[ViewVC] Diff of: jsr166/jsr166/src/jsr166e/ForkJoinPool.java

Comparing jsr166/src/jsr166e/ForkJoinPool.java (file contents):
Revision 1.9 by dl, Tue Oct 30 14:23:03 2012 UTC vs.
Revision 1.60 by jsr166, Wed Jun 19 16:36:45 2013 UTC

#	Line 6 \| Line 6
6
7		package jsr166e;
8
9	+	import java.lang.Thread.UncaughtExceptionHandler;
10		import java.util.ArrayList;
11		import java.util.Arrays;
12		import java.util.Collection;
13		import java.util.Collections;
14		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;
#	Line 20 \| Line 20 \| import java.util.concurrent.RejectedExec
20		import java.util.concurrent.RunnableFuture;
21		import java.util.concurrent.ThreadLocalRandom;
22		import java.util.concurrent.TimeUnit;
23	–	import java.util.concurrent.atomic.AtomicInteger;
24	–	import java.util.concurrent.atomic.AtomicLong;
25	–	import java.util.concurrent.locks.AbstractQueuedSynchronizer;
26	–	import java.util.concurrent.locks.Condition;
23
24		/**
25		* An {@link ExecutorService} for running {@link ForkJoinTask}s.
#	Line 43 \| Line 39 \| import java.util.concurrent.locks.Condit
39		* ForkJoinPool}s may also be appropriate for use with event-style
40		* tasks that are never joined.
41		*
42	<	* <p>A static {@link #commonPool} is available and appropriate for
42	>	* <p>A static {@link #commonPool()} is available and appropriate for
43		* most applications. The common pool is used by any ForkJoinTask that
44		* is not explicitly submitted to a specified pool. Using the common
45		* pool normally reduces resource usage (its threads are slowly
46		* reclaimed during periods of non-use, and reinstated upon subsequent
47	<	* use). The common pool is by default constructed with default
52	<	* parameters, but these may be controlled by setting any or all of
53	<	* the three properties {@code
54	<	* java.util.concurrent.ForkJoinPool.common.{parallelism,
55	<	* threadFactory, exceptionHandler}}.
47	>	* use).
48		*
49		* <p>For applications that require separate or custom pools, a {@code
50		* ForkJoinPool} may be constructed with a given target parallelism
51		* level; by default, equal to the number of available processors. The
52		* pool attempts to maintain enough active (or available) threads by
53		* dynamically adding, suspending, or resuming internal worker
54	<	* threads, even if some tasks are stalled waiting to join
55	<	* others. However, no such adjustments are guaranteed in the face of
56	<	* blocked IO or other unmanaged synchronization. The nested {@link
54	>	* threads, even if some tasks are stalled waiting to join others.
55	>	* However, no such adjustments are guaranteed in the face of blocked
56	>	* I/O or other unmanaged synchronization. The nested {@link
57		* ManagedBlocker} interface enables extension of the kinds of
58		* synchronization accommodated.
59		*
#	Line 72 \| Line 64 \| import java.util.concurrent.locks.Condit
64		* {@link #toString} returns indications of pool state in a
65		* convenient form for informal monitoring.
66		*
67	<	* <p> As is the case with other ExecutorServices, there are three
67	>	* <p>As is the case with other ExecutorServices, there are three
68		* main task execution methods summarized in the following table.
69		* These are designed to be used primarily by clients not already
70		* engaged in fork/join computations in the current pool. The main
#	Line 85 \| Line 77 \| import java.util.concurrent.locks.Condit
77		* there is little difference among choice of methods.
78		*
79		* <table BORDER CELLPADDING=3 CELLSPACING=1>
80	+	* <caption>Summary of task execution methods</caption>
81		* <tr>
82		* <td></td>
83		* <td ALIGN=CENTER> <b>Call from non-fork/join clients</b></td>
84		* <td ALIGN=CENTER> <b>Call from within fork/join computations</b></td>
85		* </tr>
86		* <tr>
87	<	* <td> <b>Arrange async execution</td>
87	>	* <td> <b>Arrange async execution</b></td>
88		* <td> {@link #execute(ForkJoinTask)}</td>
89		* <td> {@link ForkJoinTask#fork}</td>
90		* </tr>
91		* <tr>
92	<	* <td> <b>Await and obtain result</td>
92	>	* <td> <b>Await and obtain result</b></td>
93		* <td> {@link #invoke(ForkJoinTask)}</td>
94		* <td> {@link ForkJoinTask#invoke}</td>
95		* </tr>
96		* <tr>
97	<	* <td> <b>Arrange exec and obtain Future</td>
97	>	* <td> <b>Arrange exec and obtain Future</b></td>
98		* <td> {@link #submit(ForkJoinTask)}</td>
99		* <td> {@link ForkJoinTask#fork} (ForkJoinTasks <em>are</em> Futures)</td>
100		* </tr>
101		* </table>
102		*
103	+	* <p>The common pool is by default constructed with default
104	+	* parameters, but these may be controlled by setting three
105	+	* {@linkplain System#getProperty system properties}:
106	+	* <ul>
107	+	* <li>{@code java.util.concurrent.ForkJoinPool.common.parallelism}
108	+	* - the parallelism level, a non-negative integer
109	+	* <li>{@code java.util.concurrent.ForkJoinPool.common.threadFactory}
110	+	* - the class name of a {@link ForkJoinWorkerThreadFactory}
111	+	* <li>{@code java.util.concurrent.ForkJoinPool.common.exceptionHandler}
112	+	* - the class name of a {@link UncaughtExceptionHandler}
113	+	* </ul>
114	+	* The system class loader is used to load these classes.
115	+	* Upon any error in establishing these settings, default parameters
116	+	* are used. It is possible to disable or limit the use of threads in
117	+	* the common pool by setting the parallelism property to zero, and/or
118	+	* using a factory that may return {@code null}.
119	+	*
120		* <p><b>Implementation notes</b>: This implementation restricts the
121		* maximum number of running threads to 32767. Attempts to create
122		* pools with greater than the maximum number result in
#	Line 151 \| Line 161 \| public class ForkJoinPool extends Abstra
161		* (http://research.sun.com/scalable/pubs/index.html) and
162		* "Idempotent work stealing" by Michael, Saraswat, and Vechev,
163		* PPoPP 2009 (http://portal.acm.org/citation.cfm?id=1504186).
164	<	* The main differences ultimately stem from GC requirements that
165	<	* we null out taken slots as soon as we can, to maintain as small
166	<	* a footprint as possible even in programs generating huge
167	<	* numbers of tasks. To accomplish this, we shift the CAS
168	<	* arbitrating pop vs poll (steal) from being on the indices
169	<	* ("base" and "top") to the slots themselves. So, both a
170	<	* successful pop and poll mainly entail a CAS of a slot from
171	<	* non-null to null. Because we rely on CASes of references, we
172	<	* do not need tag bits on base or top. They are simple ints as
173	<	* used in any circular array-based queue (see for example
174	<	* ArrayDeque). Updates to the indices must still be ordered in a
175	<	* way that guarantees that top == base means the queue is empty,
176	<	* but otherwise may err on the side of possibly making the queue
177	<	* appear nonempty when a push, pop, or poll have not fully
178	<	* committed. Note that this means that the poll operation,
179	<	* considered individually, is not wait-free. One thief cannot
180	<	* successfully continue until another in-progress one (or, if
181	<	* previously empty, a push) completes. However, in the
182	<	* aggregate, we ensure at least probabilistic non-blockingness.
183	<	* If an attempted steal fails, a thief always chooses a different
184	<	* random victim target to try next. So, in order for one thief to
185	<	* progress, it suffices for any in-progress poll or new push on
186	<	* any empty queue to complete. (This is why we normally use
187	<	* method pollAt and its variants that try once at the apparent
188	<	* base index, else consider alternative actions, rather than
189	<	* method poll.)
164	>	* See also "Correct and Efficient Work-Stealing for Weak Memory
165	>	* Models" by Le, Pop, Cohen, and Nardelli, PPoPP 2013
166	>	* (http://www.di.ens.fr/~zappa/readings/ppopp13.pdf) for an
167	>	* analysis of memory ordering (atomic, volatile etc) issues. The
168	>	* main differences ultimately stem from GC requirements that we
169	>	* null out taken slots as soon as we can, to maintain as small a
170	>	* footprint as possible even in programs generating huge numbers
171	>	* of tasks. To accomplish this, we shift the CAS arbitrating pop
172	>	* vs poll (steal) from being on the indices ("base" and "top") to
173	>	* the slots themselves. So, both a successful pop and poll
174	>	* mainly entail a CAS of a slot from non-null to null. Because
175	>	* we rely on CASes of references, we do not need tag bits on base
176	>	* or top. They are simple ints as used in any circular
177	>	* array-based queue (see for example ArrayDeque). Updates to the
178	>	* indices must still be ordered in a way that guarantees that top
179	>	* == base means the queue is empty, but otherwise may err on the
180	>	* side of possibly making the queue appear nonempty when a push,
181	>	* pop, or poll have not fully committed. Note that this means
182	>	* that the poll operation, considered individually, is not
183	>	* wait-free. One thief cannot successfully continue until another
184	>	* in-progress one (or, if previously empty, a push) completes.
185	>	* However, in the aggregate, we ensure at least probabilistic
186	>	* non-blockingness. If an attempted steal fails, a thief always
187	>	* chooses a different random victim target to try next. So, in
188	>	* order for one thief to progress, it suffices for any
189	>	* in-progress poll or new push on any empty queue to
190	>	* complete. (This is why we normally use method pollAt and its
191	>	* variants that try once at the apparent base index, else
192	>	* consider alternative actions, rather than method poll.)
193		*
194		* This approach also enables support of a user mode in which local
195		* task processing is in FIFO, not LIFO order, simply by using
#	Line 193 \| Line 206 \| public class ForkJoinPool extends Abstra
206		* WorkQueues are also used in a similar way for tasks submitted
207		* to the pool. We cannot mix these tasks in the same queues used
208		* for work-stealing (this would contaminate lifo/fifo
209	<	* processing). Instead, we loosely associate submission queues
209	>	* processing). Instead, we randomly associate submission queues
210		* with submitting threads, using a form of hashing. The
211	<	* ThreadLocal Submitter class contains a value initially used as
212	<	* a hash code for choosing existing queues, but may be randomly
213	<	* repositioned upon contention with other submitters. In
214	<	* essence, submitters act like workers except that they never
215	<	* take tasks, and they are multiplexed on to a finite number of
216	<	* shared work queues. However, classes are set up so that future
217	<	* extensions could allow submitters to optionally help perform
218	<	* tasks as well. Insertion of tasks in shared mode requires a
219	<	* lock (mainly to protect in the case of resizing) but we use
220	<	* only a simple spinlock (using bits in field runState), because
221	<	* submitters encountering a busy queue move on to try or create
222	<	* other queues -- they block only when creating and registering
223	<	* new queues.
211	>	* Submitter probe value serves as a hash code for
212	>	* choosing existing queues, and may be randomly repositioned upon
213	>	* contention with other submitters. In essence, submitters act
214	>	* like workers except that they are restricted to executing local
215	>	* tasks that they submitted (or in the case of CountedCompleters,
216	>	* others with the same root task). However, because most
217	>	* shared/external queue operations are more expensive than
218	>	* internal, and because, at steady state, external submitters
219	>	* will compete for CPU with workers, ForkJoinTask.join and
220	>	* related methods disable them from repeatedly helping to process
221	>	* tasks if all workers are active. Insertion of tasks in shared
222	>	* mode requires a lock (mainly to protect in the case of
223	>	* resizing) but we use only a simple spinlock (using bits in
224	>	* field qlock), because submitters encountering a busy queue move
225	>	* on to try or create other queues -- they block only when
226	>	* creating and registering new queues.
227		*
228		* Management
229		* ==========
#	Line 229 \| Line 245 \| public class ForkJoinPool extends Abstra
245		* and their negations (used for thresholding) to fit into 16bit
246		* fields.
247		*
248	<	* Field "runState" contains 32 bits needed to register and
249	<	* deregister WorkQueues, as well as to enable shutdown. It is
250	<	* only modified under a lock (normally briefly held, but
251	<	* occasionally protecting allocations and resizings) but even
252	<	* when locked remains available to check consistency.
248	>	* Field "plock" is a form of sequence lock with a saturating
249	>	* shutdown bit (similarly for per-queue "qlocks"), mainly
250	>	* protecting updates to the workQueues array, as well as to
251	>	* enable shutdown. When used as a lock, it is normally only very
252	>	* briefly held, so is nearly always available after at most a
253	>	* brief spin, but we use a monitor-based backup strategy to
254	>	* block when needed.
255		*
256		* Recording WorkQueues. WorkQueues are recorded in the
257		* "workQueues" array that is created upon first use and expanded
#	Line 242 \| Line 260 \| public class ForkJoinPool extends Abstra
260		* by a lock but the array is otherwise concurrently readable, and
261		* accessed directly. To simplify index-based operations, the
262		* array size is always a power of two, and all readers must
263	<	* tolerate null slots. Shared (submission) queues are at even
264	<	* indices, worker queues at odd indices. Grouping them together
265	<	* in this way simplifies and speeds up task scanning.
263	>	* tolerate null slots. Worker queues are at odd indices. Shared
264	>	* (submission) queues are at even indices, up to a maximum of 64
265	>	* slots, to limit growth even if array needs to expand to add
266	>	* more workers. Grouping them together in this way simplifies and
267	>	* speeds up task scanning.
268		*
269		* All worker thread creation is on-demand, triggered by task
270		* submissions, replacement of terminated workers, and/or
#	Line 289 \| Line 309 \| public class ForkJoinPool extends Abstra
309		* has not yet entered the wait queue. We solve this by requiring
310		* a full sweep of all workers (via repeated calls to method
311		* scan()) both before and after a newly waiting worker is added
312	<	* to the wait queue. During a rescan, the worker might release
313	<	* some other queued worker rather than itself, which has the same
314	<	* net effect. Because enqueued workers may actually be rescanning
315	<	* rather than waiting, we set and clear the "parker" field of
316	<	* WorkQueues to reduce unnecessary calls to unpark. (This
317	<	* requires a secondary recheck to avoid missed signals.) Note
318	<	* the unusual conventions about Thread.interrupts surrounding
319	<	* parking and other blocking: Because interrupts are used solely
320	<	* to alert threads to check termination, which is checked anyway
321	<	* upon blocking, we clear status (using Thread.interrupted)
322	<	* before any call to park, so that park does not immediately
303	<	* return due to status being set via some other unrelated call to
304	<	* interrupt in user code.
312	>	* to the wait queue. Because enqueued workers may actually be
313	>	* rescanning rather than waiting, we set and clear the "parker"
314	>	* field of WorkQueues to reduce unnecessary calls to unpark.
315	>	* (This requires a secondary recheck to avoid missed signals.)
316	>	* Note the unusual conventions about Thread.interrupts
317	>	* surrounding parking and other blocking: Because interrupts are
318	>	* used solely to alert threads to check termination, which is
319	>	* checked anyway upon blocking, we clear status (using
320	>	* Thread.interrupted) before any call to park, so that park does
321	>	* not immediately return due to status being set via some other
322	>	* unrelated call to interrupt in user code.
323		*
324		* Signalling. We create or wake up workers only when there
325		* appears to be at least one task they might be able to find and
326		* execute. When a submission is added or another worker adds a
327	<	* task to a queue that previously had fewer than two tasks, they
328	<	* signal waiting workers (or trigger creation of new ones if
329	<	* fewer than the given parallelism level -- see signalWork).
330	<	* These primary signals are buttressed by signals during rescans;
331	<	* together these cover the signals needed in cases when more
332	<	* tasks are pushed but untaken, and improve performance compared
333	<	* to having one thread wake up all workers.
327	>	* task to a queue that has fewer than two tasks, they signal
328	>	* waiting workers (or trigger creation of new ones if fewer than
329	>	* the given parallelism level -- signalWork). These primary
330	>	* signals are buttressed by others whenever other threads remove
331	>	* a task from a queue and notice that there are other tasks there
332	>	* as well. So in general, pools will be over-signalled. On most
333	>	* platforms, signalling (unpark) overhead time is noticeably
334	>	* long, and the time between signalling a thread and it actually
335	>	* making progress can be very noticeably long, so it is worth
336	>	* offloading these delays from critical paths as much as
337	>	* possible. Additionally, workers spin-down gradually, by staying
338	>	* alive so long as they see the ctl state changing. Similar
339	>	* stability-sensing techniques are also used before blocking in
340	>	* awaitJoin and helpComplete.
341		*
342		* Trimming workers. To release resources after periods of lack of
343		* use, a worker starting to wait when the pool is quiescent will
#	Line 323 \| Line 348 \| public class ForkJoinPool extends Abstra
348		* periods of non-use.
349		*
350		* Shutdown and Termination. A call to shutdownNow atomically sets
351	<	* a runState bit and then (non-atomically) sets each worker's
352	<	* runState status, cancels all unprocessed tasks, and wakes up
351	>	* a plock bit and then (non-atomically) sets each worker's
352	>	* qlock status, cancels all unprocessed tasks, and wakes up
353		* all waiting workers. Detecting whether termination should
354		* commence after a non-abrupt shutdown() call requires more work
355		* and bookkeeping. We need consensus about quiescence (i.e., that
#	Line 352 \| Line 377 \| public class ForkJoinPool extends Abstra
377		* method tryCompensate() may create or re-activate a spare
378		* thread to compensate for blocked joiners until they unblock.
379		*
380	<	* A third form (implemented in tryRemoveAndExec and
381	<	* tryPollForAndExec) amounts to helping a hypothetical
382	<	* compensator: If we can readily tell that a possible action of a
383	<	* compensator is to steal and execute the task being joined, the
384	<	* joining thread can do so directly, without the need for a
385	<	* compensation thread (although at the expense of larger run-time
386	<	* stacks, but the tradeoff is typically worthwhile).
380	>	* A third form (implemented in tryRemoveAndExec) amounts to
381	>	* helping a hypothetical compensator: If we can readily tell that
382	>	* a possible action of a compensator is to steal and execute the
383	>	* task being joined, the joining thread can do so directly,
384	>	* without the need for a compensation thread (although at the
385	>	* expense of larger run-time stacks, but the tradeoff is
386	>	* typically worthwhile).
387		*
388		* The ManagedBlocker extension API can't use helping so relies
389		* only on compensation in method awaitBlocker.
#	Line 380 \| Line 405 \| public class ForkJoinPool extends Abstra
405		* steals, rather than use per-task bookkeeping. This sometimes
406		* requires a linear scan of workQueues array to locate stealers,
407		* but often doesn't because stealers leave hints (that may become
408	<	* stale/wrong) of where to locate them. A stealHint is only a
409	<	* hint because a worker might have had multiple steals and the
410	<	* hint records only one of them (usually the most current).
411	<	* Hinting isolates cost to when it is needed, rather than adding
412	<	* to per-task overhead. (2) It is "shallow", ignoring nesting
413	<	* and potentially cyclic mutual steals. (3) It is intentionally
408	>	* stale/wrong) of where to locate them. It is only a hint
409	>	* because a worker might have had multiple steals and the hint
410	>	* records only one of them (usually the most current). Hinting
411	>	* isolates cost to when it is needed, rather than adding to
412	>	* per-task overhead. (2) It is "shallow", ignoring nesting and
413	>	* potentially cyclic mutual steals. (3) It is intentionally
414		* racy: field currentJoin is updated only while actively joining,
415		* which means that we miss links in the chain during long-lived
416		* tasks, GC stalls etc (which is OK since blocking in such cases
#	Line 393 \| Line 418 \| public class ForkJoinPool extends Abstra
418		* to find work (see MAX_HELP) and fall back to suspending the
419		* worker and if necessary replacing it with another.
420		*
421	+	* Helping actions for CountedCompleters are much simpler: Method
422	+	* helpComplete can take and execute any task with the same root
423	+	* as the task being waited on. However, this still entails some
424	+	* traversal of completer chains, so is less efficient than using
425	+	* CountedCompleters without explicit joins.
426	+	*
427		* It is impossible to keep exactly the target parallelism number
428		* of threads running at any given time. Determining the
429		* existence of conservatively safe helping targets, the
#	Line 414 \| Line 445 \| public class ForkJoinPool extends Abstra
445		* intractable) game with an opponent that may choose the worst
446		* (for us) active thread to stall at any time. We take several
447		* precautions to bound losses (and thus bound gains), mainly in
448	<	* methods tryCompensate and awaitJoin: (1) We only try
449	<	* compensation after attempting enough helping steps (measured
450	<	* via counting and timing) that we have already consumed the
451	<	* estimated cost of creating and activating a new thread. (2) We
452	<	* allow up to 50% of threads to be blocked before initially
453	<	* adding any others, and unless completely saturated, check that
454	<	* some work is available for a new worker before adding. Also, we
455	<	* create up to only 50% more threads until entering a mode that
456	<	* only adds a thread if all others are possibly blocked. All
457	<	* together, this means that we might be half as fast to react,
458	<	* and create half as many threads as possible in the ideal case,
459	<	* but present vastly fewer anomalies in all other cases compared
460	<	* to both more aggressive and more conservative alternatives.
461	<	*
462	<	* Style notes: There is a lot of representation-level coupling
463	<	* among classes ForkJoinPool, ForkJoinWorkerThread, and
464	<	* ForkJoinTask. The fields of WorkQueue maintain data structures
465	<	* managed by ForkJoinPool, so are directly accessed. There is
466	<	* little point trying to reduce this, since any associated future
467	<	* changes in representations will need to be accompanied by
468	<	* algorithmic changes anyway. Several methods intrinsically
469	<	* sprawl because they must accumulate sets of consistent reads of
470	<	* volatiles held in local variables. Methods signalWork() and
471	<	* scan() are the main bottlenecks, so are especially heavily
448	>	* methods tryCompensate and awaitJoin.
449	>	*
450	>	* Common Pool
451	>	* ===========
452	>	*
453	>	* The static common pool always exists after static
454	>	* initialization. Since it (or any other created pool) need
455	>	* never be used, we minimize initial construction overhead and
456	>	* footprint to the setup of about a dozen fields, with no nested
457	>	* allocation. Most bootstrapping occurs within method
458	>	* fullExternalPush during the first submission to the pool.
459	>	*
460	>	* When external threads submit to the common pool, they can
461	>	* perform subtask processing (see externalHelpJoin and related
462	>	* methods). This caller-helps policy makes it sensible to set
463	>	* common pool parallelism level to one (or more) less than the
464	>	* total number of available cores, or even zero for pure
465	>	* caller-runs. We do not need to record whether external
466	>	* submissions are to the common pool -- if not, externalHelpJoin
467	>	* returns quickly (at the most helping to signal some common pool
468	>	* workers). These submitters would otherwise be blocked waiting
469	>	* for completion, so the extra effort (with liberally sprinkled
470	>	* task status checks) in inapplicable cases amounts to an odd
471	>	* form of limited spin-wait before blocking in ForkJoinTask.join.
472	>	*
473	>	* Style notes
474	>	* ===========
475	>	*
476	>	* There is a lot of representation-level coupling among classes
477	>	* ForkJoinPool, ForkJoinWorkerThread, and ForkJoinTask. The
478	>	* fields of WorkQueue maintain data structures managed by
479	>	* ForkJoinPool, so are directly accessed. There is little point
480	>	* trying to reduce this, since any associated future changes in
481	>	* representations will need to be accompanied by algorithmic
482	>	* changes anyway. Several methods intrinsically sprawl because
483	>	* they must accumulate sets of consistent reads of volatiles held
484	>	* in local variables. Methods signalWork() and scan() are the
485	>	* main bottlenecks, so are especially heavily
486		* micro-optimized/mangled. There are lots of inline assignments
487		* (of form "while ((local = field) != 0)") which are usually the
488		* simplest way to ensure the required read orderings (which are
#	Line 445 \| Line 490 \| public class ForkJoinPool extends Abstra
490		* declarations of these locals at the heads of methods or blocks.
491		* There are several occurrences of the unusual "do {} while
492		* (!cas...)" which is the simplest way to force an update of a
493	<	* CAS'ed variable. There are also other coding oddities that help
493	>	* CAS'ed variable. There are also other coding oddities (including
494	>	* several unnecessary-looking hoisted null checks) that help
495		* some methods perform reasonably even when interpreted (not
496		* compiled).
497		*
#	Line 486 \| Line 532 \| public class ForkJoinPool extends Abstra
532		*
533		* @param pool the pool this thread works in
534		* @throws NullPointerException if the pool is null
535	+	* @return the new worker thread
536		*/
537		public ForkJoinWorkerThread newThread(ForkJoinPool pool);
538		}
#	Line 494 \| Line 541 \| public class ForkJoinPool extends Abstra
541		* Default ForkJoinWorkerThreadFactory implementation; creates a
542		* new ForkJoinWorkerThread.
543		*/
544	<	static class DefaultForkJoinWorkerThreadFactory
544	>	static final class DefaultForkJoinWorkerThreadFactory
545		implements ForkJoinWorkerThreadFactory {
546	<	public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
546	>	public final ForkJoinWorkerThread newThread(ForkJoinPool pool) {
547		return new ForkJoinWorkerThread(pool);
548		}
549		}
#	Line 508 \| Line 555 \| public class ForkJoinPool extends Abstra
555		* actually do anything beyond having a unique identity.
556		*/
557		static final class EmptyTask extends ForkJoinTask<Void> {
558	+	private static final long serialVersionUID = -7721805057305804111L;
559		EmptyTask() { status = ForkJoinTask.NORMAL; } // force done
560		public final Void getRawResult() { return null; }
561		public final void setRawResult(Void x) {}
#	Line 528 \| Line 576 \| public class ForkJoinPool extends Abstra
576		*
577		* Field "top" is the index (mod array.length) of the next queue
578		* slot to push to or pop from. It is written only by owner thread
579	<	* for push, or under lock for trySharedPush, and accessed by
580	<	* other threads only after reading (volatile) base. Both top and
581	<	* base are allowed to wrap around on overflow, but (top - base)
582	<	* (or more commonly -(base - top) to force volatile read of base
583	<	* before top) still estimates size.
579	>	* for push, or under lock for external/shared push, and accessed
580	>	* by other threads only after reading (volatile) base. Both top
581	>	* and base are allowed to wrap around on overflow, but (top -
582	>	* base) (or more commonly -(base - top) to force volatile read of
583	>	* base before top) still estimates size. The lock ("qlock") is
584	>	* forced to -1 on termination, causing all further lock attempts
585	>	* to fail. (Note: we don't need CAS for termination state because
586	>	* upon pool shutdown, all shared-queues will stop being used
587	>	* anyway.) Nearly all lock bodies are set up so that exceptions
588	>	* within lock bodies are "impossible" (modulo JVM errors that
589	>	* would cause failure anyway.)
590		*
591		* The array slots are read and written using the emulation of
592		* volatiles/atomics provided by Unsafe. Insertions must in
593		* general use putOrderedObject as a form of releasing store to
594		* ensure that all writes to the task object are ordered before
595	<	* its publication in the queue. (Although we can avoid one case
596	<	* of this when locked in trySharedPush.) All removals entail a
597	<	* CAS to null. The array is always a power of two. To ensure
598	<	* safety of Unsafe array operations, all accesses perform
545	<	* explicit null checks and implicit bounds checks via
546	<	* power-of-two masking.
595	>	* its publication in the queue. All removals entail a CAS to
596	>	* null. The array is always a power of two. To ensure safety of
597	>	* Unsafe array operations, all accesses perform explicit null
598	>	* checks and implicit bounds checks via power-of-two masking.
599		*
600		* In addition to basic queuing support, this class contains
601		* fields described elsewhere to control execution. It turns out
602	<	* to work better memory-layout-wise to include them in this
603	<	* class rather than a separate class.
602	>	* to work better memory-layout-wise to include them in this class
603	>	* rather than a separate class.
604		*
605		* Performance on most platforms is very sensitive to placement of
606		* instances of both WorkQueues and their arrays -- we absolutely
607		* do not want multiple WorkQueue instances or multiple queue
608		* arrays sharing cache lines. (It would be best for queue objects
609		* and their arrays to share, but there is nothing available to
610	<	* help arrange that). Unfortunately, because they are recorded
611	<	* in a common array, WorkQueue instances are often moved to be
560	<	* adjacent by garbage collectors. To reduce impact, we use field
561	<	* padding that works OK on common platforms; this effectively
562	<	* trades off slightly slower average field access for the sake of
563	<	* avoiding really bad worst-case access. (Until better JVM
564	<	* support is in place, this padding is dependent on transient
565	<	* properties of JVM field layout rules.) We also take care in
566	<	* allocating, sizing and resizing the array. Non-shared queue
567	<	* arrays are initialized (via method growArray) by workers before
568	<	* use. Others are allocated on first use.
610	>	* help arrange that). The @Contended annotation alerts JVMs to
611	>	* try to keep instances apart.
612		*/
613		static final class WorkQueue {
614		/**
#	Line 588 \| Line 631 \| public class ForkJoinPool extends Abstra
631		*/
632		static final int MAXIMUM_QUEUE_CAPACITY = 1 << 26; // 64M
633
634	<	volatile long totalSteals; // cumulative number of steals
635	<	int seed; // for random scanning; initialize nonzero
634	>	// Heuristic padding to ameliorate unfortunate memory placements
635	>	volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
636	>
637		volatile int eventCount; // encoded inactivation count; < 0 if inactive
638		int nextWait; // encoded record of next event waiter
639	<	int rescans; // remaining scans until block
640	<	int nsteals; // top-level task executions since last idle
641	<	final int mode; // lifo, fifo, or shared
642	<	int poolIndex; // index of this queue in pool (or 0)
643	<	int stealHint; // index of most recent known stealer
600	<	volatile int runState; // 1: locked, -1: terminate; else 0
639	>	int nsteals; // number of steals
640	>	int hint; // steal index hint
641	>	short poolIndex; // index of this queue in pool
642	>	final short mode; // 0: lifo, > 0: fifo, < 0: shared
643	>	volatile int qlock; // 1: locked, -1: terminate; else 0
644		volatile int base; // index of next slot for poll
645		int top; // index of next slot for push
646		ForkJoinTask<?>[] array; // the elements (initially unallocated)
#	Line 606 \| Line 649 \| public class ForkJoinPool extends Abstra
649		volatile Thread parker; // == owner during call to park; else null
650		volatile ForkJoinTask<?> currentJoin; // task being joined in awaitJoin
651		ForkJoinTask<?> currentSteal; // current non-local task being executed
609	–	// Heuristic padding to ameliorate unfortunate memory placements
610	–	Object p00, p01, p02, p03, p04, p05, p06, p07;
611	–	Object p08, p09, p0a, p0b, p0c, p0d, p0e;
652
653	<	WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode) {
654	<	this.mode = mode;
653	>	volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17;
654	>	volatile Object pad18, pad19, pad1a, pad1b, pad1c, pad1d;
655	>
656	>	WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode,
657	>	int seed) {
658		this.pool = pool;
659		this.owner = owner;
660	+	this.mode = (short)mode;
661	+	this.hint = seed; // store initial seed for runWorker
662		// Place indices in the center of array (that is not yet allocated)
663		base = top = INITIAL_QUEUE_CAPACITY >>> 1;
664		}
#	Line 638 \| Line 683 \| public class ForkJoinPool extends Abstra
683		(n == -1 &&
684		((a = array) == null \|\|
685		(m = a.length - 1) < 0 \|\|
686	<	U.getObjectVolatile
687	<	(a, ((m & (s - 1)) << ASHIFT) + ABASE) == null)));
686	>	U.getObject
687	>	(a, (long)((m & (s - 1)) << ASHIFT) + ABASE) == null)));
688		}
689
690		/**
691	<	* Pushes a task. Call only by owner in unshared queues.
691	>	* Pushes a task. Call only by owner in unshared queues. (The
692	>	* shared-queue version is embedded in method externalPush.)
693		*
694		* @param task the task. Caller must ensure non-null.
695	<	* @throw RejectedExecutionException if array cannot be resized
695	>	* @throws RejectedExecutionException if array cannot be resized
696		*/
697		final void push(ForkJoinTask<?> task) {
698		ForkJoinTask<?>[] a; ForkJoinPool p;
699	<	int s = top, m, n;
699	>	int s = top, n;
700		if ((a = array) != null) { // ignore if queue removed
701	<	U.putOrderedObject
702	<	(a, (((m = a.length - 1) & s) << ASHIFT) + ABASE, task);
703	<	if ((n = (top = s + 1) - base) <= 2) {
704	<	if ((p = pool) != null)
659	<	p.signalWork();
660	<	}
701	>	int m = a.length - 1;
702	>	U.putOrderedObject(a, ((m & s) << ASHIFT) + ABASE, task);
703	>	if ((n = (top = s + 1) - base) <= 2)
704	>	(p = pool).signalWork(p.workQueues, this);
705		else if (n >= m)
706	<	growArray(true);
706	>	growArray();
707		}
708		}
709
710		/**
711	<	* Pushes a task if lock is free and array is either big
712	<	* enough or can be resized to be big enough.
713	<	*
670	<	* @param task the task. Caller must ensure non-null.
671	<	* @return true if submitted
711	>	* Initializes or doubles the capacity of array. Call either
712	>	* by owner or with lock held -- it is OK for base, but not
713	>	* top, to move while resizings are in progress.
714		*/
715	<	final boolean trySharedPush(ForkJoinTask<?> task) {
716	<	boolean submitted = false;
717	<	if (runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
718	<	ForkJoinTask<?>[] a = array;
719	<	int s = top;
720	<	try {
721	<	if ((a != null && a.length > s + 1 - base) \|\|
722	<	(a = growArray(false)) != null) { // must presize
723	<	int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
724	<	U.putObject(a, (long)j, task); // don't need "ordered"
725	<	top = s + 1;
726	<	submitted = true;
727	<	}
728	<	} finally {
729	<	runState = 0; // unlock
730	<	}
715	>	final ForkJoinTask<?>[] growArray() {
716	>	ForkJoinTask<?>[] oldA = array;
717	>	int size = oldA != null ? oldA.length << 1 : INITIAL_QUEUE_CAPACITY;
718	>	if (size > MAXIMUM_QUEUE_CAPACITY)
719	>	throw new RejectedExecutionException("Queue capacity exceeded");
720	>	int oldMask, t, b;
721	>	ForkJoinTask<?>[] a = array = new ForkJoinTask<?>[size];
722	>	if (oldA != null && (oldMask = oldA.length - 1) >= 0 &&
723	>	(t = top) - (b = base) > 0) {
724	>	int mask = size - 1;
725	>	do {
726	>	ForkJoinTask<?> x;
727	>	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
728	>	int j = ((b & mask) << ASHIFT) + ABASE;
729	>	x = (ForkJoinTask<?>)U.getObjectVolatile(oldA, oldj);
730	>	if (x != null &&
731	>	U.compareAndSwapObject(oldA, oldj, x, null))
732	>	U.putObjectVolatile(a, j, x);
733	>	} while (++b != t);
734		}
735	<	return submitted;
735	>	return a;
736		}
737
738		/**
#	Line 710 \| Line 755 \| public class ForkJoinPool extends Abstra
755		return null;
756		}
757
713	–	final ForkJoinTask<?> sharedPop() {
714	–	ForkJoinTask<?> task = null;
715	–	if (runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
716	–	try {
717	–	ForkJoinTask<?>[] a; int m;
718	–	if ((a = array) != null && (m = a.length - 1) >= 0) {
719	–	for (int s; (s = top - 1) - base >= 0;) {
720	–	long j = ((m & s) << ASHIFT) + ABASE;
721	–	ForkJoinTask<?> t =
722	–	(ForkJoinTask<?>)U.getObject(a, j);
723	–	if (t == null)
724	–	break;
725	–	if (U.compareAndSwapObject(a, j, t, null)) {
726	–	top = s;
727	–	task = t;
728	–	break;
729	–	}
730	–	}
731	–	}
732	–	} finally {
733	–	runState = 0;
734	–	}
735	–	}
736	–	return task;
737	–	}
738	–
739	–	/**
740	–	* Version of pop that takes top element only if it
741	–	* its root is the given CountedCompleter.
742	–	*/
743	–	final ForkJoinTask<?> popCC(CountedCompleter<?> root) {
744	–	ForkJoinTask<?>[] a; int m;
745	–	if (root != null && (a = array) != null && (m = a.length - 1) >= 0) {
746	–	for (int s; (s = top - 1) - base >= 0;) {
747	–	long j = ((m & s) << ASHIFT) + ABASE;
748	–	ForkJoinTask<?> t =
749	–	(ForkJoinTask<?>)U.getObject(a, j);
750	–	if (t == null \|\| !(t instanceof CountedCompleter) \|\|
751	–	((CountedCompleter<?>)t).getRoot() != root)
752	–	break;
753	–	if (U.compareAndSwapObject(a, j, t, null)) {
754	–	top = s;
755	–	return t;
756	–	}
757	–	if (root.status < 0)
758	–	break;
759	–	}
760	–	}
761	–	return null;
762	–	}
763	–
764	–	/**
765	–	* Shared version of popCC
766	–	*/
767	–	final ForkJoinTask<?> sharedPopCC(CountedCompleter<?> root) {
768	–	ForkJoinTask<?> task = null;
769	–	if (root != null &&
770	–	runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
771	–	try {
772	–	ForkJoinTask<?>[] a; int m;
773	–	if ((a = array) != null && (m = a.length - 1) >= 0) {
774	–	for (int s; (s = top - 1) - base >= 0;) {
775	–	long j = ((m & s) << ASHIFT) + ABASE;
776	–	ForkJoinTask<?> t =
777	–	(ForkJoinTask<?>)U.getObject(a, j);
778	–	if (t == null \|\| !(t instanceof CountedCompleter) \|\|
779	–	((CountedCompleter<?>)t).getRoot() != root)
780	–	break;
781	–	if (U.compareAndSwapObject(a, j, t, null)) {
782	–	top = s;
783	–	task = t;
784	–	break;
785	–	}
786	–	if (root.status < 0)
787	–	break;
788	–	}
789	–	}
790	–	} finally {
791	–	runState = 0;
792	–	}
793	–	}
794	–	return task;
795	–	}
796	–
758		/**
759		* Takes a task in FIFO order if b is base of queue and a task
760		* can be claimed without contention. Specialized versions
#	Line 804 \| Line 765 \| public class ForkJoinPool extends Abstra
765		if ((a = array) != null) {
766		int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
767		if ((t = (ForkJoinTask<?>)U.getObjectVolatile(a, j)) != null &&
768	<	base == b &&
769	<	U.compareAndSwapObject(a, j, t, null)) {
809	<	base = b + 1;
768	>	base == b && U.compareAndSwapObject(a, j, t, null)) {
769	>	U.putOrderedInt(this, QBASE, b + 1);
770		return t;
771		}
772		}
#	Line 822 \| Line 782 \| public class ForkJoinPool extends Abstra
782		int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
783		t = (ForkJoinTask<?>)U.getObjectVolatile(a, j);
784		if (t != null) {
785	<	if (base == b &&
786	<	U.compareAndSwapObject(a, j, t, null)) {
827	<	base = b + 1;
785	>	if (U.compareAndSwapObject(a, j, t, null)) {
786	>	U.putOrderedInt(this, QBASE, b + 1);
787		return t;
788		}
789		}
790		else if (base == b) {
791		if (b + 1 == top)
792		break;
793	<	Thread.yield(); // wait for lagging update
793	>	Thread.yield(); // wait for lagging update (very rare)
794		}
795		}
796		return null;
#	Line 858 \| Line 817 \| public class ForkJoinPool extends Abstra
817
818		/**
819		* Pops the given task only if it is at the current top.
820	+	* (A shared version is available only via FJP.tryExternalUnpush)
821		*/
822		final boolean tryUnpush(ForkJoinTask<?> t) {
823		ForkJoinTask<?>[] a; int s;
#	Line 871 \| Line 831 \| public class ForkJoinPool extends Abstra
831		}
832
833		/**
874	–	* Version of tryUnpush for shared queues; called by non-FJ
875	–	* submitters after prechecking that task probably exists.
876	–	*/
877	–	final boolean trySharedUnpush(ForkJoinTask<?> t) {
878	–	boolean success = false;
879	–	if (runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
880	–	try {
881	–	ForkJoinTask<?>[] a; int s;
882	–	if ((a = array) != null && (s = top) != base &&
883	–	U.compareAndSwapObject
884	–	(a, (((a.length - 1) & --s) << ASHIFT) + ABASE, t, null)) {
885	–	top = s;
886	–	success = true;
887	–	}
888	–	} finally {
889	–	runState = 0; // unlock
890	–	}
891	–	}
892	–	return success;
893	–	}
894	–
895	–	/**
896	–	* Polls the given task only if it is at the current base.
897	–	*/
898	–	final boolean pollFor(ForkJoinTask<?> task) {
899	–	ForkJoinTask<?>[] a; int b;
900	–	if ((b = base) - top < 0 && (a = array) != null) {
901	–	int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
902	–	if (U.getObjectVolatile(a, j) == task && base == b &&
903	–	U.compareAndSwapObject(a, j, task, null)) {
904	–	base = b + 1;
905	–	return true;
906	–	}
907	–	}
908	–	return false;
909	–	}
910	–
911	–	/**
912	–	* Initializes or doubles the capacity of array. Call either
913	–	* by owner or with lock held -- it is OK for base, but not
914	–	* top, to move while resizings are in progress.
915	–	*
916	–	* @param rejectOnFailure if true, throw exception if capacity
917	–	* exceeded (relayed ultimately to user); else return null.
918	–	*/
919	–	final ForkJoinTask<?>[] growArray(boolean rejectOnFailure) {
920	–	ForkJoinTask<?>[] oldA = array;
921	–	int size = oldA != null ? oldA.length << 1 : INITIAL_QUEUE_CAPACITY;
922	–	if (size <= MAXIMUM_QUEUE_CAPACITY) {
923	–	int oldMask, t, b;
924	–	ForkJoinTask<?>[] a = array = new ForkJoinTask<?>[size];
925	–	if (oldA != null && (oldMask = oldA.length - 1) >= 0 &&
926	–	(t = top) - (b = base) > 0) {
927	–	int mask = size - 1;
928	–	do {
929	–	ForkJoinTask<?> x;
930	–	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
931	–	int j = ((b & mask) << ASHIFT) + ABASE;
932	–	x = (ForkJoinTask<?>)U.getObjectVolatile(oldA, oldj);
933	–	if (x != null &&
934	–	U.compareAndSwapObject(oldA, oldj, x, null))
935	–	U.putObjectVolatile(a, j, x);
936	–	} while (++b != t);
937	–	}
938	–	return a;
939	–	}
940	–	else if (!rejectOnFailure)
941	–	return null;
942	–	else
943	–	throw new RejectedExecutionException("Queue capacity exceeded");
944	–	}
945	–
946	–	/**
834		* Removes and cancels all known tasks, ignoring any exceptions.
835		*/
836		final void cancelAll() {
#	Line 953 \| Line 840 \| public class ForkJoinPool extends Abstra
840		ForkJoinTask.cancelIgnoringExceptions(t);
841		}
842
843	<	/**
957	<	* Computes next value for random probes. Scans don't require
958	<	* a very high quality generator, but also not a crummy one.
959	<	* Marsaglia xor-shift is cheap and works well enough. Note:
960	<	* This is manually inlined in its usages in ForkJoinPool to
961	<	* avoid writes inside busy scan loops.
962	<	*/
963	<	final int nextSeed() {
964	<	int r = seed;
965	<	r ^= r << 13;
966	<	r ^= r >>> 17;
967	<	return seed = r ^= r << 5;
968	<	}
969	<
970	<	// Execution methods
971	<
972	<	/**
973	<	* Pops and runs tasks until empty.
974	<	*/
975	<	private void popAndExecAll() {
976	<	// A bit faster than repeated pop calls
977	<	ForkJoinTask<?>[] a; int m, s; long j; ForkJoinTask<?> t;
978	<	while ((a = array) != null && (m = a.length - 1) >= 0 &&
979	<	(s = top - 1) - base >= 0 &&
980	<	(t = ((ForkJoinTask<?>)
981	<	U.getObject(a, j = ((m & s) << ASHIFT) + ABASE)))
982	<	!= null) {
983	<	if (U.compareAndSwapObject(a, j, t, null)) {
984	<	top = s;
985	<	t.doExec();
986	<	}
987	<	}
988	<	}
843	>	// Specialized execution methods
844
845		/**
846		* Polls and runs tasks until empty.
847		*/
848	<	private void pollAndExecAll() {
848	>	final void pollAndExecAll() {
849		for (ForkJoinTask<?> t; (t = poll()) != null;)
850		t.doExec();
851		}
852
853		/**
854	<	* If present, removes from queue and executes the given task, or
855	<	* any other cancelled task. Returns (true) immediately on any CAS
854	>	* Executes a top-level task and any local tasks remaining
855	>	* after execution.
856	>	*/
857	>	final void runTask(ForkJoinTask<?> task) {
858	>	if ((currentSteal = task) != null) {
859	>	task.doExec();
860	>	ForkJoinTask<?>[] a = array;
861	>	int md = mode;
862	>	++nsteals;
863	>	currentSteal = null;
864	>	if (md != 0)
865	>	pollAndExecAll();
866	>	else if (a != null) {
867	>	int s, m = a.length - 1;
868	>	while ((s = top - 1) - base >= 0) {
869	>	long i = ((m & s) << ASHIFT) + ABASE;
870	>	ForkJoinTask<?> t = (ForkJoinTask<?>)U.getObject(a, i);
871	>	if (t == null)
872	>	break;
873	>	if (U.compareAndSwapObject(a, i, t, null)) {
874	>	top = s;
875	>	t.doExec();
876	>	}
877	>	}
878	>	}
879	>	}
880	>	}
881	>
882	>	/**
883	>	* If present, removes from queue and executes the given task,
884	>	* or any other cancelled task. Returns (true) on any CAS
885		* or consistency check failure so caller can retry.
886		*
887	<	* @return 0 if no progress can be made, else positive
1004	<	* (this unusual convention simplifies use with tryHelpStealer.)
887	>	* @return false if no progress can be made, else true
888		*/
889	<	final int tryRemoveAndExec(ForkJoinTask<?> task) {
890	<	int stat = 1;
1008	<	boolean removed = false, empty = true;
889	>	final boolean tryRemoveAndExec(ForkJoinTask<?> task) {
890	>	boolean stat;
891		ForkJoinTask<?>[] a; int m, s, b, n;
892	<	if ((a = array) != null && (m = a.length - 1) >= 0 &&
892	>	if (task != null && (a = array) != null && (m = a.length - 1) >= 0 &&
893		(n = (s = top) - (b = base)) > 0) {
894	+	boolean removed = false, empty = true;
895	+	stat = true;
896		for (ForkJoinTask<?> t;;) { // traverse from s to b
897	<	int j = ((--s & m) << ASHIFT) + ABASE;
898	<	t = (ForkJoinTask<?>)U.getObjectVolatile(a, j);
897	>	long j = ((--s & m) << ASHIFT) + ABASE;
898	>	t = (ForkJoinTask<?>)U.getObject(a, j);
899		if (t == null) // inconsistent length
900		break;
901		else if (t == task) {
#	Line 1035 \| Line 919 \| public class ForkJoinPool extends Abstra
919		}
920		if (--n == 0) {
921		if (!empty && base == b)
922	<	stat = 0;
922	>	stat = false;
923		break;
924		}
925		}
926	+	if (removed)
927	+	task.doExec();
928		}
929	<	if (removed)
930	<	task.doExec();
929	>	else
930	>	stat = false;
931		return stat;
932		}
933
934		/**
935	<	* Executes a top-level task and any local tasks remaining
936	<	* after execution.
935	>	* Tries to poll for and execute the given task or any other
936	>	* task in its CountedCompleter computation.
937		*/
938	<	final void runTask(ForkJoinTask<?> t) {
939	<	if (t != null) {
940	<	currentSteal = t;
941	<	t.doExec();
942	<	if (top != base) { // process remaining local tasks
943	<	if (mode == 0)
944	<	popAndExecAll();
945	<	else
946	<	pollAndExecAll();
938	>	final boolean pollAndExecCC(CountedCompleter<?> root) {
939	>	ForkJoinTask<?>[] a; int b; Object o; CountedCompleter<?> t, r;
940	>	if ((b = base) - top < 0 && (a = array) != null) {
941	>	long j = (((a.length - 1) & b) << ASHIFT) + ABASE;
942	>	if ((o = U.getObjectVolatile(a, j)) == null)
943	>	return true; // retry
944	>	if (o instanceof CountedCompleter) {
945	>	for (t = (CountedCompleter<?>)o, r = t;;) {
946	>	if (r == root) {
947	>	if (base == b &&
948	>	U.compareAndSwapObject(a, j, t, null)) {
949	>	U.putOrderedInt(this, QBASE, b + 1);
950	>	t.doExec();
951	>	}
952	>	return true;
953	>	}
954	>	else if ((r = r.completer) == null)
955	>	break; // not part of root computation
956	>	}
957		}
1062	–	++nsteals;
1063	–	currentSteal = null;
958		}
959	+	return false;
960		}
961
962		/**
963	<	* Executes a non-top-level (stolen) task.
963	>	* Tries to pop and execute the given task or any other task
964	>	* in its CountedCompleter computation.
965		*/
966	<	final void runSubtask(ForkJoinTask<?> t) {
967	<	if (t != null) {
968	<	ForkJoinTask<?> ps = currentSteal;
969	<	currentSteal = t;
970	<	t.doExec();
971	<	currentSteal = ps;
966	>	final boolean externalPopAndExecCC(CountedCompleter<?> root) {
967	>	ForkJoinTask<?>[] a; int s; Object o; CountedCompleter<?> t, r;
968	>	if (base - (s = top) < 0 && (a = array) != null) {
969	>	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
970	>	if ((o = U.getObject(a, j)) instanceof CountedCompleter) {
971	>	for (t = (CountedCompleter<?>)o, r = t;;) {
972	>	if (r == root) {
973	>	if (U.compareAndSwapInt(this, QLOCK, 0, 1)) {
974	>	if (top == s && array == a &&
975	>	U.compareAndSwapObject(a, j, t, null)) {
976	>	top = s - 1;
977	>	qlock = 0;
978	>	t.doExec();
979	>	}
980	>	else
981	>	qlock = 0;
982	>	}
983	>	return true;
984	>	}
985	>	else if ((r = r.completer) == null)
986	>	break;
987	>	}
988	>	}
989	>	}
990	>	return false;
991	>	}
992	>
993	>	/**
994	>	* Internal version
995	>	*/
996	>	final boolean internalPopAndExecCC(CountedCompleter<?> root) {
997	>	ForkJoinTask<?>[] a; int s; Object o; CountedCompleter<?> t, r;
998	>	if (base - (s = top) < 0 && (a = array) != null) {
999	>	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
1000	>	if ((o = U.getObject(a, j)) instanceof CountedCompleter) {
1001	>	for (t = (CountedCompleter<?>)o, r = t;;) {
1002	>	if (r == root) {
1003	>	if (U.compareAndSwapObject(a, j, t, null)) {
1004	>	top = s - 1;
1005	>	t.doExec();
1006	>	}
1007	>	return true;
1008	>	}
1009	>	else if ((r = r.completer) == null)
1010	>	break;
1011	>	}
1012	>	}
1013		}
1014	+	return false;
1015		}
1016
1017		/**
#	Line 1088 \| Line 1026 \| public class ForkJoinPool extends Abstra
1026		s != Thread.State.TIMED_WAITING);
1027		}
1028
1091	–	/**
1092	–	* If this owned and is not already interrupted, try to
1093	–	* interrupt and/or unpark, ignoring exceptions.
1094	–	*/
1095	–	final void interruptOwner() {
1096	–	Thread wt, p;
1097	–	if ((wt = owner) != null && !wt.isInterrupted()) {
1098	–	try {
1099	–	wt.interrupt();
1100	–	} catch (SecurityException ignore) {
1101	–	}
1102	–	}
1103	–	if ((p = parker) != null)
1104	–	U.unpark(p);
1105	–	}
1106	–
1029		// Unsafe mechanics
1030		private static final sun.misc.Unsafe U;
1031	<	private static final long RUNSTATE;
1031	>	private static final long QBASE;
1032	>	private static final long QLOCK;
1033		private static final int ABASE;
1034		private static final int ASHIFT;
1035		static {
1113	–	int s;
1036		try {
1037		U = getUnsafe();
1038		Class<?> k = WorkQueue.class;
1039		Class<?> ak = ForkJoinTask[].class;
1040	<	RUNSTATE = U.objectFieldOffset
1041	<	(k.getDeclaredField("runState"));
1040	>	QBASE = U.objectFieldOffset
1041	>	(k.getDeclaredField("base"));
1042	>	QLOCK = U.objectFieldOffset
1043	>	(k.getDeclaredField("qlock"));
1044		ABASE = U.arrayBaseOffset(ak);
1045	<	s = U.arrayIndexScale(ak);
1045	>	int scale = U.arrayIndexScale(ak);
1046	>	if ((scale & (scale - 1)) != 0)
1047	>	throw new Error("data type scale not a power of two");
1048	>	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
1049		} catch (Exception e) {
1050		throw new Error(e);
1051		}
1125	–	if ((s & (s-1)) != 0)
1126	–	throw new Error("data type scale not a power of two");
1127	–	ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
1052		}
1053		}
1054
1055	+	// static fields (initialized in static initializer below)
1056	+
1057		/**
1058	<	* Per-thread records for threads that submit to pools. Currently
1059	<	* holds only pseudo-random seed / index that is used to choose
1060	<	* submission queues in method doSubmit. In the future, this may
1061	<	* also incorporate a means to implement different task rejection
1062	<	* and resubmission policies.
1137	<	*
1138	<	* Seeds for submitters and workers/workQueues work in basically
1139	<	* the same way but are initialized and updated using slightly
1140	<	* different mechanics. Both are initialized using the same
1141	<	* approach as in class ThreadLocal, where successive values are
1142	<	* unlikely to collide with previous values. This is done during
1143	<	* registration for workers, but requires a separate AtomicInteger
1144	<	* for submitters. Seeds are then randomly modified upon
1145	<	* collisions using xorshifts, which requires a non-zero seed.
1058	>	* Per-thread submission bookkeeping. Shared across all pools
1059	>	* to reduce ThreadLocal pollution and because random motion
1060	>	* to avoid contention in one pool is likely to hold for others.
1061	>	* Lazily initialized on first submission (but null-checked
1062	>	* in other contexts to avoid unnecessary initialization).
1063		*/
1064	<	static final class Submitter {
1148	<	int seed;
1149	<	Submitter() {
1150	<	int s = nextSubmitterSeed.getAndAdd(SEED_INCREMENT);
1151	<	seed = (s == 0) ? 1 : s; // ensure non-zero
1152	<	}
1153	<	}
1154	<
1155	<	/** ThreadLocal class for Submitters */
1156	<	static final class ThreadSubmitter extends ThreadLocal<Submitter> {
1157	<	public Submitter initialValue() { return new Submitter(); }
1158	<	}
1159	<
1160	<	// static fields (initialized in static initializer below)
1064	>	static final ThreadLocal<Submitter> submitters;
1065
1066		/**
1067		* Creates a new ForkJoinWorkerThread. This factory is used unless
#	Line 1166 \| Line 1070 \| public class ForkJoinPool extends Abstra
1070		public static final ForkJoinWorkerThreadFactory
1071		defaultForkJoinWorkerThreadFactory;
1072
1169	–
1170	–	/** Property prefix for constructing common pool */
1171	–	private static final String propPrefix =
1172	–	"java.util.concurrent.ForkJoinPool.common.";
1173	–
1174	–	/**
1175	–	* Common (static) pool. Non-null for public use unless a static
1176	–	* construction exception, but internal usages must null-check on
1177	–	* use.
1178	–	*/
1179	–	static final ForkJoinPool commonPool;
1180	–
1073		/**
1074	<	* Common pool parallelism. Must equal commonPool.parallelism.
1074	>	* Permission required for callers of methods that may start or
1075	>	* kill threads.
1076		*/
1077	<	static final int commonPoolParallelism;
1077	>	private static final RuntimePermission modifyThreadPermission;
1078
1079		/**
1080	<	* Generator for assigning sequence numbers as pool names.
1080	>	* Common (static) pool. Non-null for public use unless a static
1081	>	* construction exception, but internal usages null-check on use
1082	>	* to paranoically avoid potential initialization circularities
1083	>	* as well as to simplify generated code.
1084		*/
1085	<	private static final AtomicInteger poolNumberGenerator;
1085	>	static final ForkJoinPool common;
1086
1087		/**
1088	<	* Generator for initial hashes/seeds for submitters. Accessed by
1089	<	* Submitter class constructor.
1088	>	* Common pool parallelism. To allow simpler use and management
1089	>	* when common pool threads are disabled, we allow the underlying
1090	>	* common.parallelism field to be zero, but in that case still report
1091	>	* parallelism as 1 to reflect resulting caller-runs mechanics.
1092		*/
1093	<	static final AtomicInteger nextSubmitterSeed;
1093	>	static final int commonParallelism;
1094
1095		/**
1096	<	* Permission required for callers of methods that may start or
1199	<	* kill threads.
1096	>	* Sequence number for creating workerNamePrefix.
1097		*/
1098	<	private static final RuntimePermission modifyThreadPermission;
1098	>	private static int poolNumberSequence;
1099
1100		/**
1101	<	* Per-thread submission bookkeeping. Shared across all pools
1102	<	* to reduce ThreadLocal pollution and because random motion
1206	<	* to avoid contention in one pool is likely to hold for others.
1101	>	* Returns the next sequence number. We don't expect this to
1102	>	* ever contend, so use simple builtin sync.
1103		*/
1104	<	private static final ThreadSubmitter submitters;
1104	>	private static final synchronized int nextPoolId() {
1105	>	return ++poolNumberSequence;
1106	>	}
1107
1108		// static constants
1109
1110		/**
1111	<	* Initial timeout value (in nanoseconds) for the thread triggering
1112	<	* quiescence to park waiting for new work. On timeout, the thread
1113	<	* will instead try to shrink the number of workers.
1111	>	* Initial timeout value (in nanoseconds) for the thread
1112	>	* triggering quiescence to park waiting for new work. On timeout,
1113	>	* the thread will instead try to shrink the number of
1114	>	* workers. The value should be large enough to avoid overly
1115	>	* aggressive shrinkage during most transient stalls (long GCs
1116	>	* etc).
1117		*/
1118	<	private static final long IDLE_TIMEOUT = 1000L * 1000L * 1000L; // 1sec
1118	>	private static final long IDLE_TIMEOUT = 2000L * 1000L * 1000L; // 2sec
1119
1120		/**
1121		* Timeout value when there are more threads than parallelism level
1122		*/
1123	<	private static final long FAST_IDLE_TIMEOUT = 100L * 1000L * 1000L;
1123	>	private static final long FAST_IDLE_TIMEOUT = 200L * 1000L * 1000L;
1124	>
1125	>	/**
1126	>	* Tolerance for idle timeouts, to cope with timer undershoots
1127	>	*/
1128	>	private static final long TIMEOUT_SLOP = 2000000L;
1129
1130		/**
1131		* The maximum stolen->joining link depth allowed in method
1132	<	* tryHelpStealer. Must be a power of two. This value also
1227	<	* controls the maximum number of times to try to help join a task
1228	<	* without any apparent progress or change in pool state before
1229	<	* giving up and blocking (see awaitJoin). Depths for legitimate
1132	>	* tryHelpStealer. Must be a power of two. Depths for legitimate
1133		* chains are unbounded, but we use a fixed constant to avoid
1134		* (otherwise unchecked) cycles and to bound staleness of
1135		* traversal parameters at the expense of sometimes blocking when
#	Line 1235 \| Line 1138 \| public class ForkJoinPool extends Abstra
1138		private static final int MAX_HELP = 64;
1139
1140		/**
1238	–	* Secondary time-based bound (in nanosecs) for helping attempts
1239	–	* before trying compensated blocking in awaitJoin. Used in
1240	–	* conjunction with MAX_HELP to reduce variance due to different
1241	–	* polling rates associated with different helping options. The
1242	–	* value should roughly approximate the time required to create
1243	–	* and/or activate a worker thread.
1244	–	*/
1245	–	private static final long COMPENSATION_DELAY = 1L << 18; // ~0.25 millisec
1246	–
1247	–	/**
1141		* Increment for seed generators. See class ThreadLocal for
1142		* explanation.
1143		*/
1144		private static final int SEED_INCREMENT = 0x61c88647;
1145
1146	<	/**
1146	>	/*
1147		* Bits and masks for control variables
1148		*
1149		* Field ctl is a long packed with:
#	Line 1278 \| Line 1171 \| public class ForkJoinPool extends Abstra
1171		* scan for them to avoid queuing races. Note however that
1172		* eventCount updates lag releases so usage requires care.
1173		*
1174	<	* Field runState is an int packed with:
1174	>	* Field plock is an int packed with:
1175		* SHUTDOWN: true if shutdown is enabled (1 bit)
1176	<	* SEQ: a sequence number updated upon (de)registering workers (30 bits)
1177	<	* INIT: set true after workQueues array construction (1 bit)
1176	>	* SEQ: a sequence lock, with PL_LOCK bit set if locked (30 bits)
1177	>	* SIGNAL: set when threads may be waiting on the lock (1 bit)
1178		*
1179		* The sequence number enables simple consistency checks:
1180		* Staleness of read-only operations on the workQueues array can
1181	<	* be checked by comparing runState before vs after the reads.
1181	>	* be checked by comparing plock before vs after the reads.
1182		*/
1183
1184		// bit positions/shifts for fields
#	Line 1297 \| Line 1190 \| public class ForkJoinPool extends Abstra
1190		// bounds
1191		private static final int SMASK = 0xffff; // short bits
1192		private static final int MAX_CAP = 0x7fff; // max #workers - 1
1193	<	private static final int SQMASK = 0xfffe; // even short bits
1193	>	private static final int EVENMASK = 0xfffe; // even short bits
1194	>	private static final int SQMASK = 0x007e; // max 64 (even) slots
1195		private static final int SHORT_SIGN = 1 << 15;
1196		private static final int INT_SIGN = 1 << 31;
1197
#	Line 1322 \| Line 1216 \| public class ForkJoinPool extends Abstra
1216		private static final int E_MASK = 0x7fffffff; // no STOP_BIT
1217		private static final int E_SEQ = 1 << EC_SHIFT;
1218
1219	<	// runState bits
1219	>	// plock bits
1220		private static final int SHUTDOWN = 1 << 31;
1221	+	private static final int PL_LOCK = 2;
1222	+	private static final int PL_SIGNAL = 1;
1223	+	private static final int PL_SPINS = 1 << 8;
1224
1225		// access mode for WorkQueue
1226		static final int LIFO_QUEUE = 0;
1227		static final int FIFO_QUEUE = 1;
1228		static final int SHARED_QUEUE = -1;
1229
1230	<	// Instance fields
1231	<
1335	<	/*
1336	<	* Field layout order in this class tends to matter more than one
1337	<	* would like. Runtime layout order is only loosely related to
1338	<	* declaration order and may differ across JVMs, but the following
1339	<	* empirically works OK on current JVMs.
1340	<	*/
1230	>	// Heuristic padding to ameliorate unfortunate memory placements
1231	>	volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
1232
1233	+	// Instance fields
1234		volatile long stealCount; // collects worker counts
1235		volatile long ctl; // main pool control
1236	<	final int parallelism; // parallelism level
1237	<	final int localMode; // per-worker scheduling mode
1238	<	volatile int nextWorkerNumber; // to create worker name string
1239	<	final int submitMask; // submit queue index bound
1348	<	int nextSeed; // for initializing worker seeds
1349	<	volatile int mainLock; // spinlock for array updates
1350	<	volatile int runState; // shutdown status and seq
1236	>	volatile int plock; // shutdown status and seqLock
1237	>	volatile int indexSeed; // worker/submitter index seed
1238	>	final short parallelism; // parallelism level
1239	>	final short mode; // LIFO/FIFO
1240		WorkQueue[] workQueues; // main registry
1241	<	final ForkJoinWorkerThreadFactory factory; // factory for new workers
1242	<	final Thread.UncaughtExceptionHandler ueh; // per-worker UEH
1241	>	final ForkJoinWorkerThreadFactory factory;
1242	>	final UncaughtExceptionHandler ueh; // per-worker UEH
1243		final String workerNamePrefix; // to create worker name string
1244
1245	<	/*
1246	<	* Mechanics for main lock protecting worker array updates. Uses
1358	<	* the same strategy as ConcurrentHashMap bins -- a spinLock for
1359	<	* normal cases, but falling back to builtin lock when (rarely)
1360	<	* needed. See internal ConcurrentHashMap documentation for
1361	<	* explanation.
1362	<	*/
1363	<
1364	<	static final int LOCK_WAITING = 2; // bit to indicate need for signal
1365	<	static final int MAX_LOCK_SPINS = 1 << 8;
1245	>	volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17;
1246	>	volatile Object pad18, pad19, pad1a, pad1b;
1247
1248	<	private void tryAwaitMainLock() {
1249	<	int spins = MAX_LOCK_SPINS, r = 0, h;
1250	<	while (((h = mainLock) & 1) != 0) {
1251	<	if (r == 0)
1252	<	r = ThreadLocalRandom.current().nextInt(); // randomize spins
1248	>	/**
1249	>	* Acquires the plock lock to protect worker array and related
1250	>	* updates. This method is called only if an initial CAS on plock
1251	>	* fails. This acts as a spinlock for normal cases, but falls back
1252	>	* to builtin monitor to block when (rarely) needed. This would be
1253	>	* a terrible idea for a highly contended lock, but works fine as
1254	>	* a more conservative alternative to a pure spinlock.
1255	>	*/
1256	>	private int acquirePlock() {
1257	>	int spins = PL_SPINS, ps, nps;
1258	>	for (;;) {
1259	>	if (((ps = plock) & PL_LOCK) == 0 &&
1260	>	U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK))
1261	>	return nps;
1262		else if (spins >= 0) {
1263	<	r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
1374	<	if (r >= 0)
1263	>	if (ThreadLocalRandom.current().nextInt() >= 0)
1264		--spins;
1265		}
1266	<	else if (U.compareAndSwapInt(this, MAINLOCK, h, h \| LOCK_WAITING)) {
1266	>	else if (U.compareAndSwapInt(this, PLOCK, ps, ps \| PL_SIGNAL)) {
1267		synchronized (this) {
1268	<	if ((mainLock & LOCK_WAITING) != 0) {
1268	>	if ((plock & PL_SIGNAL) != 0) {
1269		try {
1270		wait();
1271		} catch (InterruptedException ie) {
1272	<	Thread.currentThread().interrupt();
1272	>	try {
1273	>	Thread.currentThread().interrupt();
1274	>	} catch (SecurityException ignore) {
1275	>	}
1276		}
1277		}
1278		else
1279	<	notifyAll(); // possibly won race vs signaller
1279	>	notifyAll();
1280		}
1389	–	break;
1281		}
1282		}
1283		}
1284
1394	–	// Creating, registering, and deregistering workers
1395	–
1285		/**
1286	<	* Tries to create and start a worker
1286	>	* Unlocks and signals any thread waiting for plock. Called only
1287	>	* when CAS of seq value for unlock fails.
1288		*/
1289	<	private void addWorker() {
1290	<	Throwable ex = null;
1291	<	ForkJoinWorkerThread wt = null;
1402	<	try {
1403	<	if ((wt = factory.newThread(this)) != null) {
1404	<	wt.start();
1405	<	return;
1406	<	}
1407	<	} catch (Throwable e) {
1408	<	ex = e;
1409	<	}
1410	<	deregisterWorker(wt, ex); // adjust counts etc on failure
1289	>	private void releasePlock(int ps) {
1290	>	plock = ps;
1291	>	synchronized (this) { notifyAll(); }
1292		}
1293
1294		/**
1295	<	* Callback from ForkJoinWorkerThread constructor to assign a
1296	<	* public name. This must be separate from registerWorker because
1416	<	* it is called during the "super" constructor call in
1417	<	* ForkJoinWorkerThread.
1295	>	* Tries to create and start one worker if fewer than target
1296	>	* parallelism level exist. Adjusts counts etc on failure.
1297		*/
1298	<	final String nextWorkerName() {
1299	<	int n;
1300	<	do {} while(!U.compareAndSwapInt(this, NEXTWORKERNUMBER,
1301	<	n = nextWorkerNumber, ++n));
1302	<	return workerNamePrefix.concat(Integer.toString(n));
1298	>	private void tryAddWorker() {
1299	>	long c; int u, e;
1300	>	while ((u = (int)((c = ctl) >>> 32)) < 0 &&
1301	>	(u & SHORT_SIGN) != 0 && (e = (int)c) >= 0) {
1302	>	long nc = ((long)(((u + UTC_UNIT) & UTC_MASK) \|
1303	>	((u + UAC_UNIT) & UAC_MASK)) << 32) \| (long)e;
1304	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1305	>	ForkJoinWorkerThreadFactory fac;
1306	>	Throwable ex = null;
1307	>	ForkJoinWorkerThread wt = null;
1308	>	try {
1309	>	if ((fac = factory) != null &&
1310	>	(wt = fac.newThread(this)) != null) {
1311	>	wt.start();
1312	>	break;
1313	>	}
1314	>	} catch (Throwable rex) {
1315	>	ex = rex;
1316	>	}
1317	>	deregisterWorker(wt, ex);
1318	>	break;
1319	>	}
1320	>	}
1321		}
1322
1323	+	// Registering and deregistering workers
1324	+
1325		/**
1326	<	* Callback from ForkJoinWorkerThread constructor to establish its
1327	<	* poolIndex and record its WorkQueue. To avoid scanning bias due
1328	<	* to packing entries in front of the workQueues array, we treat
1329	<	* the array as a simple power-of-two hash table using per-thread
1330	<	* seed as hash, expanding as needed.
1331	<	*
1332	<	* @param w the worker's queue
1333	<	*/
1334	<	final void registerWorker(WorkQueue w) {
1335	<	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1336	<	tryAwaitMainLock();
1326	>	* Callback from ForkJoinWorkerThread to establish and record its
1327	>	* WorkQueue. To avoid scanning bias due to packing entries in
1328	>	* front of the workQueues array, we treat the array as a simple
1329	>	* power-of-two hash table using per-thread seed as hash,
1330	>	* expanding as needed.
1331	>	*
1332	>	* @param wt the worker thread
1333	>	* @return the worker's queue
1334	>	*/
1335	>	final WorkQueue registerWorker(ForkJoinWorkerThread wt) {
1336	>	UncaughtExceptionHandler handler; WorkQueue[] ws; int s, ps;
1337	>	wt.setDaemon(true);
1338	>	if ((handler = ueh) != null)
1339	>	wt.setUncaughtExceptionHandler(handler);
1340	>	do {} while (!U.compareAndSwapInt(this, INDEXSEED, s = indexSeed,
1341	>	s += SEED_INCREMENT) \|\|
1342	>	s == 0); // skip 0
1343	>	WorkQueue w = new WorkQueue(this, wt, mode, s);
1344	>	if (((ps = plock) & PL_LOCK) != 0 \|\|
1345	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1346	>	ps = acquirePlock();
1347	>	int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1348		try {
1349	<	WorkQueue[] ws;
1350	<	if ((ws = workQueues) == null)
1351	<	ws = workQueues = new WorkQueue[submitMask + 1];
1352	<	if (w != null) {
1353	<	int rs, n = ws.length, m = n - 1;
1354	<	int s = nextSeed += SEED_INCREMENT; // rarely-colliding sequence
1445	<	w.seed = (s == 0) ? 1 : s; // ensure non-zero seed
1446	<	int r = (s << 1) \| 1; // use odd-numbered indices
1447	<	if (ws[r &= m] != null) { // collision
1448	<	int probes = 0; // step by approx half size
1449	<	int step = (n <= 4) ? 2 : ((n >>> 1) & SQMASK) + 2;
1349	>	if ((ws = workQueues) != null) { // skip if shutting down
1350	>	int n = ws.length, m = n - 1;
1351	>	int r = (s << 1) \| 1; // use odd-numbered indices
1352	>	if (ws[r &= m] != null) { // collision
1353	>	int probes = 0; // step by approx half size
1354	>	int step = (n <= 4) ? 2 : ((n >>> 1) & EVENMASK) + 2;
1355		while (ws[r = (r + step) & m] != null) {
1356		if (++probes >= n) {
1357		workQueues = ws = Arrays.copyOf(ws, n <<= 1);
#	Line 1455 \| Line 1360 \| public class ForkJoinPool extends Abstra
1360		}
1361		}
1362		}
1363	<	w.eventCount = w.poolIndex = r; // establish before recording
1364	<	ws[r] = w; // also update seq
1365	<	runState = ((rs = runState) & SHUTDOWN) \| ((rs + 2) & ~SHUTDOWN);
1363	>	w.poolIndex = (short)r;
1364	>	w.eventCount = r; // volatile write orders
1365	>	ws[r] = w;
1366		}
1367		} finally {
1368	<	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1369	<	mainLock = 0;
1465	<	synchronized (this) { notifyAll(); };
1466	<	}
1368	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1369	>	releasePlock(nps);
1370		}
1371	<
1371	>	wt.setName(workerNamePrefix.concat(Integer.toString(w.poolIndex >>> 1)));
1372	>	return w;
1373		}
1374
1375		/**
1376		* Final callback from terminating worker, as well as upon failure
1377	<	* to construct or start a worker in addWorker. Removes record of
1378	<	* worker from array, and adjusts counts. If pool is shutting
1379	<	* down, tries to complete termination.
1377	>	* to construct or start a worker. Removes record of worker from
1378	>	* array, and adjusts counts. If pool is shutting down, tries to
1379	>	* complete termination.
1380		*
1381	<	* @param wt the worker thread or null if addWorker failed
1381	>	* @param wt the worker thread, or null if construction failed
1382		* @param ex the exception causing failure, or null if none
1383		*/
1384		final void deregisterWorker(ForkJoinWorkerThread wt, Throwable ex) {
1385		WorkQueue w = null;
1386		if (wt != null && (w = wt.workQueue) != null) {
1387	<	w.runState = -1; // ensure runState is set
1388	<	long steals = w.totalSteals + w.nsteals, sc;
1389	<	do {} while(!U.compareAndSwapLong(this, STEALCOUNT,
1390	<	sc = stealCount, sc + steals));
1391	<	int idx = w.poolIndex;
1392	<	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1393	<	tryAwaitMainLock();
1387	>	int ps; long sc;
1388	>	w.qlock = -1; // ensure set
1389	>	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1390	>	sc = stealCount,
1391	>	sc + w.nsteals));
1392	>	if (((ps = plock) & PL_LOCK) != 0 \|\|
1393	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1394	>	ps = acquirePlock();
1395	>	int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1396		try {
1397	+	int idx = w.poolIndex;
1398		WorkQueue[] ws = workQueues;
1399		if (ws != null && idx >= 0 && idx < ws.length && ws[idx] == w)
1400		ws[idx] = null;
1401		} finally {
1402	<	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1403	<	mainLock = 0;
1497	<	synchronized (this) { notifyAll(); };
1498	<	}
1402	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1403	>	releasePlock(nps);
1404		}
1405		}
1406
1407	<	long c; // adjust ctl counts
1407	>	long c; // adjust ctl counts
1408		do {} while (!U.compareAndSwapLong
1409		(this, CTL, c = ctl, (((c - AC_UNIT) & AC_MASK) \|
1410		((c - TC_UNIT) & TC_MASK) \|
1411		(c & ~(AC_MASK\|TC_MASK)))));
1412
1413	<	if (!tryTerminate(false, false) && w != null) {
1414	<	w.cancelAll(); // cancel remaining tasks
1415	<	if (w.array != null) // suppress signal if never ran
1416	<	signalWork(); // wake up or create replacement
1417	<	if (ex == null) // help clean refs on way out
1418	<	ForkJoinTask.helpExpungeStaleExceptions();
1419	<	}
1420	<
1421	<	if (ex != null) // rethrow
1422	<	U.throwException(ex);
1423	<	}
1424	<
1425	<	// Submissions
1426	<
1427	<	/**
1428	<	* Unless shutting down, adds the given task to a submission queue
1429	<	* at submitter's current queue index (modulo submission
1430	<	* range). If no queue exists at the index, one is created. If
1526	<	* the queue is busy, another index is randomly chosen. The
1527	<	* submitMask bounds the effective number of queues to the
1528	<	* (nearest power of two for) parallelism level.
1529	<	*
1530	<	* @param task the task. Caller must ensure non-null.
1531	<	*/
1532	<	private void doSubmit(ForkJoinTask<?> task) {
1533	<	Submitter s = submitters.get();
1534	<	for (int r = s.seed, m = submitMask;;) {
1535	<	WorkQueue[] ws; WorkQueue q;
1536	<	int k = r & m & SQMASK; // use only even indices
1537	<	if (runState < 0)
1538	<	throw new RejectedExecutionException(); // shutting down
1539	<	else if ((ws = workQueues) == null \|\| ws.length <= k) {
1540	<	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1541	<	tryAwaitMainLock();
1542	<	try {
1543	<	if (workQueues == null)
1544	<	workQueues = new WorkQueue[submitMask + 1];
1545	<	} finally {
1546	<	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1547	<	mainLock = 0;
1548	<	synchronized (this) { notifyAll(); };
1413	>	if (!tryTerminate(false, false) && w != null && w.array != null) {
1414	>	w.cancelAll(); // cancel remaining tasks
1415	>	WorkQueue[] ws; WorkQueue v; Thread p; int u, i, e;
1416	>	while ((u = (int)((c = ctl) >>> 32)) < 0 && (e = (int)c) >= 0) {
1417	>	if (e > 0) { // activate or create replacement
1418	>	if ((ws = workQueues) == null \|\|
1419	>	(i = e & SMASK) >= ws.length \|\|
1420	>	(v = ws[i]) == null)
1421	>	break;
1422	>	long nc = (((long)(v.nextWait & E_MASK)) \|
1423	>	((long)(u + UAC_UNIT) << 32));
1424	>	if (v.eventCount != (e \| INT_SIGN))
1425	>	break;
1426	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1427	>	v.eventCount = (e + E_SEQ) & E_MASK;
1428	>	if ((p = v.parker) != null)
1429	>	U.unpark(p);
1430	>	break;
1431		}
1432		}
1433	<	}
1434	<	else if ((q = ws[k]) == null) { // create new queue
1435	<	WorkQueue nq = new WorkQueue(this, null, SHARED_QUEUE);
1436	<	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1555	<	tryAwaitMainLock();
1556	<	try {
1557	<	int rs = runState; // to update seq
1558	<	if (ws == workQueues && ws[k] == null) {
1559	<	ws[k] = nq;
1560	<	runState = ((rs & SHUTDOWN) \| ((rs + 2) & ~SHUTDOWN));
1561	<	}
1562	<	} finally {
1563	<	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1564	<	mainLock = 0;
1565	<	synchronized (this) { notifyAll(); };
1566	<	}
1433	>	else {
1434	>	if ((short)u < 0)
1435	>	tryAddWorker();
1436	>	break;
1437		}
1438		}
1569	–	else if (q.trySharedPush(task)) {
1570	–	signalWork();
1571	–	return;
1572	–	}
1573	–	else if (m > 1) { // move to a different index
1574	–	r ^= r << 13; // same xorshift as WorkQueues
1575	–	r ^= r >>> 17;
1576	–	s.seed = r ^= r << 5;
1577	–	}
1578	–	else
1579	–	Thread.yield(); // yield if no alternatives
1439		}
1440	+	if (ex == null) // help clean refs on way out
1441	+	ForkJoinTask.helpExpungeStaleExceptions();
1442	+	else // rethrow
1443	+	ForkJoinTask.rethrow(ex);
1444		}
1445
1446	<	/**
1584	<	* Submits the given (non-null) task to the common pool, if possible.
1585	<	*/
1586	<	static void submitToCommonPool(ForkJoinTask<?> task) {
1587	<	ForkJoinPool p;
1588	<	if ((p = commonPool) == null)
1589	<	throw new RejectedExecutionException("Common Pool Unavailable");
1590	<	p.doSubmit(task);
1591	<	}
1446	>	// Submissions
1447
1448		/**
1449	<	* Returns true if caller is (or may be) submitter to the common
1450	<	* pool, and not all workers are active, and there appear to be
1451	<	* tasks in the associated submission queue.
1449	>	* Per-thread records for threads that submit to pools. Currently
1450	>	* holds only pseudo-random seed / index that is used to choose
1451	>	* submission queues in method externalPush. In the future, this may
1452	>	* also incorporate a means to implement different task rejection
1453	>	* and resubmission policies.
1454	>	*
1455	>	* Seeds for submitters and workers/workQueues work in basically
1456	>	* the same way but are initialized and updated using slightly
1457	>	* different mechanics. Both are initialized using the same
1458	>	* approach as in class ThreadLocal, where successive values are
1459	>	* unlikely to collide with previous values. Seeds are then
1460	>	* randomly modified upon collisions using xorshifts, which
1461	>	* requires a non-zero seed.
1462		*/
1463	<	static boolean canHelpCommonPool() {
1464	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
1465	<	int k = submitters.get().seed & SQMASK;
1601	<	return ((p = commonPool) != null &&
1602	<	(int)(p.ctl >> AC_SHIFT) < 0 &&
1603	<	(ws = p.workQueues) != null &&
1604	<	ws.length > (k &= p.submitMask) &&
1605	<	(q = ws[k]) != null &&
1606	<	q.top - q.base > 0);
1463	>	static final class Submitter {
1464	>	int seed;
1465	>	Submitter(int s) { seed = s; }
1466		}
1467
1468		/**
1469	<	* Returns true if the given task was submitted to common pool
1470	<	* and has not yet commenced execution, and is available for
1471	<	* removal according to execution policies; if so removing the
1472	<	* submission from the pool.
1469	>	* Unless shutting down, adds the given task to a submission queue
1470	>	* at submitter's current queue index (modulo submission
1471	>	* range). Only the most common path is directly handled in this
1472	>	* method. All others are relayed to fullExternalPush.
1473		*
1474	<	* @param task the task
1616	<	* @return true if successful
1474	>	* @param task the task. Caller must ensure non-null.
1475		*/
1476	<	static boolean tryUnsubmitFromCommonPool(ForkJoinTask<?> task) {
1477	<	// Peek, looking for task and eligibility before
1478	<	// using trySharedUnpush to actually take it under lock
1479	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
1480	<	ForkJoinTask<?>[] a; int s;
1481	<	int k = submitters.get().seed & SQMASK;
1482	<	return ((p = commonPool) != null &&
1483	<	(int)(p.ctl >> AC_SHIFT) < 0 &&
1484	<	(ws = p.workQueues) != null &&
1485	<	ws.length > (k &= p.submitMask) &&
1486	<	(q = ws[k]) != null &&
1487	<	(a = q.array) != null &&
1488	<	(s = q.top - 1) - q.base >= 0 &&
1489	<	s >= 0 && s < a.length &&
1490	<	a[s] == task &&
1491	<	q.trySharedUnpush(task));
1476	>	final void externalPush(ForkJoinTask<?> task) {
1477	>	Submitter z = submitters.get();
1478	>	WorkQueue q; int r, m, s, n, am; ForkJoinTask<?>[] a;
1479	>	int ps = plock;
1480	>	WorkQueue[] ws = workQueues;
1481	>	if (z != null && ps > 0 && ws != null && (m = (ws.length - 1)) >= 0 &&
1482	>	(q = ws[m & (r = z.seed) & SQMASK]) != null && r != 0 &&
1483	>	U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock
1484	>	if ((a = q.array) != null &&
1485	>	(am = a.length - 1) > (n = (s = q.top) - q.base)) {
1486	>	int j = ((am & s) << ASHIFT) + ABASE;
1487	>	U.putOrderedObject(a, j, task);
1488	>	q.top = s + 1; // push on to deque
1489	>	q.qlock = 0;
1490	>	if (n <= 1)
1491	>	signalWork(ws, q);
1492	>	return;
1493	>	}
1494	>	q.qlock = 0;
1495	>	}
1496	>	fullExternalPush(task);
1497		}
1498
1499		/**
1500	<	* Tries to pop a task from common pool with given root
1501	<	*/
1502	<	static ForkJoinTask<?> popCCFromCommonPool(CountedCompleter<?> root) {
1503	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
1504	<	ForkJoinTask<?> t;
1505	<	int k = submitters.get().seed & SQMASK;
1506	<	if (root != null &&
1507	<	(p = commonPool) != null &&
1508	<	(int)(p.ctl >> AC_SHIFT) < 0 &&
1509	<	(ws = p.workQueues) != null &&
1510	<	ws.length > (k &= p.submitMask) &&
1511	<	(q = ws[k]) != null && q.top - q.base > 0 &&
1512	<	root.status < 0 &&
1513	<	(t = q.sharedPopCC(root)) != null)
1514	<	return t;
1515	<	return null;
1500	>	* Full version of externalPush. This method is called, among
1501	>	* other times, upon the first submission of the first task to the
1502	>	* pool, so must perform secondary initialization. It also
1503	>	* detects first submission by an external thread by looking up
1504	>	* its ThreadLocal, and creates a new shared queue if the one at
1505	>	* index if empty or contended. The plock lock body must be
1506	>	* exception-free (so no try/finally) so we optimistically
1507	>	* allocate new queues outside the lock and throw them away if
1508	>	* (very rarely) not needed.
1509	>	*
1510	>	* Secondary initialization occurs when plock is zero, to create
1511	>	* workQueue array and set plock to a valid value. This lock body
1512	>	* must also be exception-free. Because the plock seq value can
1513	>	* eventually wrap around zero, this method harmlessly fails to
1514	>	* reinitialize if workQueues exists, while still advancing plock.
1515	>	*/
1516	>	private void fullExternalPush(ForkJoinTask<?> task) {
1517	>	int r = 0; // random index seed
1518	>	for (Submitter z = submitters.get();;) {
1519	>	WorkQueue[] ws; WorkQueue q; int ps, m, k;
1520	>	if (z == null) {
1521	>	if (U.compareAndSwapInt(this, INDEXSEED, r = indexSeed,
1522	>	r += SEED_INCREMENT) && r != 0)
1523	>	submitters.set(z = new Submitter(r));
1524	>	}
1525	>	else if (r == 0) { // move to a different index
1526	>	r = z.seed;
1527	>	r ^= r << 13; // same xorshift as WorkQueues
1528	>	r ^= r >>> 17;
1529	>	z.seed = r ^= (r << 5);
1530	>	}
1531	>	if ((ps = plock) < 0)
1532	>	throw new RejectedExecutionException();
1533	>	else if (ps == 0 \|\| (ws = workQueues) == null \|\|
1534	>	(m = ws.length - 1) < 0) { // initialize workQueues
1535	>	int p = parallelism; // find power of two table size
1536	>	int n = (p > 1) ? p - 1 : 1; // ensure at least 2 slots
1537	>	n \|= n >>> 1; n \|= n >>> 2; n \|= n >>> 4;
1538	>	n \|= n >>> 8; n \|= n >>> 16; n = (n + 1) << 1;
1539	>	WorkQueue[] nws = ((ws = workQueues) == null \|\| ws.length == 0 ?
1540	>	new WorkQueue[n] : null);
1541	>	if (((ps = plock) & PL_LOCK) != 0 \|\|
1542	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1543	>	ps = acquirePlock();
1544	>	if (((ws = workQueues) == null \|\| ws.length == 0) && nws != null)
1545	>	workQueues = nws;
1546	>	int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1547	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1548	>	releasePlock(nps);
1549	>	}
1550	>	else if ((q = ws[k = r & m & SQMASK]) != null) {
1551	>	if (q.qlock == 0 && U.compareAndSwapInt(q, QLOCK, 0, 1)) {
1552	>	ForkJoinTask<?>[] a = q.array;
1553	>	int s = q.top;
1554	>	boolean submitted = false;
1555	>	try { // locked version of push
1556	>	if ((a != null && a.length > s + 1 - q.base) \|\|
1557	>	(a = q.growArray()) != null) { // must presize
1558	>	int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
1559	>	U.putOrderedObject(a, j, task);
1560	>	q.top = s + 1;
1561	>	submitted = true;
1562	>	}
1563	>	} finally {
1564	>	q.qlock = 0; // unlock
1565	>	}
1566	>	if (submitted) {
1567	>	signalWork(ws, q);
1568	>	return;
1569	>	}
1570	>	}
1571	>	r = 0; // move on failure
1572	>	}
1573	>	else if (((ps = plock) & PL_LOCK) == 0) { // create new queue
1574	>	q = new WorkQueue(this, null, SHARED_QUEUE, r);
1575	>	q.poolIndex = (short)k;
1576	>	if (((ps = plock) & PL_LOCK) != 0 \|\|
1577	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1578	>	ps = acquirePlock();
1579	>	if ((ws = workQueues) != null && k < ws.length && ws[k] == null)
1580	>	ws[k] = q;
1581	>	int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1582	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1583	>	releasePlock(nps);
1584	>	}
1585	>	else
1586	>	r = 0;
1587	>	}
1588		}
1589
1655	–
1590		// Maintaining ctl counts
1591
1592		/**
#	Line 1660 \| Line 1594 \| public class ForkJoinPool extends Abstra
1594		*/
1595		final void incrementActiveCount() {
1596		long c;
1597	<	do {} while (!U.compareAndSwapLong(this, CTL, c = ctl, c + AC_UNIT));
1597	>	do {} while (!U.compareAndSwapLong
1598	>	(this, CTL, c = ctl, ((c & ~AC_MASK) \|
1599	>	((c & AC_MASK) + AC_UNIT))));
1600		}
1601
1602		/**
1603	<	* Tries to create one or activate one or more workers if too few are active.
1603	>	* Tries to create or activate a worker if too few are active.
1604	>	*
1605	>	* @param ws the worker array to use to find signallees
1606	>	* @param q if non-null, the queue holding tasks to be processed
1607		*/
1608	<	final void signalWork() {
1609	<	long c; int u;
1610	<	while ((u = (int)((c = ctl) >>> 32)) < 0) { // too few active
1611	<	WorkQueue[] ws = workQueues; int e, i; WorkQueue w; Thread p;
1612	<	if ((e = (int)c) > 0) { // at least one waiting
1613	<	if (ws != null && (i = e & SMASK) < ws.length &&
1614	<	(w = ws[i]) != null && w.eventCount == (e \| INT_SIGN)) {
1615	<	long nc = (((long)(w.nextWait & E_MASK)) \|
1616	<	((long)(u + UAC_UNIT) << 32));
1678	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1679	<	w.eventCount = (e + E_SEQ) & E_MASK;
1680	<	if ((p = w.parker) != null)
1681	<	U.unpark(p); // activate and release
1682	<	break;
1683	<	}
1684	<	}
1685	<	else
1686	<	break;
1608	>	final void signalWork(WorkQueue[] ws, WorkQueue q) {
1609	>	for (;;) {
1610	>	long c; int e, u, i; WorkQueue w; Thread p;
1611	>	if ((u = (int)((c = ctl) >>> 32)) >= 0)
1612	>	break;
1613	>	if ((e = (int)c) <= 0) {
1614	>	if ((short)u < 0)
1615	>	tryAddWorker();
1616	>	break;
1617		}
1618	<	else if (e == 0 && (u & SHORT_SIGN) != 0) { // too few total
1619	<	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) \|
1620	<	((u + UAC_UNIT) & UAC_MASK)) << 32;
1621	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1622	<	addWorker();
1623	<	break;
1624	<	}
1618	>	if (ws == null \|\| ws.length <= (i = e & SMASK) \|\|
1619	>	(w = ws[i]) == null)
1620	>	break;
1621	>	long nc = (((long)(w.nextWait & E_MASK)) \|
1622	>	((long)(u + UAC_UNIT)) << 32);
1623	>	int ne = (e + E_SEQ) & E_MASK;
1624	>	if (w.eventCount == (e \| INT_SIGN) &&
1625	>	U.compareAndSwapLong(this, CTL, c, nc)) {
1626	>	w.eventCount = ne;
1627	>	if ((p = w.parker) != null)
1628	>	U.unpark(p);
1629	>	break;
1630		}
1631	<	else
1631	>	if (q != null && q.base >= q.top)
1632		break;
1633		}
1634		}
#	Line 1704 \| Line 1639 \| public class ForkJoinPool extends Abstra
1639		* Top-level runloop for workers, called by ForkJoinWorkerThread.run.
1640		*/
1641		final void runWorker(WorkQueue w) {
1642	<	w.growArray(false); // initialize queue array in this thread
1643	<	do { w.runTask(scan(w)); } while (w.runState >= 0);
1642	>	w.growArray(); // allocate queue
1643	>	for (int r = w.hint; scan(w, r) == 0; ) {
1644	>	r ^= r << 13; r ^= r >>> 17; r ^= r << 5; // xorshift
1645	>	}
1646		}
1647
1648		/**
1649	<	* Scans for and, if found, returns one task, else possibly
1649	>	* Scans for and, if found, runs one task, else possibly
1650		* inactivates the worker. This method operates on single reads of
1651		* volatile state and is designed to be re-invoked continuously,
1652		* in part because it returns upon detecting inconsistencies,
1653		* contention, or state changes that indicate possible success on
1654		* re-invocation.
1655		*
1656	<	* The scan searches for tasks across a random permutation of
1657	<	* queues (starting at a random index and stepping by a random
1658	<	* relative prime, checking each at least once). The scan
1659	<	* terminates upon either finding a non-empty queue, or completing
1660	<	* the sweep. If the worker is not inactivated, it takes and
1661	<	* returns a task from this queue. On failure to find a task, we
1662	<	* take one of the following actions, after which the caller will
1663	<	* retry calling this method unless terminated.
1664	<	*
1728	<	* * If pool is terminating, terminate the worker.
1729	<	*
1730	<	* * If not a complete sweep, try to release a waiting worker. If
1731	<	* the scan terminated because the worker is inactivated, then the
1732	<	* released worker will often be the calling worker, and it can
1733	<	* succeed obtaining a task on the next call. Or maybe it is
1734	<	* another worker, but with same net effect. Releasing in other
1735	<	* cases as well ensures that we have enough workers running.
1736	<	*
1737	<	* * If not already enqueued, try to inactivate and enqueue the
1738	<	* worker on wait queue. Or, if inactivating has caused the pool
1739	<	* to be quiescent, relay to idleAwaitWork to check for
1740	<	* termination and possibly shrink pool.
1741	<	*
1742	<	* * If already inactive, and the caller has run a task since the
1743	<	* last empty scan, return (to allow rescan) unless others are
1744	<	* also inactivated. Field WorkQueue.rescans counts down on each
1745	<	* scan to ensure eventual inactivation and blocking.
1746	<	*
1747	<	* * If already enqueued and none of the above apply, park
1748	<	* awaiting signal,
1656	>	* The scan searches for tasks across queues starting at a random
1657	>	* index, checking each at least twice. The scan terminates upon
1658	>	* either finding a non-empty queue, or completing the sweep. If
1659	>	* the worker is not inactivated, it takes and runs a task from
1660	>	* this queue. Otherwise, if not activated, it tries to activate
1661	>	* itself or some other worker by signalling. On failure to find a
1662	>	* task, returns (for retry) if pool state may have changed during
1663	>	* an empty scan, or tries to inactivate if active, else possibly
1664	>	* blocks or terminates via method awaitWork.
1665		*
1666		* @param w the worker (via its WorkQueue)
1667	<	* @return a task or null if none found
1667	>	* @param r a random seed
1668	>	* @return worker qlock status if would have waited, else 0
1669		*/
1670	<	private final ForkJoinTask<?> scan(WorkQueue w) {
1671	<	WorkQueue[] ws; // first update random seed
1672	<	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1673	<	int rs = runState, m; // volatile read order matters
1674	<	if ((ws = workQueues) != null && (m = ws.length - 1) > 0) {
1675	<	int ec = w.eventCount; // ec is negative if inactive
1676	<	int step = (r >>> 16) \| 1; // relative prime
1677	<	for (int j = (m + 1) << 2; ; r += step) {
1678	<	WorkQueue q; ForkJoinTask<?> t; ForkJoinTask<?>[] a; int b;
1679	<	if ((q = ws[r & m]) != null && (b = q.base) - q.top < 0 &&
1680	<	(a = q.array) != null) { // probably nonempty
1681	<	int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1682	<	t = (ForkJoinTask<?>)U.getObjectVolatile(a, i);
1683	<	if (q.base == b && ec >= 0 && t != null &&
1684	<	U.compareAndSwapObject(a, i, t, null)) {
1685	<	if (q.top - (q.base = b + 1) > 0)
1686	<	signalWork(); // help pushes signal
1687	<	return t;
1688	<	}
1689	<	else if (ec < 0 \|\| j <= m) {
1773	<	rs = 0; // mark scan as imcomplete
1774	<	break; // caller can retry after release
1670	>	private final int scan(WorkQueue w, int r) {
1671	>	WorkQueue[] ws; int m;
1672	>	long c = ctl; // for consistency check
1673	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0 && w != null) {
1674	>	for (int j = m + m + 1, ec = w.eventCount;;) {
1675	>	WorkQueue q; int b, e; ForkJoinTask<?>[] a; ForkJoinTask<?> t;
1676	>	if ((q = ws[(r - j) & m]) != null &&
1677	>	(b = q.base) - q.top < 0 && (a = q.array) != null) {
1678	>	long i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1679	>	if ((t = ((ForkJoinTask<?>)
1680	>	U.getObjectVolatile(a, i))) != null) {
1681	>	if (ec < 0)
1682	>	helpRelease(c, ws, w, q, b);
1683	>	else if (q.base == b &&
1684	>	U.compareAndSwapObject(a, i, t, null)) {
1685	>	U.putOrderedInt(q, QBASE, b + 1);
1686	>	if ((b + 1) - q.top < 0)
1687	>	signalWork(ws, q);
1688	>	w.runTask(t);
1689	>	}
1690		}
1691	+	break;
1692		}
1693	<	if (--j < 0)
1693	>	else if (--j < 0) {
1694	>	if ((ec \| (e = (int)c)) < 0) // inactive or terminating
1695	>	return awaitWork(w, c, ec);
1696	>	else if (ctl == c) { // try to inactivate and enqueue
1697	>	long nc = (long)ec \| ((c - AC_UNIT) & (AC_MASK\|TC_MASK));
1698	>	w.nextWait = e;
1699	>	w.eventCount = ec \| INT_SIGN;
1700	>	if (!U.compareAndSwapLong(this, CTL, c, nc))
1701	>	w.eventCount = ec; // back out
1702	>	}
1703		break;
1704	+	}
1705		}
1706	+	}
1707	+	return 0;
1708	+	}
1709
1710	<	long c = ctl; int e = (int)c, a = (int)(c >> AC_SHIFT), nr, ns;
1711	<	if (e < 0) // decode ctl on empty scan
1712	<	w.runState = -1; // pool is terminating
1713	<	else if (rs == 0 \|\| rs != runState) { // incomplete scan
1714	<	WorkQueue v; Thread p; // try to release a waiter
1715	<	if (e > 0 && a < 0 && w.eventCount == ec &&
1716	<	(v = ws[e & m]) != null && v.eventCount == (e \| INT_SIGN)) {
1717	<	long nc = ((long)(v.nextWait & E_MASK) \|
1718	<	((c + AC_UNIT) & (AC_MASK\|TC_MASK)));
1719	<	if (ctl == c && U.compareAndSwapLong(this, CTL, c, nc)) {
1720	<	v.eventCount = (e + E_SEQ) & E_MASK;
1721	<	if ((p = v.parker) != null)
1722	<	U.unpark(p);
1723	<	}
1724	<	}
1710	>	/**
1711	>	* A continuation of scan(), possibly blocking or terminating
1712	>	* worker w. Returns without blocking if pool state has apparently
1713	>	* changed since last invocation. Also, if inactivating w has
1714	>	* caused the pool to become quiescent, checks for pool
1715	>	* termination, and, so long as this is not the only worker, waits
1716	>	* for event for up to a given duration. On timeout, if ctl has
1717	>	* not changed, terminates the worker, which will in turn wake up
1718	>	* another worker to possibly repeat this process.
1719	>	*
1720	>	* @param w the calling worker
1721	>	* @param c the ctl value on entry to scan
1722	>	* @param ec the worker's eventCount on entry to scan
1723	>	*/
1724	>	private final int awaitWork(WorkQueue w, long c, int ec) {
1725	>	int stat, ns; long parkTime, deadline;
1726	>	if ((stat = w.qlock) >= 0 && w.eventCount == ec && ctl == c &&
1727	>	!Thread.interrupted()) {
1728	>	int e = (int)c;
1729	>	int u = (int)(c >>> 32);
1730	>	int d = (u >> UAC_SHIFT) + parallelism; // active count
1731	>
1732	>	if (e < 0 \|\| (d <= 0 && tryTerminate(false, false)))
1733	>	stat = w.qlock = -1; // pool is terminating
1734	>	else if ((ns = w.nsteals) != 0) { // collect steals and retry
1735	>	long sc;
1736	>	w.nsteals = 0;
1737	>	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1738	>	sc = stealCount, sc + ns));
1739		}
1740	<	else if (ec >= 0) { // try to enqueue/inactivate
1741	<	long nc = (long)ec \| ((c - AC_UNIT) & (AC_MASK\|TC_MASK));
1742	<	w.nextWait = e;
1743	<	w.eventCount = ec \| INT_SIGN; // mark as inactive
1744	<	if (ctl != c \|\| !U.compareAndSwapLong(this, CTL, c, nc))
1745	<	w.eventCount = ec; // unmark on CAS failure
1746	<	else {
1747	<	if ((ns = w.nsteals) != 0) {
1748	<	w.nsteals = 0; // set rescans if ran task
1806	<	w.rescans = (a > 0) ? 0 : a + parallelism;
1807	<	w.totalSteals += ns;
1808	<	}
1809	<	if (a == 1 - parallelism) // quiescent
1810	<	idleAwaitWork(w, nc, c);
1740	>	else {
1741	>	long pc = ((d > 0 \|\| ec != (e \| INT_SIGN)) ? 0L :
1742	>	((long)(w.nextWait & E_MASK)) \| // ctl to restore
1743	>	((long)(u + UAC_UNIT)) << 32);
1744	>	if (pc != 0L) { // timed wait if last waiter
1745	>	int dc = -(short)(c >>> TC_SHIFT);
1746	>	parkTime = (dc < 0 ? FAST_IDLE_TIMEOUT:
1747	>	(dc + 1) * IDLE_TIMEOUT);
1748	>	deadline = System.nanoTime() + parkTime - TIMEOUT_SLOP;
1749		}
1750	<	}
1751	<	else if (w.eventCount < 0) { // already queued
1752	<	int ac = a + parallelism;
1815	<	if ((nr = w.rescans) > 0) // continue rescanning
1816	<	w.rescans = (ac < nr) ? ac : nr - 1;
1817	<	else if (((w.seed >>> 16) & ac) == 0) { // randomize park
1818	<	Thread.interrupted(); // clear status
1750	>	else
1751	>	parkTime = deadline = 0L;
1752	>	if (w.eventCount == ec && ctl == c) {
1753		Thread wt = Thread.currentThread();
1754		U.putObject(wt, PARKBLOCKER, this);
1755		w.parker = wt; // emulate LockSupport.park
1756	<	if (w.eventCount < 0) // recheck
1757	<	U.park(false, 0L);
1756	>	if (w.eventCount == ec && ctl == c)
1757	>	U.park(false, parkTime); // must recheck before park
1758		w.parker = null;
1759		U.putObject(wt, PARKBLOCKER, null);
1760	+	if (parkTime != 0L && ctl == c &&
1761	+	deadline - System.nanoTime() <= 0L &&
1762	+	U.compareAndSwapLong(this, CTL, c, pc))
1763	+	stat = w.qlock = -1; // shrink pool
1764		}
1765		}
1766		}
1767	<	return null;
1767	>	return stat;
1768		}
1769
1770		/**
1771	<	* If inactivating worker w has caused the pool to become
1772	<	* quiescent, checks for pool termination, and, so long as this is
1773	<	* not the only worker, waits for event for up to a given
1774	<	* duration. On timeout, if ctl has not changed, terminates the
1775	<	* worker, which will in turn wake up another worker to possibly
1776	<	* repeat this process.
1777	<	*
1778	<	* @param w the calling worker
1779	<	* @param currentCtl the ctl value triggering possible quiescence
1780	<	* @param prevCtl the ctl value to restore if thread is terminated
1781	<	*/
1782	<	private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) {
1783	<	if (w.eventCount < 0 && !tryTerminate(false, false) &&
1784	<	(int)prevCtl != 0 && !hasQueuedSubmissions() && ctl == currentCtl) {
1785	<	int dc = -(short)(currentCtl >>> TC_SHIFT);
1786	<	long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT;
1787	<	long deadline = System.nanoTime() + parkTime - 100000L; // 1ms slop
1788	<	Thread wt = Thread.currentThread();
1789	<	while (ctl == currentCtl) {
1790	<	Thread.interrupted(); // timed variant of version in scan()
1853	<	U.putObject(wt, PARKBLOCKER, this);
1854	<	w.parker = wt;
1855	<	if (ctl == currentCtl)
1856	<	U.park(false, parkTime);
1857	<	w.parker = null;
1858	<	U.putObject(wt, PARKBLOCKER, null);
1859	<	if (ctl != currentCtl)
1860	<	break;
1861	<	if (deadline - System.nanoTime() <= 0L &&
1862	<	U.compareAndSwapLong(this, CTL, currentCtl, prevCtl)) {
1863	<	w.eventCount = (w.eventCount + E_SEQ) \| E_MASK;
1864	<	w.runState = -1; // shrink
1865	<	break;
1866	<	}
1771	>	* Possibly releases (signals) a worker. Called only from scan()
1772	>	* when a worker with apparently inactive status finds a non-empty
1773	>	* queue. This requires revalidating all of the associated state
1774	>	* from caller.
1775	>	*/
1776	>	private final void helpRelease(long c, WorkQueue[] ws, WorkQueue w,
1777	>	WorkQueue q, int b) {
1778	>	WorkQueue v; int e, i; Thread p;
1779	>	if (w != null && w.eventCount < 0 && (e = (int)c) > 0 &&
1780	>	ws != null && ws.length > (i = e & SMASK) &&
1781	>	(v = ws[i]) != null && ctl == c) {
1782	>	long nc = (((long)(v.nextWait & E_MASK)) \|
1783	>	((long)((int)(c >>> 32) + UAC_UNIT)) << 32);
1784	>	int ne = (e + E_SEQ) & E_MASK;
1785	>	if (q != null && q.base == b && w.eventCount < 0 &&
1786	>	v.eventCount == (e \| INT_SIGN) &&
1787	>	U.compareAndSwapLong(this, CTL, c, nc)) {
1788	>	v.eventCount = ne;
1789	>	if ((p = v.parker) != null)
1790	>	U.unpark(p);
1791		}
1792		}
1793		}
#	Line 1888 \| Line 1812 \| public class ForkJoinPool extends Abstra
1812		*/
1813		private int tryHelpStealer(WorkQueue joiner, ForkJoinTask<?> task) {
1814		int stat = 0, steps = 0; // bound to avoid cycles
1815	<	if (joiner != null && task != null) { // hoist null checks
1815	>	if (task != null && joiner != null &&
1816	>	joiner.base - joiner.top >= 0) { // hoist checks
1817		restart: for (;;) {
1818		ForkJoinTask<?> subtask = task; // current target
1819		for (WorkQueue j = joiner, v;;) { // v is stealer of subtask
#	Line 1899 \| Line 1824 \| public class ForkJoinPool extends Abstra
1824		}
1825		if ((ws = workQueues) == null \|\| (m = ws.length - 1) <= 0)
1826		break restart; // shutting down
1827	<	if ((v = ws[h = (j.stealHint \| 1) & m]) == null \|\|
1827	>	if ((v = ws[h = (j.hint \| 1) & m]) == null \|\|
1828		v.currentSteal != subtask) {
1829		for (int origin = h;;) { // find stealer
1830		if (((h = (h + 2) & m) & 15) == 1 &&
#	Line 1907 \| Line 1832 \| public class ForkJoinPool extends Abstra
1832		continue restart; // occasional staleness check
1833		if ((v = ws[h]) != null &&
1834		v.currentSteal == subtask) {
1835	<	j.stealHint = h; // save hint
1835	>	j.hint = h; // save hint
1836		break;
1837		}
1838		if (h == origin)
#	Line 1915 \| Line 1840 \| public class ForkJoinPool extends Abstra
1840		}
1841		}
1842		for (;;) { // help stealer or descend to its stealer
1843	<	ForkJoinTask[] a; int b;
1843	>	ForkJoinTask[] a; int b;
1844		if (subtask.status < 0) // surround probes with
1845		continue restart; // consistency checks
1846		if ((b = v.base) - v.top < 0 && (a = v.array) != null) {
#	Line 1926 \| Line 1851 \| public class ForkJoinPool extends Abstra
1851		v.currentSteal != subtask)
1852		continue restart; // stale
1853		stat = 1; // apparent progress
1854	<	if (t != null && v.base == b &&
1855	<	U.compareAndSwapObject(a, i, t, null)) {
1856	<	v.base = b + 1; // help stealer
1857	<	joiner.runSubtask(t);
1854	>	if (v.base == b) {
1855	>	if (t == null)
1856	>	break restart;
1857	>	if (U.compareAndSwapObject(a, i, t, null)) {
1858	>	U.putOrderedInt(v, QBASE, b + 1);
1859	>	ForkJoinTask<?> ps = joiner.currentSteal;
1860	>	int jt = joiner.top;
1861	>	do {
1862	>	joiner.currentSteal = t;
1863	>	t.doExec(); // clear local tasks too
1864	>	} while (task.status >= 0 &&
1865	>	joiner.top != jt &&
1866	>	(t = joiner.pop()) != null);
1867	>	joiner.currentSteal = ps;
1868	>	break restart;
1869	>	}
1870		}
1934	–	else if (v.base == b && ++steps == MAX_HELP)
1935	–	break restart; // v apparently stalled
1871		}
1872		else { // empty -- try to descend
1873		ForkJoinTask<?> next = v.currentJoin;
#	Line 1955 \| Line 1890 \| public class ForkJoinPool extends Abstra
1890		}
1891
1892		/**
1893	<	* If task is at base of some steal queue, steals and executes it.
1893	>	* Analog of tryHelpStealer for CountedCompleters. Tries to steal
1894	>	* and run tasks within the target's computation.
1895		*
1896	<	* @param joiner the joining worker
1961	<	* @param task the task
1896	>	* @param task the task to join
1897		*/
1898	<	private void tryPollForAndExec(WorkQueue joiner, ForkJoinTask<?> task) {
1899	<	WorkQueue[] ws;
1900	<	if ((ws = workQueues) != null) {
1901	<	for (int j = 1; j < ws.length && task.status >= 0; j += 2) {
1902	<	WorkQueue q = ws[j];
1903	<	if (q != null && q.pollFor(task)) {
1904	<	joiner.runSubtask(task);
1898	>	private int helpComplete(WorkQueue joiner, CountedCompleter<?> task) {
1899	>	WorkQueue[] ws; int m;
1900	>	int s = 0;
1901	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0 &&
1902	>	joiner != null && task != null) {
1903	>	int j = joiner.poolIndex;
1904	>	int scans = m + m + 1;
1905	>	long c = 0L; // for stability check
1906	>	for (int k = scans; ; j += 2) {
1907	>	WorkQueue q;
1908	>	if ((s = task.status) < 0)
1909	>	break;
1910	>	else if (joiner.internalPopAndExecCC(task))
1911	>	k = scans;
1912	>	else if ((s = task.status) < 0)
1913		break;
1914	+	else if ((q = ws[j & m]) != null && q.pollAndExecCC(task))
1915	+	k = scans;
1916	+	else if (--k < 0) {
1917	+	if (c == (c = ctl))
1918	+	break;
1919	+	k = scans;
1920		}
1921		}
1922		}
1923	+	return s;
1924		}
1925
1926		/**
1927		* Tries to decrement active count (sometimes implicitly) and
1928		* possibly release or create a compensating worker in preparation
1929		* for blocking. Fails on contention or termination. Otherwise,
1930	<	* adds a new thread if no idle workers are available and either
1931	<	* pool would become completely starved or: (at least half
1932	<	* starved, and fewer than 50% spares exist, and there is at least
1933	<	* one task apparently available). Even though the availability
1984	<	* check requires a full scan, it is worthwhile in reducing false
1985	<	* alarms.
1986	<	*
1987	<	* @param task if non-null, a task being waited for
1988	<	* @param blocker if non-null, a blocker being waited for
1989	<	* @return true if the caller can block, else should recheck and retry
1930	>	* adds a new thread if no idle workers are available and pool
1931	>	* may become starved.
1932	>	*
1933	>	* @param c the assumed ctl value
1934		*/
1935	<	final boolean tryCompensate(ForkJoinTask<?> task, ManagedBlocker blocker) {
1992	<	int pc = parallelism, e;
1993	<	long c = ctl;
1935	>	final boolean tryCompensate(long c) {
1936		WorkQueue[] ws = workQueues;
1937	<	if ((e = (int)c) >= 0 && ws != null) {
1938	<	int u, a, ac, hc;
1939	<	int tc = (short)((u = (int)(c >>> 32)) >>> UTC_SHIFT) + pc;
1940	<	boolean replace = false;
1941	<	if ((a = u >> UAC_SHIFT) <= 0) {
1942	<	if ((ac = a + pc) <= 1)
1943	<	replace = true;
1944	<	else if ((e > 0 \|\| (task != null &&
1945	<	ac <= (hc = pc >>> 1) && tc < pc + hc))) {
1946	<	WorkQueue w;
1947	<	for (int j = 0; j < ws.length; ++j) {
1948	<	if ((w = ws[j]) != null && !w.isEmpty()) {
1949	<	replace = true;
1950	<	break; // in compensation range and tasks available
1951	<	}
1952	<	}
1953	<	}
1937	>	int pc = parallelism, e = (int)c, m, tc;
1938	>	if (ws != null && (m = ws.length - 1) >= 0 && e >= 0 && ctl == c) {
1939	>	WorkQueue w = ws[e & m];
1940	>	if (e != 0 && w != null) {
1941	>	Thread p;
1942	>	long nc = ((long)(w.nextWait & E_MASK) \|
1943	>	(c & (AC_MASK\|TC_MASK)));
1944	>	int ne = (e + E_SEQ) & E_MASK;
1945	>	if (w.eventCount == (e \| INT_SIGN) &&
1946	>	U.compareAndSwapLong(this, CTL, c, nc)) {
1947	>	w.eventCount = ne;
1948	>	if ((p = w.parker) != null)
1949	>	U.unpark(p);
1950	>	return true; // replace with idle worker
1951	>	}
1952	>	}
1953	>	else if ((tc = (short)(c >>> TC_SHIFT)) >= 0 &&
1954	>	(int)(c >> AC_SHIFT) + pc > 1) {
1955	>	long nc = ((c - AC_UNIT) & AC_MASK) \| (c & ~AC_MASK);
1956	>	if (U.compareAndSwapLong(this, CTL, c, nc))
1957	>	return true; // no compensation
1958		}
1959	<	if ((task == null \|\| task.status >= 0) && // recheck need to block
1960	<	(blocker == null \|\| !blocker.isReleasable()) && ctl == c) {
1961	<	if (!replace) { // no compensation
1962	<	long nc = ((c - AC_UNIT) & AC_MASK) \| (c & ~AC_MASK);
1963	<	if (U.compareAndSwapLong(this, CTL, c, nc))
1964	<	return true;
1965	<	}
1966	<	else if (e != 0) { // release an idle worker
1967	<	WorkQueue w; Thread p; int i;
1968	<	if ((i = e & SMASK) < ws.length && (w = ws[i]) != null) {
2023	<	long nc = ((long)(w.nextWait & E_MASK) \|
2024	<	(c & (AC_MASK\|TC_MASK)));
2025	<	if (w.eventCount == (e \| INT_SIGN) &&
2026	<	U.compareAndSwapLong(this, CTL, c, nc)) {
2027	<	w.eventCount = (e + E_SEQ) & E_MASK;
2028	<	if ((p = w.parker) != null)
2029	<	U.unpark(p);
1959	>	else if (tc + pc < MAX_CAP) {
1960	>	long nc = ((c + TC_UNIT) & TC_MASK) \| (c & ~TC_MASK);
1961	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1962	>	ForkJoinWorkerThreadFactory fac;
1963	>	Throwable ex = null;
1964	>	ForkJoinWorkerThread wt = null;
1965	>	try {
1966	>	if ((fac = factory) != null &&
1967	>	(wt = fac.newThread(this)) != null) {
1968	>	wt.start();
1969		return true;
1970		}
1971	+	} catch (Throwable rex) {
1972	+	ex = rex;
1973		}
1974	<	}
2034	<	else if (tc < MAX_CAP) { // create replacement
2035	<	long nc = ((c + TC_UNIT) & TC_MASK) \| (c & ~TC_MASK);
2036	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
2037	<	addWorker();
2038	<	return true;
2039	<	}
1974	>	deregisterWorker(wt, ex); // clean up and return false
1975		}
1976		}
1977		}
#	Line 2051 \| Line 1986 \| public class ForkJoinPool extends Abstra
1986		* @return task status on exit
1987		*/
1988		final int awaitJoin(WorkQueue joiner, ForkJoinTask<?> task) {
1989	<	int s;
1990	<	if ((s = task.status) >= 0) {
1989	>	int s = 0;
1990	>	if (task != null && (s = task.status) >= 0 && joiner != null) {
1991		ForkJoinTask<?> prevJoin = joiner.currentJoin;
1992		joiner.currentJoin = task;
1993	<	long startTime = 0L;
1994	<	for (int k = 0;;) {
1995	<	if ((s = (joiner.isEmpty() ? // try to help
1996	<	tryHelpStealer(joiner, task) :
1997	<	joiner.tryRemoveAndExec(task))) == 0 &&
1993	>	do {} while (joiner.tryRemoveAndExec(task) && // process local tasks
1994	>	(s = task.status) >= 0);
1995	>	if (s >= 0 && (task instanceof CountedCompleter))
1996	>	s = helpComplete(joiner, (CountedCompleter<?>)task);
1997	>	long cc = 0; // for stability checks
1998	>	while (s >= 0 && (s = task.status) >= 0) {
1999	>	if ((s = tryHelpStealer(joiner, task)) == 0 &&
2000		(s = task.status) >= 0) {
2001	<	if (k == 0) {
2002	<	startTime = System.nanoTime();
2003	<	tryPollForAndExec(joiner, task); // check uncommon case
2004	<	}
2068	<	else if ((k & (MAX_HELP - 1)) == 0 &&
2069	<	System.nanoTime() - startTime >=
2070	<	COMPENSATION_DELAY &&
2071	<	tryCompensate(task, null)) {
2072	<	if (task.trySetSignal()) {
2001	>	if (!tryCompensate(cc))
2002	>	cc = ctl;
2003	>	else {
2004	>	if (task.trySetSignal() && (s = task.status) >= 0) {
2005		synchronized (task) {
2006		if (task.status >= 0) {
2007		try { // see ForkJoinTask
#	Line 2081 \| Line 2013 \| public class ForkJoinPool extends Abstra
2013		task.notifyAll();
2014		}
2015		}
2016	<	long c; // re-activate
2016	>	long c; // reactivate
2017		do {} while (!U.compareAndSwapLong
2018	<	(this, CTL, c = ctl, c + AC_UNIT));
2018	>	(this, CTL, c = ctl,
2019	>	((c & ~AC_MASK) \|
2020	>	((c & AC_MASK) + AC_UNIT))));
2021		}
2022		}
2089	–	if (s < 0 \|\| (s = task.status) < 0) {
2090	–	joiner.currentJoin = prevJoin;
2091	–	break;
2092	–	}
2093	–	else if ((k++ & (MAX_HELP - 1)) == MAX_HELP >>> 1)
2094	–	Thread.yield(); // for politeness
2023		}
2024	+	joiner.currentJoin = prevJoin;
2025		}
2026		return s;
2027		}
#	Line 2104 \| Line 2033 \| public class ForkJoinPool extends Abstra
2033		*
2034		* @param joiner the joining worker
2035		* @param task the task
2107	–	* @return task status on exit
2036		*/
2037	<	final int helpJoinOnce(WorkQueue joiner, ForkJoinTask<?> task) {
2037	>	final void helpJoinOnce(WorkQueue joiner, ForkJoinTask<?> task) {
2038		int s;
2039	<	while ((s = task.status) >= 0 &&
2040	<	(joiner.isEmpty() ?
2041	<	tryHelpStealer(joiner, task) :
2042	<	joiner.tryRemoveAndExec(task)) != 0)
2043	<	;
2044	<	return s;
2039	>	if (joiner != null && task != null && (s = task.status) >= 0) {
2040	>	ForkJoinTask<?> prevJoin = joiner.currentJoin;
2041	>	joiner.currentJoin = task;
2042	>	do {} while (joiner.tryRemoveAndExec(task) && // process local tasks
2043	>	(s = task.status) >= 0);
2044	>	if (s >= 0) {
2045	>	if (task instanceof CountedCompleter)
2046	>	helpComplete(joiner, (CountedCompleter<?>)task);
2047	>	do {} while (task.status >= 0 &&
2048	>	tryHelpStealer(joiner, task) > 0);
2049	>	}
2050	>	joiner.currentJoin = prevJoin;
2051	>	}
2052		}
2053
2054		/**
2055		* Returns a (probably) non-empty steal queue, if one is found
2056	<	* during a random, then cyclic scan, else null. This method must
2057	<	* be retried by caller if, by the time it tries to use the queue,
2058	<	* it is empty.
2059	<	*/
2060	<	private WorkQueue findNonEmptyStealQueue(WorkQueue w) {
2061	<	// Similar to loop in scan(), but ignoring submissions
2062	<	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
2063	<	int step = (r >>> 16) \| 1;
2064	<	for (WorkQueue[] ws;;) {
2065	<	int rs = runState, m;
2066	<	if ((ws = workQueues) == null \|\| (m = ws.length - 1) < 1)
2067	<	return null;
2133	<	for (int j = (m + 1) << 2; ; r += step) {
2134	<	WorkQueue q = ws[((r << 1) \| 1) & m];
2135	<	if (q != null && !q.isEmpty())
2136	<	return q;
2137	<	else if (--j < 0) {
2138	<	if (runState == rs)
2139	<	return null;
2140	<	break;
2056	>	* during a scan, else null. This method must be retried by
2057	>	* caller if, by the time it tries to use the queue, it is empty.
2058	>	*/
2059	>	private WorkQueue findNonEmptyStealQueue() {
2060	>	int r = ThreadLocalRandom.current().nextInt();
2061	>	for (;;) {
2062	>	int ps = plock, m; WorkQueue[] ws; WorkQueue q;
2063	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
2064	>	for (int j = (m + 1) << 2; j >= 0; --j) {
2065	>	if ((q = ws[(((r - j) << 1) \| 1) & m]) != null &&
2066	>	q.base - q.top < 0)
2067	>	return q;
2068		}
2069		}
2070	+	if (plock == ps)
2071	+	return null;
2072		}
2073		}
2074
#	Line 2150 \| Line 2079 \| public class ForkJoinPool extends Abstra
2079		* find tasks either.
2080		*/
2081		final void helpQuiescePool(WorkQueue w) {
2082	+	ForkJoinTask<?> ps = w.currentSteal;
2083		for (boolean active = true;;) {
2084	<	ForkJoinTask<?> localTask; // exhaust local queue
2085	<	while ((localTask = w.nextLocalTask()) != null)
2086	<	localTask.doExec();
2087	<	WorkQueue q = findNonEmptyStealQueue(w);
2158	<	if (q != null) {
2159	<	ForkJoinTask<?> t; int b;
2084	>	long c; WorkQueue q; ForkJoinTask<?> t; int b;
2085	>	while ((t = w.nextLocalTask()) != null)
2086	>	t.doExec();
2087	>	if ((q = findNonEmptyStealQueue()) != null) {
2088		if (!active) { // re-establish active count
2161	–	long c;
2089		active = true;
2090		do {} while (!U.compareAndSwapLong
2091	<	(this, CTL, c = ctl, c + AC_UNIT));
2091	>	(this, CTL, c = ctl,
2092	>	((c & ~AC_MASK) \|
2093	>	((c & AC_MASK) + AC_UNIT))));
2094	>	}
2095	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) {
2096	>	(w.currentSteal = t).doExec();
2097	>	w.currentSteal = ps;
2098		}
2166	–	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2167	–	w.runSubtask(t);
2099		}
2100	<	else {
2101	<	long c;
2102	<	if (active) { // decrement active count without queuing
2100	>	else if (active) { // decrement active count without queuing
2101	>	long nc = ((c = ctl) & ~AC_MASK) \| ((c & AC_MASK) - AC_UNIT);
2102	>	if ((int)(nc >> AC_SHIFT) + parallelism == 0)
2103	>	break; // bypass decrement-then-increment
2104	>	if (U.compareAndSwapLong(this, CTL, c, nc))
2105		active = false;
2173	–	do {} while (!U.compareAndSwapLong
2174	–	(this, CTL, c = ctl, c -= AC_UNIT));
2175	–	}
2176	–	else
2177	–	c = ctl; // re-increment on exit
2178	–	if ((int)(c >> AC_SHIFT) + parallelism == 0) {
2179	–	do {} while (!U.compareAndSwapLong
2180	–	(this, CTL, c = ctl, c + AC_UNIT));
2181	–	break;
2182	–	}
2183	–	}
2184	–	}
2185	–	}
2186	–
2187	–	/**
2188	–	* Restricted version of helpQuiescePool for non-FJ callers
2189	–	*/
2190	–	static void externalHelpQuiescePool() {
2191	–	ForkJoinPool p; WorkQueue[] ws; WorkQueue q, sq;
2192	–	ForkJoinTask<?>[] a; int b;
2193	–	ForkJoinTask<?> t = null;
2194	–	int k = submitters.get().seed & SQMASK;
2195	–	if ((p = commonPool) != null &&
2196	–	(int)(p.ctl >> AC_SHIFT) < 0 &&
2197	–	(ws = p.workQueues) != null &&
2198	–	ws.length > (k &= p.submitMask) &&
2199	–	(q = ws[k]) != null) {
2200	–	while (q.top - q.base > 0) {
2201	–	if ((t = q.sharedPop()) != null)
2202	–	break;
2106		}
2107	<	if (t == null && (sq = p.findNonEmptyStealQueue(q)) != null &&
2108	<	(b = sq.base) - sq.top < 0)
2109	<	t = sq.pollAt(b);
2110	<	if (t != null)
2111	<	t.doExec();
2107	>	else if ((int)((c = ctl) >> AC_SHIFT) + parallelism <= 0 &&
2108	>	U.compareAndSwapLong
2109	>	(this, CTL, c, ((c & ~AC_MASK) \|
2110	>	((c & AC_MASK) + AC_UNIT))))
2111	>	break;
2112		}
2113		}
2114
#	Line 2219 \| Line 2122 \| public class ForkJoinPool extends Abstra
2122		WorkQueue q; int b;
2123		if ((t = w.nextLocalTask()) != null)
2124		return t;
2125	<	if ((q = findNonEmptyStealQueue(w)) == null)
2125	>	if ((q = findNonEmptyStealQueue()) == null)
2126		return null;
2127		if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2128		return t;
#	Line 2227 \| Line 2130 \| public class ForkJoinPool extends Abstra
2130		}
2131
2132		/**
2133	<	* Returns the approximate (non-atomic) number of idle threads per
2134	<	* active thread to offset steal queue size for method
2135	<	* ForkJoinTask.getSurplusQueuedTaskCount().
2136	<	*/
2137	<	final int idlePerActive() {
2138	<	// Approximate at powers of two for small values, saturate past 4
2139	<	int p = parallelism;
2140	<	int a = p + (int)(ctl >> AC_SHIFT);
2141	<	return (a > (p >>>= 1) ? 0 :
2142	<	a > (p >>>= 1) ? 1 :
2143	<	a > (p >>>= 1) ? 2 :
2144	<	a > (p >>>= 1) ? 4 :
2145	<	8);
2146	<	}
2147	<
2148	<	/**
2149	<	* Returns approximate submission queue length for the given caller
2150	<	*/
2151	<	static int getEstimatedSubmitterQueueLength() {
2152	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
2153	<	int k = submitters.get().seed & SQMASK;
2154	<	return ((p = commonPool) != null &&
2155	<	p.runState >= 0 &&
2156	<	(ws = p.workQueues) != null &&
2157	<	ws.length > (k &= p.submitMask) &&
2158	<	(q = ws[k]) != null) ?
2159	<	q.queueSize() : 0;
2133	>	* Returns a cheap heuristic guide for task partitioning when
2134	>	* programmers, frameworks, tools, or languages have little or no
2135	>	* idea about task granularity. In essence by offering this
2136	>	* method, we ask users only about tradeoffs in overhead vs
2137	>	* expected throughput and its variance, rather than how finely to
2138	>	* partition tasks.
2139	>	*
2140	>	* In a steady state strict (tree-structured) computation, each
2141	>	* thread makes available for stealing enough tasks for other
2142	>	* threads to remain active. Inductively, if all threads play by
2143	>	* the same rules, each thread should make available only a
2144	>	* constant number of tasks.
2145	>	*
2146	>	* The minimum useful constant is just 1. But using a value of 1
2147	>	* would require immediate replenishment upon each steal to
2148	>	* maintain enough tasks, which is infeasible. Further,
2149	>	* partitionings/granularities of offered tasks should minimize
2150	>	* steal rates, which in general means that threads nearer the top
2151	>	* of computation tree should generate more than those nearer the
2152	>	* bottom. In perfect steady state, each thread is at
2153	>	* approximately the same level of computation tree. However,
2154	>	* producing extra tasks amortizes the uncertainty of progress and
2155	>	* diffusion assumptions.
2156	>	*
2157	>	* So, users will want to use values larger (but not much larger)
2158	>	* than 1 to both smooth over transient shortages and hedge
2159	>	* against uneven progress; as traded off against the cost of
2160	>	* extra task overhead. We leave the user to pick a threshold
2161	>	* value to compare with the results of this call to guide
2162	>	* decisions, but recommend values such as 3.
2163	>	*
2164	>	* When all threads are active, it is on average OK to estimate
2165	>	* surplus strictly locally. In steady-state, if one thread is
2166	>	* maintaining say 2 surplus tasks, then so are others. So we can
2167	>	* just use estimated queue length. However, this strategy alone
2168	>	* leads to serious mis-estimates in some non-steady-state
2169	>	* conditions (ramp-up, ramp-down, other stalls). We can detect
2170	>	* many of these by further considering the number of "idle"
2171	>	* threads, that are known to have zero queued tasks, so
2172	>	* compensate by a factor of (#idle/#active) threads.
2173	>	*
2174	>	* Note: The approximation of #busy workers as #active workers is
2175	>	* not very good under current signalling scheme, and should be
2176	>	* improved.
2177	>	*/
2178	>	static int getSurplusQueuedTaskCount() {
2179	>	Thread t; ForkJoinWorkerThread wt; ForkJoinPool pool; WorkQueue q;
2180	>	if (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)) {
2181	>	int p = (pool = (wt = (ForkJoinWorkerThread)t).pool).parallelism;
2182	>	int n = (q = wt.workQueue).top - q.base;
2183	>	int a = (int)(pool.ctl >> AC_SHIFT) + p;
2184	>	return n - (a > (p >>>= 1) ? 0 :
2185	>	a > (p >>>= 1) ? 1 :
2186	>	a > (p >>>= 1) ? 2 :
2187	>	a > (p >>>= 1) ? 4 :
2188	>	8);
2189	>	}
2190	>	return 0;
2191		}
2192
2193		// Termination
#	Line 2273 \| Line 2207 \| public class ForkJoinPool extends Abstra
2207		* @return true if now terminating or terminated
2208		*/
2209		private boolean tryTerminate(boolean now, boolean enable) {
2210	+	int ps;
2211	+	if (this == common) // cannot shut down
2212	+	return false;
2213	+	if ((ps = plock) >= 0) { // enable by setting plock
2214	+	if (!enable)
2215	+	return false;
2216	+	if ((ps & PL_LOCK) != 0 \|\|
2217	+	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
2218	+	ps = acquirePlock();
2219	+	int nps = ((ps + PL_LOCK) & ~SHUTDOWN) \| SHUTDOWN;
2220	+	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
2221	+	releasePlock(nps);
2222	+	}
2223		for (long c;;) {
2224	<	if (((c = ctl) & STOP_BIT) != 0) { // already terminating
2225	<	if ((short)(c >>> TC_SHIFT) == -parallelism) {
2226	<	synchronized(this) {
2227	<	notifyAll(); // signal when 0 workers
2224	>	if (((c = ctl) & STOP_BIT) != 0) { // already terminating
2225	>	if ((short)(c >>> TC_SHIFT) + parallelism <= 0) {
2226	>	synchronized (this) {
2227	>	notifyAll(); // signal when 0 workers
2228		}
2229		}
2230		return true;
2231		}
2232	<	if (runState >= 0) { // not yet enabled
2233	<	if (!enable)
2234	<	return false;
2288	<	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
2289	<	tryAwaitMainLock();
2290	<	try {
2291	<	runState \|= SHUTDOWN;
2292	<	} finally {
2293	<	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
2294	<	mainLock = 0;
2295	<	synchronized (this) { notifyAll(); };
2296	<	}
2297	<	}
2298	<	}
2299	<	if (!now) { // check if idle & no tasks
2300	<	if ((int)(c >> AC_SHIFT) != -parallelism \|\|
2301	<	hasQueuedSubmissions())
2232	>	if (!now) { // check if idle & no tasks
2233	>	WorkQueue[] ws; WorkQueue w;
2234	>	if ((int)(c >> AC_SHIFT) + parallelism > 0)
2235		return false;
2236	<	// Check for unqueued inactive workers. One pass suffices.
2237	<	WorkQueue[] ws = workQueues; WorkQueue w;
2238	<	if (ws != null) {
2239	<	for (int i = 1; i < ws.length; i += 2) {
2240	<	if ((w = ws[i]) != null && w.eventCount >= 0)
2236	>	if ((ws = workQueues) != null) {
2237	>	for (int i = 0; i < ws.length; ++i) {
2238	>	if ((w = ws[i]) != null &&
2239	>	(!w.isEmpty() \|\|
2240	>	((i & 1) != 0 && w.eventCount >= 0))) {
2241	>	signalWork(ws, w);
2242		return false;
2243	+	}
2244		}
2245		}
2246		}
2247		if (U.compareAndSwapLong(this, CTL, c, c \| STOP_BIT)) {
2248		for (int pass = 0; pass < 3; ++pass) {
2249	<	WorkQueue[] ws = workQueues;
2250	<	if (ws != null) {
2316	<	WorkQueue w;
2249	>	WorkQueue[] ws; WorkQueue w; Thread wt;
2250	>	if ((ws = workQueues) != null) {
2251		int n = ws.length;
2252		for (int i = 0; i < n; ++i) {
2253		if ((w = ws[i]) != null) {
2254	<	w.runState = -1;
2254	>	w.qlock = -1;
2255		if (pass > 0) {
2256		w.cancelAll();
2257	<	if (pass > 1)
2258	<	w.interruptOwner();
2257	>	if (pass > 1 && (wt = w.owner) != null) {
2258	>	if (!wt.isInterrupted()) {
2259	>	try {
2260	>	wt.interrupt();
2261	>	} catch (Throwable ignore) {
2262	>	}
2263	>	}
2264	>	U.unpark(wt);
2265	>	}
2266		}
2267		}
2268		}
2269		// Wake up workers parked on event queue
2270		int i, e; long cc; Thread p;
2271		while ((e = (int)(cc = ctl) & E_MASK) != 0 &&
2272	<	(i = e & SMASK) < n &&
2272	>	(i = e & SMASK) < n && i >= 0 &&
2273		(w = ws[i]) != null) {
2274		long nc = ((long)(w.nextWait & E_MASK) \|
2275		((cc + AC_UNIT) & AC_MASK) \|
#	Line 2336 \| Line 2277 \| public class ForkJoinPool extends Abstra
2277		if (w.eventCount == (e \| INT_SIGN) &&
2278		U.compareAndSwapLong(this, CTL, cc, nc)) {
2279		w.eventCount = (e + E_SEQ) & E_MASK;
2280	<	w.runState = -1;
2280	>	w.qlock = -1;
2281		if ((p = w.parker) != null)
2282		U.unpark(p);
2283		}
#	Line 2347 \| Line 2288 \| public class ForkJoinPool extends Abstra
2288		}
2289		}
2290
2291	+	// external operations on common pool
2292	+
2293	+	/**
2294	+	* Returns common pool queue for a thread that has submitted at
2295	+	* least one task.
2296	+	*/
2297	+	static WorkQueue commonSubmitterQueue() {
2298	+	Submitter z; ForkJoinPool p; WorkQueue[] ws; int m, r;
2299	+	return ((z = submitters.get()) != null &&
2300	+	(p = common) != null &&
2301	+	(ws = p.workQueues) != null &&
2302	+	(m = ws.length - 1) >= 0) ?
2303	+	ws[m & z.seed & SQMASK] : null;
2304	+	}
2305	+
2306	+	/**
2307	+	* Tries to pop the given task from submitter's queue in common pool.
2308	+	*/
2309	+	final boolean tryExternalUnpush(ForkJoinTask<?> task) {
2310	+	WorkQueue joiner; ForkJoinTask<?>[] a; int m, s;
2311	+	Submitter z = submitters.get();
2312	+	WorkQueue[] ws = workQueues;
2313	+	boolean popped = false;
2314	+	if (z != null && ws != null && (m = ws.length - 1) >= 0 &&
2315	+	(joiner = ws[z.seed & m & SQMASK]) != null &&
2316	+	joiner.base != (s = joiner.top) &&
2317	+	(a = joiner.array) != null) {
2318	+	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
2319	+	if (U.getObject(a, j) == task &&
2320	+	U.compareAndSwapInt(joiner, QLOCK, 0, 1)) {
2321	+	if (joiner.top == s && joiner.array == a &&
2322	+	U.compareAndSwapObject(a, j, task, null)) {
2323	+	joiner.top = s - 1;
2324	+	popped = true;
2325	+	}
2326	+	joiner.qlock = 0;
2327	+	}
2328	+	}
2329	+	return popped;
2330	+	}
2331	+
2332	+	final int externalHelpComplete(CountedCompleter<?> task) {
2333	+	WorkQueue joiner; int m, j;
2334	+	Submitter z = submitters.get();
2335	+	WorkQueue[] ws = workQueues;
2336	+	int s = 0;
2337	+	if (z != null && ws != null && (m = ws.length - 1) >= 0 &&
2338	+	(joiner = ws[(j = z.seed) & m & SQMASK]) != null && task != null) {
2339	+	int scans = m + m + 1;
2340	+	long c = 0L; // for stability check
2341	+	j \|= 1; // poll odd queues
2342	+	for (int k = scans; ; j += 2) {
2343	+	WorkQueue q;
2344	+	if ((s = task.status) < 0)
2345	+	break;
2346	+	else if (joiner.externalPopAndExecCC(task))
2347	+	k = scans;
2348	+	else if ((s = task.status) < 0)
2349	+	break;
2350	+	else if ((q = ws[j & m]) != null && q.pollAndExecCC(task))
2351	+	k = scans;
2352	+	else if (--k < 0) {
2353	+	if (c == (c = ctl))
2354	+	break;
2355	+	k = scans;
2356	+	}
2357	+	}
2358	+	}
2359	+	return s;
2360	+	}
2361	+
2362		// Exported methods
2363
2364		// Constructors
#	Line 2363 \| Line 2375 \| public class ForkJoinPool extends Abstra
2375		* java.lang.RuntimePermission}{@code ("modifyThread")}
2376		*/
2377		public ForkJoinPool() {
2378	<	this(Runtime.getRuntime().availableProcessors(),
2378	>	this(Math.min(MAX_CAP, Runtime.getRuntime().availableProcessors()),
2379		defaultForkJoinWorkerThreadFactory, null, false);
2380		}
2381
#	Line 2411 \| Line 2423 \| public class ForkJoinPool extends Abstra
2423		*/
2424		public ForkJoinPool(int parallelism,
2425		ForkJoinWorkerThreadFactory factory,
2426	<	Thread.UncaughtExceptionHandler handler,
2426	>	UncaughtExceptionHandler handler,
2427		boolean asyncMode) {
2428	+	this(checkParallelism(parallelism),
2429	+	checkFactory(factory),
2430	+	handler,
2431	+	(asyncMode ? FIFO_QUEUE : LIFO_QUEUE),
2432	+	"ForkJoinPool-" + nextPoolId() + "-worker-");
2433		checkPermission();
2434	<	if (factory == null)
2435	<	throw new NullPointerException();
2434	>	}
2435	>
2436	>	private static int checkParallelism(int parallelism) {
2437		if (parallelism <= 0 \|\| parallelism > MAX_CAP)
2438		throw new IllegalArgumentException();
2439	<	this.parallelism = parallelism;
2440	<	this.factory = factory;
2441	<	this.ueh = handler;
2442	<	this.localMode = asyncMode ? FIFO_QUEUE : LIFO_QUEUE;
2443	<	long np = (long)(-parallelism); // offset ctl counts
2444	<	this.ctl = ((np << AC_SHIFT) & AC_MASK) \| ((np << TC_SHIFT) & TC_MASK);
2445	<	// Use nearest power 2 for workQueues size. See Hackers Delight sec 3.2.
2446	<	int n = parallelism - 1;
2429	<	n \|= n >>> 1; n \|= n >>> 2; n \|= n >>> 4; n \|= n >>> 8; n \|= n >>> 16;
2430	<	this.submitMask = ((n + 1) << 1) - 1;
2431	<	int pn = poolNumberGenerator.incrementAndGet();
2432	<	StringBuilder sb = new StringBuilder("ForkJoinPool-");
2433	<	sb.append(Integer.toString(pn));
2434	<	sb.append("-worker-");
2435	<	this.workerNamePrefix = sb.toString();
2436	<	this.runState = 1; // set init flag
2439	>	return parallelism;
2440	>	}
2441	>
2442	>	private static ForkJoinWorkerThreadFactory checkFactory
2443	>	(ForkJoinWorkerThreadFactory factory) {
2444	>	if (factory == null)
2445	>	throw new NullPointerException();
2446	>	return factory;
2447		}
2448
2449		/**
2450	<	* Constructor for common pool, suitable only for static initialization.
2451	<	* Basically the same as above, but uses smallest possible initial footprint.
2452	<	*/
2453	<	ForkJoinPool(int parallelism, int submitMask,
2454	<	ForkJoinWorkerThreadFactory factory,
2455	<	Thread.UncaughtExceptionHandler handler) {
2450	>	* Creates a {@code ForkJoinPool} with the given parameters, without
2451	>	* any security checks or parameter validation. Invoked directly by
2452	>	* makeCommonPool.
2453	>	*/
2454	>	private ForkJoinPool(int parallelism,
2455	>	ForkJoinWorkerThreadFactory factory,
2456	>	UncaughtExceptionHandler handler,
2457	>	int mode,
2458	>	String workerNamePrefix) {
2459	>	this.workerNamePrefix = workerNamePrefix;
2460		this.factory = factory;
2461		this.ueh = handler;
2462	<	this.submitMask = submitMask;
2463	<	this.parallelism = parallelism;
2464	<	long np = (long)(-parallelism);
2462	>	this.mode = (short)mode;
2463	>	this.parallelism = (short)parallelism;
2464	>	long np = (long)(-parallelism); // offset ctl counts
2465		this.ctl = ((np << AC_SHIFT) & AC_MASK) \| ((np << TC_SHIFT) & TC_MASK);
2452	–	this.localMode = LIFO_QUEUE;
2453	–	this.workerNamePrefix = "ForkJoinPool.commonPool-worker-";
2454	–	this.runState = 1;
2466		}
2467
2468		/**
2469	<	* Returns the common pool instance.
2469	>	* Returns the common pool instance. This pool is statically
2470	>	* constructed; its run state is unaffected by attempts to {@link
2471	>	* #shutdown} or {@link #shutdownNow}. However this pool and any
2472	>	* ongoing processing are automatically terminated upon program
2473	>	* {@link System#exit}. Any program that relies on asynchronous
2474	>	* task processing to complete before program termination should
2475	>	* invoke {@code commonPool().}{@link #awaitQuiescence awaitQuiescence},
2476	>	* before exit.
2477		*
2478		* @return the common pool instance
2479	+	* @since 1.8
2480		*/
2481		public static ForkJoinPool commonPool() {
2482	<	ForkJoinPool p;
2483	<	if ((p = commonPool) == null)
2465	<	throw new Error("Common Pool Unavailable");
2466	<	return p;
2482	>	// assert common != null : "static init error";
2483	>	return common;
2484		}
2485
2486		// Execution methods
#	Line 2487 \| Line 2504 \| public class ForkJoinPool extends Abstra
2504		public <T> T invoke(ForkJoinTask<T> task) {
2505		if (task == null)
2506		throw new NullPointerException();
2507	<	doSubmit(task);
2507	>	externalPush(task);
2508		return task.join();
2509		}
2510
#	Line 2502 \| Line 2519 \| public class ForkJoinPool extends Abstra
2519		public void execute(ForkJoinTask<?> task) {
2520		if (task == null)
2521		throw new NullPointerException();
2522	<	doSubmit(task);
2522	>	externalPush(task);
2523		}
2524
2525		// AbstractExecutorService methods
#	Line 2519 \| Line 2536 \| public class ForkJoinPool extends Abstra
2536		if (task instanceof ForkJoinTask<?>) // avoid re-wrap
2537		job = (ForkJoinTask<?>) task;
2538		else
2539	<	job = new ForkJoinTask.AdaptedRunnableAction(task);
2540	<	doSubmit(job);
2539	>	job = new ForkJoinTask.RunnableExecuteAction(task);
2540	>	externalPush(job);
2541		}
2542
2543		/**
#	Line 2535 \| Line 2552 \| public class ForkJoinPool extends Abstra
2552		public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) {
2553		if (task == null)
2554		throw new NullPointerException();
2555	<	doSubmit(task);
2555	>	externalPush(task);
2556		return task;
2557		}
2558
#	Line 2546 \| Line 2563 \| public class ForkJoinPool extends Abstra
2563		*/
2564		public <T> ForkJoinTask<T> submit(Callable<T> task) {
2565		ForkJoinTask<T> job = new ForkJoinTask.AdaptedCallable<T>(task);
2566	<	doSubmit(job);
2566	>	externalPush(job);
2567		return job;
2568		}
2569
#	Line 2557 \| Line 2574 \| public class ForkJoinPool extends Abstra
2574		*/
2575		public <T> ForkJoinTask<T> submit(Runnable task, T result) {
2576		ForkJoinTask<T> job = new ForkJoinTask.AdaptedRunnable<T>(task, result);
2577	<	doSubmit(job);
2577	>	externalPush(job);
2578		return job;
2579		}
2580
#	Line 2574 \| Line 2591 \| public class ForkJoinPool extends Abstra
2591		job = (ForkJoinTask<?>) task;
2592		else
2593		job = new ForkJoinTask.AdaptedRunnableAction(task);
2594	<	doSubmit(job);
2594	>	externalPush(job);
2595		return job;
2596		}
2597
#	Line 2586 \| Line 2603 \| public class ForkJoinPool extends Abstra
2603		// In previous versions of this class, this method constructed
2604		// a task to run ForkJoinTask.invokeAll, but now external
2605		// invocation of multiple tasks is at least as efficient.
2606	<	List<ForkJoinTask<T>> fs = new ArrayList<ForkJoinTask<T>>(tasks.size());
2590	<	// Workaround needed because method wasn't declared with
2591	<	// wildcards in return type but should have been.
2592	<	@SuppressWarnings({"unchecked", "rawtypes"})
2593	<	List<Future<T>> futures = (List<Future<T>>) (List) fs;
2606	>	ArrayList<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
2607
2608		boolean done = false;
2609		try {
2610		for (Callable<T> t : tasks) {
2611		ForkJoinTask<T> f = new ForkJoinTask.AdaptedCallable<T>(t);
2612	<	doSubmit(f);
2613	<	fs.add(f);
2612	>	futures.add(f);
2613	>	externalPush(f);
2614		}
2615	<	for (ForkJoinTask<T> f : fs)
2616	<	f.quietlyJoin();
2615	>	for (int i = 0, size = futures.size(); i < size; i++)
2616	>	((ForkJoinTask<?>)futures.get(i)).quietlyJoin();
2617		done = true;
2618		return futures;
2619		} finally {
2620		if (!done)
2621	<	for (ForkJoinTask<T> f : fs)
2622	<	f.cancel(false);
2621	>	for (int i = 0, size = futures.size(); i < size; i++)
2622	>	futures.get(i).cancel(false);
2623		}
2624		}
2625
#	Line 2625 \| Line 2638 \| public class ForkJoinPool extends Abstra
2638		*
2639		* @return the handler, or {@code null} if none
2640		*/
2641	<	public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
2641	>	public UncaughtExceptionHandler getUncaughtExceptionHandler() {
2642		return ueh;
2643		}
2644
#	Line 2635 \| Line 2648 \| public class ForkJoinPool extends Abstra
2648		* @return the targeted parallelism level of this pool
2649		*/
2650		public int getParallelism() {
2651	<	return parallelism;
2651	>	int par;
2652	>	return ((par = parallelism) > 0) ? par : 1;
2653		}
2654
2655		/**
2656		* Returns the targeted parallelism level of the common pool.
2657		*
2658		* @return the targeted parallelism level of the common pool
2659	+	* @since 1.8
2660		*/
2661		public static int getCommonPoolParallelism() {
2662	<	return commonPoolParallelism;
2662	>	return commonParallelism;
2663		}
2664
2665		/**
#	Line 2666 \| Line 2681 \| public class ForkJoinPool extends Abstra
2681		* @return {@code true} if this pool uses async mode
2682		*/
2683		public boolean getAsyncMode() {
2684	<	return localMode != 0;
2684	>	return mode == FIFO_QUEUE;
2685		}
2686
2687		/**
#	Line 2713 \| Line 2728 \| public class ForkJoinPool extends Abstra
2728		* @return {@code true} if all threads are currently idle
2729		*/
2730		public boolean isQuiescent() {
2731	<	return (int)(ctl >> AC_SHIFT) + parallelism == 0;
2731	>	return parallelism + (int)(ctl >> AC_SHIFT) <= 0;
2732		}
2733
2734		/**
#	Line 2733 \| Line 2748 \| public class ForkJoinPool extends Abstra
2748		if ((ws = workQueues) != null) {
2749		for (int i = 1; i < ws.length; i += 2) {
2750		if ((w = ws[i]) != null)
2751	<	count += w.totalSteals;
2751	>	count += w.nsteals;
2752		}
2753		}
2754		return count;
#	Line 2869 \| Line 2884 \| public class ForkJoinPool extends Abstra
2884		qs += size;
2885		else {
2886		qt += size;
2887	<	st += w.totalSteals;
2887	>	st += w.nsteals;
2888		if (w.isApparentlyUnblocked())
2889		++rc;
2890		}
#	Line 2885 \| Line 2900 \| public class ForkJoinPool extends Abstra
2900		if ((c & STOP_BIT) != 0)
2901		level = (tc == 0) ? "Terminated" : "Terminating";
2902		else
2903	<	level = runState < 0 ? "Shutting down" : "Running";
2903	>	level = plock < 0 ? "Shutting down" : "Running";
2904		return super.toString() +
2905		"[" + level +
2906		", parallelism = " + pc +
#	Line 2902 \| Line 2917 \| public class ForkJoinPool extends Abstra
2917		* Possibly initiates an orderly shutdown in which previously
2918		* submitted tasks are executed, but no new tasks will be
2919		* accepted. Invocation has no effect on execution state if this
2920	<	* is the {@link #commonPool}, and no additional effect if
2920	>	* is the {@link #commonPool()}, and no additional effect if
2921		* already shut down. Tasks that are in the process of being
2922		* submitted concurrently during the course of this method may or
2923		* may not be rejected.
#	Line 2914 \| Line 2929 \| public class ForkJoinPool extends Abstra
2929		*/
2930		public void shutdown() {
2931		checkPermission();
2932	<	if (this != commonPool)
2918	<	tryTerminate(false, true);
2932	>	tryTerminate(false, true);
2933		}
2934
2935		/**
2936		* Possibly attempts to cancel and/or stop all tasks, and reject
2937		* all subsequently submitted tasks. Invocation has no effect on
2938	<	* execution state if this is the {@link #commonPool}, and no
2938	>	* execution state if this is the {@link #commonPool()}, and no
2939		* additional effect if already shut down. Otherwise, tasks that
2940		* are in the process of being submitted or executed concurrently
2941		* during the course of this method may or may not be
#	Line 2938 \| Line 2952 \| public class ForkJoinPool extends Abstra
2952		*/
2953		public List<Runnable> shutdownNow() {
2954		checkPermission();
2955	<	if (this != commonPool)
2942	<	tryTerminate(true, true);
2955	>	tryTerminate(true, true);
2956		return Collections.emptyList();
2957		}
2958
#	Line 2951 \| Line 2964 \| public class ForkJoinPool extends Abstra
2964		public boolean isTerminated() {
2965		long c = ctl;
2966		return ((c & STOP_BIT) != 0L &&
2967	<	(short)(c >>> TC_SHIFT) == -parallelism);
2967	>	(short)(c >>> TC_SHIFT) + parallelism <= 0);
2968		}
2969
2970		/**
#	Line 2959 \| Line 2972 \| public class ForkJoinPool extends Abstra
2972		* commenced but not yet completed. This method may be useful for
2973		* debugging. A return of {@code true} reported a sufficient
2974		* period after shutdown may indicate that submitted tasks have
2975	<	* ignored or suppressed interruption, or are waiting for IO,
2975	>	* ignored or suppressed interruption, or are waiting for I/O,
2976		* causing this executor not to properly terminate. (See the
2977		* advisory notes for class {@link ForkJoinTask} stating that
2978		* tasks should not normally entail blocking operations. But if
#	Line 2970 \| Line 2983 \| public class ForkJoinPool extends Abstra
2983		public boolean isTerminating() {
2984		long c = ctl;
2985		return ((c & STOP_BIT) != 0L &&
2986	<	(short)(c >>> TC_SHIFT) != -parallelism);
2986	>	(short)(c >>> TC_SHIFT) + parallelism > 0);
2987		}
2988
2989		/**
#	Line 2979 \| Line 2992 \| public class ForkJoinPool extends Abstra
2992		* @return {@code true} if this pool has been shut down
2993		*/
2994		public boolean isShutdown() {
2995	<	return runState < 0;
2995	>	return plock < 0;
2996		}
2997
2998		/**
2999	<	* Blocks until all tasks have completed execution after a shutdown
3000	<	* request, or the timeout occurs, or the current thread is
3001	<	* interrupted, whichever happens first.
2999	>	* Blocks until all tasks have completed execution after a
3000	>	* shutdown request, or the timeout occurs, or the current thread
3001	>	* is interrupted, whichever happens first. Because the {@link
3002	>	* #commonPool()} never terminates until program shutdown, when
3003	>	* applied to the common pool, this method is equivalent to {@link
3004	>	* #awaitQuiescence(long, TimeUnit)} but always returns {@code false}.
3005		*
3006		* @param timeout the maximum time to wait
3007		* @param unit the time unit of the timeout argument
#	Line 2995 \| Line 3011 \| public class ForkJoinPool extends Abstra
3011		*/
3012		public boolean awaitTermination(long timeout, TimeUnit unit)
3013		throws InterruptedException {
3014	+	if (Thread.interrupted())
3015	+	throw new InterruptedException();
3016	+	if (this == common) {
3017	+	awaitQuiescence(timeout, unit);
3018	+	return false;
3019	+	}
3020		long nanos = unit.toNanos(timeout);
3021		if (isTerminated())
3022		return true;
3023	+	if (nanos <= 0L)
3024	+	return false;
3025	+	long deadline = System.nanoTime() + nanos;
3026	+	synchronized (this) {
3027	+	for (;;) {
3028	+	if (isTerminated())
3029	+	return true;
3030	+	if (nanos <= 0L)
3031	+	return false;
3032	+	long millis = TimeUnit.NANOSECONDS.toMillis(nanos);
3033	+	wait(millis > 0L ? millis : 1L);
3034	+	nanos = deadline - System.nanoTime();
3035	+	}
3036	+	}
3037	+	}
3038	+
3039	+	/**
3040	+	* If called by a ForkJoinTask operating in this pool, equivalent
3041	+	* in effect to {@link ForkJoinTask#helpQuiesce}. Otherwise,
3042	+	* waits and/or attempts to assist performing tasks until this
3043	+	* pool {@link #isQuiescent} or the indicated timeout elapses.
3044	+	*
3045	+	* @param timeout the maximum time to wait
3046	+	* @param unit the time unit of the timeout argument
3047	+	* @return {@code true} if quiescent; {@code false} if the
3048	+	* timeout elapsed.
3049	+	*/
3050	+	public boolean awaitQuiescence(long timeout, TimeUnit unit) {
3051	+	long nanos = unit.toNanos(timeout);
3052	+	ForkJoinWorkerThread wt;
3053	+	Thread thread = Thread.currentThread();
3054	+	if ((thread instanceof ForkJoinWorkerThread) &&
3055	+	(wt = (ForkJoinWorkerThread)thread).pool == this) {
3056	+	helpQuiescePool(wt.workQueue);
3057	+	return true;
3058	+	}
3059		long startTime = System.nanoTime();
3060	<	boolean terminated = false;
3061	<	synchronized(this) {
3062	<	for (long waitTime = nanos, millis = 0L;;) {
3063	<	if (terminated = isTerminated() \|\|
3064	<	waitTime <= 0L \|\|
3065	<	(millis = unit.toMillis(waitTime)) <= 0L)
3060	>	WorkQueue[] ws;
3061	>	int r = 0, m;
3062	>	boolean found = true;
3063	>	while (!isQuiescent() && (ws = workQueues) != null &&
3064	>	(m = ws.length - 1) >= 0) {
3065	>	if (!found) {
3066	>	if ((System.nanoTime() - startTime) > nanos)
3067	>	return false;
3068	>	Thread.yield(); // cannot block
3069	>	}
3070	>	found = false;
3071	>	for (int j = (m + 1) << 2; j >= 0; --j) {
3072	>	ForkJoinTask<?> t; WorkQueue q; int b;
3073	>	if ((q = ws[r++ & m]) != null && (b = q.base) - q.top < 0) {
3074	>	found = true;
3075	>	if ((t = q.pollAt(b)) != null)
3076	>	t.doExec();
3077		break;
3078	<	wait(millis);
3010	<	waitTime = nanos - (System.nanoTime() - startTime);
3078	>	}
3079		}
3080		}
3081	<	return terminated;
3081	>	return true;
3082	>	}
3083	>
3084	>	/**
3085	>	* Waits and/or attempts to assist performing tasks indefinitely
3086	>	* until the {@link #commonPool()} {@link #isQuiescent}.
3087	>	*/
3088	>	static void quiesceCommonPool() {
3089	>	common.awaitQuiescence(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
3090		}
3091
3092		/**
#	Line 3022 \| Line 3098 \| public class ForkJoinPool extends Abstra
3098		* not necessary. Method {@code block} blocks the current thread
3099		* if necessary (perhaps internally invoking {@code isReleasable}
3100		* before actually blocking). These actions are performed by any
3101	<	* thread invoking {@link ForkJoinPool#managedBlock}. The
3102	<	* unusual methods in this API accommodate synchronizers that may,
3103	<	* but don't usually, block for long periods. Similarly, they
3101	>	* thread invoking {@link ForkJoinPool#managedBlock(ManagedBlocker)}.
3102	>	* The unusual methods in this API accommodate synchronizers that
3103	>	* may, but don't usually, block for long periods. Similarly, they
3104		* allow more efficient internal handling of cases in which
3105		* additional workers may be, but usually are not, needed to
3106		* ensure sufficient parallelism. Toward this end,
#	Line 3082 \| Line 3158 \| public class ForkJoinPool extends Abstra
3158
3159		/**
3160		* Returns {@code true} if blocking is unnecessary.
3161	+	* @return {@code true} if blocking is unnecessary
3162		*/
3163		boolean isReleasable();
3164		}
#	Line 3109 \| Line 3186 \| public class ForkJoinPool extends Abstra
3186		public static void managedBlock(ManagedBlocker blocker)
3187		throws InterruptedException {
3188		Thread t = Thread.currentThread();
3189	<	ForkJoinPool p = ((t instanceof ForkJoinWorkerThread) ?
3190	<	((ForkJoinWorkerThread)t).pool : null);
3191	<	while (!blocker.isReleasable()) {
3192	<	if (p == null \|\| p.tryCompensate(null, blocker)) {
3193	<	try {
3194	<	do {} while (!blocker.isReleasable() && !blocker.block());
3195	<	} finally {
3196	<	if (p != null)
3189	>	if (t instanceof ForkJoinWorkerThread) {
3190	>	ForkJoinPool p = ((ForkJoinWorkerThread)t).pool;
3191	>	while (!blocker.isReleasable()) {
3192	>	if (p.tryCompensate(p.ctl)) {
3193	>	try {
3194	>	do {} while (!blocker.isReleasable() &&
3195	>	!blocker.block());
3196	>	} finally {
3197		p.incrementActiveCount();
3198	+	}
3199	+	break;
3200		}
3122	–	break;
3201		}
3202		}
3203	+	else {
3204	+	do {} while (!blocker.isReleasable() &&
3205	+	!blocker.block());
3206	+	}
3207		}
3208
3209		// AbstractExecutorService overrides. These rely on undocumented
#	Line 3142 \| Line 3224 \| public class ForkJoinPool extends Abstra
3224		private static final long PARKBLOCKER;
3225		private static final int ABASE;
3226		private static final int ASHIFT;
3145	–	private static final long NEXTWORKERNUMBER;
3227		private static final long STEALCOUNT;
3228	<	private static final long MAINLOCK;
3228	>	private static final long PLOCK;
3229	>	private static final long INDEXSEED;
3230	>	private static final long QBASE;
3231	>	private static final long QLOCK;
3232
3233		static {
3234	<	poolNumberGenerator = new AtomicInteger();
3151	<	nextSubmitterSeed = new AtomicInteger(0x55555555);
3152	<	modifyThreadPermission = new RuntimePermission("modifyThread");
3153	<	defaultForkJoinWorkerThreadFactory =
3154	<	new DefaultForkJoinWorkerThreadFactory();
3155	<	submitters = new ThreadSubmitter();
3156	<	int s;
3234	>	// initialize field offsets for CAS etc
3235		try {
3236		U = getUnsafe();
3237		Class<?> k = ForkJoinPool.class;
3160	–	Class<?> ak = ForkJoinTask[].class;
3238		CTL = U.objectFieldOffset
3239		(k.getDeclaredField("ctl"));
3163	–	NEXTWORKERNUMBER = U.objectFieldOffset
3164	–	(k.getDeclaredField("nextWorkerNumber"));
3240		STEALCOUNT = U.objectFieldOffset
3241		(k.getDeclaredField("stealCount"));
3242	<	MAINLOCK = U.objectFieldOffset
3243	<	(k.getDeclaredField("mainLock"));
3242	>	PLOCK = U.objectFieldOffset
3243	>	(k.getDeclaredField("plock"));
3244	>	INDEXSEED = U.objectFieldOffset
3245	>	(k.getDeclaredField("indexSeed"));
3246		Class<?> tk = Thread.class;
3247		PARKBLOCKER = U.objectFieldOffset
3248		(tk.getDeclaredField("parkBlocker"));
3249	+	Class<?> wk = WorkQueue.class;
3250	+	QBASE = U.objectFieldOffset
3251	+	(wk.getDeclaredField("base"));
3252	+	QLOCK = U.objectFieldOffset
3253	+	(wk.getDeclaredField("qlock"));
3254	+	Class<?> ak = ForkJoinTask[].class;
3255		ABASE = U.arrayBaseOffset(ak);
3256	<	s = U.arrayIndexScale(ak);
3257	<	ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
3258	<	} catch (Exception e) {
3259	<	throw new Error(e);
3177	<	}
3178	<	if ((s & (s-1)) != 0)
3179	<	throw new Error("data type scale not a power of two");
3180	<	try { // Establish common pool
3181	<	String pp = System.getProperty(propPrefix + "parallelism");
3182	<	String fp = System.getProperty(propPrefix + "threadFactory");
3183	<	String up = System.getProperty(propPrefix + "exceptionHandler");
3184	<	ForkJoinWorkerThreadFactory fac = (fp == null) ?
3185	<	defaultForkJoinWorkerThreadFactory :
3186	<	((ForkJoinWorkerThreadFactory)ClassLoader.
3187	<	getSystemClassLoader().loadClass(fp).newInstance());
3188	<	Thread.UncaughtExceptionHandler ueh = (up == null)? null :
3189	<	((Thread.UncaughtExceptionHandler)ClassLoader.
3190	<	getSystemClassLoader().loadClass(up).newInstance());
3191	<	int par;
3192	<	if ((pp == null \|\| (par = Integer.parseInt(pp)) <= 0))
3193	<	par = Runtime.getRuntime().availableProcessors();
3194	<	if (par > MAX_CAP)
3195	<	par = MAX_CAP;
3196	<	commonPoolParallelism = par;
3197	<	int n = par - 1; // precompute submit mask
3198	<	n \|= n >>> 1; n \|= n >>> 2; n \|= n >>> 4;
3199	<	n \|= n >>> 8; n \|= n >>> 16;
3200	<	int mask = ((n + 1) << 1) - 1;
3201	<	commonPool = new ForkJoinPool(par, mask, fac, ueh);
3256	>	int scale = U.arrayIndexScale(ak);
3257	>	if ((scale & (scale - 1)) != 0)
3258	>	throw new Error("data type scale not a power of two");
3259	>	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
3260		} catch (Exception e) {
3261		throw new Error(e);
3262		}
3263	+
3264	+	submitters = new ThreadLocal<Submitter>();
3265	+	defaultForkJoinWorkerThreadFactory =
3266	+	new DefaultForkJoinWorkerThreadFactory();
3267	+	modifyThreadPermission = new RuntimePermission("modifyThread");
3268	+
3269	+	common = java.security.AccessController.doPrivileged
3270	+	(new java.security.PrivilegedAction<ForkJoinPool>() {
3271	+	public ForkJoinPool run() { return makeCommonPool(); }});
3272	+	int par = common.parallelism; // report 1 even if threads disabled
3273	+	commonParallelism = par > 0 ? par : 1;
3274	+	}
3275	+
3276	+	/**
3277	+	* Creates and returns the common pool, respecting user settings
3278	+	* specified via system properties.
3279	+	*/
3280	+	private static ForkJoinPool makeCommonPool() {
3281	+	int parallelism = -1;
3282	+	ForkJoinWorkerThreadFactory factory
3283	+	= defaultForkJoinWorkerThreadFactory;
3284	+	UncaughtExceptionHandler handler = null;
3285	+	try { // ignore exceptions in accessing/parsing properties
3286	+	String pp = System.getProperty
3287	+	("java.util.concurrent.ForkJoinPool.common.parallelism");
3288	+	String fp = System.getProperty
3289	+	("java.util.concurrent.ForkJoinPool.common.threadFactory");
3290	+	String hp = System.getProperty
3291	+	("java.util.concurrent.ForkJoinPool.common.exceptionHandler");
3292	+	if (pp != null)
3293	+	parallelism = Integer.parseInt(pp);
3294	+	if (fp != null)
3295	+	factory = ((ForkJoinWorkerThreadFactory)ClassLoader.
3296	+	getSystemClassLoader().loadClass(fp).newInstance());
3297	+	if (hp != null)
3298	+	handler = ((UncaughtExceptionHandler)ClassLoader.
3299	+	getSystemClassLoader().loadClass(hp).newInstance());
3300	+	} catch (Exception ignore) {
3301	+	}
3302	+
3303	+	if (parallelism < 0 && // default 1 less than #cores
3304	+	(parallelism = Runtime.getRuntime().availableProcessors() - 1) < 0)
3305	+	parallelism = 0;
3306	+	if (parallelism > MAX_CAP)
3307	+	parallelism = MAX_CAP;
3308	+	return new ForkJoinPool(parallelism, factory, handler, LIFO_QUEUE,
3309	+	"ForkJoinPool.commonPool-worker-");
3310		}
3311
3312		/**
#	Line 3214 \| Line 3319 \| public class ForkJoinPool extends Abstra
3319		private static sun.misc.Unsafe getUnsafe() {
3320		try {
3321		return sun.misc.Unsafe.getUnsafe();
3322	<	} catch (SecurityException se) {
3323	<	try {
3324	<	return java.security.AccessController.doPrivileged
3325	<	(new java.security
3326	<	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
3327	<	public sun.misc.Unsafe run() throws Exception {
3328	<	java.lang.reflect.Field f = sun.misc
3329	<	.Unsafe.class.getDeclaredField("theUnsafe");
3330	<	f.setAccessible(true);
3331	<	return (sun.misc.Unsafe) f.get(null);
3332	<	}});
3333	<	} catch (java.security.PrivilegedActionException e) {
3334	<	throw new RuntimeException("Could not initialize intrinsics",
3335	<	e.getCause());
3336	<	}
3322	>	} catch (SecurityException tryReflectionInstead) {}
3323	>	try {
3324	>	return java.security.AccessController.doPrivileged
3325	>	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
3326	>	public sun.misc.Unsafe run() throws Exception {
3327	>	Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
3328	>	for (java.lang.reflect.Field f : k.getDeclaredFields()) {
3329	>	f.setAccessible(true);
3330	>	Object x = f.get(null);
3331	>	if (k.isInstance(x))
3332	>	return k.cast(x);
3333	>	}
3334	>	throw new NoSuchFieldError("the Unsafe");
3335	>	}});
3336	>	} catch (java.security.PrivilegedActionException e) {
3337	>	throw new RuntimeException("Could not initialize intrinsics",
3338	>	e.getCause());
3339		}
3340		}
3234	–
3341		}

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+Removed lines
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+Changed lines
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Comparing jsr166/src/jsr166e/ForkJoinPool.java (file contents): Revision 1.9 by dl, Tue Oct 30 14:23:03 2012 UTC vs. Revision 1.60 by jsr166, Wed Jun 19 16:36:45 2013 UTC

Diff Legend

Comparing jsr166/src/jsr166e/ForkJoinPool.java (file contents):
Revision 1.9 by dl, Tue Oct 30 14:23:03 2012 UTC vs.
Revision 1.60 by jsr166, Wed Jun 19 16:36:45 2013 UTC