjectVolatile(a, i);
1924	>	if (subtask.status < 0 || j.currentJoin != subtask ||
1925	>	v.currentSteal != subtask)
1926	>	continue restart;   // stale
1927	>	stat = 1;               // apparent progress
1928	>	if (t != null && v.base == b &&
1929	>	U.compareAndSwapObject(a, i, t, null)) {
1930	>	v.base = b + 1;     // help stealer
1931	>	joiner.runSubtask(t);
1932	>	}
1933	>	else if (v.base == b && ++steps == MAX_HELP)
1934	>	break restart;      // v apparently stalled
1935	>	}
1936	>	else {                      // empty -- try to descend
1937	>	ForkJoinTask<?> next = v.currentJoin;
1938	>	if (subtask.status < 0 || j.currentJoin != subtask ||
1939	>	v.currentSteal != subtask)
1940	>	continue restart;   // stale
1941	>	else if (next == null || ++steps == MAX_HELP)
1942	>	break restart;      // dead-end or maybe cyclic
1943	>	else {
1944	>	subtask = next;
1945	>	j = v;
1946	>	break;
1947	>	}
1948	>	}
1949	>	}
1950	>	}
1951	>	}
1952	>	}
1953	>	return stat;
1954	>	}
1955
1956		/**
1957	<	* Creates a ForkJoinPool with a pool size equal to the number of
1958	<	* processors available on the system and using the default
1959	<	* ForkJoinWorkerThreadFactory,
1960	<	* @throws SecurityException if a security manager exists and
327	<	*         the caller is not permitted to modify threads
328	<	*         because it does not hold {@link
329	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1957	>	* If task is at base of some steal queue, steals and executes it.
1958	>	*
1959	>	* @param joiner the joining worker
1960	>	* @param task the task
1961		*/
1962	<	public ForkJoinPool() {
1963	<	this(Runtime.getRuntime().availableProcessors(),
1964	<	defaultForkJoinWorkerThreadFactory);
1962	>	private void tryPollForAndExec(WorkQueue joiner, ForkJoinTask<?> task) {
1963	>	WorkQueue[] ws;
1964	>	if ((ws = workQueues) != null) {
1965	>	for (int j = 1; j < ws.length && task.status >= 0; j += 2) {
1966	>	WorkQueue q = ws[j];
1967	>	if (q != null && q.pollFor(task)) {
1968	>	joiner.runSubtask(task);
1969	>	break;
1970	>	}
1971	>	}
1972	>	}
1973		}
1974
1975		/**
1976	<	* Creates a ForkJoinPool with the indicated parellelism level
1977	<	* threads, and using the default ForkJoinWorkerThreadFactory,
1978	<	* @param parallelism the number of worker threads
1979	<	* @throws IllegalArgumentException if parallelism less than or
1980	<	* equal to zero
1981	<	* @throws SecurityException if a security manager exists and
1982	<	*         the caller is not permitted to modify threads
1983	<	*         because it does not hold {@link
1984	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1985	<	*/
1986	<	public ForkJoinPool(int parallelism) {
1987	<	this(parallelism, defaultForkJoinWorkerThreadFactory);
1976	>	* Tries to decrement active count (sometimes implicitly) and
1977	>	* possibly release or create a compensating worker in preparation
1978	>	* for blocking. Fails on contention or termination. Otherwise,
1979	>	* adds a new thread if no idle workers are available and either
1980	>	* pool would become completely starved or: (at least half
1981	>	* starved, and fewer than 50% spares exist, and there is at least
1982	>	* one task apparently available). Even though the availability
1983	>	* check requires a full scan, it is worthwhile in reducing false
1984	>	* alarms.
1985	>	*
1986	>	* @param task if non-null, a task being waited for
1987	>	* @param blocker if non-null, a blocker being waited for
1988	>	* @return true if the caller can block, else should recheck and retry
1989	>	*/
1990	>	final boolean tryCompensate(ForkJoinTask<?> task, ManagedBlocker blocker) {
1991	>	int pc = parallelism, e;
1992	>	long c = ctl;
1993	>	WorkQueue[] ws = workQueues;
1994	>	if ((e = (int)c) >= 0 && ws != null) {
1995	>	int u, a, ac, hc;
1996	>	int tc = (short)((u = (int)(c >>> 32)) >>> UTC_SHIFT) + pc;
1997	>	boolean replace = false;
1998	>	if ((a = u >> UAC_SHIFT) <= 0) {
1999	>	if ((ac = a + pc) <= 1)
2000	>	replace = true;
2001	>	else if ((e > 0 || (task != null &&
2002	>	ac <= (hc = pc >>> 1) && tc < pc + hc))) {
2003	>	WorkQueue w;
2004	>	for (int j = 0; j < ws.length; ++j) {
2005	>	if ((w = ws[j]) != null && !w.isEmpty()) {
2006	>	replace = true;
2007	>	break;   // in compensation range and tasks available
2008	>	}
2009	>	}
2010	>	}
2011	>	}
2012	>	if ((task == null || task.status >= 0) && // recheck need to block
2013	>	(blocker == null || !blocker.isReleasable()) && ctl == c) {
2014	>	if (!replace) {          // no compensation
2015	>	long nc = ((c - AC_UNIT) & AC_MASK) | (c & ~AC_MASK);
2016	>	if (U.compareAndSwapLong(this, CTL, c, nc))
2017	>	return true;
2018	>	}
2019	>	else if (e != 0) {       // release an idle worker
2020	>	WorkQueue w; Thread p; int i;
2021	>	if ((i = e & SMASK) < ws.length && (w = ws[i]) != null) {
2022	>	long nc = ((long)(w.nextWait & E_MASK) |
2023	>	(c & (AC_MASK|TC_MASK)));
2024	>	if (w.eventCount == (e | INT_SIGN) &&
2025	>	U.compareAndSwapLong(this, CTL, c, nc)) {
2026	>	w.eventCount = (e + E_SEQ) & E_MASK;
2027	>	if ((p = w.parker) != null)
2028	>	U.unpark(p);
2029	>	return true;
2030	>	}
2031	>	}
2032	>	}
2033	>	else if (tc < MAX_CAP) { // create replacement
2034	>	long nc = ((c + TC_UNIT) & TC_MASK) | (c & ~TC_MASK);
2035	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
2036	>	addWorker();
2037	>	return true;
2038	>	}
2039	>	}
2040	>	}
2041	>	}
2042	>	return false;
2043		}
2044
2045		/**
2046	<	* Creates a ForkJoinPool with parallelism equal to the number of
2047	<	* processors available on the system and using the given
2048	<	* ForkJoinWorkerThreadFactory,
2049	<	* @param factory the factory for creating new threads
2050	<	* @throws NullPointerException if factory is null
357	<	* @throws SecurityException if a security manager exists and
358	<	*         the caller is not permitted to modify threads
359	<	*         because it does not hold {@link
360	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
2046	>	* Helps and/or blocks until the given task is done.
2047	>	*
2048	>	* @param joiner the joining worker
2049	>	* @param task the task
2050	>	* @return task status on exit
2051		*/
2052	<	public ForkJoinPool(ForkJoinWorkerThreadFactory factory) {
2053	<	this(Runtime.getRuntime().availableProcessors(), factory);
2052	>	final int awaitJoin(WorkQueue joiner, ForkJoinTask<?> task) {
2053	>	int s;
2054	>	if ((s = task.status) >= 0) {
2055	>	ForkJoinTask<?> prevJoin = joiner.currentJoin;
2056	>	joiner.currentJoin = task;
2057	>	long startTime = 0L;
2058	>	for (int k = 0;;) {
2059	>	if ((s = (joiner.isEmpty() ?           // try to help
2060	>	tryHelpStealer(joiner, task) :
2061	>	joiner.tryRemoveAndExec(task))) == 0 &&
2062	>	(s = task.status) >= 0) {
2063	>	if (k == 0) {
2064	>	startTime = System.nanoTime();
2065	>	tryPollForAndExec(joiner, task); // check uncommon case
2066	>	}
2067	>	else if ((k & (MAX_HELP - 1)) == 0 &&
2068	>	System.nanoTime() - startTime >=
2069	>	COMPENSATION_DELAY &&
2070	>	tryCompensate(task, null)) {
2071	>	if (task.trySetSignal()) {
2072	>	synchronized (task) {
2073	>	if (task.status >= 0) {
2074	>	try {                // see ForkJoinTask
2075	>	task.wait();     //  for explanation
2076	>	} catch (InterruptedException ie) {
2077	>	}
2078	>	}
2079	>	else
2080	>	task.notifyAll();
2081	>	}
2082	>	}
2083	>	long c;                          // re-activate
2084	>	do {} while (!U.compareAndSwapLong
2085	>	(this, CTL, c = ctl, c + AC_UNIT));
2086	>	}
2087	>	}
2088	>	if (s < 0 || (s = task.status) < 0) {
2089	>	joiner.currentJoin = prevJoin;
2090	>	break;
2091	>	}
2092	>	else if ((k++ & (MAX_HELP - 1)) == MAX_HELP >>> 1)
2093	>	Thread.yield();                     // for politeness
2094	>	}
2095	>	}
2096	>	return s;
2097		}
2098
2099		/**
2100	<	* Creates a ForkJoinPool with the given parallelism and factory.
2100	>	* Stripped-down variant of awaitJoin used by timed joins. Tries
2101	>	* to help join only while there is continuous progress. (Caller
2102	>	* will then enter a timed wait.)
2103		*
2104	<	* @param parallelism the targeted number of worker threads
2105	<	* @param factory the factory for creating new threads
2106	<	* @throws IllegalArgumentException if parallelism less than or
372	<	* equal to zero, or greater than implementation limit.
373	<	* @throws NullPointerException if factory is null
374	<	* @throws SecurityException if a security manager exists and
375	<	*         the caller is not permitted to modify threads
376	<	*         because it does not hold {@link
377	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
2104	>	* @param joiner the joining worker
2105	>	* @param task the task
2106	>	* @return task status on exit
2107		*/
2108	<	public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) {
2109	<	if (parallelism <= 0 || parallelism > MAX_THREADS)
2110	<	throw new IllegalArgumentException();
2111	<	if (factory == null)
2112	<	throw new NullPointerException();
2113	<	checkPermission();
2114	<	this.factory = factory;
2115	<	this.parallelism = parallelism;
387	<	this.maxPoolSize = MAX_THREADS;
388	<	this.maintainsParallelism = true;
389	<	this.poolNumber = poolNumberGenerator.incrementAndGet();
390	<	this.workerLock = new ReentrantLock();
391	<	this.termination = workerLock.newCondition();
392	<	this.stealCount = new AtomicLong();
393	<	this.submissionQueue = new LinkedTransferQueue<ForkJoinTask<?>>();
394	<	createAndStartInitialWorkers(parallelism);
2108	>	final int helpJoinOnce(WorkQueue joiner, ForkJoinTask<?> task) {
2109	>	int s;
2110	>	while ((s = task.status) >= 0 &&
2111	>	(joiner.isEmpty() ?
2112	>	tryHelpStealer(joiner, task) :
2113	>	joiner.tryRemoveAndExec(task)) != 0)
2114	>	;
2115	>	return s;
2116		}
2117
2118		/**
2119	<	* Create new worker using factory.
2120	<	* @param index the index to assign worker
2121	<	* @return new worker, or null of factory failed
2122	<	*/
2123	<	private ForkJoinWorkerThread createWorker(int index) {
2124	<	Thread.UncaughtExceptionHandler h = ueh;
2125	<	ForkJoinWorkerThread w = factory.newThread(this);
2126	<	if (w != null) {
2127	<	w.poolIndex = index;
2128	<	w.setDaemon(true);
2129	<	w.setName("ForkJoinPool-" + poolNumber + "-worker-" + index);
2130	<	if (h != null)
2131	<	w.setUncaughtExceptionHandler(h);
2119	>	* Returns a (probably) non-empty steal queue, if one is found
2120	>	* during a random, then cyclic scan, else null.  This method must
2121	>	* be retried by caller if, by the time it tries to use the queue,
2122	>	* it is empty.
2123	>	*/
2124	>	private WorkQueue findNonEmptyStealQueue(WorkQueue w) {
2125	>	// Similar to loop in scan(), but ignoring submissions
2126	>	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
2127	>	int step = (r >>> 16) | 1;
2128	>	for (WorkQueue[] ws;;) {
2129	>	int rs = runState, m;
2130	>	if ((ws = workQueues) == null || (m = ws.length - 1) < 1)
2131	>	return null;
2132	>	for (int j = (m + 1) << 2; ; r += step) {
2133	>	WorkQueue q = ws[((r << 1) | 1) & m];
2134	>	if (q != null && !q.isEmpty())
2135	>	return q;
2136	>	else if (--j < 0) {
2137	>	if (runState == rs)
2138	>	return null;
2139	>	break;
2140	>	}
2141	>	}
2142		}
412	–	return w;
2143		}
2144
2145		/**
2146	<	* Return a good size for worker array given pool size.
2147	<	* Currently requires size to be a power of two.
2148	<	*/
2149	<	private static int arraySizeFor(int ps) {
2150	<	return ps <= 1? 1 : (1 << (32 - Integer.numberOfLeadingZeros(ps-1)));
2146	>	* Runs tasks until {@code isQuiescent()}. We piggyback on
2147	>	* active count ctl maintenance, but rather than blocking
2148	>	* when tasks cannot be found, we rescan until all others cannot
2149	>	* find tasks either.
2150	>	*/
2151	>	final void helpQuiescePool(WorkQueue w) {
2152	>	for (boolean active = true;;) {
2153	>	ForkJoinTask<?> localTask; // exhaust local queue
2154	>	while ((localTask = w.nextLocalTask()) != null)
2155	>	localTask.doExec();
2156	>	WorkQueue q = findNonEmptyStealQueue(w);
2157	>	if (q != null) {
2158	>	ForkJoinTask<?> t; int b;
2159	>	if (!active) {      // re-establish active count
2160	>	long c;
2161	>	active = true;
2162	>	do {} while (!U.compareAndSwapLong
2163	>	(this, CTL, c = ctl, c + AC_UNIT));
2164	>	}
2165	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2166	>	w.runSubtask(t);
2167	>	}
2168	>	else {
2169	>	long c;
2170	>	if (active) {       // decrement active count without queuing
2171	>	active = false;
2172	>	do {} while (!U.compareAndSwapLong
2173	>	(this, CTL, c = ctl, c -= AC_UNIT));
2174	>	}
2175	>	else
2176	>	c = ctl;        // re-increment on exit
2177	>	if ((int)(c >> AC_SHIFT) + parallelism == 0) {
2178	>	do {} while (!U.compareAndSwapLong
2179	>	(this, CTL, c = ctl, c + AC_UNIT));
2180	>	break;
2181	>	}
2182	>	}
2183	>	}
2184		}
2185
2186		/**
2187	<	* Create or resize array if necessary to hold newLength
425	<	* @return the array
2187	>	* Restricted version of helpQuiescePool for non-FJ callers
2188		*/
2189	<	private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
2190	<	ForkJoinWorkerThread[] ws = workers;
2191	<	if (ws == null)
2192	<	return workers = new ForkJoinWorkerThread[arraySizeFor(newLength)];
2193	<	else if (newLength > ws.length)
2194	<	return workers = Arrays.copyOf(ws, arraySizeFor(newLength));
2195	<	else
2196	<	return ws;
2189	>	static void externalHelpQuiescePool() {
2190	>	ForkJoinPool p; WorkQueue[] ws; WorkQueue q, sq;
2191	>	ForkJoinTask<?>[] a; int b;
2192	>	ForkJoinTask<?> t = null;
2193	>	int k = submitters.get().seed & SQMASK;
2194	>	if ((p = commonPool) != null &&
2195	>	(int)(p.ctl >> AC_SHIFT) < 0 &&
2196	>	(ws = p.workQueues) != null &&
2197	>	ws.length > (k &= p.submitMask) &&
2198	>	(q = ws[k]) != null) {
2199	>	while (q.top - q.base > 0) {
2200	>	if ((t = q.sharedPop()) != null)
2201	>	break;
2202	>	}
2203	>	if (t == null && (sq = p.findNonEmptyStealQueue(q)) != null &&
2204	>	(b = sq.base) - sq.top < 0)
2205	>	t = sq.pollAt(b);
2206	>	if (t != null)
2207	>	t.doExec();
2208	>	}
2209		}
2210
2211		/**
2212	<	* Try to shrink workers into smaller array after one or more terminate
2212	>	* Gets and removes a local or stolen task for the given worker.
2213	>	*
2214	>	* @return a task, if available
2215		*/
2216	<	private void tryShrinkWorkerArray() {
2217	<	ForkJoinWorkerThread[] ws = workers;
2218	<	int len = ws.length;
2219	<	int last = len - 1;
2220	<	while (last >= 0 && ws[last] == null)
2221	<	--last;
2222	<	int newLength = arraySizeFor(last+1);
2223	<	if (newLength < len)
2224	<	workers = Arrays.copyOf(ws, newLength);
2216	>	final ForkJoinTask<?> nextTaskFor(WorkQueue w) {
2217	>	for (ForkJoinTask<?> t;;) {
2218	>	WorkQueue q; int b;
2219	>	if ((t = w.nextLocalTask()) != null)
2220	>	return t;
2221	>	if ((q = findNonEmptyStealQueue(w)) == null)
2222	>	return null;
2223	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2224	>	return t;
2225	>	}
2226		}
2227
2228		/**
2229	<	* Initial worker array and worker creation and startup. (This
2230	<	* must be done under lock to avoid interference by some of the
2231	<	* newly started threads while creating others.)
2229	>	* Returns the approximate (non-atomic) number of idle threads per
2230	>	* active thread to offset steal queue size for method
2231	>	* ForkJoinTask.getSurplusQueuedTaskCount().
2232		*/
2233	<	private void createAndStartInitialWorkers(int ps) {
2234	<	final ReentrantLock lock = this.workerLock;
2235	<	lock.lock();
2236	<	try {
2237	<	ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps);
2238	<	for (int i = 0; i < ps; ++i) {
2239	<	ForkJoinWorkerThread w = createWorker(i);
2240	<	if (w != null) {
2241	<	ws[i] = w;
465	<	w.start();
466	<	updateWorkerCount(1);
467	<	}
468	<	}
469	<	} finally {
470	<	lock.unlock();
471	<	}
2233	>	final int idlePerActive() {
2234	>	// Approximate at powers of two for small values, saturate past 4
2235	>	int p = parallelism;
2236	>	int a = p + (int)(ctl >> AC_SHIFT);
2237	>	return (a > (p >>>= 1) ? 0 :
2238	>	a > (p >>>= 1) ? 1 :
2239	>	a > (p >>>= 1) ? 2 :
2240	>	a > (p >>>= 1) ? 4 :
2241	>	8);
2242		}
2243
2244		/**
2245	<	* Worker creation and startup for threads added via setParallelism.
2245	>	* Returns approximate submission queue length for the given caller
2246		*/
2247	<	private void createAndStartAddedWorkers() {
2248	<	resumeAllSpares();  // Allow spares to convert to nonspare
2249	<	int ps = parallelism;
2250	<	ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps);
2251	<	int len = ws.length;
2252	<	// Sweep through slots, to keep lowest indices most populated
2253	<	int k = 0;
2254	<	while (k < len) {
2255	<	if (ws[k] != null) {
2256	<	++k;
2257	<	continue;
2247	>	static int getEstimatedSubmitterQueueLength() {
2248	>	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
2249	>	int k = submitters.get().seed & SQMASK;
2250	>	return ((p = commonPool) != null &&
2251	>	p.runState >= 0 &&
2252	>	(ws = p.workQueues) != null &&
2253	>	ws.length > (k &= p.submitMask) &&
2254	>	(q = ws[k]) != null) ?
2255	>	q.queueSize() : 0;
2256	>	}
2257	>
2258	>	//  Termination
2259	>
2260	>	/**
2261	>	* Possibly initiates and/or completes termination.  The caller
2262	>	* triggering termination runs three passes through workQueues:
2263	>	* (0) Setting termination status, followed by wakeups of queued
2264	>	* workers; (1) cancelling all tasks; (2) interrupting lagging
2265	>	* threads (likely in external tasks, but possibly also blocked in
2266	>	* joins).  Each pass repeats previous steps because of potential
2267	>	* lagging thread creation.
2268	>	*
2269	>	* @param now if true, unconditionally terminate, else only
2270	>	* if no work and no active workers
2271	>	* @param enable if true, enable shutdown when next possible
2272	>	* @return true if now terminating or terminated
2273	>	*/
2274	>	private boolean tryTerminate(boolean now, boolean enable) {
2275	>	for (long c;;) {
2276	>	if (((c = ctl) & STOP_BIT) != 0) {      // already terminating
2277	>	if ((short)(c >>> TC_SHIFT) == -parallelism) {
2278	>	synchronized(this) {
2279	>	notifyAll();                // signal when 0 workers
2280	>	}
2281	>	}
2282	>	return true;
2283		}
2284	<	int s = workerCounts;
2285	<	int tc = totalCountOf(s);
2286	<	int rc = runningCountOf(s);
2287	<	if (rc >= ps || tc >= ps)
2288	<	break;
2289	<	if (casWorkerCounts (s, workerCountsFor(tc+1, rc+1))) {
2290	<	ForkJoinWorkerThread w = createWorker(k);
2291	<	if (w != null) {
2292	<	ws[k++] = w;
2293	<	w.start();
2284	>	if (runState >= 0) {                    // not yet enabled
2285	>	if (!enable)
2286	>	return false;
2287	>	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
2288	>	tryAwaitMainLock();
2289	>	try {
2290	>	runState |= SHUTDOWN;
2291	>	} finally {
2292	>	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
2293	>	mainLock = 0;
2294	>	synchronized (this) { notifyAll(); };
2295	>	}
2296		}
2297	<	else {
2298	<	updateWorkerCount(-1); // back out on failed creation
2299	<	break;
2297	>	}
2298	>	if (!now) {                             // check if idle & no tasks
2299	>	if ((int)(c >> AC_SHIFT) != -parallelism ||
2300	>	hasQueuedSubmissions())
2301	>	return false;
2302	>	// Check for unqueued inactive workers. One pass suffices.
2303	>	WorkQueue[] ws = workQueues; WorkQueue w;
2304	>	if (ws != null) {
2305	>	for (int i = 1; i < ws.length; i += 2) {
2306	>	if ((w = ws[i]) != null && w.eventCount >= 0)
2307	>	return false;
2308	>	}
2309	>	}
2310	>	}
2311	>	if (U.compareAndSwapLong(this, CTL, c, c | STOP_BIT)) {
2312	>	for (int pass = 0; pass < 3; ++pass) {
2313	>	WorkQueue[] ws = workQueues;
2314	>	if (ws != null) {
2315	>	WorkQueue w;
2316	>	int n = ws.length;
2317	>	for (int i = 0; i < n; ++i) {
2318	>	if ((w = ws[i]) != null) {
2319	>	w.runState = -1;
2320	>	if (pass > 0) {
2321	>	w.cancelAll();
2322	>	if (pass > 1)
2323	>	w.interruptOwner();
2324	>	}
2325	>	}
2326	>	}
2327	>	// Wake up workers parked on event queue
2328	>	int i, e; long cc; Thread p;
2329	>	while ((e = (int)(cc = ctl) & E_MASK) != 0 &&
2330	>	(i = e & SMASK) < n &&
2331	>	(w = ws[i]) != null) {
2332	>	long nc = ((long)(w.nextWait & E_MASK) |
2333	>	((cc + AC_UNIT) & AC_MASK) |
2334	>	(cc & (TC_MASK|STOP_BIT)));
2335	>	if (w.eventCount == (e | INT_SIGN) &&
2336	>	U.compareAndSwapLong(this, CTL, cc, nc)) {
2337	>	w.eventCount = (e + E_SEQ) & E_MASK;
2338	>	w.runState = -1;
2339	>	if ((p = w.parker) != null)
2340	>	U.unpark(p);
2341	>	}
2342	>	}
2343	>	}
2344		}
2345		}
2346		}
2347		}
2348
2349	<	// Execution methods
2349	>	// Exported methods
2350	>
2351	>	// Constructors
2352
2353		/**
2354	<	* Common code for execute, invoke and submit
2354	>	* Creates a {@code ForkJoinPool} with parallelism equal to {@link
2355	>	* java.lang.Runtime#availableProcessors}, using the {@linkplain
2356	>	* #defaultForkJoinWorkerThreadFactory default thread factory},
2357	>	* no UncaughtExceptionHandler, and non-async LIFO processing mode.
2358	>	*
2359	>	* @throws SecurityException if a security manager exists and
2360	>	*         the caller is not permitted to modify threads
2361	>	*         because it does not hold {@link
2362	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
2363		*/
2364	<	private <T> void doSubmit(ForkJoinTask<T> task) {
2365	<	if (isShutdown())
2366	<	throw new RejectedExecutionException();
516	<	submissionQueue.offer(task);
517	<	signalIdleWorkers();
2364	>	public ForkJoinPool() {
2365	>	this(Runtime.getRuntime().availableProcessors(),
2366	>	defaultForkJoinWorkerThreadFactory, null, false);
2367		}
2368
2369		/**
2370	<	* Performs the given task; returning its result upon completion
2370	>	* Creates a {@code ForkJoinPool} with the indicated parallelism
2371	>	* level, the {@linkplain
2372	>	* #defaultForkJoinWorkerThreadFactory default thread factory},
2373	>	* no UncaughtExceptionHandler, and non-async LIFO processing mode.
2374	>	*
2375	>	* @param parallelism the parallelism level
2376	>	* @throws IllegalArgumentException if parallelism less than or
2377	>	*         equal to zero, or greater than implementation limit
2378	>	* @throws SecurityException if a security manager exists and
2379	>	*         the caller is not permitted to modify threads
2380	>	*         because it does not hold {@link
2381	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
2382	>	*/
2383	>	public ForkJoinPool(int parallelism) {
2384	>	this(parallelism, defaultForkJoinWorkerThreadFactory, null, false);
2385	>	}
2386	>
2387	>	/**
2388	>	* Creates a {@code ForkJoinPool} with the given parameters.
2389	>	*
2390	>	* @param parallelism the parallelism level. For default value,
2391	>	* use {@link java.lang.Runtime#availableProcessors}.
2392	>	* @param factory the factory for creating new threads. For default value,
2393	>	* use {@link #defaultForkJoinWorkerThreadFactory}.
2394	>	* @param handler the handler for internal worker threads that
2395	>	* terminate due to unrecoverable errors encountered while executing
2396	>	* tasks. For default value, use {@code null}.
2397	>	* @param asyncMode if true,
2398	>	* establishes local first-in-first-out scheduling mode for forked
2399	>	* tasks that are never joined. This mode may be more appropriate
2400	>	* than default locally stack-based mode in applications in which
2401	>	* worker threads only process event-style asynchronous tasks.
2402	>	* For default value, use {@code false}.
2403	>	* @throws IllegalArgumentException if parallelism less than or
2404	>	*         equal to zero, or greater than implementation limit
2405	>	* @throws NullPointerException if the factory is null
2406	>	* @throws SecurityException if a security manager exists and
2407	>	*         the caller is not permitted to modify threads
2408	>	*         because it does not hold {@link
2409	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
2410	>	*/
2411	>	public ForkJoinPool(int parallelism,
2412	>	ForkJoinWorkerThreadFactory factory,
2413	>	Thread.UncaughtExceptionHandler handler,
2414	>	boolean asyncMode) {
2415	>	checkPermission();
2416	>	if (factory == null)
2417	>	throw new NullPointerException();
2418	>	if (parallelism <= 0 || parallelism > MAX_CAP)
2419	>	throw new IllegalArgumentException();
2420	>	this.parallelism = parallelism;
2421	>	this.factory = factory;
2422	>	this.ueh = handler;
2423	>	this.localMode = asyncMode ? FIFO_QUEUE : LIFO_QUEUE;
2424	>	long np = (long)(-parallelism); // offset ctl counts
2425	>	this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
2426	>	// Use nearest power 2 for workQueues size. See Hackers Delight sec 3.2.
2427	>	int n = parallelism - 1;
2428	>	n |= n >>> 1; n |= n >>> 2; n |= n >>> 4; n |= n >>> 8; n |= n >>> 16;
2429	>	this.submitMask = ((n + 1) << 1) - 1;
2430	>	int pn = poolNumberGenerator.incrementAndGet();
2431	>	StringBuilder sb = new StringBuilder("ForkJoinPool-");
2432	>	sb.append(Integer.toString(pn));
2433	>	sb.append("-worker-");
2434	>	this.workerNamePrefix = sb.toString();
2435	>	this.runState = 1;              // set init flag
2436	>	}
2437	>
2438	>	/**
2439	>	* Constructor for common pool, suitable only for static initialization.
2440	>	* Basically the same as above, but uses smallest possible initial footprint.
2441	>	*/
2442	>	ForkJoinPool(int parallelism, int submitMask,
2443	>	ForkJoinWorkerThreadFactory factory,
2444	>	Thread.UncaughtExceptionHandler handler) {
2445	>	this.factory = factory;
2446	>	this.ueh = handler;
2447	>	this.submitMask = submitMask;
2448	>	this.parallelism = parallelism;
2449	>	long np = (long)(-parallelism);
2450	>	this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
2451	>	this.localMode = LIFO_QUEUE;
2452	>	this.workerNamePrefix = "ForkJoinPool.commonPool-worker-";
2453	>	this.runState = 1;
2454	>	}
2455	>
2456	>	/**
2457	>	* Returns the common pool instance.
2458	>	*
2459	>	* @return the common pool instance
2460	>	*/
2461	>	public static ForkJoinPool commonPool() {
2462	>	ForkJoinPool p;
2463	>	if ((p = commonPool) == null)
2464	>	throw new Error("Common Pool Unavailable");
2465	>	return p;
2466	>	}
2467	>
2468	>	// Execution methods
2469	>
2470	>	/**
2471	>	* Performs the given task, returning its result upon completion.
2472	>	* If the computation encounters an unchecked Exception or Error,
2473	>	* it is rethrown as the outcome of this invocation.  Rethrown
2474	>	* exceptions behave in the same way as regular exceptions, but,
2475	>	* when possible, contain stack traces (as displayed for example
2476	>	* using {@code ex.printStackTrace()}) of both the current thread
2477	>	* as well as the thread actually encountering the exception;
2478	>	* minimally only the latter.
2479	>	*
2480		* @param task the task
2481		* @return the task's result
2482	<	* @throws NullPointerException if task is null
2483	<	* @throws RejectedExecutionException if pool is shut down
2482	>	* @throws NullPointerException if the task is null
2483	>	* @throws RejectedExecutionException if the task cannot be
2484	>	*         scheduled for execution
2485		*/
2486		public <T> T invoke(ForkJoinTask<T> task) {
2487	+	if (task == null)
2488	+	throw new NullPointerException();
2489		doSubmit(task);
2490		return task.join();
2491		}
2492
2493		/**
2494		* Arranges for (asynchronous) execution of the given task.
2495	+	*
2496		* @param task the task
2497	<	* @throws NullPointerException if task is null
2498	<	* @throws RejectedExecutionException if pool is shut down
2497	>	* @throws NullPointerException if the task is null
2498	>	* @throws RejectedExecutionException if the task cannot be
2499	>	*         scheduled for execution
2500		*/
2501	<	public <T> void execute(ForkJoinTask<T> task) {
2501	>	public void execute(ForkJoinTask<?> task) {
2502	>	if (task == null)
2503	>	throw new NullPointerException();
2504		doSubmit(task);
2505		}
2506
2507		// AbstractExecutorService methods
2508
2509	+	/**
2510	+	* @throws NullPointerException if the task is null
2511	+	* @throws RejectedExecutionException if the task cannot be
2512	+	*         scheduled for execution
2513	+	*/
2514		public void execute(Runnable task) {
2515	<	doSubmit(new AdaptedRunnable<Void>(task, null));
2515	>	if (task == null)
2516	>	throw new NullPointerException();
2517	>	ForkJoinTask<?> job;
2518	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
2519	>	job = (ForkJoinTask<?>) task;
2520	>	else
2521	>	job = new ForkJoinTask.AdaptedRunnableAction(task);
2522	>	doSubmit(job);
2523	>	}
2524	>
2525	>	/**
2526	>	* Submits a ForkJoinTask for execution.
2527	>	*
2528	>	* @param task the task to submit
2529	>	* @return the task
2530	>	* @throws NullPointerException if the task is null
2531	>	* @throws RejectedExecutionException if the task cannot be
2532	>	*         scheduled for execution
2533	>	*/
2534	>	public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) {
2535	>	if (task == null)
2536	>	throw new NullPointerException();
2537	>	doSubmit(task);
2538	>	return task;
2539		}
2540
2541	+	/**
2542	+	* @throws NullPointerException if the task is null
2543	+	* @throws RejectedExecutionException if the task cannot be
2544	+	*         scheduled for execution
2545	+	*/
2546		public <T> ForkJoinTask<T> submit(Callable<T> task) {
2547	<	ForkJoinTask<T> job = new AdaptedCallable<T>(task);
2547	>	ForkJoinTask<T> job = new ForkJoinTask.AdaptedCallable<T>(task);
2548		doSubmit(job);
2549		return job;
2550		}
2551
2552	+	/**
2553	+	* @throws NullPointerException if the task is null
2554	+	* @throws RejectedExecutionException if the task cannot be
2555	+	*         scheduled for execution
2556	+	*/
2557		public <T> ForkJoinTask<T> submit(Runnable task, T result) {
2558	<	ForkJoinTask<T> job = new AdaptedRunnable<T>(task, result);
2558	>	ForkJoinTask<T> job = new ForkJoinTask.AdaptedRunnable<T>(task, result);
2559		doSubmit(job);
2560		return job;
2561		}
2562
2563	+	/**
2564	+	* @throws NullPointerException if the task is null
2565	+	* @throws RejectedExecutionException if the task cannot be
2566	+	*         scheduled for execution
2567	+	*/
2568		public ForkJoinTask<?> submit(Runnable task) {
2569	<	ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null);
2569	>	if (task == null)
2570	>	throw new NullPointerException();
2571	>	ForkJoinTask<?> job;
2572	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
2573	>	job = (ForkJoinTask<?>) task;
2574	>	else
2575	>	job = new ForkJoinTask.AdaptedRunnableAction(task);
2576		doSubmit(job);
2577		return job;
2578		}
2579
2580		/**
2581	<	* Adaptor for Runnables. This implements RunnableFuture
2582	<	* to be compliant with AbstractExecutorService constraints
2581	>	* @throws NullPointerException       {@inheritDoc}
2582	>	* @throws RejectedExecutionException {@inheritDoc}
2583		*/
570	–	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
571	–	implements RunnableFuture<T> {
572	–	final Runnable runnable;
573	–	final T resultOnCompletion;
574	–	T result;
575	–	AdaptedRunnable(Runnable runnable, T result) {
576	–	if (runnable == null) throw new NullPointerException();
577	–	this.runnable = runnable;
578	–	this.resultOnCompletion = result;
579	–	}
580	–	public T getRawResult() { return result; }
581	–	public void setRawResult(T v) { result = v; }
582	–	public boolean exec() {
583	–	runnable.run();
584	–	result = resultOnCompletion;
585	–	return true;
586	–	}
587	–	public void run() { invoke(); }
588	–	}
589	–
590	–	/**
591	–	* Adaptor for Callables
592	–	*/
593	–	static final class AdaptedCallable<T> extends ForkJoinTask<T>
594	–	implements RunnableFuture<T> {
595	–	final Callable<T> callable;
596	–	T result;
597	–	AdaptedCallable(Callable<T> callable) {
598	–	if (callable == null) throw new NullPointerException();
599	–	this.callable = callable;
600	–	}
601	–	public T getRawResult() { return result; }
602	–	public void setRawResult(T v) { result = v; }
603	–	public boolean exec() {
604	–	try {
605	–	result = callable.call();
606	–	return true;
607	–	} catch (Error err) {
608	–	throw err;
609	–	} catch (RuntimeException rex) {
610	–	throw rex;
611	–	} catch (Exception ex) {
612	–	throw new RuntimeException(ex);
613	–	}
614	–	}
615	–	public void run() { invoke(); }
616	–	}
617	–
2584		public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) {
2585	<	ArrayList<ForkJoinTask<T>> ts =
2586	<	new ArrayList<ForkJoinTask<T>>(tasks.size());
2587	<	for (Callable<T> c : tasks)
2588	<	ts.add(new AdaptedCallable<T>(c));
2589	<	invoke(new InvokeAll<T>(ts));
2590	<	return (List<Future<T>>)(List)ts;
2591	<	}
2585	>	// In previous versions of this class, this method constructed
2586	>	// a task to run ForkJoinTask.invokeAll, but now external
2587	>	// invocation of multiple tasks is at least as efficient.
2588	>	List<ForkJoinTask<T>> fs = new ArrayList<ForkJoinTask<T>>(tasks.size());
2589	>	// Workaround needed because method wasn't declared with
2590	>	// wildcards in return type but should have been.
2591	>	@SuppressWarnings({"unchecked", "rawtypes"})
2592	>	List<Future<T>> futures = (List<Future<T>>) (List) fs;
2593
2594	<	static final class InvokeAll<T> extends RecursiveAction {
2595	<	final ArrayList<ForkJoinTask<T>> tasks;
2596	<	InvokeAll(ArrayList<ForkJoinTask<T>> tasks) { this.tasks = tasks; }
2597	<	public void compute() {
2598	<	try { invokeAll(tasks); } catch(Exception ignore) {}
2594	>	boolean done = false;
2595	>	try {
2596	>	for (Callable<T> t : tasks) {
2597	>	ForkJoinTask<T> f = new ForkJoinTask.AdaptedCallable<T>(t);
2598	>	doSubmit(f);
2599	>	fs.add(f);
2600	>	}
2601	>	for (ForkJoinTask<T> f : fs)
2602	>	f.quietlyJoin();
2603	>	done = true;
2604	>	return futures;
2605	>	} finally {
2606	>	if (!done)
2607	>	for (ForkJoinTask<T> f : fs)
2608	>	f.cancel(false);
2609		}
2610		}
2611
635	–	// Configuration and status settings and queries
636	–
2612		/**
2613	<	* Returns the factory used for constructing new workers
2613	>	* Returns the factory used for constructing new workers.
2614		*
2615		* @return the factory used for constructing new workers
2616		*/
#	Line 646 | Line 2621 | public class ForkJoinPool extends Abstra
2621		/**
2622		* Returns the handler for internal worker threads that terminate
2623		* due to unrecoverable errors encountered while executing tasks.
2624	<	* @return the handler, or null if none
2624	>	*
2625	>	* @return the handler, or {@code null} if none
2626		*/
2627		public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
2628	<	Thread.UncaughtExceptionHandler h;
653	<	final ReentrantLock lock = this.workerLock;
654	<	lock.lock();
655	<	try {
656	<	h = ueh;
657	<	} finally {
658	<	lock.unlock();
659	<	}
660	<	return h;
2628	>	return ueh;
2629		}
2630
2631		/**
2632	<	* Sets the handler for internal worker threads that terminate due
665	<	* to unrecoverable errors encountered while executing tasks.
666	<	* Unless set, the current default or ThreadGroup handler is used
667	<	* as handler.
2632	>	* Returns the targeted parallelism level of this pool.
2633		*
2634	<	* @param h the new handler
670	<	* @return the old handler, or null if none
671	<	* @throws SecurityException if a security manager exists and
672	<	*         the caller is not permitted to modify threads
673	<	*         because it does not hold {@link
674	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
675	<	*/
676	<	public Thread.UncaughtExceptionHandler
677	<	setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
678	<	checkPermission();
679	<	Thread.UncaughtExceptionHandler old = null;
680	<	final ReentrantLock lock = this.workerLock;
681	<	lock.lock();
682	<	try {
683	<	old = ueh;
684	<	ueh = h;
685	<	ForkJoinWorkerThread[] ws = workers;
686	<	for (int i = 0; i < ws.length; ++i) {
687	<	ForkJoinWorkerThread w = ws[i];
688	<	if (w != null)
689	<	w.setUncaughtExceptionHandler(h);
690	<	}
691	<	} finally {
692	<	lock.unlock();
693	<	}
694	<	return old;
695	<	}
696	<
697	<
698	<	/**
699	<	* Sets the target paralleism level of this pool.
700	<	* @param parallelism the target parallelism
701	<	* @throws IllegalArgumentException if parallelism less than or
702	<	* equal to zero or greater than maximum size bounds.
703	<	* @throws SecurityException if a security manager exists and
704	<	*         the caller is not permitted to modify threads
705	<	*         because it does not hold {@link
706	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
2634	>	* @return the targeted parallelism level of this pool
2635		*/
2636	<	public void setParallelism(int parallelism) {
2637	<	checkPermission();
710	<	if (parallelism <= 0 || parallelism > maxPoolSize)
711	<	throw new IllegalArgumentException();
712	<	final ReentrantLock lock = this.workerLock;
713	<	lock.lock();
714	<	try {
715	<	if (!isTerminating()) {
716	<	int p = this.parallelism;
717	<	this.parallelism = parallelism;
718	<	if (parallelism > p)
719	<	createAndStartAddedWorkers();
720	<	else
721	<	trimSpares();
722	<	}
723	<	} finally {
724	<	lock.unlock();
725	<	}
726	<	signalIdleWorkers();
2636	>	public int getParallelism() {
2637	>	return parallelism;
2638		}
2639
2640		/**
2641	<	* Returns the targeted number of worker threads in this pool.
2641	>	* Returns the targeted parallelism level of the common pool.
2642		*
2643	<	* @return the targeted number of worker threads in this pool
2643	>	* @return the targeted parallelism level of the common pool
2644		*/
2645	<	public int getParallelism() {
2646	<	return parallelism;
2645	>	public static int getCommonPoolParallelism() {
2646	>	return commonPoolParallelism;
2647		}
2648
2649		/**
2650		* Returns the number of worker threads that have started but not
2651	<	* yet terminated.  This result returned by this method may differ
2652	<	* from <code>getParallelism</code> when threads are created to
2651	>	* yet terminated.  The result returned by this method may differ
2652	>	* from {@link #getParallelism} when threads are created to
2653		* maintain parallelism when others are cooperatively blocked.
2654		*
2655		* @return the number of worker threads
2656		*/
2657		public int getPoolSize() {
2658	<	return totalCountOf(workerCounts);
2658	>	return parallelism + (short)(ctl >>> TC_SHIFT);
2659		}
2660
2661		/**
2662	<	* Returns the maximum number of threads allowed to exist in the
2663	<	* pool, even if there are insufficient unblocked running threads.
2664	<	* @return the maximum
2665	<	*/
755	<	public int getMaximumPoolSize() {
756	<	return maxPoolSize;
757	<	}
758	<
759	<	/**
760	<	* Sets the maximum number of threads allowed to exist in the
761	<	* pool, even if there are insufficient unblocked running threads.
762	<	* Setting this value has no effect on current pool size. It
763	<	* controls construction of new threads.
764	<	* @throws IllegalArgumentException if negative or greater then
765	<	* internal implementation limit.
766	<	*/
767	<	public void setMaximumPoolSize(int newMax) {
768	<	if (newMax < 0 || newMax > MAX_THREADS)
769	<	throw new IllegalArgumentException();
770	<	maxPoolSize = newMax;
771	<	}
772	<
773	<
774	<	/**
775	<	* Returns true if this pool dynamically maintains its target
776	<	* parallelism level. If false, new threads are added only to
777	<	* avoid possible starvation.
778	<	* This setting is by default true;
779	<	* @return true if maintains parallelism
780	<	*/
781	<	public boolean getMaintainsParallelism() {
782	<	return maintainsParallelism;
783	<	}
784	<
785	<	/**
786	<	* Sets whether this pool dynamically maintains its target
787	<	* parallelism level. If false, new threads are added only to
788	<	* avoid possible starvation.
789	<	* @param enable true to maintains parallelism
2662	>	* Returns {@code true} if this pool uses local first-in-first-out
2663	>	* scheduling mode for forked tasks that are never joined.
2664	>	*
2665	>	* @return {@code true} if this pool uses async mode
2666		*/
2667	<	public void setMaintainsParallelism(boolean enable) {
2668	<	maintainsParallelism = enable;
2667	>	public boolean getAsyncMode() {
2668	>	return localMode != 0;
2669		}
2670
2671		/**
2672		* Returns an estimate of the number of worker threads that are
2673		* not blocked waiting to join tasks or for other managed
2674	<	* synchronization.
2674	>	* synchronization. This method may overestimate the
2675	>	* number of running threads.
2676		*
2677		* @return the number of worker threads
2678		*/
2679		public int getRunningThreadCount() {
2680	<	return runningCountOf(workerCounts);
2680	>	int rc = 0;
2681	>	WorkQueue[] ws; WorkQueue w;
2682	>	if ((ws = workQueues) != null) {
2683	>	for (int i = 1; i < ws.length; i += 2) {
2684	>	if ((w = ws[i]) != null && w.isApparentlyUnblocked())
2685	>	++rc;
2686	>	}
2687	>	}
2688	>	return rc;
2689		}
2690
2691		/**
2692		* Returns an estimate of the number of threads that are currently
2693		* stealing or executing tasks. This method may overestimate the
2694		* number of active threads.
2695	<	* @return the number of active threads.
2695	>	*
2696	>	* @return the number of active threads
2697		*/
2698		public int getActiveThreadCount() {
2699	<	return activeCountOf(runControl);
2699	>	int r = parallelism + (int)(ctl >> AC_SHIFT);
2700	>	return (r <= 0) ? 0 : r; // suppress momentarily negative values
2701		}
2702
2703		/**
2704	<	* Returns an estimate of the number of threads that are currently
2705	<	* idle waiting for tasks. This method may underestimate the
2706	<	* number of idle threads.
2707	<	* @return the number of idle threads.
2708	<	*/
2709	<	final int getIdleThreadCount() {
2710	<	int c = runningCountOf(workerCounts) - activeCountOf(runControl);
2711	<	return (c <= 0)? 0 : c;
2712	<	}
826	<
827	<	/**
828	<	* Returns true if all worker threads are currently idle. An idle
829	<	* worker is one that cannot obtain a task to execute because none
830	<	* are available to steal from other threads, and there are no
831	<	* pending submissions to the pool. This method is conservative:
832	<	* It might not return true immediately upon idleness of all
833	<	* threads, but will eventually become true if threads remain
834	<	* inactive.
835	<	* @return true if all threads are currently idle
2704	>	* Returns {@code true} if all worker threads are currently idle.
2705	>	* An idle worker is one that cannot obtain a task to execute
2706	>	* because none are available to steal from other threads, and
2707	>	* there are no pending submissions to the pool. This method is
2708	>	* conservative; it might not return {@code true} immediately upon
2709	>	* idleness of all threads, but will eventually become true if
2710	>	* threads remain inactive.
2711	>	*
2712	>	* @return {@code true} if all threads are currently idle
2713		*/
2714		public boolean isQuiescent() {
2715	<	return activeCountOf(runControl) == 0;
2715	>	return (int)(ctl >> AC_SHIFT) + parallelism == 0;
2716		}
2717
2718		/**
#	Line 843 | Line 2720 | public class ForkJoinPool extends Abstra
2720		* one thread's work queue by another. The reported value
2721		* underestimates the actual total number of steals when the pool
2722		* is not quiescent. This value may be useful for monitoring and
2723	<	* tuning fork/join programs: In general, steal counts should be
2723	>	* tuning fork/join programs: in general, steal counts should be
2724		* high enough to keep threads busy, but low enough to avoid
2725		* overhead and contention across threads.
2726	<	* @return the number of steals.
2726	>	*
2727	>	* @return the number of steals
2728		*/
2729		public long getStealCount() {
2730	<	return stealCount.get();
2731	<	}
2732	<
2733	<	/**
2734	<	* Accumulate steal count from a worker. Call only
2735	<	* when worker known to be idle.
2736	<	*/
2737	<	private void updateStealCount(ForkJoinWorkerThread w) {
2738	<	int sc = w.getAndClearStealCount();
861	<	if (sc != 0)
862	<	stealCount.addAndGet(sc);
2730	>	long count = stealCount;
2731	>	WorkQueue[] ws; WorkQueue w;
2732	>	if ((ws = workQueues) != null) {
2733	>	for (int i = 1; i < ws.length; i += 2) {
2734	>	if ((w = ws[i]) != null)
2735	>	count += w.totalSteals;
2736	>	}
2737	>	}
2738	>	return count;
2739		}
2740
2741		/**
#	Line 869 | Line 2745 | public class ForkJoinPool extends Abstra
2745		* an approximation, obtained by iterating across all threads in
2746		* the pool. This method may be useful for tuning task
2747		* granularities.
2748	<	* @return the number of queued tasks.
2748	>	*
2749	>	* @return the number of queued tasks
2750		*/
2751		public long getQueuedTaskCount() {
2752		long count = 0;
2753	<	ForkJoinWorkerThread[] ws = workers;
2754	<	for (int i = 0; i < ws.length; ++i) {
2755	<	ForkJoinWorkerThread t = ws[i];
2756	<	if (t != null)
2757	<	count += t.getQueueSize();
2753	>	WorkQueue[] ws; WorkQueue w;
2754	>	if ((ws = workQueues) != null) {
2755	>	for (int i = 1; i < ws.length; i += 2) {
2756	>	if ((w = ws[i]) != null)
2757	>	count += w.queueSize();
2758	>	}
2759		}
2760		return count;
2761		}
2762
2763		/**
2764	<	* Returns an estimate of the number tasks submitted to this pool
2765	<	* that have not yet begun executing. This method takes time
2766	<	* proportional to the number of submissions.
2767	<	* @return the number of queued submissions.
2764	>	* Returns an estimate of the number of tasks submitted to this
2765	>	* pool that have not yet begun executing.  This method may take
2766	>	* time proportional to the number of submissions.
2767	>	*
2768	>	* @return the number of queued submissions
2769		*/
2770		public int getQueuedSubmissionCount() {
2771	<	return submissionQueue.size();
2771	>	int count = 0;
2772	>	WorkQueue[] ws; WorkQueue w;
2773	>	if ((ws = workQueues) != null) {
2774	>	for (int i = 0; i < ws.length; i += 2) {
2775	>	if ((w = ws[i]) != null)
2776	>	count += w.queueSize();
2777	>	}
2778	>	}
2779	>	return count;
2780		}
2781
2782		/**
2783	<	* Returns true if there are any tasks submitted to this pool
2784	<	* that have not yet begun executing.
2785	<	* @return <code>true</code> if there are any queued submissions.
2783	>	* Returns {@code true} if there are any tasks submitted to this
2784	>	* pool that have not yet begun executing.
2785	>	*
2786	>	* @return {@code true} if there are any queued submissions
2787		*/
2788		public boolean hasQueuedSubmissions() {
2789	<	return !submissionQueue.isEmpty();
2789	>	WorkQueue[] ws; WorkQueue w;
2790	>	if ((ws = workQueues) != null) {
2791	>	for (int i = 0; i < ws.length; i += 2) {
2792	>	if ((w = ws[i]) != null && !w.isEmpty())
2793	>	return true;
2794	>	}
2795	>	}
2796	>	return false;
2797		}
2798
2799		/**
2800		* Removes and returns the next unexecuted submission if one is
2801		* available.  This method may be useful in extensions to this
2802		* class that re-assign work in systems with multiple pools.
2803	<	* @return the next submission, or null if none
2803	>	*
2804	>	* @return the next submission, or {@code null} if none
2805		*/
2806		protected ForkJoinTask<?> pollSubmission() {
2807	<	return submissionQueue.poll();
2807	>	WorkQueue[] ws; WorkQueue w; ForkJoinTask<?> t;
2808	>	if ((ws = workQueues) != null) {
2809	>	for (int i = 0; i < ws.length; i += 2) {
2810	>	if ((w = ws[i]) != null && (t = w.poll()) != null)
2811	>	return t;
2812	>	}
2813	>	}
2814	>	return null;
2815	>	}
2816	>
2817	>	/**
2818	>	* Removes all available unexecuted submitted and forked tasks
2819	>	* from scheduling queues and adds them to the given collection,
2820	>	* without altering their execution status. These may include
2821	>	* artificially generated or wrapped tasks. This method is
2822	>	* designed to be invoked only when the pool is known to be
2823	>	* quiescent. Invocations at other times may not remove all
2824	>	* tasks. A failure encountered while attempting to add elements
2825	>	* to collection {@code c} may result in elements being in
2826	>	* neither, either or both collections when the associated
2827	>	* exception is thrown.  The behavior of this operation is
2828	>	* undefined if the specified collection is modified while the
2829	>	* operation is in progress.
2830	>	*
2831	>	* @param c the collection to transfer elements into
2832	>	* @return the number of elements transferred
2833	>	*/
2834	>	protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) {
2835	>	int count = 0;
2836	>	WorkQueue[] ws; WorkQueue w; ForkJoinTask<?> t;
2837	>	if ((ws = workQueues) != null) {
2838	>	for (int i = 0; i < ws.length; ++i) {
2839	>	if ((w = ws[i]) != null) {
2840	>	while ((t = w.poll()) != null) {
2841	>	c.add(t);
2842	>	++count;
2843	>	}
2844	>	}
2845	>	}
2846	>	}
2847	>	return count;
2848		}
2849
2850		/**
#	Line 919 | Line 2855 | public class ForkJoinPool extends Abstra
2855		* @return a string identifying this pool, as well as its state
2856		*/
2857		public String toString() {
2858	<	int ps = parallelism;
2859	<	int wc = workerCounts;
2860	<	int rc = runControl;
2861	<	long st = getStealCount();
2862	<	long qt = getQueuedTaskCount();
2863	<	long qs = getQueuedSubmissionCount();
2858	>	// Use a single pass through workQueues to collect counts
2859	>	long qt = 0L, qs = 0L; int rc = 0;
2860	>	long st = stealCount;
2861	>	long c = ctl;
2862	>	WorkQueue[] ws; WorkQueue w;
2863	>	if ((ws = workQueues) != null) {
2864	>	for (int i = 0; i < ws.length; ++i) {
2865	>	if ((w = ws[i]) != null) {
2866	>	int size = w.queueSize();
2867	>	if ((i & 1) == 0)
2868	>	qs += size;
2869	>	else {
2870	>	qt += size;
2871	>	st += w.totalSteals;
2872	>	if (w.isApparentlyUnblocked())
2873	>	++rc;
2874	>	}
2875	>	}
2876	>	}
2877	>	}
2878	>	int pc = parallelism;
2879	>	int tc = pc + (short)(c >>> TC_SHIFT);
2880	>	int ac = pc + (int)(c >> AC_SHIFT);
2881	>	if (ac < 0) // ignore transient negative
2882	>	ac = 0;
2883	>	String level;
2884	>	if ((c & STOP_BIT) != 0)
2885	>	level = (tc == 0) ? "Terminated" : "Terminating";
2886	>	else
2887	>	level = runState < 0 ? "Shutting down" : "Running";
2888		return super.toString() +
2889	<	"[" + runStateToString(runStateOf(rc)) +
2890	<	", parallelism = " + ps +
2891	<	", size = " + totalCountOf(wc) +
2892	<	", active = " + activeCountOf(rc) +
2893	<	", running = " + runningCountOf(wc) +
2889	>	"[" + level +
2890	>	", parallelism = " + pc +
2891	>	", size = " + tc +
2892	>	", active = " + ac +
2893	>	", running = " + rc +
2894		", steals = " + st +
2895		", tasks = " + qt +
2896		", submissions = " + qs +
2897		"]";
2898		}
2899
940	–	private static String runStateToString(int rs) {
941	–	switch(rs) {
942	–	case RUNNING: return "Running";
943	–	case SHUTDOWN: return "Shutting down";
944	–	case TERMINATING: return "Terminating";
945	–	case TERMINATED: return "Terminated";
946	–	default: throw new Error("Unknown run state");
947	–	}
948	–	}
949	–
950	–	// lifecycle control
951	–
2900		/**
2901	<	* Initiates an orderly shutdown in which previously submitted
2902	<	* tasks are executed, but no new tasks will be accepted.
2903	<	* Invocation has no additional effect if already shut down.
2904	<	* Tasks that are in the process of being submitted concurrently
2905	<	* during the course of this method may or may not be rejected.
2901	>	* Possibly initiates an orderly shutdown in which previously
2902	>	* submitted tasks are executed, but no new tasks will be
2903	>	* accepted. Invocation has no effect on execution state if this
2904	>	* is the {@link #commonPool}, and no additional effect if
2905	>	* already shut down.  Tasks that are in the process of being
2906	>	* submitted concurrently during the course of this method may or
2907	>	* may not be rejected.
2908	>	*
2909		* @throws SecurityException if a security manager exists and
2910		*         the caller is not permitted to modify threads
2911		*         because it does not hold {@link
2912	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
2912	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
2913		*/
2914		public void shutdown() {
2915		checkPermission();
2916	<	transitionRunStateTo(SHUTDOWN);
2917	<	if (canTerminateOnShutdown(runControl))
967	<	terminateOnShutdown();
2916	>	if (this != commonPool)
2917	>	tryTerminate(false, true);
2918		}
2919
2920		/**
2921	<	* Attempts to stop all actively executing tasks, and cancels all
2922	<	* waiting tasks.  Tasks that are in the process of being
2923	<	* submitted or executed concurrently during the course of this
2924	<	* method may or may not be rejected. Unlike some other executors,
2925	<	* this method cancels rather than collects non-executed tasks,
2926	<	* so always returns an empty list.
2921	>	* Possibly attempts to cancel and/or stop all tasks, and reject
2922	>	* all subsequently submitted tasks.  Invocation has no effect on
2923	>	* execution state if this is the {@link #commonPool}, and no
2924	>	* additional effect if already shut down. Otherwise, tasks that
2925	>	* are in the process of being submitted or executed concurrently
2926	>	* during the course of this method may or may not be
2927	>	* rejected. This method cancels both existing and unexecuted
2928	>	* tasks, in order to permit termination in the presence of task
2929	>	* dependencies. So the method always returns an empty list
2930	>	* (unlike the case for some other Executors).
2931	>	*
2932		* @return an empty list
2933		* @throws SecurityException if a security manager exists and
2934		*         the caller is not permitted to modify threads
2935		*         because it does not hold {@link
2936	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
2936	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
2937		*/
2938		public List<Runnable> shutdownNow() {
2939		checkPermission();
2940	<	terminate();
2940	>	if (this != commonPool)
2941	>	tryTerminate(true, true);
2942		return Collections.emptyList();
2943		}
2944
2945		/**
2946	<	* Returns <code>true</code> if all tasks have completed following shut down.
2946	>	* Returns {@code true} if all tasks have completed following shut down.
2947		*
2948	<	* @return <code>true</code> if all tasks have completed following shut down
2948	>	* @return {@code true} if all tasks have completed following shut down
2949		*/
2950		public boolean isTerminated() {
2951	<	return runStateOf(runControl) == TERMINATED;
2951	>	long c = ctl;
2952	>	return ((c & STOP_BIT) != 0L &&
2953	>	(short)(c >>> TC_SHIFT) == -parallelism);
2954		}
2955
2956		/**
2957	<	* Returns <code>true</code> if the process of termination has
2958	<	* commenced but possibly not yet completed.
2957	>	* Returns {@code true} if the process of termination has
2958	>	* commenced but not yet completed.  This method may be useful for
2959	>	* debugging. A return of {@code true} reported a sufficient
2960	>	* period after shutdown may indicate that submitted tasks have
2961	>	* ignored or suppressed interruption, or are waiting for IO,
2962	>	* causing this executor not to properly terminate. (See the
2963	>	* advisory notes for class {@link ForkJoinTask} stating that
2964	>	* tasks should not normally entail blocking operations.  But if
2965	>	* they do, they must abort them on interrupt.)
2966		*
2967	<	* @return <code>true</code> if terminating
2967	>	* @return {@code true} if terminating but not yet terminated
2968		*/
2969		public boolean isTerminating() {
2970	<	return runStateOf(runControl) >= TERMINATING;
2970	>	long c = ctl;
2971	>	return ((c & STOP_BIT) != 0L &&
2972	>	(short)(c >>> TC_SHIFT) != -parallelism);
2973		}
2974
2975		/**
2976	<	* Returns <code>true</code> if this pool has been shut down.
2976	>	* Returns {@code true} if this pool has been shut down.
2977		*
2978	<	* @return <code>true</code> if this pool has been shut down
2978	>	* @return {@code true} if this pool has been shut down
2979		*/
2980		public boolean isShutdown() {
2981	<	return runStateOf(runControl) >= SHUTDOWN;
2981	>	return runState < 0;
2982		}
2983
2984		/**
#	Line 1021 | Line 2988 | public class ForkJoinPool extends Abstra
2988		*
2989		* @param timeout the maximum time to wait
2990		* @param unit the time unit of the timeout argument
2991	<	* @return <code>true</code> if this executor terminated and
2992	<	*         <code>false</code> if the timeout elapsed before termination
2991	>	* @return {@code true} if this executor terminated and
2992	>	*         {@code false} if the timeout elapsed before termination
2993		* @throws InterruptedException if interrupted while waiting
2994		*/
2995		public boolean awaitTermination(long timeout, TimeUnit unit)
2996		throws InterruptedException {
2997		long nanos = unit.toNanos(timeout);
2998	<	final ReentrantLock lock = this.workerLock;
1032	<	lock.lock();
1033	<	try {
1034	<	for (;;) {
1035	<	if (isTerminated())
1036	<	return true;
1037	<	if (nanos <= 0)
1038	<	return false;
1039	<	nanos = termination.awaitNanos(nanos);
1040	<	}
1041	<	} finally {
1042	<	lock.unlock();
1043	<	}
1044	<	}
1045	<
1046	<	// Shutdown and termination support
1047	<
1048	<	/**
1049	<	* Callback from terminating worker. Null out the corresponding
1050	<	* workers slot, and if terminating, try to terminate, else try to
1051	<	* shrink workers array.
1052	<	* @param w the worker
1053	<	*/
1054	<	final void workerTerminated(ForkJoinWorkerThread w) {
1055	<	updateStealCount(w);
1056	<	updateWorkerCount(-1);
1057	<	final ReentrantLock lock = this.workerLock;
1058	<	lock.lock();
1059	<	try {
1060	<	ForkJoinWorkerThread[] ws = workers;
1061	<	int idx = w.poolIndex;
1062	<	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1063	<	ws[idx] = null;
1064	<	if (totalCountOf(workerCounts) == 0) {
1065	<	terminate(); // no-op if already terminating
1066	<	transitionRunStateTo(TERMINATED);
1067	<	termination.signalAll();
1068	<	}
1069	<	else if (!isTerminating()) {
1070	<	tryShrinkWorkerArray();
1071	<	tryResumeSpare(true); // allow replacement
1072	<	}
1073	<	} finally {
1074	<	lock.unlock();
1075	<	}
1076	<	signalIdleWorkers();
1077	<	}
1078	<
1079	<	/**
1080	<	* Initiate termination.
1081	<	*/
1082	<	private void terminate() {
1083	<	if (transitionRunStateTo(TERMINATING)) {
1084	<	stopAllWorkers();
1085	<	resumeAllSpares();
1086	<	signalIdleWorkers();
1087	<	cancelQueuedSubmissions();
1088	<	cancelQueuedWorkerTasks();
1089	<	interruptUnterminatedWorkers();
1090	<	signalIdleWorkers(); // resignal after interrupt
1091	<	}
1092	<	}
1093	<
1094	<	/**
1095	<	* Possibly terminate when on shutdown state
1096	<	*/
1097	<	private void terminateOnShutdown() {
1098	<	if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
1099	<	terminate();
1100	<	}
1101	<
1102	<	/**
1103	<	* Clear out and cancel submissions
1104	<	*/
1105	<	private void cancelQueuedSubmissions() {
1106	<	ForkJoinTask<?> task;
1107	<	while ((task = pollSubmission()) != null)
1108	<	task.cancel(false);
1109	<	}
1110	<
1111	<	/**
1112	<	* Clean out worker queues.
1113	<	*/
1114	<	private void cancelQueuedWorkerTasks() {
1115	<	final ReentrantLock lock = this.workerLock;
1116	<	lock.lock();
1117	<	try {
1118	<	ForkJoinWorkerThread[] ws = workers;
1119	<	for (int i = 0; i < ws.length; ++i) {
1120	<	ForkJoinWorkerThread t = ws[i];
1121	<	if (t != null)
1122	<	t.cancelTasks();
1123	<	}
1124	<	} finally {
1125	<	lock.unlock();
1126	<	}
1127	<	}
1128	<
1129	<	/**
1130	<	* Set each worker's status to terminating. Requires lock to avoid
1131	<	* conflicts with add/remove
1132	<	*/
1133	<	private void stopAllWorkers() {
1134	<	final ReentrantLock lock = this.workerLock;
1135	<	lock.lock();
1136	<	try {
1137	<	ForkJoinWorkerThread[] ws = workers;
1138	<	for (int i = 0; i < ws.length; ++i) {
1139	<	ForkJoinWorkerThread t = ws[i];
1140	<	if (t != null)
1141	<	t.shutdownNow();
1142	<	}
1143	<	} finally {
1144	<	lock.unlock();
1145	<	}
1146	<	}
1147	<
1148	<	/**
1149	<	* Interrupt all unterminated workers.  This is not required for
1150	<	* sake of internal control, but may help unstick user code during
1151	<	* shutdown.
1152	<	*/
1153	<	private void interruptUnterminatedWorkers() {
1154	<	final ReentrantLock lock = this.workerLock;
1155	<	lock.lock();
1156	<	try {
1157	<	ForkJoinWorkerThread[] ws = workers;
1158	<	for (int i = 0; i < ws.length; ++i) {
1159	<	ForkJoinWorkerThread t = ws[i];
1160	<	if (t != null && !t.isTerminated()) {
1161	<	try {
1162	<	t.interrupt();
1163	<	} catch (SecurityException ignore) {
1164	<	}
1165	<	}
1166	<	}
1167	<	} finally {
1168	<	lock.unlock();
1169	<	}
1170	<	}
1171	<
1172	<
1173	<	/*
1174	<	* Nodes for event barrier to manage idle threads.  Queue nodes
1175	<	* are basic Treiber stack nodes, also used for spare stack.
1176	<	*
1177	<	* The event barrier has an event count and a wait queue (actually
1178	<	* a Treiber stack).  Workers are enabled to look for work when
1179	<	* the eventCount is incremented. If they fail to find work, they
1180	<	* may wait for next count. Upon release, threads help others wake
1181	<	* up.
1182	<	*
1183	<	* Synchronization events occur only in enough contexts to
1184	<	* maintain overall liveness:
1185	<	*
1186	<	*   - Submission of a new task to the pool
1187	<	*   - Resizes or other changes to the workers array
1188	<	*   - pool termination
1189	<	*   - A worker pushing a task on an empty queue
1190	<	*
1191	<	* The case of pushing a task occurs often enough, and is heavy
1192	<	* enough compared to simple stack pushes, to require special
1193	<	* handling: Method signalWork returns without advancing count if
1194	<	* the queue appears to be empty.  This would ordinarily result in
1195	<	* races causing some queued waiters not to be woken up. To avoid
1196	<	* this, the first worker enqueued in method sync (see
1197	<	* syncIsReleasable) rescans for tasks after being enqueued, and
1198	<	* helps signal if any are found. This works well because the
1199	<	* worker has nothing better to do, and so might as well help
1200	<	* alleviate the overhead and contention on the threads actually
1201	<	* doing work.  Also, since event counts increments on task
1202	<	* availability exist to maintain liveness (rather than to force
1203	<	* refreshes etc), it is OK for callers to exit early if
1204	<	* contending with another signaller.
1205	<	*/
1206	<	static final class WaitQueueNode {
1207	<	WaitQueueNode next; // only written before enqueued
1208	<	volatile ForkJoinWorkerThread thread; // nulled to cancel wait
1209	<	final long count; // unused for spare stack
1210	<
1211	<	WaitQueueNode(long c, ForkJoinWorkerThread w) {
1212	<	count = c;
1213	<	thread = w;
1214	<	}
1215	<
1216	<	/**
1217	<	* Wake up waiter, returning false if known to already
1218	<	*/
1219	<	boolean signal() {
1220	<	ForkJoinWorkerThread t = thread;
1221	<	if (t == null)
1222	<	return false;
1223	<	thread = null;
1224	<	LockSupport.unpark(t);
2998	>	if (isTerminated())
2999		return true;
3000	<	}
3001	<
3002	<	/**
3003	<	* Await release on sync
3004	<	*/
3005	<	void awaitSyncRelease(ForkJoinPool p) {
3006	<	while (thread != null && !p.syncIsReleasable(this))
1233	<	LockSupport.park(this);
1234	<	}
1235	<
1236	<	/**
1237	<	* Await resumption as spare
1238	<	*/
1239	<	void awaitSpareRelease() {
1240	<	while (thread != null) {
1241	<	if (!Thread.interrupted())
1242	<	LockSupport.park(this);
1243	<	}
1244	<	}
1245	<	}
1246	<
1247	<	/**
1248	<	* Ensures that no thread is waiting for count to advance from the
1249	<	* current value of eventCount read on entry to this method, by
1250	<	* releasing waiting threads if necessary.
1251	<	* @return the count
1252	<	*/
1253	<	final long ensureSync() {
1254	<	long c = eventCount;
1255	<	WaitQueueNode q;
1256	<	while ((q = syncStack) != null && q.count < c) {
1257	<	if (casBarrierStack(q, null)) {
1258	<	do {
1259	<	q.signal();
1260	<	} while ((q = q.next) != null);
1261	<	break;
1262	<	}
1263	<	}
1264	<	return c;
1265	<	}
1266	<
1267	<	/**
1268	<	* Increments event count and releases waiting threads.
1269	<	*/
1270	<	private void signalIdleWorkers() {
1271	<	long c;
1272	<	do;while (!casEventCount(c = eventCount, c+1));
1273	<	ensureSync();
1274	<	}
1275	<
1276	<	/**
1277	<	* Signal threads waiting to poll a task. Because method sync
1278	<	* rechecks availability, it is OK to only proceed if queue
1279	<	* appears to be non-empty, and OK to skip under contention to
1280	<	* increment count (since some other thread succeeded).
1281	<	*/
1282	<	final void signalWork() {
1283	<	long c;
1284	<	WaitQueueNode q;
1285	<	if (syncStack != null &&
1286	<	casEventCount(c = eventCount, c+1) &&
1287	<	(((q = syncStack) != null && q.count <= c) &&
1288	<	(!casBarrierStack(q, q.next) || !q.signal())))
1289	<	ensureSync();
1290	<	}
1291	<
1292	<	/**
1293	<	* Waits until event count advances from last value held by
1294	<	* caller, or if excess threads, caller is resumed as spare, or
1295	<	* caller or pool is terminating. Updates caller's event on exit.
1296	<	* @param w the calling worker thread
1297	<	*/
1298	<	final void sync(ForkJoinWorkerThread w) {
1299	<	updateStealCount(w); // Transfer w's count while it is idle
1300	<
1301	<	while (!w.isShutdown() && !isTerminating() && !suspendIfSpare(w)) {
1302	<	long prev = w.lastEventCount;
1303	<	WaitQueueNode node = null;
1304	<	WaitQueueNode h;
1305	<	while (eventCount == prev &&
1306	<	((h = syncStack) == null || h.count == prev)) {
1307	<	if (node == null)
1308	<	node = new WaitQueueNode(prev, w);
1309	<	if (casBarrierStack(node.next = h, node)) {
1310	<	node.awaitSyncRelease(this);
1311	<	break;
1312	<	}
1313	<	}
1314	<	long ec = ensureSync();
1315	<	if (ec != prev) {
1316	<	w.lastEventCount = ec;
1317	<	break;
1318	<	}
1319	<	}
1320	<	}
1321	<
1322	<	/**
1323	<	* Returns true if worker waiting on sync can proceed:
1324	<	*  - on signal (thread == null)
1325	<	*  - on event count advance (winning race to notify vs signaller)
1326	<	*  - on Interrupt
1327	<	*  - if the first queued node, we find work available
1328	<	* If node was not signalled and event count not advanced on exit,
1329	<	* then we also help advance event count.
1330	<	* @return true if node can be released
1331	<	*/
1332	<	final boolean syncIsReleasable(WaitQueueNode node) {
1333	<	long prev = node.count;
1334	<	if (!Thread.interrupted() && node.thread != null &&
1335	<	(node.next != null ||
1336	<	!ForkJoinWorkerThread.hasQueuedTasks(workers)) &&
1337	<	eventCount == prev)
1338	<	return false;
1339	<	if (node.thread != null) {
1340	<	node.thread = null;
1341	<	long ec = eventCount;
1342	<	if (prev <= ec) // help signal
1343	<	casEventCount(ec, ec+1);
1344	<	}
1345	<	return true;
1346	<	}
1347	<
1348	<	/**
1349	<	* Returns true if a new sync event occurred since last call to
1350	<	* sync or this method, if so, updating caller's count.
1351	<	*/
1352	<	final boolean hasNewSyncEvent(ForkJoinWorkerThread w) {
1353	<	long lc = w.lastEventCount;
1354	<	long ec = ensureSync();
1355	<	if (ec == lc)
1356	<	return false;
1357	<	w.lastEventCount = ec;
1358	<	return true;
1359	<	}
1360	<
1361	<	//  Parallelism maintenance
1362	<
1363	<	/**
1364	<	* Decrement running count; if too low, add spare.
1365	<	*
1366	<	* Conceptually, all we need to do here is add or resume a
1367	<	* spare thread when one is about to block (and remove or
1368	<	* suspend it later when unblocked -- see suspendIfSpare).
1369	<	* However, implementing this idea requires coping with
1370	<	* several problems: We have imperfect information about the
1371	<	* states of threads. Some count updates can and usually do
1372	<	* lag run state changes, despite arrangements to keep them
1373	<	* accurate (for example, when possible, updating counts
1374	<	* before signalling or resuming), especially when running on
1375	<	* dynamic JVMs that don't optimize the infrequent paths that
1376	<	* update counts. Generating too many threads can make these
1377	<	* problems become worse, because excess threads are more
1378	<	* likely to be context-switched with others, slowing them all
1379	<	* down, especially if there is no work available, so all are
1380	<	* busy scanning or idling.  Also, excess spare threads can
1381	<	* only be suspended or removed when they are idle, not
1382	<	* immediately when they aren't needed. So adding threads will
1383	<	* raise parallelism level for longer than necessary.  Also,
1384	<	* FJ applications often enounter highly transient peaks when
1385	<	* many threads are blocked joining, but for less time than it
1386	<	* takes to create or resume spares.
1387	<	*
1388	<	* @param joinMe if non-null, return early if done
1389	<	* @param maintainParallelism if true, try to stay within
1390	<	* target counts, else create only to avoid starvation
1391	<	* @return true if joinMe known to be done
1392	<	*/
1393	<	final boolean preJoin(ForkJoinTask<?> joinMe, boolean maintainParallelism) {
1394	<	maintainParallelism &= maintainsParallelism; // overrride
1395	<	boolean dec = false;  // true when running count decremented
1396	<	while (spareStack == null || !tryResumeSpare(dec)) {
1397	<	int counts = workerCounts;
1398	<	if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat
1399	<	if (!needSpare(counts, maintainParallelism))
1400	<	break;
1401	<	if (joinMe.status < 0)
1402	<	return true;
1403	<	if (tryAddSpare(counts))
1404	<	break;
1405	<	}
1406	<	}
1407	<	return false;
1408	<	}
1409	<
1410	<	/**
1411	<	* Same idea as preJoin
1412	<	*/
1413	<	final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){
1414	<	maintainParallelism &= maintainsParallelism;
1415	<	boolean dec = false;
1416	<	while (spareStack == null || !tryResumeSpare(dec)) {
1417	<	int counts = workerCounts;
1418	<	if (dec || (dec = casWorkerCounts(counts, --counts))) {
1419	<	if (!needSpare(counts, maintainParallelism))
1420	<	break;
1421	<	if (blocker.isReleasable())
1422	<	return true;
1423	<	if (tryAddSpare(counts))
3000	>	long startTime = System.nanoTime();
3001	>	boolean terminated = false;
3002	>	synchronized(this) {
3003	>	for (long waitTime = nanos, millis = 0L;;) {
3004	>	if (terminated = isTerminated() ||
3005	>	waitTime <= 0L ||
3006	>	(millis = unit.toMillis(waitTime)) <= 0L)
3007		break;
3008	+	wait(millis);
3009	+	waitTime = nanos - (System.nanoTime() - startTime);
3010		}
3011		}
3012	<	return false;
1428	<	}
1429	<
1430	<	/**
1431	<	* Returns true if a spare thread appears to be needed.  If
1432	<	* maintaining parallelism, returns true when the deficit in
1433	<	* running threads is more than the surplus of total threads, and
1434	<	* there is apparently some work to do.  This self-limiting rule
1435	<	* means that the more threads that have already been added, the
1436	<	* less parallelism we will tolerate before adding another.
1437	<	* @param counts current worker counts
1438	<	* @param maintainParallelism try to maintain parallelism
1439	<	*/
1440	<	private boolean needSpare(int counts, boolean maintainParallelism) {
1441	<	int ps = parallelism;
1442	<	int rc = runningCountOf(counts);
1443	<	int tc = totalCountOf(counts);
1444	<	int runningDeficit = ps - rc;
1445	<	int totalSurplus = tc - ps;
1446	<	return (tc < maxPoolSize &&
1447	<	(rc == 0 || totalSurplus < 0 ||
1448	<	(maintainParallelism &&
1449	<	runningDeficit > totalSurplus &&
1450	<	ForkJoinWorkerThread.hasQueuedTasks(workers))));
1451	<	}
1452	<
1453	<	/**
1454	<	* Add a spare worker if lock available and no more than the
1455	<	* expected numbers of threads exist
1456	<	* @return true if successful
1457	<	*/
1458	<	private boolean tryAddSpare(int expectedCounts) {
1459	<	final ReentrantLock lock = this.workerLock;
1460	<	int expectedRunning = runningCountOf(expectedCounts);
1461	<	int expectedTotal = totalCountOf(expectedCounts);
1462	<	boolean success = false;
1463	<	boolean locked = false;
1464	<	// confirm counts while locking; CAS after obtaining lock
1465	<	try {
1466	<	for (;;) {
1467	<	int s = workerCounts;
1468	<	int tc = totalCountOf(s);
1469	<	int rc = runningCountOf(s);
1470	<	if (rc > expectedRunning || tc > expectedTotal)
1471	<	break;
1472	<	if (!locked && !(locked = lock.tryLock()))
1473	<	break;
1474	<	if (casWorkerCounts(s, workerCountsFor(tc+1, rc+1))) {
1475	<	createAndStartSpare(tc);
1476	<	success = true;
1477	<	break;
1478	<	}
1479	<	}
1480	<	} finally {
1481	<	if (locked)
1482	<	lock.unlock();
1483	<	}
1484	<	return success;
1485	<	}
1486	<
1487	<	/**
1488	<	* Add the kth spare worker. On entry, pool coounts are already
1489	<	* adjusted to reflect addition.
1490	<	*/
1491	<	private void createAndStartSpare(int k) {
1492	<	ForkJoinWorkerThread w = null;
1493	<	ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(k + 1);
1494	<	int len = ws.length;
1495	<	// Probably, we can place at slot k. If not, find empty slot
1496	<	if (k < len && ws[k] != null) {
1497	<	for (k = 0; k < len && ws[k] != null; ++k)
1498	<	;
1499	<	}
1500	<	if (k < len && !isTerminating() && (w = createWorker(k)) != null) {
1501	<	ws[k] = w;
1502	<	w.start();
1503	<	}
1504	<	else
1505	<	updateWorkerCount(-1); // adjust on failure
1506	<	signalIdleWorkers();
1507	<	}
1508	<
1509	<	/**
1510	<	* Suspend calling thread w if there are excess threads.  Called
1511	<	* only from sync.  Spares are enqueued in a Treiber stack
1512	<	* using the same WaitQueueNodes as barriers.  They are resumed
1513	<	* mainly in preJoin, but are also woken on pool events that
1514	<	* require all threads to check run state.
1515	<	* @param w the caller
1516	<	*/
1517	<	private boolean suspendIfSpare(ForkJoinWorkerThread w) {
1518	<	WaitQueueNode node = null;
1519	<	int s;
1520	<	while (parallelism < runningCountOf(s = workerCounts)) {
1521	<	if (node == null)
1522	<	node = new WaitQueueNode(0, w);
1523	<	if (casWorkerCounts(s, s-1)) { // representation-dependent
1524	<	// push onto stack
1525	<	do;while (!casSpareStack(node.next = spareStack, node));
1526	<	// block until released by resumeSpare
1527	<	node.awaitSpareRelease();
1528	<	return true;
1529	<	}
1530	<	}
1531	<	return false;
1532	<	}
1533	<
1534	<	/**
1535	<	* Try to pop and resume a spare thread.
1536	<	* @param updateCount if true, increment running count on success
1537	<	* @return true if successful
1538	<	*/
1539	<	private boolean tryResumeSpare(boolean updateCount) {
1540	<	WaitQueueNode q;
1541	<	while ((q = spareStack) != null) {
1542	<	if (casSpareStack(q, q.next)) {
1543	<	if (updateCount)
1544	<	updateRunningCount(1);
1545	<	q.signal();
1546	<	return true;
1547	<	}
1548	<	}
1549	<	return false;
1550	<	}
1551	<
1552	<	/**
1553	<	* Pop and resume all spare threads. Same idea as ensureSync.
1554	<	* @return true if any spares released
1555	<	*/
1556	<	private boolean resumeAllSpares() {
1557	<	WaitQueueNode q;
1558	<	while ( (q = spareStack) != null) {
1559	<	if (casSpareStack(q, null)) {
1560	<	do {
1561	<	updateRunningCount(1);
1562	<	q.signal();
1563	<	} while ((q = q.next) != null);
1564	<	return true;
1565	<	}
1566	<	}
1567	<	return false;
1568	<	}
1569	<
1570	<	/**
1571	<	* Pop and shutdown excessive spare threads. Call only while
1572	<	* holding lock. This is not guaranteed to eliminate all excess
1573	<	* threads, only those suspended as spares, which are the ones
1574	<	* unlikely to be needed in the future.
1575	<	*/
1576	<	private void trimSpares() {
1577	<	int surplus = totalCountOf(workerCounts) - parallelism;
1578	<	WaitQueueNode q;
1579	<	while (surplus > 0 && (q = spareStack) != null) {
1580	<	if (casSpareStack(q, null)) {
1581	<	do {
1582	<	updateRunningCount(1);
1583	<	ForkJoinWorkerThread w = q.thread;
1584	<	if (w != null && surplus > 0 &&
1585	<	runningCountOf(workerCounts) > 0 && w.shutdown())
1586	<	--surplus;
1587	<	q.signal();
1588	<	} while ((q = q.next) != null);
1589	<	}
1590	<	}
3012	>	return terminated;
3013		}
3014
3015		/**
3016		* Interface for extending managed parallelism for tasks running
3017	<	* in ForkJoinPools. A ManagedBlocker provides two methods.
3018	<	* Method <code>isReleasable</code> must return true if blocking is not
3019	<	* necessary. Method <code>block</code> blocks the current thread
3020	<	* if necessary (perhaps internally invoking isReleasable before
3021	<	* actually blocking.).
3017	>	* in {@link ForkJoinPool}s.
3018	>	*
3019	>	* <p>A {@code ManagedBlocker} provides two methods.  Method
3020	>	* {@code isReleasable} must return {@code true} if blocking is
3021	>	* not necessary. Method {@code block} blocks the current thread
3022	>	* if necessary (perhaps internally invoking {@code isReleasable}
3023	>	* before actually blocking). These actions are performed by any
3024	>	* thread invoking {@link ForkJoinPool#managedBlock}.  The
3025	>	* unusual methods in this API accommodate synchronizers that may,
3026	>	* but don't usually, block for long periods. Similarly, they
3027	>	* allow more efficient internal handling of cases in which
3028	>	* additional workers may be, but usually are not, needed to
3029	>	* ensure sufficient parallelism.  Toward this end,
3030	>	* implementations of method {@code isReleasable} must be amenable
3031	>	* to repeated invocation.
3032	>	*
3033		* <p>For example, here is a ManagedBlocker based on a
3034		* ReentrantLock:
3035	<	* <pre>
3036	<	*   class ManagedLocker implements ManagedBlocker {
3037	<	*     final ReentrantLock lock;
3038	<	*     boolean hasLock = false;
3039	<	*     ManagedLocker(ReentrantLock lock) { this.lock = lock; }
3040	<	*     public boolean block() {
3041	<	*        if (!hasLock)
3042	<	*           lock.lock();
3043	<	*        return true;
3044	<	*     }
3045	<	*     public boolean isReleasable() {
3046	<	*        return hasLock || (hasLock = lock.tryLock());
1614	<	*     }
3035	>	*  <pre> {@code
3036	>	* class ManagedLocker implements ManagedBlocker {
3037	>	*   final ReentrantLock lock;
3038	>	*   boolean hasLock = false;
3039	>	*   ManagedLocker(ReentrantLock lock) { this.lock = lock; }
3040	>	*   public boolean block() {
3041	>	*     if (!hasLock)
3042	>	*       lock.lock();
3043	>	*     return true;
3044	>	*   }
3045	>	*   public boolean isReleasable() {
3046	>	*     return hasLock || (hasLock = lock.tryLock());
3047		*   }
3048	<	* </pre>
3048	>	* }}</pre>
3049	>	*
3050	>	* <p>Here is a class that possibly blocks waiting for an
3051	>	* item on a given queue:
3052	>	*  <pre> {@code
3053	>	* class QueueTaker<E> implements ManagedBlocker {
3054	>	*   final BlockingQueue<E> queue;
3055	>	*   volatile E item = null;
3056	>	*   QueueTaker(BlockingQueue<E> q) { this.queue = q; }
3057	>	*   public boolean block() throws InterruptedException {
3058	>	*     if (item == null)
3059	>	*       item = queue.take();
3060	>	*     return true;
3061	>	*   }
3062	>	*   public boolean isReleasable() {
3063	>	*     return item != null || (item = queue.poll()) != null;
3064	>	*   }
3065	>	*   public E getItem() { // call after pool.managedBlock completes
3066	>	*     return item;
3067	>	*   }
3068	>	* }}</pre>
3069		*/
3070		public static interface ManagedBlocker {
3071		/**
3072		* Possibly blocks the current thread, for example waiting for
3073		* a lock or condition.
3074	<	* @return true if no additional blocking is necessary (i.e.,
3075	<	* if isReleasable would return true).
3074	>	*
3075	>	* @return {@code true} if no additional blocking is necessary
3076	>	* (i.e., if isReleasable would return true)
3077		* @throws InterruptedException if interrupted while waiting
3078	<	* (the method is not required to do so, but is allowe to).
3078	>	* (the method is not required to do so, but is allowed to)
3079		*/
3080		boolean block() throws InterruptedException;
3081
3082		/**
3083	<	* Returns true if blocking is unnecessary.
3083	>	* Returns {@code true} if blocking is unnecessary.
3084		*/
3085		boolean isReleasable();
3086		}
3087
3088		/**
3089		* Blocks in accord with the given blocker.  If the current thread
3090	<	* is a ForkJoinWorkerThread, this method possibly arranges for a
3091	<	* spare thread to be activated if necessary to ensure parallelism
3092	<	* while the current thread is blocked.  If
3093	<	* <code>maintainParallelism</code> is true and the pool supports
3094	<	* it ({@link #getMaintainsParallelism}), this method attempts to
3095	<	* maintain the pool's nominal parallelism. Otherwise if activates
3096	<	* a thread only if necessary to avoid complete starvation. This
3097	<	* option may be preferable when blockages use timeouts, or are
3098	<	* almost always brief.
3099	<	*
3100	<	* <p> If the caller is not a ForkJoinTask, this method is behaviorally
3101	<	* equivalent to
3102	<	* <pre>
3103	<	*   while (!blocker.isReleasable())
1651	<	*      if (blocker.block())
1652	<	*         return;
1653	<	* </pre>
1654	<	* If the caller is a ForkJoinTask, then the pool may first
1655	<	* be expanded to ensure parallelism, and later adjusted.
3090	>	* is a {@link ForkJoinWorkerThread}, this method possibly
3091	>	* arranges for a spare thread to be activated if necessary to
3092	>	* ensure sufficient parallelism while the current thread is blocked.
3093	>	*
3094	>	* <p>If the caller is not a {@link ForkJoinTask}, this method is
3095	>	* behaviorally equivalent to
3096	>	*  <pre> {@code
3097	>	* while (!blocker.isReleasable())
3098	>	*   if (blocker.block())
3099	>	*     return;
3100	>	* }</pre>
3101	>	*
3102	>	* If the caller is a {@code ForkJoinTask}, then the pool may
3103	>	* first be expanded to ensure parallelism, and later adjusted.
3104		*
3105		* @param blocker the blocker
3106	<	* @param maintainParallelism if true and supported by this pool,
1659	<	* attempt to maintain the pool's nominal parallelism; otherwise
1660	<	* activate a thread only if necessary to avoid complete
1661	<	* starvation.
1662	<	* @throws InterruptedException if blocker.block did so.
3106	>	* @throws InterruptedException if blocker.block did so
3107		*/
3108	<	public static void managedBlock(ManagedBlocker blocker,
1665	<	boolean maintainParallelism)
3108	>	public static void managedBlock(ManagedBlocker blocker)
3109		throws InterruptedException {
3110		Thread t = Thread.currentThread();
3111	<	ForkJoinPool pool = (t instanceof ForkJoinWorkerThread?
3112	<	((ForkJoinWorkerThread)t).pool : null);
3113	<	if (!blocker.isReleasable()) {
3114	<	try {
3115	<	if (pool == null ||
3116	<	!pool.preBlock(blocker, maintainParallelism))
3117	<	awaitBlocker(blocker);
3118	<	} finally {
3119	<	if (pool != null)
3120	<	pool.updateRunningCount(1);
3111	>	ForkJoinPool p = ((t instanceof ForkJoinWorkerThread) ?
3112	>	((ForkJoinWorkerThread)t).pool : null);
3113	>	while (!blocker.isReleasable()) {
3114	>	if (p == null || p.tryCompensate(null, blocker)) {
3115	>	try {
3116	>	do {} while (!blocker.isReleasable() && !blocker.block());
3117	>	} finally {
3118	>	if (p != null)
3119	>	p.incrementActiveCount();
3120	>	}
3121	>	break;
3122		}
3123		}
3124		}
3125
3126	<	private static void awaitBlocker(ManagedBlocker blocker)
3127	<	throws InterruptedException {
3128	<	do;while (!blocker.isReleasable() && !blocker.block());
1685	<	}
1686	<
1687	<	// AbstractExecutorService overrides
3126	>	// AbstractExecutorService overrides.  These rely on undocumented
3127	>	// fact that ForkJoinTask.adapt returns ForkJoinTasks that also
3128	>	// implement RunnableFuture.
3129
3130		protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
3131	<	return new AdaptedRunnable(runnable, value);
3131	>	return new ForkJoinTask.AdaptedRunnable<T>(runnable, value);
3132		}
3133
3134		protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
3135	<	return new AdaptedCallable(callable);
3135	>	return new ForkJoinTask.AdaptedCallable<T>(callable);
3136		}
3137
3138	<
3139	<	// Temporary Unsafe mechanics for preliminary release
3140	<
3141	<	static final Unsafe _unsafe;
3142	<	static final long eventCountOffset;
3143	<	static final long workerCountsOffset;
3144	<	static final long runControlOffset;
3145	<	static final long syncStackOffset;
3146	<	static final long spareStackOffset;
3138	>	// Unsafe mechanics
3139	>	private static final sun.misc.Unsafe U;
3140	>	private static final long CTL;
3141	>	private static final long PARKBLOCKER;
3142	>	private static final int ABASE;
3143	>	private static final int ASHIFT;
3144	>	private static final long NEXTWORKERNUMBER;
3145	>	private static final long STEALCOUNT;
3146	>	private static final long MAINLOCK;
3147
3148		static {
3149	+	poolNumberGenerator = new AtomicInteger();
3150	+	nextSubmitterSeed = new AtomicInteger(0x55555555);
3151	+	modifyThreadPermission = new RuntimePermission("modifyThread");
3152	+	defaultForkJoinWorkerThreadFactory =
3153	+	new DefaultForkJoinWorkerThreadFactory();
3154	+	submitters = new ThreadSubmitter();
3155	+	int s;
3156		try {
3157	<	if (ForkJoinPool.class.getClassLoader() != null) {
3158	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
3159	<	f.setAccessible(true);
3160	<	_unsafe = (Unsafe)f.get(null);
3161	<	}
3162	<	else
3163	<	_unsafe = Unsafe.getUnsafe();
3164	<	eventCountOffset = _unsafe.objectFieldOffset
3165	<	(ForkJoinPool.class.getDeclaredField("eventCount"));
3166	<	workerCountsOffset = _unsafe.objectFieldOffset
3167	<	(ForkJoinPool.class.getDeclaredField("workerCounts"));
3168	<	runControlOffset = _unsafe.objectFieldOffset
3169	<	(ForkJoinPool.class.getDeclaredField("runControl"));
3170	<	syncStackOffset = _unsafe.objectFieldOffset
3171	<	(ForkJoinPool.class.getDeclaredField("syncStack"));
3172	<	spareStackOffset = _unsafe.objectFieldOffset
3173	<	(ForkJoinPool.class.getDeclaredField("spareStack"));
3157	>	U = getUnsafe();
3158	>	Class<?> k = ForkJoinPool.class;
3159	>	Class<?> ak = ForkJoinTask[].class;
3160	>	CTL = U.objectFieldOffset
3161	>	(k.getDeclaredField("ctl"));
3162	>	NEXTWORKERNUMBER = U.objectFieldOffset
3163	>	(k.getDeclaredField("nextWorkerNumber"));
3164	>	STEALCOUNT = U.objectFieldOffset
3165	>	(k.getDeclaredField("stealCount"));
3166	>	MAINLOCK = U.objectFieldOffset
3167	>	(k.getDeclaredField("mainLock"));
3168	>	Class<?> tk = Thread.class;
3169	>	PARKBLOCKER = U.objectFieldOffset
3170	>	(tk.getDeclaredField("parkBlocker"));
3171	>	ABASE = U.arrayBaseOffset(ak);
3172	>	s = U.arrayIndexScale(ak);
3173	>	ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
3174		} catch (Exception e) {
3175	<	throw new RuntimeException("Could not initialize intrinsics", e);
3175	>	throw new Error(e);
3176	>	}
3177	>	if ((s & (s-1)) != 0)
3178	>	throw new Error("data type scale not a power of two");
3179	>	try { // Establish common pool
3180	>	String pp = System.getProperty(propPrefix + "parallelism");
3181	>	String fp = System.getProperty(propPrefix + "threadFactory");
3182	>	String up = System.getProperty(propPrefix + "exceptionHandler");
3183	>	ForkJoinWorkerThreadFactory fac = (fp == null) ?
3184	>	defaultForkJoinWorkerThreadFactory :
3185	>	((ForkJoinWorkerThreadFactory)ClassLoader.
3186	>	getSystemClassLoader().loadClass(fp).newInstance());
3187	>	Thread.UncaughtExceptionHandler ueh = (up == null)? null :
3188	>	((Thread.UncaughtExceptionHandler)ClassLoader.
3189	>	getSystemClassLoader().loadClass(up).newInstance());
3190	>	int par;
3191	>	if ((pp == null || (par = Integer.parseInt(pp)) <= 0))
3192	>	par = Runtime.getRuntime().availableProcessors();
3193	>	if (par > MAX_CAP)
3194	>	par = MAX_CAP;
3195	>	commonPoolParallelism = par;
3196	>	int n = par - 1; // precompute submit mask
3197	>	n |= n >>> 1; n |= n >>> 2; n |= n >>> 4;
3198	>	n |= n >>> 8; n |= n >>> 16;
3199	>	int mask = ((n + 1) << 1) - 1;
3200	>	commonPool = new ForkJoinPool(par, mask, fac, ueh);
3201	>	} catch (Exception e) {
3202	>	throw new Error(e);
3203		}
3204		}
3205
3206	<	private boolean casEventCount(long cmp, long val) {
3207	<	return _unsafe.compareAndSwapLong(this, eventCountOffset, cmp, val);
3208	<	}
3209	<	private boolean casWorkerCounts(int cmp, int val) {
3210	<	return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val);
3211	<	}
3212	<	private boolean casRunControl(int cmp, int val) {
3213	<	return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val);
3214	<	}
3215	<	private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) {
3216	<	return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val);
3217	<	}
3218	<	private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
3219	<	return _unsafe.compareAndSwapObject(this, syncStackOffset, cmp, val);
3206	>	/**
3207	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
3208	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
3209	>	* into a jdk.
3210	>	*
3211	>	* @return a sun.misc.Unsafe
3212	>	*/
3213	>	private static sun.misc.Unsafe getUnsafe() {
3214	>	try {
3215	>	return sun.misc.Unsafe.getUnsafe();
3216	>	} catch (SecurityException se) {
3217	>	try {
3218	>	return java.security.AccessController.doPrivileged
3219	>	(new java.security
3220	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
3221	>	public sun.misc.Unsafe run() throws Exception {
3222	>	java.lang.reflect.Field f = sun.misc
3223	>	.Unsafe.class.getDeclaredField("theUnsafe");
3224	>	f.setAccessible(true);
3225	>	return (sun.misc.Unsafe) f.get(null);
3226	>	}});
3227	>	} catch (java.security.PrivilegedActionException e) {
3228	>	throw new RuntimeException("Could not initialize intrinsics",
3229	>	e.getCause());
3230	>	}
3231	>	}
3232		}
3233	+
3234		}

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