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

Comparing jsr166/src/jsr166e/ForkJoinPool.java (file contents):
Revision 1.15 by jsr166, Sun Nov 18 06:31:13 2012 UTC vs.
Revision 1.66 by jsr166, Thu Nov 5 16:22:39 2015 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;
#	Line 17 \| Line 18 \| import java.util.concurrent.ExecutorServ
18		import java.util.concurrent.Future;
19		import java.util.concurrent.RejectedExecutionException;
20		import java.util.concurrent.RunnableFuture;
20	–	import java.util.concurrent.ThreadLocalRandom;
21		import java.util.concurrent.TimeUnit;
22
23		/**
#	Line 38 \| Line 38 \| import java.util.concurrent.TimeUnit;
38		* ForkJoinPool}s may also be appropriate for use with event-style
39		* tasks that are never joined.
40		*
41	<	* <p>A static {@link #commonPool} is available and appropriate for
41	>	* <p>A static {@link #commonPool()} is available and appropriate for
42		* most applications. The common pool is used by any ForkJoinTask that
43		* is not explicitly submitted to a specified pool. Using the common
44		* pool normally reduces resource usage (its threads are slowly
#	Line 50 \| Line 50 \| import java.util.concurrent.TimeUnit;
50		* level; by default, equal to the number of available processors. The
51		* pool attempts to maintain enough active (or available) threads by
52		* dynamically adding, suspending, or resuming internal worker
53	<	* threads, even if some tasks are stalled waiting to join
54	<	* others. However, no such adjustments are guaranteed in the face of
55	<	* blocked IO or other unmanaged synchronization. The nested {@link
53	>	* threads, even if some tasks are stalled waiting to join others.
54	>	* However, no such adjustments are guaranteed in the face of blocked
55	>	* I/O or other unmanaged synchronization. The nested {@link
56		* ManagedBlocker} interface enables extension of the kinds of
57		* synchronization accommodated.
58		*
#	Line 63 \| Line 63 \| import java.util.concurrent.TimeUnit;
63		* {@link #toString} returns indications of pool state in a
64		* convenient form for informal monitoring.
65		*
66	<	* <p> As is the case with other ExecutorServices, there are three
66	>	* <p>As is the case with other ExecutorServices, there are three
67		* main task execution methods summarized in the following table.
68		* These are designed to be used primarily by clients not already
69		* engaged in fork/join computations in the current pool. The main
#	Line 76 \| Line 76 \| import java.util.concurrent.TimeUnit;
76		* there is little difference among choice of methods.
77		*
78		* <table BORDER CELLPADDING=3 CELLSPACING=1>
79	+	* <caption>Summary of task execution methods</caption>
80		* <tr>
81		* <td></td>
82		* <td ALIGN=CENTER> <b>Call from non-fork/join clients</b></td>
83		* <td ALIGN=CENTER> <b>Call from within fork/join computations</b></td>
84		* </tr>
85		* <tr>
86	<	* <td> <b>Arrange async execution</td>
86	>	* <td> <b>Arrange async execution</b></td>
87		* <td> {@link #execute(ForkJoinTask)}</td>
88		* <td> {@link ForkJoinTask#fork}</td>
89		* </tr>
90		* <tr>
91	<	* <td> <b>Await and obtain result</td>
91	>	* <td> <b>Await and obtain result</b></td>
92		* <td> {@link #invoke(ForkJoinTask)}</td>
93		* <td> {@link ForkJoinTask#invoke}</td>
94		* </tr>
95		* <tr>
96	<	* <td> <b>Arrange exec and obtain Future</td>
96	>	* <td> <b>Arrange exec and obtain Future</b></td>
97		* <td> {@link #submit(ForkJoinTask)}</td>
98		* <td> {@link ForkJoinTask#fork} (ForkJoinTasks <em>are</em> Futures)</td>
99		* </tr>
100		* </table>
101		*
102		* <p>The common pool is by default constructed with default
103	<	* parameters, but these may be controlled by setting three {@link
104	<	* System#getProperty properties} with prefix {@code
105	<	* java.util.concurrent.ForkJoinPool.common}: {@code parallelism} --
106	<	* an integer greater than zero, {@code threadFactory} -- the class
107	<	* name of a {@link ForkJoinWorkerThreadFactory}, and {@code
108	<	* exceptionHandler} -- the class name of a {@link
109	<	* java.lang.Thread.UncaughtExceptionHandler
110	<	* Thread.UncaughtExceptionHandler}. Upon any error in establishing
111	<	* these settings, default parameters are used.
103	>	* parameters, but these may be controlled by setting three
104	>	* {@linkplain System#getProperty system properties}:
105	>	* <ul>
106	>	* <li>{@code java.util.concurrent.ForkJoinPool.common.parallelism}
107	>	* - the parallelism level, a non-negative integer
108	>	* <li>{@code java.util.concurrent.ForkJoinPool.common.threadFactory}
109	>	* - the class name of a {@link ForkJoinWorkerThreadFactory}
110	>	* <li>{@code java.util.concurrent.ForkJoinPool.common.exceptionHandler}
111	>	* - the class name of a {@link UncaughtExceptionHandler}
112	>	* </ul>
113	>	* The system class loader is used to load these classes.
114	>	* Upon any error in establishing these settings, default parameters
115	>	* are used. It is possible to disable or limit the use of threads in
116	>	* the common pool by setting the parallelism property to zero, and/or
117	>	* using a factory that may return {@code null}.
118		*
119		* <p><b>Implementation notes</b>: This implementation restricts the
120		* maximum number of running threads to 32767. Attempts to create
#	Line 153 \| Line 160 \| public class ForkJoinPool extends Abstra
160		* (http://research.sun.com/scalable/pubs/index.html) and
161		* "Idempotent work stealing" by Michael, Saraswat, and Vechev,
162		* PPoPP 2009 (http://portal.acm.org/citation.cfm?id=1504186).
163	<	* The main differences ultimately stem from GC requirements that
164	<	* we null out taken slots as soon as we can, to maintain as small
165	<	* a footprint as possible even in programs generating huge
166	<	* numbers of tasks. To accomplish this, we shift the CAS
167	<	* arbitrating pop vs poll (steal) from being on the indices
168	<	* ("base" and "top") to the slots themselves. So, both a
169	<	* successful pop and poll mainly entail a CAS of a slot from
170	<	* non-null to null. Because we rely on CASes of references, we
171	<	* do not need tag bits on base or top. They are simple ints as
172	<	* used in any circular array-based queue (see for example
173	<	* ArrayDeque). Updates to the indices must still be ordered in a
174	<	* way that guarantees that top == base means the queue is empty,
175	<	* but otherwise may err on the side of possibly making the queue
176	<	* appear nonempty when a push, pop, or poll have not fully
177	<	* committed. Note that this means that the poll operation,
178	<	* considered individually, is not wait-free. One thief cannot
179	<	* successfully continue until another in-progress one (or, if
180	<	* previously empty, a push) completes. However, in the
181	<	* aggregate, we ensure at least probabilistic non-blockingness.
182	<	* If an attempted steal fails, a thief always chooses a different
183	<	* random victim target to try next. So, in order for one thief to
184	<	* progress, it suffices for any in-progress poll or new push on
185	<	* any empty queue to complete. (This is why we normally use
186	<	* method pollAt and its variants that try once at the apparent
187	<	* base index, else consider alternative actions, rather than
188	<	* method poll.)
163	>	* See also "Correct and Efficient Work-Stealing for Weak Memory
164	>	* Models" by Le, Pop, Cohen, and Nardelli, PPoPP 2013
165	>	* (http://www.di.ens.fr/~zappa/readings/ppopp13.pdf) for an
166	>	* analysis of memory ordering (atomic, volatile etc) issues. The
167	>	* main differences ultimately stem from GC requirements that we
168	>	* null out taken slots as soon as we can, to maintain as small a
169	>	* footprint as possible even in programs generating huge numbers
170	>	* of tasks. To accomplish this, we shift the CAS arbitrating pop
171	>	* vs poll (steal) from being on the indices ("base" and "top") to
172	>	* the slots themselves. So, both a successful pop and poll
173	>	* mainly entail a CAS of a slot from non-null to null. Because
174	>	* we rely on CASes of references, we do not need tag bits on base
175	>	* or top. They are simple ints as used in any circular
176	>	* array-based queue (see for example ArrayDeque). Updates to the
177	>	* indices must still be ordered in a way that guarantees that top
178	>	* == base means the queue is empty, but otherwise may err on the
179	>	* side of possibly making the queue appear nonempty when a push,
180	>	* pop, or poll have not fully committed. Note that this means
181	>	* that the poll operation, considered individually, is not
182	>	* wait-free. One thief cannot successfully continue until another
183	>	* in-progress one (or, if previously empty, a push) completes.
184	>	* However, in the aggregate, we ensure at least probabilistic
185	>	* non-blockingness. If an attempted steal fails, a thief always
186	>	* chooses a different random victim target to try next. So, in
187	>	* order for one thief to progress, it suffices for any
188	>	* in-progress poll or new push on any empty queue to
189	>	* complete. (This is why we normally use method pollAt and its
190	>	* variants that try once at the apparent base index, else
191	>	* consider alternative actions, rather than method poll.)
192		*
193		* This approach also enables support of a user mode in which local
194		* task processing is in FIFO, not LIFO order, simply by using
#	Line 197 \| Line 207 \| public class ForkJoinPool extends Abstra
207		* for work-stealing (this would contaminate lifo/fifo
208		* processing). Instead, we randomly associate submission queues
209		* with submitting threads, using a form of hashing. The
210	<	* ThreadLocal Submitter class contains a value initially used as
211	<	* a hash code for choosing existing queues, but may be randomly
212	<	* repositioned upon contention with other submitters. In
213	<	* essence, submitters act like workers except that they are
214	<	* restricted to executing local tasks that they submitted (or in
215	<	* the case of CountedCompleters, others with the same root task).
216	<	* However, because most shared/external queue operations are more
217	<	* expensive than internal, and because, at steady state, external
218	<	* submitters will compete for CPU with workers, ForkJoinTask.join
219	<	* and related methods disable them from repeatedly helping to
220	<	* process tasks if all workers are active. Insertion of tasks in
221	<	* shared mode requires a lock (mainly to protect in the case of
210	>	* Submitter probe value serves as a hash code for
211	>	* choosing existing queues, and may be randomly repositioned upon
212	>	* contention with other submitters. In essence, submitters act
213	>	* like workers except that they are restricted to executing local
214	>	* tasks that they submitted (or in the case of CountedCompleters,
215	>	* others with the same root task). However, because most
216	>	* shared/external queue operations are more expensive than
217	>	* internal, and because, at steady state, external submitters
218	>	* will compete for CPU with workers, ForkJoinTask.join and
219	>	* related methods disable them from repeatedly helping to process
220	>	* tasks if all workers are active. Insertion of tasks in shared
221	>	* mode requires a lock (mainly to protect in the case of
222		* resizing) but we use only a simple spinlock (using bits in
223		* field qlock), because submitters encountering a busy queue move
224		* on to try or create other queues -- they block only when
#	Line 240 \| Line 250 \| public class ForkJoinPool extends Abstra
250		* enable shutdown. When used as a lock, it is normally only very
251		* briefly held, so is nearly always available after at most a
252		* brief spin, but we use a monitor-based backup strategy to
253	<	* blocking when needed.
253	>	* block when needed.
254		*
255		* Recording WorkQueues. WorkQueues are recorded in the
256		* "workQueues" array that is created upon first use and expanded
#	Line 249 \| Line 259 \| public class ForkJoinPool extends Abstra
259		* by a lock but the array is otherwise concurrently readable, and
260		* accessed directly. To simplify index-based operations, the
261		* array size is always a power of two, and all readers must
262	<	* tolerate null slots. Worker queues are at odd indices Shared
262	>	* tolerate null slots. Worker queues are at odd indices. Shared
263		* (submission) queues are at even indices, up to a maximum of 64
264		* slots, to limit growth even if array needs to expand to add
265		* more workers. Grouping them together in this way simplifies and
#	Line 298 \| Line 308 \| public class ForkJoinPool extends Abstra
308		* has not yet entered the wait queue. We solve this by requiring
309		* a full sweep of all workers (via repeated calls to method
310		* scan()) both before and after a newly waiting worker is added
311	<	* to the wait queue. During a rescan, the worker might release
312	<	* some other queued worker rather than itself, which has the same
313	<	* net effect. Because enqueued workers may actually be rescanning
314	<	* rather than waiting, we set and clear the "parker" field of
315	<	* WorkQueues to reduce unnecessary calls to unpark. (This
316	<	* requires a secondary recheck to avoid missed signals.) Note
317	<	* the unusual conventions about Thread.interrupts surrounding
318	<	* parking and other blocking: Because interrupts are used solely
319	<	* to alert threads to check termination, which is checked anyway
320	<	* upon blocking, we clear status (using Thread.interrupted)
321	<	* before any call to park, so that park does not immediately
312	<	* return due to status being set via some other unrelated call to
313	<	* interrupt in user code.
311	>	* to the wait queue. Because enqueued workers may actually be
312	>	* rescanning rather than waiting, we set and clear the "parker"
313	>	* field of WorkQueues to reduce unnecessary calls to unpark.
314	>	* (This requires a secondary recheck to avoid missed signals.)
315	>	* Note the unusual conventions about Thread.interrupts
316	>	* surrounding parking and other blocking: Because interrupts are
317	>	* used solely to alert threads to check termination, which is
318	>	* checked anyway upon blocking, we clear status (using
319	>	* Thread.interrupted) before any call to park, so that park does
320	>	* not immediately return due to status being set via some other
321	>	* unrelated call to interrupt in user code.
322		*
323		* Signalling. We create or wake up workers only when there
324		* appears to be at least one task they might be able to find and
325	<	* execute. However, many other threads may notice the same task
326	<	* and each signal to wake up a thread that might take it. So in
327	<	* general, pools will be over-signalled. When a submission is
328	<	* added or another worker adds a task to a queue that is
329	<	* apparently empty, they signal waiting workers (or trigger
330	<	* creation of new ones if fewer than the given parallelism level
331	<	* -- see signalWork). These primary signals are buttressed by
332	<	* signals whenever other threads scan for work or do not have a
333	<	* task to process. On most platforms, signalling (unpark)
334	<	* overhead time is noticeably long, and the time between
335	<	* signalling a thread and it actually making progress can be very
336	<	* noticeably long, so it is worth offloading these delays from
337	<	* critical paths as much as possible.
325	>	* execute. When a submission is added or another worker adds a
326	>	* task to a queue that has fewer than two tasks, they signal
327	>	* waiting workers (or trigger creation of new ones if fewer than
328	>	* the given parallelism level -- signalWork). These primary
329	>	* signals are buttressed by others whenever other threads remove
330	>	* a task from a queue and notice that there are other tasks there
331	>	* as well. So in general, pools will be over-signalled. On most
332	>	* platforms, signalling (unpark) overhead time is noticeably
333	>	* long, and the time between signalling a thread and it actually
334	>	* making progress can be very noticeably long, so it is worth
335	>	* offloading these delays from critical paths as much as
336	>	* possible. Additionally, workers spin-down gradually, by staying
337	>	* alive so long as they see the ctl state changing. Similar
338	>	* stability-sensing techniques are also used before blocking in
339	>	* awaitJoin and helpComplete.
340		*
341		* Trimming workers. To release resources after periods of lack of
342		* use, a worker starting to wait when the pool is quiescent will
#	Line 394 \| Line 404 \| public class ForkJoinPool extends Abstra
404		* steals, rather than use per-task bookkeeping. This sometimes
405		* requires a linear scan of workQueues array to locate stealers,
406		* but often doesn't because stealers leave hints (that may become
407	<	* stale/wrong) of where to locate them. A stealHint is only a
408	<	* hint because a worker might have had multiple steals and the
409	<	* hint records only one of them (usually the most current).
410	<	* Hinting isolates cost to when it is needed, rather than adding
411	<	* to per-task overhead. (2) It is "shallow", ignoring nesting
412	<	* and potentially cyclic mutual steals. (3) It is intentionally
407	>	* stale/wrong) of where to locate them. It is only a hint
408	>	* because a worker might have had multiple steals and the hint
409	>	* records only one of them (usually the most current). Hinting
410	>	* isolates cost to when it is needed, rather than adding to
411	>	* per-task overhead. (2) It is "shallow", ignoring nesting and
412	>	* potentially cyclic mutual steals. (3) It is intentionally
413		* racy: field currentJoin is updated only while actively joining,
414		* which means that we miss links in the chain during long-lived
415		* tasks, GC stalls etc (which is OK since blocking in such cases
#	Line 439 \| Line 449 \| public class ForkJoinPool extends Abstra
449		* Common Pool
450		* ===========
451		*
452	<	* The static commonPool always exists after static
452	>	* The static common pool always exists after static
453		* initialization. Since it (or any other created pool) need
454		* never be used, we minimize initial construction overhead and
455		* footprint to the setup of about a dozen fields, with no nested
#	Line 447 \| Line 457 \| public class ForkJoinPool extends Abstra
457		* fullExternalPush during the first submission to the pool.
458		*
459		* When external threads submit to the common pool, they can
460	<	* perform some subtask processing (see externalHelpJoin and
461	<	* related methods). We do not need to record whether these
460	>	* perform subtask processing (see externalHelpJoin and related
461	>	* methods). This caller-helps policy makes it sensible to set
462	>	* common pool parallelism level to one (or more) less than the
463	>	* total number of available cores, or even zero for pure
464	>	* caller-runs. We do not need to record whether external
465		* submissions are to the common pool -- if not, externalHelpJoin
466		* returns quickly (at the most helping to signal some common pool
467		* workers). These submitters would otherwise be blocked waiting
#	Line 517 \| Line 530 \| public class ForkJoinPool extends Abstra
530		* Returns a new worker thread operating in the given pool.
531		*
532		* @param pool the pool this thread works in
533	+	* @return the new worker thread
534		* @throws NullPointerException if the pool is null
535		*/
536		public ForkJoinWorkerThread newThread(ForkJoinPool pool);
#	Line 526 \| Line 540 \| public class ForkJoinPool extends Abstra
540		* Default ForkJoinWorkerThreadFactory implementation; creates a
541		* new ForkJoinWorkerThread.
542		*/
543	<	static class DefaultForkJoinWorkerThreadFactory
543	>	static final class DefaultForkJoinWorkerThreadFactory
544		implements ForkJoinWorkerThreadFactory {
545	<	public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
545	>	public final ForkJoinWorkerThread newThread(ForkJoinPool pool) {
546		return new ForkJoinWorkerThread(pool);
547		}
548		}
#	Line 592 \| Line 606 \| public class ForkJoinPool extends Abstra
606		* do not want multiple WorkQueue instances or multiple queue
607		* arrays sharing cache lines. (It would be best for queue objects
608		* and their arrays to share, but there is nothing available to
609	<	* help arrange that). Unfortunately, because they are recorded
610	<	* in a common array, WorkQueue instances are often moved to be
597	<	* adjacent by garbage collectors. To reduce impact, we use field
598	<	* padding that works OK on common platforms; this effectively
599	<	* trades off slightly slower average field access for the sake of
600	<	* avoiding really bad worst-case access. (Until better JVM
601	<	* support is in place, this padding is dependent on transient
602	<	* properties of JVM field layout rules.) We also take care in
603	<	* allocating, sizing and resizing the array. Non-shared queue
604	<	* arrays are initialized by workers before use. Others are
605	<	* allocated on first use.
609	>	* help arrange that). The @Contended annotation alerts JVMs to
610	>	* try to keep instances apart.
611		*/
612		static final class WorkQueue {
613		/**
#	Line 625 \| Line 630 \| public class ForkJoinPool extends Abstra
630		*/
631		static final int MAXIMUM_QUEUE_CAPACITY = 1 << 26; // 64M
632
633	<	int seed; // for random scanning; initialize nonzero
633	>	// Heuristic padding to ameliorate unfortunate memory placements
634	>	volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
635	>
636		volatile int eventCount; // encoded inactivation count; < 0 if inactive
637		int nextWait; // encoded record of next event waiter
638	<	final int mode; // lifo, fifo, or shared
639	<	int nsteals; // cumulative number of steals
640	<	int poolIndex; // index of this queue in pool (or 0)
641	<	int stealHint; // index of most recent known stealer
638	>	int nsteals; // number of steals
639	>	int hint; // steal index hint
640	>	short poolIndex; // index of this queue in pool
641	>	final short mode; // 0: lifo, > 0: fifo, < 0: shared
642		volatile int qlock; // 1: locked, -1: terminate; else 0
643		volatile int base; // index of next slot for poll
644		int top; // index of next slot for push
#	Line 641 \| Line 648 \| public class ForkJoinPool extends Abstra
648		volatile Thread parker; // == owner during call to park; else null
649		volatile ForkJoinTask<?> currentJoin; // task being joined in awaitJoin
650		ForkJoinTask<?> currentSteal; // current non-local task being executed
644	–	// Heuristic padding to ameliorate unfortunate memory placements
645	–	Object p00, p01, p02, p03, p04, p05, p06, p07;
646	–	Object p08, p09, p0a, p0b, p0c, p0d, p0e;
651
652	<	WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode) {
653	<	this.mode = mode;
652	>	volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17;
653	>	volatile Object pad18, pad19, pad1a, pad1b, pad1c, pad1d;
654	>
655	>	WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode,
656	>	int seed) {
657		this.pool = pool;
658		this.owner = owner;
659	+	this.mode = (short)mode;
660	+	this.hint = seed; // store initial seed for runWorker
661		// Place indices in the center of array (that is not yet allocated)
662		base = top = INITIAL_QUEUE_CAPACITY >>> 1;
663		}
664
665		/**
666	<	* Pushes a task. Call only by owner in unshared queues.
667	<	* Cases needing resizing or rejection are relayed to fullPush
668	<	* (that also handles shared queues).
666	>	* Returns the approximate number of tasks in the queue.
667	>	*/
668	>	final int queueSize() {
669	>	int n = base - top; // non-owner callers must read base first
670	>	return (n >= 0) ? 0 : -n; // ignore transient negative
671	>	}
672	>
673	>	/**
674	>	* Provides a more accurate estimate of whether this queue has
675	>	* any tasks than does queueSize, by checking whether a
676	>	* near-empty queue has at least one unclaimed task.
677	>	*/
678	>	final boolean isEmpty() {
679	>	ForkJoinTask<?>[] a; int m, s;
680	>	int n = base - (s = top);
681	>	return (n >= 0 \|\|
682	>	(n == -1 &&
683	>	((a = array) == null \|\|
684	>	(m = a.length - 1) < 0 \|\|
685	>	U.getObject
686	>	(a, (long)((m & (s - 1)) << ASHIFT) + ABASE) == null)));
687	>	}
688	>
689	>	/**
690	>	* Pushes a task. Call only by owner in unshared queues. (The
691	>	* shared-queue version is embedded in method externalPush.)
692		*
693		* @param task the task. Caller must ensure non-null.
694	<	* @throw RejectedExecutionException if array cannot be resized
694	>	* @throws RejectedExecutionException if array cannot be resized
695		*/
696		final void push(ForkJoinTask<?> task) {
697	<	ForkJoinPool p; ForkJoinTask<?>[] a;
697	>	ForkJoinTask<?>[] a; ForkJoinPool p;
698		int s = top, n;
699	<	if ((a = array) != null && a.length > (n = s + 1 - base)) {
700	<	U.putOrderedObject
701	<	(a, (((a.length - 1) & s) << ASHIFT) + ABASE, task);
702	<	top = s + 1;
703	<	if (n <= 1 && (p = pool) != null)
704	<	p.signalWork(this, 1);
699	>	if ((a = array) != null) { // ignore if queue removed
700	>	int m = a.length - 1;
701	>	U.putOrderedObject(a, ((m & s) << ASHIFT) + ABASE, task);
702	>	if ((n = (top = s + 1) - base) <= 2)
703	>	(p = pool).signalWork(p.workQueues, this);
704	>	else if (n >= m)
705	>	growArray();
706		}
674	–	else
675	–	fullPush(task, true);
707		}
708
709		/**
710	<	* Pushes a task if lock is free and array is either big
711	<	* enough or can be resized to be big enough. Note: a
712	<	* specialization of a common fast path of this method is in
713	<	* ForkJoinPool.externalPush. When called from a FJWT queue,
714	<	* this can fail only if the pool has been shut down or
715	<	* an out of memory error.
716	<	*
717	<	* @param task the task. Caller must ensure non-null.
718	<	* @param owned if true, throw RJE on failure
719	<	*/
720	<	final boolean fullPush(ForkJoinTask<?> task, boolean owned) {
721	<	ForkJoinPool p; ForkJoinTask<?>[] a;
722	<	if (owned) {
723	<	if (qlock < 0) // must be shutting down
724	<	throw new RejectedExecutionException();
710	>	* Initializes or doubles the capacity of array. Call either
711	>	* by owner or with lock held -- it is OK for base, but not
712	>	* top, to move while resizings are in progress.
713	>	*/
714	>	final ForkJoinTask<?>[] growArray() {
715	>	ForkJoinTask<?>[] oldA = array;
716	>	int size = oldA != null ? oldA.length << 1 : INITIAL_QUEUE_CAPACITY;
717	>	if (size > MAXIMUM_QUEUE_CAPACITY)
718	>	throw new RejectedExecutionException("Queue capacity exceeded");
719	>	int oldMask, t, b;
720	>	ForkJoinTask<?>[] a = array = new ForkJoinTask<?>[size];
721	>	if (oldA != null && (oldMask = oldA.length - 1) >= 0 &&
722	>	(t = top) - (b = base) > 0) {
723	>	int mask = size - 1;
724	>	do {
725	>	ForkJoinTask<?> x;
726	>	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
727	>	int j = ((b & mask) << ASHIFT) + ABASE;
728	>	x = (ForkJoinTask<?>)U.getObjectVolatile(oldA, oldj);
729	>	if (x != null &&
730	>	U.compareAndSwapObject(oldA, oldj, x, null))
731	>	U.putObjectVolatile(a, j, x);
732	>	} while (++b != t);
733		}
734	<	else if (!U.compareAndSwapInt(this, QLOCK, 0, 1))
696	<	return false;
697	<	try {
698	<	int s = top, oldLen, len;
699	<	if ((a = array) == null)
700	<	a = array = new ForkJoinTask<?>[len=INITIAL_QUEUE_CAPACITY];
701	<	else if ((oldLen = a.length) > s + 1 - base)
702	<	len = oldLen;
703	<	else if ((len = oldLen << 1) > MAXIMUM_QUEUE_CAPACITY)
704	<	throw new RejectedExecutionException("Capacity exceeded");
705	<	else {
706	<	int oldMask, b;
707	<	ForkJoinTask<?>[] oldA = a;
708	<	a = array = new ForkJoinTask<?>[len];
709	<	if ((oldMask = oldLen - 1) >= 0 && s - (b = base) > 0) {
710	<	int mask = len - 1;
711	<	do {
712	<	ForkJoinTask<?> x;
713	<	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
714	<	int j = ((b & mask) << ASHIFT) + ABASE;
715	<	x = (ForkJoinTask<?>)
716	<	U.getObjectVolatile(oldA, oldj);
717	<	if (x != null &&
718	<	U.compareAndSwapObject(oldA, oldj, x, null))
719	<	U.putObjectVolatile(a, j, x);
720	<	} while (++b != s);
721	<	}
722	<	}
723	<	U.putOrderedObject
724	<	(a, (((len - 1) & s) << ASHIFT) + ABASE, task);
725	<	top = s + 1;
726	<	} finally {
727	<	if (!owned)
728	<	qlock = 0;
729	<	}
730	<	if ((p = pool) != null)
731	<	p.signalWork(this, 1);
732	<	return true;
734	>	return a;
735		}
736
737		/**
#	Line 762 \| Line 764 \| public class ForkJoinPool extends Abstra
764		if ((a = array) != null) {
765		int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
766		if ((t = (ForkJoinTask<?>)U.getObjectVolatile(a, j)) != null &&
767	<	base == b &&
768	<	U.compareAndSwapObject(a, j, t, null)) {
767	<	base = b + 1;
767	>	base == b && U.compareAndSwapObject(a, j, t, null)) {
768	>	U.putOrderedInt(this, QBASE, b + 1);
769		return t;
770		}
771		}
#	Line 780 \| Line 781 \| public class ForkJoinPool extends Abstra
781		int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
782		t = (ForkJoinTask<?>)U.getObjectVolatile(a, j);
783		if (t != null) {
784	<	if (base == b &&
785	<	U.compareAndSwapObject(a, j, t, null)) {
785	<	base = b + 1;
784	>	if (U.compareAndSwapObject(a, j, t, null)) {
785	>	U.putOrderedInt(this, QBASE, b + 1);
786		return t;
787		}
788		}
#	Line 839 \| Line 839 \| public class ForkJoinPool extends Abstra
839		ForkJoinTask.cancelIgnoringExceptions(t);
840		}
841
842	<	/**
843	<	* Computes next value for random probes. Scans don't require
844	<	* a very high quality generator, but also not a crummy one.
845	<	* Marsaglia xor-shift is cheap and works well enough. Note:
846	<	* This is manually inlined in its usages in ForkJoinPool to
847	<	* avoid writes inside busy scan loops.
848	<	*/
849	<	final int nextSeed() {
850	<	int r = seed;
851	<	r ^= r << 13;
852	<	r ^= r >>> 17;
853	<	return seed = r ^= r << 5;
854	<	}
842	>	// Specialized execution methods
843
844		/**
845	<	* Provides a more accurate estimate of size than (top - base)
858	<	* by ordering reads and checking whether a near-empty queue
859	<	* has at least one unclaimed task.
845	>	* Polls and runs tasks until empty.
846		*/
847	<	final int queueSize() {
848	<	ForkJoinTask<?>[] a; int k, s, n;
849	<	return ((n = base - (s = top)) < 0 &&
864	<	(n != -1 \|\|
865	<	((a = array) != null && (k = a.length) > 0 &&
866	<	U.getObject
867	<	(a, (long)((((k - 1) & (s - 1)) << ASHIFT) + ABASE)) != null))) ?
868	<	-n : 0;
847	>	final void pollAndExecAll() {
848	>	for (ForkJoinTask<?> t; (t = poll()) != null;)
849	>	t.doExec();
850		}
851
871	–	// Specialized execution methods
872	–
852		/**
853	<	* Pops and runs tasks until empty.
853	>	* Executes a top-level task and any local tasks remaining
854	>	* after execution.
855		*/
856	<	private void popAndExecAll() {
857	<	// A bit faster than repeated pop calls
858	<	ForkJoinTask<?>[] a; int m, s; long j; ForkJoinTask<?> t;
859	<	while ((a = array) != null && (m = a.length - 1) >= 0 &&
860	<	(s = top - 1) - base >= 0 &&
861	<	(t = ((ForkJoinTask<?>)
862	<	U.getObject(a, j = ((m & s) << ASHIFT) + ABASE)))
863	<	!= null) {
864	<	if (U.compareAndSwapObject(a, j, t, null)) {
865	<	top = s;
866	<	t.doExec();
856	>	final void runTask(ForkJoinTask<?> task) {
857	>	if ((currentSteal = task) != null) {
858	>	task.doExec();
859	>	ForkJoinTask<?>[] a = array;
860	>	int md = mode;
861	>	++nsteals;
862	>	currentSteal = null;
863	>	if (md != 0)
864	>	pollAndExecAll();
865	>	else if (a != null) {
866	>	int s, m = a.length - 1;
867	>	while ((s = top - 1) - base >= 0) {
868	>	long i = ((m & s) << ASHIFT) + ABASE;
869	>	ForkJoinTask<?> t = (ForkJoinTask<?>)U.getObject(a, i);
870	>	if (t == null)
871	>	break;
872	>	if (U.compareAndSwapObject(a, i, t, null)) {
873	>	top = s;
874	>	t.doExec();
875	>	}
876	>	}
877		}
878		}
879		}
880
881		/**
892	–	* Polls and runs tasks until empty.
893	–	*/
894	–	private void pollAndExecAll() {
895	–	for (ForkJoinTask<?> t; (t = poll()) != null;)
896	–	t.doExec();
897	–	}
898	–
899	–	/**
882		* If present, removes from queue and executes the given task,
883		* or any other cancelled task. Returns (true) on any CAS
884		* or consistency check failure so caller can retry.
885		*
886	<	* @return false if no progress can be made, else true;
886	>	* @return false if no progress can be made, else true
887		*/
888		final boolean tryRemoveAndExec(ForkJoinTask<?> task) {
889	<	boolean stat = true, removed = false, empty = true;
889	>	boolean stat;
890		ForkJoinTask<?>[] a; int m, s, b, n;
891	<	if ((a = array) != null && (m = a.length - 1) >= 0 &&
891	>	if (task != null && (a = array) != null && (m = a.length - 1) >= 0 &&
892		(n = (s = top) - (b = base)) > 0) {
893	+	boolean removed = false, empty = true;
894	+	stat = true;
895		for (ForkJoinTask<?> t;;) { // traverse from s to b
896	<	int j = ((--s & m) << ASHIFT) + ABASE;
897	<	t = (ForkJoinTask<?>)U.getObjectVolatile(a, j);
896	>	long j = ((--s & m) << ASHIFT) + ABASE;
897	>	t = (ForkJoinTask<?>)U.getObject(a, j);
898		if (t == null) // inconsistent length
899		break;
900		else if (t == task) {
#	Line 938 \| Line 922 \| public class ForkJoinPool extends Abstra
922		break;
923		}
924		}
925	+	if (removed)
926	+	task.doExec();
927		}
928	<	if (removed)
929	<	task.doExec();
928	>	else
929	>	stat = false;
930		return stat;
931		}
932
933		/**
934	<	* Polls for and executes the given task or any other task in
935	<	* its CountedCompleter computation
934	>	* Tries to poll for and execute the given task or any other
935	>	* task in its CountedCompleter computation.
936		*/
937	<	final boolean pollAndExecCC(ForkJoinTask<?> root) {
938	<	ForkJoinTask<?>[] a; int b; Object o;
939	<	outer: while ((b = base) - top < 0 && (a = array) != null) {
937	>	final boolean pollAndExecCC(CountedCompleter<?> root) {
938	>	ForkJoinTask<?>[] a; int b; Object o; CountedCompleter<?> t, r;
939	>	if ((b = base) - top < 0 && (a = array) != null) {
940		long j = (((a.length - 1) & b) << ASHIFT) + ABASE;
941	<	if ((o = U.getObject(a, j)) == null \|\|
942	<	!(o instanceof CountedCompleter))
943	<	break;
944	<	for (CountedCompleter<?> t = (CountedCompleter<?>)o, r = t;;) {
945	<	if (r == root) {
946	<	if (base == b &&
947	<	U.compareAndSwapObject(a, j, t, null)) {
948	<	base = b + 1;
949	<	t.doExec();
941	>	if ((o = U.getObjectVolatile(a, j)) == null)
942	>	return true; // retry
943	>	if (o instanceof CountedCompleter) {
944	>	for (t = (CountedCompleter<?>)o, r = t;;) {
945	>	if (r == root) {
946	>	if (base == b &&
947	>	U.compareAndSwapObject(a, j, t, null)) {
948	>	U.putOrderedInt(this, QBASE, b + 1);
949	>	t.doExec();
950	>	}
951		return true;
952		}
953	<	else
954	<	break; // restart
953	>	else if ((r = r.completer) == null)
954	>	break; // not part of root computation
955		}
969	–	if ((r = r.completer) == null)
970	–	break outer; // not part of root computation
956		}
957		}
958		return false;
959		}
960
961		/**
962	<	* Executes a top-level task and any local tasks remaining
963	<	* after execution.
962	>	* Tries to pop and execute the given task or any other task
963	>	* in its CountedCompleter computation.
964		*/
965	<	final void runTask(ForkJoinTask<?> t) {
966	<	if (t != null) {
967	<	(currentSteal = t).doExec();
968	<	currentSteal = null;
969	<	if (++nsteals < 0) { // spill on overflow
970	<	ForkJoinPool p;
971	<	if ((p = pool) != null)
972	<	p.collectStealCount(this);
973	<	}
974	<	if (top != base) { // process remaining local tasks
975	<	if (mode == 0)
976	<	popAndExecAll();
977	<	else
978	<	pollAndExecAll();
965	>	final boolean externalPopAndExecCC(CountedCompleter<?> root) {
966	>	ForkJoinTask<?>[] a; int s; Object o; CountedCompleter<?> t, r;
967	>	if (base - (s = top) < 0 && (a = array) != null) {
968	>	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
969	>	if ((o = U.getObject(a, j)) instanceof CountedCompleter) {
970	>	for (t = (CountedCompleter<?>)o, r = t;;) {
971	>	if (r == root) {
972	>	if (U.compareAndSwapInt(this, QLOCK, 0, 1)) {
973	>	if (top == s && array == a &&
974	>	U.compareAndSwapObject(a, j, t, null)) {
975	>	top = s - 1;
976	>	qlock = 0;
977	>	t.doExec();
978	>	}
979	>	else
980	>	qlock = 0;
981	>	}
982	>	return true;
983	>	}
984	>	else if ((r = r.completer) == null)
985	>	break;
986	>	}
987		}
988		}
989	+	return false;
990		}
991
992		/**
993	<	* Executes a non-top-level (stolen) task.
993	>	* Internal version
994		*/
995	<	final void runSubtask(ForkJoinTask<?> t) {
996	<	if (t != null) {
997	<	ForkJoinTask<?> ps = currentSteal;
998	<	(currentSteal = t).doExec();
999	<	currentSteal = ps;
995	>	final boolean internalPopAndExecCC(CountedCompleter<?> root) {
996	>	ForkJoinTask<?>[] a; int s; Object o; CountedCompleter<?> t, r;
997	>	if (base - (s = top) < 0 && (a = array) != null) {
998	>	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
999	>	if ((o = U.getObject(a, j)) instanceof CountedCompleter) {
1000	>	for (t = (CountedCompleter<?>)o, r = t;;) {
1001	>	if (r == root) {
1002	>	if (U.compareAndSwapObject(a, j, t, null)) {
1003	>	top = s - 1;
1004	>	t.doExec();
1005	>	}
1006	>	return true;
1007	>	}
1008	>	else if ((r = r.completer) == null)
1009	>	break;
1010	>	}
1011	>	}
1012		}
1013	+	return false;
1014		}
1015
1016		/**
#	Line 1018 \| Line 1025 \| public class ForkJoinPool extends Abstra
1025		s != Thread.State.TIMED_WAITING);
1026		}
1027
1021	–	/**
1022	–	* If this owned and is not already interrupted, try to
1023	–	* interrupt and/or unpark, ignoring exceptions.
1024	–	*/
1025	–	final void interruptOwner() {
1026	–	Thread wt, p;
1027	–	if ((wt = owner) != null && !wt.isInterrupted()) {
1028	–	try {
1029	–	wt.interrupt();
1030	–	} catch (SecurityException ignore) {
1031	–	}
1032	–	}
1033	–	if ((p = parker) != null)
1034	–	U.unpark(p);
1035	–	}
1036	–
1028		// Unsafe mechanics
1029		private static final sun.misc.Unsafe U;
1030	+	private static final long QBASE;
1031		private static final long QLOCK;
1032		private static final int ABASE;
1033		private static final int ASHIFT;
1034		static {
1043	–	int s;
1035		try {
1036		U = getUnsafe();
1037		Class<?> k = WorkQueue.class;
1038		Class<?> ak = ForkJoinTask[].class;
1039	+	QBASE = U.objectFieldOffset
1040	+	(k.getDeclaredField("base"));
1041		QLOCK = U.objectFieldOffset
1042		(k.getDeclaredField("qlock"));
1043		ABASE = U.arrayBaseOffset(ak);
1044	<	s = U.arrayIndexScale(ak);
1044	>	int scale = U.arrayIndexScale(ak);
1045	>	if ((scale & (scale - 1)) != 0)
1046	>	throw new Error("data type scale not a power of two");
1047	>	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
1048		} catch (Exception e) {
1049		throw new Error(e);
1050		}
1055	–	if ((s & (s-1)) != 0)
1056	–	throw new Error("data type scale not a power of two");
1057	–	ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
1051		}
1052		}
1053
1054	+	// static fields (initialized in static initializer below)
1055	+
1056		/**
1057	<	* Per-thread records for threads that submit to pools. Currently
1058	<	* holds only pseudo-random seed / index that is used to choose
1059	<	* submission queues in method externalPush. In the future, this may
1060	<	* also incorporate a means to implement different task rejection
1061	<	* and resubmission policies.
1067	<	*
1068	<	* Seeds for submitters and workers/workQueues work in basically
1069	<	* the same way but are initialized and updated using slightly
1070	<	* different mechanics. Both are initialized using the same
1071	<	* approach as in class ThreadLocal, where successive values are
1072	<	* unlikely to collide with previous values. Seeds are then
1073	<	* randomly modified upon collisions using xorshifts, which
1074	<	* requires a non-zero seed.
1057	>	* Per-thread submission bookkeeping. Shared across all pools
1058	>	* to reduce ThreadLocal pollution and because random motion
1059	>	* to avoid contention in one pool is likely to hold for others.
1060	>	* Lazily initialized on first submission (but null-checked
1061	>	* in other contexts to avoid unnecessary initialization).
1062		*/
1063	<	static final class Submitter {
1077	<	int seed;
1078	<	Submitter(int s) { seed = s; }
1079	<	}
1080	<
1081	<	/** Property prefix for constructing common pool */
1082	<	private static final String propPrefix =
1083	<	"java.util.concurrent.ForkJoinPool.common.";
1084	<
1085	<	// static fields (initialized in static initializer below)
1063	>	static final ThreadLocal<Submitter> submitters;
1064
1065		/**
1066		* Creates a new ForkJoinWorkerThread. This factory is used unless
#	Line 1092 \| Line 1070 \| public class ForkJoinPool extends Abstra
1070		defaultForkJoinWorkerThreadFactory;
1071
1072		/**
1095	–	* Common (static) pool. Non-null for public use unless a static
1096	–	* construction exception, but internal usages null-check on use
1097	–	* to paranoically avoid potential initialization circularities
1098	–	* as well as to simplify generated code.
1099	–	*/
1100	–	static final ForkJoinPool commonPool;
1101	–
1102	–	/**
1073		* Permission required for callers of methods that may start or
1074		* kill threads.
1075		*/
1076		private static final RuntimePermission modifyThreadPermission;
1077
1078		/**
1079	<	* Per-thread submission bookkeeping. Shared across all pools
1080	<	* to reduce ThreadLocal pollution and because random motion
1081	<	* to avoid contention in one pool is likely to hold for others.
1082	<	* Lazily initialized on first submission (but null-checked
1113	<	* in other contexts to avoid unnecessary initialization).
1079	>	* Common (static) pool. Non-null for public use unless a static
1080	>	* construction exception, but internal usages null-check on use
1081	>	* to paranoically avoid potential initialization circularities
1082	>	* as well as to simplify generated code.
1083		*/
1084	<	static final ThreadLocal<Submitter> submitters;
1084	>	static final ForkJoinPool common;
1085
1086		/**
1087	<	* Common pool parallelism. Must equal commonPool.parallelism.
1087	>	* Common pool parallelism. To allow simpler use and management
1088	>	* when common pool threads are disabled, we allow the underlying
1089	>	* common.parallelism field to be zero, but in that case still report
1090	>	* parallelism as 1 to reflect resulting caller-runs mechanics.
1091		*/
1092	<	static final int commonPoolParallelism;
1092	>	static final int commonParallelism;
1093
1094		/**
1095		* Sequence number for creating workerNamePrefix.
#	Line 1125 \| Line 1097 \| public class ForkJoinPool extends Abstra
1097		private static int poolNumberSequence;
1098
1099		/**
1100	<	* Return the next sequence number. We don't expect this to
1101	<	* ever contend so use simple builtin sync.
1100	>	* Returns the next sequence number. We don't expect this to
1101	>	* ever contend, so use simple builtin sync.
1102		*/
1103		private static final synchronized int nextPoolId() {
1104		return ++poolNumberSequence;
#	Line 1150 \| Line 1122 \| public class ForkJoinPool extends Abstra
1122		private static final long FAST_IDLE_TIMEOUT = 200L * 1000L * 1000L;
1123
1124		/**
1125	+	* Tolerance for idle timeouts, to cope with timer undershoots
1126	+	*/
1127	+	private static final long TIMEOUT_SLOP = 2000000L;
1128	+
1129	+	/**
1130		* The maximum stolen->joining link depth allowed in method
1131		* tryHelpStealer. Must be a power of two. Depths for legitimate
1132		* chains are unbounded, but we use a fixed constant to avoid
#	Line 1165 \| Line 1142 \| public class ForkJoinPool extends Abstra
1142		*/
1143		private static final int SEED_INCREMENT = 0x61c88647;
1144
1145	<	/**
1145	>	/*
1146		* Bits and masks for control variables
1147		*
1148		* Field ctl is a long packed with:
#	Line 1249 \| Line 1226 \| public class ForkJoinPool extends Abstra
1226		static final int FIFO_QUEUE = 1;
1227		static final int SHARED_QUEUE = -1;
1228
1229	<	// Instance fields
1229	>	// Heuristic padding to ameliorate unfortunate memory placements
1230	>	volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
1231
1232	<	/*
1255	<	* Field layout order in this class tends to matter more than one
1256	<	* would like. Runtime layout order is only loosely related to
1257	<	* declaration order and may differ across JVMs, but the following
1258	<	* empirically works OK on current JVMs.
1259	<	*/
1232	>	// Instance fields
1233		volatile long stealCount; // collects worker counts
1234		volatile long ctl; // main pool control
1262	–	final int parallelism; // parallelism level
1263	–	final int localMode; // per-worker scheduling mode
1264	–	volatile int indexSeed; // worker/submitter index seed
1235		volatile int plock; // shutdown status and seqLock
1236	+	volatile int indexSeed; // worker/submitter index seed
1237	+	final short parallelism; // parallelism level
1238	+	final short mode; // LIFO/FIFO
1239		WorkQueue[] workQueues; // main registry
1240	<	final ForkJoinWorkerThreadFactory factory; // factory for new workers
1241	<	final Thread.UncaughtExceptionHandler ueh; // per-worker UEH
1240	>	final ForkJoinWorkerThreadFactory factory;
1241	>	final UncaughtExceptionHandler ueh; // per-worker UEH
1242		final String workerNamePrefix; // to create worker name string
1243
1244	<	/*
1244	>	volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17;
1245	>	volatile Object pad18, pad19, pad1a, pad1b;
1246	>
1247	>	/**
1248		* Acquires the plock lock to protect worker array and related
1249		* updates. This method is called only if an initial CAS on plock
1250	<	* fails. This acts as a spinLock for normal cases, but falls back
1250	>	* fails. This acts as a spinlock for normal cases, but falls back
1251		* to builtin monitor to block when (rarely) needed. This would be
1252		* a terrible idea for a highly contended lock, but works fine as
1253	<	* a more conservative alternative to a pure spinlock. See
1278	<	* internal ConcurrentHashMap documentation for further
1279	<	* explanation of nearly the same construction.
1253	>	* a more conservative alternative to a pure spinlock.
1254		*/
1255		private int acquirePlock() {
1256	<	int spins = PL_SPINS, r = 0, ps, nps;
1256	>	int spins = PL_SPINS, ps, nps;
1257		for (;;) {
1258		if (((ps = plock) & PL_LOCK) == 0 &&
1259		U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK))
1260		return nps;
1287	–	else if (r == 0)
1288	–	r = ThreadLocalRandom.current().nextInt(); // randomize spins
1261		else if (spins >= 0) {
1262	<	r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
1291	<	if (r >= 0)
1262	>	if (ThreadLocalRandom.current().nextInt() >= 0)
1263		--spins;
1264		}
1265		else if (U.compareAndSwapInt(this, PLOCK, ps, ps \| PL_SIGNAL)) {
#	Line 1319 \| Line 1290 \| public class ForkJoinPool extends Abstra
1290		synchronized (this) { notifyAll(); }
1291		}
1292
1293	+	/**
1294	+	* Tries to create and start one worker if fewer than target
1295	+	* parallelism level exist. Adjusts counts etc on failure.
1296	+	*/
1297	+	private void tryAddWorker() {
1298	+	long c; int u, e;
1299	+	while ((u = (int)((c = ctl) >>> 32)) < 0 &&
1300	+	(u & SHORT_SIGN) != 0 && (e = (int)c) >= 0) {
1301	+	long nc = ((long)(((u + UTC_UNIT) & UTC_MASK) \|
1302	+	((u + UAC_UNIT) & UAC_MASK)) << 32) \| (long)e;
1303	+	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1304	+	ForkJoinWorkerThreadFactory fac;
1305	+	Throwable ex = null;
1306	+	ForkJoinWorkerThread wt = null;
1307	+	try {
1308	+	if ((fac = factory) != null &&
1309	+	(wt = fac.newThread(this)) != null) {
1310	+	wt.start();
1311	+	break;
1312	+	}
1313	+	} catch (Throwable rex) {
1314	+	ex = rex;
1315	+	}
1316	+	deregisterWorker(wt, ex);
1317	+	break;
1318	+	}
1319	+	}
1320	+	}
1321	+
1322		// Registering and deregistering workers
1323
1324		/**
1325	<	* Callback from ForkJoinWorkerThread constructor to establish its
1326	<	* poolIndex and record its WorkQueue. To avoid scanning bias due
1327	<	* to packing entries in front of the workQueues array, we treat
1328	<	* the array as a simple power-of-two hash table using per-thread
1329	<	* seed as hash, expanding as needed.
1330	<	*
1331	<	* @param w the worker's queue
1332	<	*/
1333	<	final void registerWorker(WorkQueue w) {
1334	<	int s, ps; // generate a rarely colliding candidate index seed
1335	<	do {} while (!U.compareAndSwapInt(this, INDEXSEED,
1336	<	s = indexSeed, s += SEED_INCREMENT) \|\|
1325	>	* Callback from ForkJoinWorkerThread to establish and record its
1326	>	* WorkQueue. To avoid scanning bias due to packing entries in
1327	>	* front of the workQueues array, we treat the array as a simple
1328	>	* power-of-two hash table using per-thread seed as hash,
1329	>	* expanding as needed.
1330	>	*
1331	>	* @param wt the worker thread
1332	>	* @return the worker's queue
1333	>	*/
1334	>	final WorkQueue registerWorker(ForkJoinWorkerThread wt) {
1335	>	UncaughtExceptionHandler handler; WorkQueue[] ws; int s, ps;
1336	>	wt.setDaemon(true);
1337	>	if ((handler = ueh) != null)
1338	>	wt.setUncaughtExceptionHandler(handler);
1339	>	do {} while (!U.compareAndSwapInt(this, INDEXSEED, s = indexSeed,
1340	>	s += SEED_INCREMENT) \|\|
1341		s == 0); // skip 0
1342	+	WorkQueue w = new WorkQueue(this, wt, mode, s);
1343		if (((ps = plock) & PL_LOCK) != 0 \|\|
1344		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1345		ps = acquirePlock();
1346		int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1347		try {
1348	<	WorkQueue[] ws;
1344	<	if (w != null && (ws = workQueues) != null) {
1345	<	w.seed = s;
1348	>	if ((ws = workQueues) != null) { // skip if shutting down
1349		int n = ws.length, m = n - 1;
1350	<	int r = (s << 1) \| 1; // use odd-numbered indices
1351	<	if (ws[r &= m] != null) { // collision
1352	<	int probes = 0; // step by approx half size
1350	>	int r = (s << 1) \| 1; // use odd-numbered indices
1351	>	if (ws[r &= m] != null) { // collision
1352	>	int probes = 0; // step by approx half size
1353		int step = (n <= 4) ? 2 : ((n >>> 1) & EVENMASK) + 2;
1354		while (ws[r = (r + step) & m] != null) {
1355		if (++probes >= n) {
#	Line 1356 \| Line 1359 \| public class ForkJoinPool extends Abstra
1359		}
1360		}
1361		}
1362	<	w.eventCount = w.poolIndex = r; // establish before recording
1362	>	w.poolIndex = (short)r;
1363	>	w.eventCount = r; // volatile write orders
1364		ws[r] = w;
1365		}
1366		} finally {
1367		if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1368		releasePlock(nps);
1369		}
1370	+	wt.setName(workerNamePrefix.concat(Integer.toString(w.poolIndex >>> 1)));
1371	+	return w;
1372		}
1373
1374		/**
#	Line 1371 \| Line 1377 \| public class ForkJoinPool extends Abstra
1377		* array, and adjusts counts. If pool is shutting down, tries to
1378		* complete termination.
1379		*
1380	<	* @param wt the worker thread or null if construction failed
1380	>	* @param wt the worker thread, or null if construction failed
1381		* @param ex the exception causing failure, or null if none
1382		*/
1383		final void deregisterWorker(ForkJoinWorkerThread wt, Throwable ex) {
1384		WorkQueue w = null;
1385		if (wt != null && (w = wt.workQueue) != null) {
1386	<	int ps;
1381	<	collectStealCount(w);
1386	>	int ps; long sc;
1387		w.qlock = -1; // ensure set
1388	+	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1389	+	sc = stealCount,
1390	+	sc + w.nsteals));
1391		if (((ps = plock) & PL_LOCK) != 0 \|\|
1392		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1393		ps = acquirePlock();
#	Line 1395 \| Line 1403 \| public class ForkJoinPool extends Abstra
1403		}
1404		}
1405
1406	<	long c; // adjust ctl counts
1406	>	long c; // adjust ctl counts
1407		do {} while (!U.compareAndSwapLong
1408		(this, CTL, c = ctl, (((c - AC_UNIT) & AC_MASK) \|
1409		((c - TC_UNIT) & TC_MASK) \|
1410		(c & ~(AC_MASK\|TC_MASK)))));
1411
1412	<	if (!tryTerminate(false, false) && w != null) {
1413	<	w.cancelAll(); // cancel remaining tasks
1414	<	if (w.array != null) // suppress signal if never ran
1415	<	signalWork(null, 1); // wake up or create replacement
1416	<	if (ex == null) // help clean refs on way out
1417	<	ForkJoinTask.helpExpungeStaleExceptions();
1412	>	if (!tryTerminate(false, false) && w != null && w.array != null) {
1413	>	w.cancelAll(); // cancel remaining tasks
1414	>	WorkQueue[] ws; WorkQueue v; Thread p; int u, i, e;
1415	>	while ((u = (int)((c = ctl) >>> 32)) < 0 && (e = (int)c) >= 0) {
1416	>	if (e > 0) { // activate or create replacement
1417	>	if ((ws = workQueues) == null \|\|
1418	>	(i = e & SMASK) >= ws.length \|\|
1419	>	(v = ws[i]) == null)
1420	>	break;
1421	>	long nc = (((long)(v.nextWait & E_MASK)) \|
1422	>	((long)(u + UAC_UNIT) << 32));
1423	>	if (v.eventCount != (e \| INT_SIGN))
1424	>	break;
1425	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1426	>	v.eventCount = (e + E_SEQ) & E_MASK;
1427	>	if ((p = v.parker) != null)
1428	>	U.unpark(p);
1429	>	break;
1430	>	}
1431	>	}
1432	>	else {
1433	>	if ((short)u < 0)
1434	>	tryAddWorker();
1435	>	break;
1436	>	}
1437	>	}
1438		}
1439	<
1440	<	if (ex != null) // rethrow
1439	>	if (ex == null) // help clean refs on way out
1440	>	ForkJoinTask.helpExpungeStaleExceptions();
1441	>	else // rethrow
1442		ForkJoinTask.rethrow(ex);
1443		}
1444
1445	+	// Submissions
1446	+
1447		/**
1448	<	* Collect worker steal count into total. Called on termination
1449	<	* and upon int overflow of local count. (There is a possible race
1450	<	* in the latter case vs any caller of getStealCount, which can
1451	<	* make its results less accurate than usual.)
1452	<	*/
1453	<	final void collectStealCount(WorkQueue w) {
1454	<	if (w != null) {
1455	<	long sc;
1456	<	int ns = w.nsteals;
1457	<	w.nsteals = 0; // handle overflow
1458	<	long steals = (ns >= 0) ? ns : 1L + (long)(Integer.MAX_VALUE);
1459	<	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1460	<	sc = stealCount, sc + steals));
1461	<	}
1448	>	* Per-thread records for threads that submit to pools. Currently
1449	>	* holds only pseudo-random seed / index that is used to choose
1450	>	* submission queues in method externalPush. In the future, this may
1451	>	* also incorporate a means to implement different task rejection
1452	>	* and resubmission policies.
1453	>	*
1454	>	* Seeds for submitters and workers/workQueues work in basically
1455	>	* the same way but are initialized and updated using slightly
1456	>	* different mechanics. Both are initialized using the same
1457	>	* approach as in class ThreadLocal, where successive values are
1458	>	* unlikely to collide with previous values. Seeds are then
1459	>	* randomly modified upon collisions using xorshifts, which
1460	>	* requires a non-zero seed.
1461	>	*/
1462	>	static final class Submitter {
1463	>	int seed;
1464	>	Submitter(int s) { seed = s; }
1465		}
1466
1433	–	// Submissions
1434	–
1467		/**
1468		* Unless shutting down, adds the given task to a submission queue
1469		* at submitter's current queue index (modulo submission
#	Line 1441 \| Line 1473 \| public class ForkJoinPool extends Abstra
1473		* @param task the task. Caller must ensure non-null.
1474		*/
1475		final void externalPush(ForkJoinTask<?> task) {
1476	<	WorkQueue[] ws; WorkQueue q; Submitter z; int m; ForkJoinTask<?>[] a;
1477	<	if ((z = submitters.get()) != null && plock > 0 &&
1478	<	(ws = workQueues) != null && (m = (ws.length - 1)) >= 0 &&
1479	<	(q = ws[m & z.seed & SQMASK]) != null &&
1476	>	Submitter z = submitters.get();
1477	>	WorkQueue q; int r, m, s, n, am; ForkJoinTask<?>[] a;
1478	>	int ps = plock;
1479	>	WorkQueue[] ws = workQueues;
1480	>	if (z != null && ps > 0 && ws != null && (m = (ws.length - 1)) >= 0 &&
1481	>	(q = ws[m & (r = z.seed) & SQMASK]) != null && r != 0 &&
1482		U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock
1483	<	int s = q.top, n;
1484	<	if ((a = q.array) != null && a.length > (n = s + 1 - q.base)) {
1485	<	U.putObject(a, (long)(((a.length - 1) & s) << ASHIFT) + ABASE,
1486	<	task);
1483	>	if ((a = q.array) != null &&
1484	>	(am = a.length - 1) > (n = (s = q.top) - q.base)) {
1485	>	int j = ((am & s) << ASHIFT) + ABASE;
1486	>	U.putOrderedObject(a, j, task);
1487		q.top = s + 1; // push on to deque
1488		q.qlock = 0;
1489		if (n <= 1)
1490	<	signalWork(q, 1);
1490	>	signalWork(ws, q);
1491		return;
1492		}
1493		q.qlock = 0;
#	Line 1464 \| Line 1498 \| public class ForkJoinPool extends Abstra
1498		/**
1499		* Full version of externalPush. This method is called, among
1500		* other times, upon the first submission of the first task to the
1501	<	* pool, so must perform secondary initialization: creating
1468	<	* workQueue array and setting plock to a valid value. It also
1501	>	* pool, so must perform secondary initialization. It also
1502		* detects first submission by an external thread by looking up
1503		* its ThreadLocal, and creates a new shared queue if the one at
1504	<	* index if empty or contended. The lock bodies must be
1504	>	* index if empty or contended. The plock lock body must be
1505		* exception-free (so no try/finally) so we optimistically
1506	<	* allocate new queues/arrays outside the locks and throw them
1507	<	* away if (very rarely) not needed. Note that the plock seq value
1508	<	* can eventually wrap around zero, but if so harmlessly fails to
1509	<	* reinitialize.
1506	>	* allocate new queues outside the lock and throw them away if
1507	>	* (very rarely) not needed.
1508	>	*
1509	>	* Secondary initialization occurs when plock is zero, to create
1510	>	* workQueue array and set plock to a valid value. This lock body
1511	>	* must also be exception-free. Because the plock seq value can
1512	>	* eventually wrap around zero, this method harmlessly fails to
1513	>	* reinitialize if workQueues exists, while still advancing plock.
1514		*/
1515		private void fullExternalPush(ForkJoinTask<?> task) {
1516	<	for (Submitter z = null;;) {
1517	<	WorkQueue[] ws; WorkQueue q; int ps, m, r, s;
1516	>	int r = 0; // random index seed
1517	>	for (Submitter z = submitters.get();;) {
1518	>	WorkQueue[] ws; WorkQueue q; int ps, m, k;
1519	>	if (z == null) {
1520	>	if (U.compareAndSwapInt(this, INDEXSEED, r = indexSeed,
1521	>	r += SEED_INCREMENT) && r != 0)
1522	>	submitters.set(z = new Submitter(r));
1523	>	}
1524	>	else if (r == 0) { // move to a different index
1525	>	r = z.seed;
1526	>	r ^= r << 13; // same xorshift as WorkQueues
1527	>	r ^= r >>> 17;
1528	>	z.seed = r ^= (r << 5);
1529	>	}
1530		if ((ps = plock) < 0)
1531		throw new RejectedExecutionException();
1532	<	else if ((ws = workQueues) == null \|\| (m = ws.length - 1) < 0) {
1533	<	int n = parallelism - 1; n \|= n >>> 1; n \|= n >>> 2;
1534	<	n \|= n >>> 4; n \|= n >>> 8; n \|= n >>> 16;
1535	<	WorkQueue[] nws = new WorkQueue[(n + 1) << 1]; // power of two
1536	<	if ((ps & PL_LOCK) != 0 \|\|
1532	>	else if (ps == 0 \|\| (ws = workQueues) == null \|\|
1533	>	(m = ws.length - 1) < 0) { // initialize workQueues
1534	>	int p = parallelism; // find power of two table size
1535	>	int n = (p > 1) ? p - 1 : 1; // ensure at least 2 slots
1536	>	n \|= n >>> 1;
1537	>	n \|= n >>> 2;
1538	>	n \|= n >>> 4;
1539	>	n \|= n >>> 8;
1540	>	n \|= n >>> 16;
1541	>	n = (n + 1) << 1;
1542	>	WorkQueue[] nws = ((ws = workQueues) == null \|\| ws.length == 0 ?
1543	>	new WorkQueue[n] : null);
1544	>	if (((ps = plock) & PL_LOCK) != 0 \|\|
1545		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1546		ps = acquirePlock();
1547	<	if ((ws = workQueues) == null)
1547	>	if (((ws = workQueues) == null \|\| ws.length == 0) && nws != null)
1548		workQueues = nws;
1549		int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1550		if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1551		releasePlock(nps);
1552		}
1553	<	else if (z == null && (z = submitters.get()) == null) {
1554	<	if (U.compareAndSwapInt(this, INDEXSEED,
1555	<	s = indexSeed, s += SEED_INCREMENT) &&
1556	<	s != 0) // skip 0
1557	<	submitters.set(z = new Submitter(s));
1553	>	else if ((q = ws[k = r & m & SQMASK]) != null) {
1554	>	if (q.qlock == 0 && U.compareAndSwapInt(q, QLOCK, 0, 1)) {
1555	>	ForkJoinTask<?>[] a = q.array;
1556	>	int s = q.top;
1557	>	boolean submitted = false;
1558	>	try { // locked version of push
1559	>	if ((a != null && a.length > s + 1 - q.base) \|\|
1560	>	(a = q.growArray()) != null) { // must presize
1561	>	int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
1562	>	U.putOrderedObject(a, j, task);
1563	>	q.top = s + 1;
1564	>	submitted = true;
1565	>	}
1566	>	} finally {
1567	>	q.qlock = 0; // unlock
1568	>	}
1569	>	if (submitted) {
1570	>	signalWork(ws, q);
1571	>	return;
1572	>	}
1573	>	}
1574	>	r = 0; // move on failure
1575		}
1576	<	else {
1577	<	int k = (r = z.seed) & m & SQMASK;
1578	<	if ((q = ws[k]) == null && (ps & PL_LOCK) == 0) {
1579	<	(q = new WorkQueue(this, null, SHARED_QUEUE)).poolIndex = k;
1580	<	if (((ps = plock) & PL_LOCK) != 0 \|\|
1581	<	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1582	<	ps = acquirePlock();
1583	<	WorkQueue w = null;
1584	<	if ((ws = workQueues) != null && k < ws.length &&
1585	<	(w = ws[k]) == null)
1586	<	ws[k] = q;
1513	<	else
1514	<	q = w;
1515	<	int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1516	<	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1517	<	releasePlock(nps);
1518	<	}
1519	<	if (q != null && q.qlock == 0 && q.fullPush(task, false))
1520	<	return;
1521	<	r ^= r << 13; // same xorshift as WorkQueues
1522	<	r ^= r >>> 17;
1523	<	z.seed = r ^= r << 5; // move to a different index
1576	>	else if (((ps = plock) & PL_LOCK) == 0) { // create new queue
1577	>	q = new WorkQueue(this, null, SHARED_QUEUE, r);
1578	>	q.poolIndex = (short)k;
1579	>	if (((ps = plock) & PL_LOCK) != 0 \|\|
1580	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1581	>	ps = acquirePlock();
1582	>	if ((ws = workQueues) != null && k < ws.length && ws[k] == null)
1583	>	ws[k] = q;
1584	>	int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1585	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1586	>	releasePlock(nps);
1587		}
1588	+	else
1589	+	r = 0;
1590		}
1591		}
1592
#	Line 1532 \| Line 1597 \| public class ForkJoinPool extends Abstra
1597		*/
1598		final void incrementActiveCount() {
1599		long c;
1600	<	do {} while (!U.compareAndSwapLong(this, CTL, c = ctl, c + AC_UNIT));
1600	>	do {} while (!U.compareAndSwapLong
1601	>	(this, CTL, c = ctl, ((c & ~AC_MASK) \|
1602	>	((c & AC_MASK) + AC_UNIT))));
1603		}
1604
1605		/**
1606	<	* Tries to create (at most one) or activate (possibly several)
1540	<	* workers if too few are active. On contention failure, continues
1541	<	* until at least one worker is signalled or the given queue is
1542	<	* empty or all workers are active.
1606	>	* Tries to create or activate a worker if too few are active.
1607		*
1608	<	* @param q if non-null, the queue holding tasks to be signalled
1609	<	* @param signals the target number of signals.
1608	>	* @param ws the worker array to use to find signallees
1609	>	* @param q if non-null, the queue holding tasks to be processed
1610		*/
1611	<	final void signalWork(WorkQueue q, int signals) {
1612	<	long c; int e, u, i; WorkQueue[] ws; WorkQueue w; Thread p;
1613	<	while ((u = (int)((c = ctl) >>> 32)) < 0) {
1614	<	if ((e = (int)c) > 0) {
1615	<	if ((ws = workQueues) != null && ws.length > (i = e & SMASK) &&
1616	<	(w = ws[i]) != null && w.eventCount == (e \| INT_SIGN)) {
1617	<	long nc = (((long)(w.nextWait & E_MASK)) \|
1618	<	((long)(u + UAC_UNIT) << 32));
1619	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1556	<	w.eventCount = (e + E_SEQ) & E_MASK;
1557	<	if ((p = w.parker) != null)
1558	<	U.unpark(p);
1559	<	if (--signals <= 0)
1560	<	break;
1561	<	}
1562	<	else
1563	<	signals = 1;
1564	<	if ((q != null && q.queueSize() == 0))
1565	<	break;
1566	<	}
1567	<	else
1568	<	break;
1611	>	final void signalWork(WorkQueue[] ws, WorkQueue q) {
1612	>	for (;;) {
1613	>	long c; int e, u, i; WorkQueue w; Thread p;
1614	>	if ((u = (int)((c = ctl) >>> 32)) >= 0)
1615	>	break;
1616	>	if ((e = (int)c) <= 0) {
1617	>	if ((short)u < 0)
1618	>	tryAddWorker();
1619	>	break;
1620		}
1621	<	else if (e == 0 && (u & SHORT_SIGN) != 0) {
1622	<	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) \|
1623	<	((u + UAC_UNIT) & UAC_MASK)) << 32;
1624	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1625	<	ForkJoinWorkerThread wt = null;
1626	<	Throwable ex = null;
1627	<	boolean started = false;
1628	<	try {
1629	<	ForkJoinWorkerThreadFactory fac;
1630	<	if ((fac = factory) != null &&
1631	<	(wt = fac.newThread(this)) != null) {
1632	<	wt.start();
1582	<	started = true;
1583	<	}
1584	<	} catch (Throwable rex) {
1585	<	ex = rex;
1586	<	}
1587	<	if (!started)
1588	<	deregisterWorker(wt, ex); // adjust counts on failure
1589	<	break;
1590	<	}
1621	>	if (ws == null \|\| ws.length <= (i = e & SMASK) \|\|
1622	>	(w = ws[i]) == null)
1623	>	break;
1624	>	long nc = (((long)(w.nextWait & E_MASK)) \|
1625	>	((long)(u + UAC_UNIT)) << 32);
1626	>	int ne = (e + E_SEQ) & E_MASK;
1627	>	if (w.eventCount == (e \| INT_SIGN) &&
1628	>	U.compareAndSwapLong(this, CTL, c, nc)) {
1629	>	w.eventCount = ne;
1630	>	if ((p = w.parker) != null)
1631	>	U.unpark(p);
1632	>	break;
1633		}
1634	<	else
1634	>	if (q != null && q.base >= q.top)
1635		break;
1636		}
1637		}
#	Line 1600 \| Line 1642 \| public class ForkJoinPool extends Abstra
1642		* Top-level runloop for workers, called by ForkJoinWorkerThread.run.
1643		*/
1644		final void runWorker(WorkQueue w) {
1645	<	// initialize queue array in this thread
1646	<	w.array = new ForkJoinTask<?>[WorkQueue.INITIAL_QUEUE_CAPACITY];
1647	<	do { w.runTask(scan(w)); } while (w.qlock >= 0);
1645	>	w.growArray(); // allocate queue
1646	>	for (int r = w.hint; scan(w, r) == 0; ) {
1647	>	r ^= r << 13; r ^= r >>> 17; r ^= r << 5; // xorshift
1648	>	}
1649		}
1650
1651		/**
1652	<	* Scans for and, if found, returns one task, else possibly
1652	>	* Scans for and, if found, runs one task, else possibly
1653		* inactivates the worker. This method operates on single reads of
1654		* volatile state and is designed to be re-invoked continuously,
1655		* in part because it returns upon detecting inconsistencies,
1656		* contention, or state changes that indicate possible success on
1657		* re-invocation.
1658		*
1659	<	* The scan searches for tasks across a random permutation of
1660	<	* queues (starting at a random index and stepping by a random
1661	<	* relative prime, checking each at least once). The scan
1662	<	* terminates upon either finding a non-empty queue, or completing
1663	<	* the sweep. If the worker is not inactivated, it takes and
1664	<	* returns a task from this queue. Otherwise, if not activated, it
1665	<	* signals workers (that may include itself) and returns so caller
1666	<	* can retry. Also returns for trtry if the worker array may have
1667	<	* changed during an empty scan. On failure to find a task, we
1625	<	* take one of the following actions, after which the caller will
1626	<	* retry calling this method unless terminated.
1627	<	*
1628	<	* * If pool is terminating, terminate the worker.
1629	<	*
1630	<	* * If not already enqueued, try to inactivate and enqueue the
1631	<	* worker on wait queue. Or, if inactivating has caused the pool
1632	<	* to be quiescent, relay to idleAwaitWork to check for
1633	<	* termination and possibly shrink pool.
1634	<	*
1635	<	* * If already enqueued and none of the above apply, possibly
1636	<	* (with 1/2 probability) park awaiting signal, else lingering to
1637	<	* help scan and signal.
1659	>	* The scan searches for tasks across queues starting at a random
1660	>	* index, checking each at least twice. The scan terminates upon
1661	>	* either finding a non-empty queue, or completing the sweep. If
1662	>	* the worker is not inactivated, it takes and runs a task from
1663	>	* this queue. Otherwise, if not activated, it tries to activate
1664	>	* itself or some other worker by signalling. On failure to find a
1665	>	* task, returns (for retry) if pool state may have changed during
1666	>	* an empty scan, or tries to inactivate if active, else possibly
1667	>	* blocks or terminates via method awaitWork.
1668		*
1669		* @param w the worker (via its WorkQueue)
1670	<	* @return a task or null if none found
1670	>	* @param r a random seed
1671	>	* @return worker qlock status if would have waited, else 0
1672		*/
1673	<	private final ForkJoinTask<?> scan(WorkQueue w) {
1674	<	WorkQueue[] ws; WorkQueue q; // first update random seed
1675	<	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1676	<	int ps = plock, m; // volatile read order matters
1677	<	if ((ws = workQueues) != null && (m = ws.length - 1) > 0) {
1678	<	int ec = w.eventCount; // ec is negative if inactive
1679	<	int step = (r >>> 16) \| 1; // relatively prime
1680	<	for (int j = (m + 1) << 2; ; --j, r += step) {
1681	<	ForkJoinTask<?> t; ForkJoinTask<?>[] a; int b, n;
1682	<	if ((q = ws[r & m]) != null && (b = q.base) - q.top < 0 &&
1683	<	(a = q.array) != null) { // probably nonempty
1684	<	int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1685	<	t = (ForkJoinTask<?>)U.getObjectVolatile(a, i);
1686	<	if (q.base == b && ec >= 0 && t != null &&
1687	<	U.compareAndSwapObject(a, i, t, null)) {
1688	<	if ((n = q.top - (q.base = b + 1)) > 0)
1689	<	signalWork(q, n);
1690	<	return t; // taken
1691	<	}
1692	<	if (j < m \|\| (ec < 0 && (ec = w.eventCount) < 0)) {
1693	<	if ((n = q.queueSize() - 1) > 0)
1694	<	signalWork(q, n);
1695	<	break; // let caller retry after signal
1696	<	}
1697	<	}
1698	<	else if (j < 0) { // end of scan
1699	<	long c = ctl; int e;
1700	<	if (plock != ps) // incomplete sweep
1670	<	break;
1671	<	if ((e = (int)c) < 0) // pool is terminating
1672	<	w.qlock = -1;
1673	<	else if (ec >= 0) { // try to enqueue/inactivate
1674	<	long nc = ((long)ec \|
1675	<	((c - AC_UNIT) & (AC_MASK\|TC_MASK)));
1673	>	private final int scan(WorkQueue w, int r) {
1674	>	WorkQueue[] ws; int m;
1675	>	long c = ctl; // for consistency check
1676	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0 && w != null) {
1677	>	for (int j = m + m + 1, ec = w.eventCount;;) {
1678	>	WorkQueue q; int b, e; ForkJoinTask<?>[] a; ForkJoinTask<?> t;
1679	>	if ((q = ws[(r - j) & m]) != null &&
1680	>	(b = q.base) - q.top < 0 && (a = q.array) != null) {
1681	>	long i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1682	>	if ((t = ((ForkJoinTask<?>)
1683	>	U.getObjectVolatile(a, i))) != null) {
1684	>	if (ec < 0)
1685	>	helpRelease(c, ws, w, q, b);
1686	>	else if (q.base == b &&
1687	>	U.compareAndSwapObject(a, i, t, null)) {
1688	>	U.putOrderedInt(q, QBASE, b + 1);
1689	>	if ((b + 1) - q.top < 0)
1690	>	signalWork(ws, q);
1691	>	w.runTask(t);
1692	>	}
1693	>	}
1694	>	break;
1695	>	}
1696	>	else if (--j < 0) {
1697	>	if ((ec \| (e = (int)c)) < 0) // inactive or terminating
1698	>	return awaitWork(w, c, ec);
1699	>	else if (ctl == c) { // try to inactivate and enqueue
1700	>	long nc = (long)ec \| ((c - AC_UNIT) & (AC_MASK\|TC_MASK));
1701		w.nextWait = e;
1702	<	w.eventCount = ec \| INT_SIGN; // mark as inactive
1703	<	if (ctl != c \|\|
1704	<	!U.compareAndSwapLong(this, CTL, c, nc))
1680	<	w.eventCount = ec; // unmark on CAS failure
1681	<	else if ((int)(c >> AC_SHIFT) == 1 - parallelism)
1682	<	idleAwaitWork(w, nc, c); // quiescent
1683	<	}
1684	<	else if (w.seed >= 0 && w.eventCount < 0) {
1685	<	Thread wt = Thread.currentThread();
1686	<	Thread.interrupted(); // clear status
1687	<	U.putObject(wt, PARKBLOCKER, this);
1688	<	w.parker = wt; // emulate LockSupport.park
1689	<	if (w.eventCount < 0) // recheck
1690	<	U.park(false, 0L);
1691	<	w.parker = null;
1692	<	U.putObject(wt, PARKBLOCKER, null);
1702	>	w.eventCount = ec \| INT_SIGN;
1703	>	if (!U.compareAndSwapLong(this, CTL, c, nc))
1704	>	w.eventCount = ec; // back out
1705		}
1706		break;
1707		}
1708		}
1709		}
1710	<	return null;
1710	>	return 0;
1711		}
1712
1713		/**
1714	<	* If inactivating worker w has caused the pool to become
1715	<	* quiescent, checks for pool termination, and, so long as this is
1716	<	* not the only worker, waits for event for up to a given
1717	<	* duration. On timeout, if ctl has not changed, terminates the
1718	<	* worker, which will in turn wake up another worker to possibly
1719	<	* repeat this process.
1714	>	* A continuation of scan(), possibly blocking or terminating
1715	>	* worker w. Returns without blocking if pool state has apparently
1716	>	* changed since last invocation. Also, if inactivating w has
1717	>	* caused the pool to become quiescent, checks for pool
1718	>	* termination, and, so long as this is not the only worker, waits
1719	>	* for event for up to a given duration. On timeout, if ctl has
1720	>	* not changed, terminates the worker, which will in turn wake up
1721	>	* another worker to possibly repeat this process.
1722		*
1723		* @param w the calling worker
1724	<	* @param currentCtl the ctl value triggering possible quiescence
1725	<	* @param prevCtl the ctl value to restore if thread is terminated
1724	>	* @param c the ctl value on entry to scan
1725	>	* @param ec the worker's eventCount on entry to scan
1726		*/
1727	<	private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) {
1728	<	if (w.eventCount < 0 &&
1729	<	(this == commonPool \|\| !tryTerminate(false, false)) &&
1730	<	(int)prevCtl != 0) {
1731	<	int dc = -(short)(currentCtl >>> TC_SHIFT);
1732	<	long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT;
1733	<	long deadline = System.nanoTime() + parkTime - 100000L; // 1ms slop
1734	<	Thread wt = Thread.currentThread();
1735	<	while (ctl == currentCtl) {
1736	<	Thread.interrupted(); // timed variant of version in scan()
1737	<	U.putObject(wt, PARKBLOCKER, this);
1738	<	w.parker = wt;
1739	<	if (ctl == currentCtl)
1740	<	U.park(false, parkTime);
1741	<	w.parker = null;
1742	<	U.putObject(wt, PARKBLOCKER, null);
1743	<	if (ctl != currentCtl)
1744	<	break;
1745	<	if (deadline - System.nanoTime() <= 0L &&
1746	<	U.compareAndSwapLong(this, CTL, currentCtl, prevCtl)) {
1747	<	w.eventCount = (w.eventCount + E_SEQ) \| E_MASK;
1748	<	w.qlock = -1; // shrink
1749	<	break;
1727	>	private final int awaitWork(WorkQueue w, long c, int ec) {
1728	>	int stat, ns; long parkTime, deadline;
1729	>	if ((stat = w.qlock) >= 0 && w.eventCount == ec && ctl == c &&
1730	>	!Thread.interrupted()) {
1731	>	int e = (int)c;
1732	>	int u = (int)(c >>> 32);
1733	>	int d = (u >> UAC_SHIFT) + parallelism; // active count
1734	>
1735	>	if (e < 0 \|\| (d <= 0 && tryTerminate(false, false)))
1736	>	stat = w.qlock = -1; // pool is terminating
1737	>	else if ((ns = w.nsteals) != 0) { // collect steals and retry
1738	>	long sc;
1739	>	w.nsteals = 0;
1740	>	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1741	>	sc = stealCount, sc + ns));
1742	>	}
1743	>	else {
1744	>	long pc = ((d > 0 \|\| ec != (e \| INT_SIGN)) ? 0L :
1745	>	((long)(w.nextWait & E_MASK)) \| // ctl to restore
1746	>	((long)(u + UAC_UNIT)) << 32);
1747	>	if (pc != 0L) { // timed wait if last waiter
1748	>	int dc = -(short)(c >>> TC_SHIFT);
1749	>	parkTime = (dc < 0 ? FAST_IDLE_TIMEOUT:
1750	>	(dc + 1) * IDLE_TIMEOUT);
1751	>	deadline = System.nanoTime() + parkTime - TIMEOUT_SLOP;
1752	>	}
1753	>	else
1754	>	parkTime = deadline = 0L;
1755	>	if (w.eventCount == ec && ctl == c) {
1756	>	Thread wt = Thread.currentThread();
1757	>	U.putObject(wt, PARKBLOCKER, this);
1758	>	w.parker = wt; // emulate LockSupport.park
1759	>	if (w.eventCount == ec && ctl == c)
1760	>	U.park(false, parkTime); // must recheck before park
1761	>	w.parker = null;
1762	>	U.putObject(wt, PARKBLOCKER, null);
1763	>	if (parkTime != 0L && ctl == c &&
1764	>	deadline - System.nanoTime() <= 0L &&
1765	>	U.compareAndSwapLong(this, CTL, c, pc))
1766	>	stat = w.qlock = -1; // shrink pool
1767		}
1768		}
1769		}
1770	+	return stat;
1771		}
1772
1773		/**
1774	<	* Scans through queues looking for work while joining a task;
1775	<	* if any are present, signals.
1776	<	*
1777	<	* @param task to return early if done
1778	<	* @param origin an index to start scan
1779	<	*/
1780	<	final int helpSignal(ForkJoinTask<?> task, int origin) {
1781	<	WorkQueue[] ws; WorkQueue q; int m, n, s;
1782	<	if (task != null && (ws = workQueues) != null &&
1783	<	(m = ws.length - 1) >= 0) {
1784	<	for (int i = 0; i <= m; ++i) {
1785	<	if ((s = task.status) < 0)
1786	<	return s;
1787	<	if ((q = ws[(i + origin) & m]) != null &&
1788	<	(n = q.queueSize()) > 0) {
1789	<	signalWork(q, n);
1790	<	if ((int)(ctl >> AC_SHIFT) >= 0)
1791	<	break;
1792	<	}
1774	>	* Possibly releases (signals) a worker. Called only from scan()
1775	>	* when a worker with apparently inactive status finds a non-empty
1776	>	* queue. This requires revalidating all of the associated state
1777	>	* from caller.
1778	>	*/
1779	>	private final void helpRelease(long c, WorkQueue[] ws, WorkQueue w,
1780	>	WorkQueue q, int b) {
1781	>	WorkQueue v; int e, i; Thread p;
1782	>	if (w != null && w.eventCount < 0 && (e = (int)c) > 0 &&
1783	>	ws != null && ws.length > (i = e & SMASK) &&
1784	>	(v = ws[i]) != null && ctl == c) {
1785	>	long nc = (((long)(v.nextWait & E_MASK)) \|
1786	>	((long)((int)(c >>> 32) + UAC_UNIT)) << 32);
1787	>	int ne = (e + E_SEQ) & E_MASK;
1788	>	if (q != null && q.base == b && w.eventCount < 0 &&
1789	>	v.eventCount == (e \| INT_SIGN) &&
1790	>	U.compareAndSwapLong(this, CTL, c, nc)) {
1791	>	v.eventCount = ne;
1792	>	if ((p = v.parker) != null)
1793	>	U.unpark(p);
1794		}
1795		}
1763	–	return 0;
1796		}
1797
1798		/**
#	Line 1783 \| Line 1815 \| public class ForkJoinPool extends Abstra
1815		*/
1816		private int tryHelpStealer(WorkQueue joiner, ForkJoinTask<?> task) {
1817		int stat = 0, steps = 0; // bound to avoid cycles
1818	<	if (joiner != null && task != null) { // hoist null checks
1818	>	if (task != null && joiner != null &&
1819	>	joiner.base - joiner.top >= 0) { // hoist checks
1820		restart: for (;;) {
1821		ForkJoinTask<?> subtask = task; // current target
1822		for (WorkQueue j = joiner, v;;) { // v is stealer of subtask
#	Line 1794 \| Line 1827 \| public class ForkJoinPool extends Abstra
1827		}
1828		if ((ws = workQueues) == null \|\| (m = ws.length - 1) <= 0)
1829		break restart; // shutting down
1830	<	if ((v = ws[h = (j.stealHint \| 1) & m]) == null \|\|
1830	>	if ((v = ws[h = (j.hint \| 1) & m]) == null \|\|
1831		v.currentSteal != subtask) {
1832		for (int origin = h;;) { // find stealer
1833		if (((h = (h + 2) & m) & 15) == 1 &&
#	Line 1802 \| Line 1835 \| public class ForkJoinPool extends Abstra
1835		continue restart; // occasional staleness check
1836		if ((v = ws[h]) != null &&
1837		v.currentSteal == subtask) {
1838	<	j.stealHint = h; // save hint
1838	>	j.hint = h; // save hint
1839		break;
1840		}
1841		if (h == origin)
#	Line 1810 \| Line 1843 \| public class ForkJoinPool extends Abstra
1843		}
1844		}
1845		for (;;) { // help stealer or descend to its stealer
1846	<	ForkJoinTask[] a; int b;
1846	>	ForkJoinTask<?>[] a; int b;
1847		if (subtask.status < 0) // surround probes with
1848		continue restart; // consistency checks
1849		if ((b = v.base) - v.top < 0 && (a = v.array) != null) {
#	Line 1821 \| Line 1854 \| public class ForkJoinPool extends Abstra
1854		v.currentSteal != subtask)
1855		continue restart; // stale
1856		stat = 1; // apparent progress
1857	<	if (t != null && v.base == b &&
1858	<	U.compareAndSwapObject(a, i, t, null)) {
1859	<	v.base = b + 1; // help stealer
1860	<	joiner.runSubtask(t);
1857	>	if (v.base == b) {
1858	>	if (t == null)
1859	>	break restart;
1860	>	if (U.compareAndSwapObject(a, i, t, null)) {
1861	>	U.putOrderedInt(v, QBASE, b + 1);
1862	>	ForkJoinTask<?> ps = joiner.currentSteal;
1863	>	int jt = joiner.top;
1864	>	do {
1865	>	joiner.currentSteal = t;
1866	>	t.doExec(); // clear local tasks too
1867	>	} while (task.status >= 0 &&
1868	>	joiner.top != jt &&
1869	>	(t = joiner.pop()) != null);
1870	>	joiner.currentSteal = ps;
1871	>	break restart;
1872	>	}
1873		}
1829	–	else if (v.base == b && ++steps == MAX_HELP)
1830	–	break restart; // v apparently stalled
1874		}
1875		else { // empty -- try to descend
1876		ForkJoinTask<?> next = v.currentJoin;
#	Line 1851 \| Line 1894 \| public class ForkJoinPool extends Abstra
1894
1895		/**
1896		* Analog of tryHelpStealer for CountedCompleters. Tries to steal
1897	<	* and run tasks within the target's computation
1897	>	* and run tasks within the target's computation.
1898		*
1899		* @param task the task to join
1857	–	* @param mode if shared, exit upon completing any task
1858	–	* if all workers are active
1859	–	*
1900		*/
1901	<	private int helpComplete(ForkJoinTask<?> task, int mode) {
1902	<	WorkQueue[] ws; WorkQueue q; int m, n, s;
1903	<	if (task != null && (ws = workQueues) != null &&
1904	<	(m = ws.length - 1) >= 0) {
1905	<	for (int j = 1, origin = j;;) {
1901	>	private int helpComplete(WorkQueue joiner, CountedCompleter<?> task) {
1902	>	WorkQueue[] ws; int m;
1903	>	int s = 0;
1904	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0 &&
1905	>	joiner != null && task != null) {
1906	>	int j = joiner.poolIndex;
1907	>	int scans = m + m + 1;
1908	>	long c = 0L; // for stability check
1909	>	for (int k = scans; ; j += 2) {
1910	>	WorkQueue q;
1911		if ((s = task.status) < 0)
1912	<	return s;
1913	<	if ((q = ws[j & m]) != null && q.pollAndExecCC(task)) {
1914	<	origin = j;
1915	<	if (mode == SHARED_QUEUE && (int)(ctl >> AC_SHIFT) >= 0)
1912	>	break;
1913	>	else if (joiner.internalPopAndExecCC(task))
1914	>	k = scans;
1915	>	else if ((s = task.status) < 0)
1916	>	break;
1917	>	else if ((q = ws[j & m]) != null && q.pollAndExecCC(task))
1918	>	k = scans;
1919	>	else if (--k < 0) {
1920	>	if (c == (c = ctl))
1921		break;
1922	+	k = scans;
1923		}
1873	–	else if ((j = (j + 2) & m) == origin)
1874	–	break;
1924		}
1925		}
1926	<	return 0;
1926	>	return s;
1927		}
1928
1929		/**
#	Line 1883 \| Line 1932 \| public class ForkJoinPool extends Abstra
1932		* for blocking. Fails on contention or termination. Otherwise,
1933		* adds a new thread if no idle workers are available and pool
1934		* may become starved.
1935	+	*
1936	+	* @param c the assumed ctl value
1937		*/
1938	<	final boolean tryCompensate() {
1939	<	int pc = parallelism, e, u, i, tc; long c;
1940	<	WorkQueue[] ws; WorkQueue w; Thread p;
1941	<	if ((e = (int)(c = ctl)) >= 0 && (ws = workQueues) != null) {
1942	<	if (e != 0 && (i = e & SMASK) < ws.length &&
1943	<	(w = ws[i]) != null && w.eventCount == (e \| INT_SIGN)) {
1938	>	final boolean tryCompensate(long c) {
1939	>	WorkQueue[] ws = workQueues;
1940	>	int pc = parallelism, e = (int)c, m, tc;
1941	>	if (ws != null && (m = ws.length - 1) >= 0 && e >= 0 && ctl == c) {
1942	>	WorkQueue w = ws[e & m];
1943	>	if (e != 0 && w != null) {
1944	>	Thread p;
1945		long nc = ((long)(w.nextWait & E_MASK) \|
1946		(c & (AC_MASK\|TC_MASK)));
1947	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1948	<	w.eventCount = (e + E_SEQ) & E_MASK;
1947	>	int ne = (e + E_SEQ) & E_MASK;
1948	>	if (w.eventCount == (e \| INT_SIGN) &&
1949	>	U.compareAndSwapLong(this, CTL, c, nc)) {
1950	>	w.eventCount = ne;
1951		if ((p = w.parker) != null)
1952		U.unpark(p);
1953		return true; // replace with idle worker
1954		}
1955		}
1956	<	else if ((short)((u = (int)(c >>> 32)) >>> UTC_SHIFT) >= 0 &&
1957	<	(u >> UAC_SHIFT) + pc > 1) {
1956	>	else if ((tc = (short)(c >>> TC_SHIFT)) >= 0 &&
1957	>	(int)(c >> AC_SHIFT) + pc > 1) {
1958		long nc = ((c - AC_UNIT) & AC_MASK) \| (c & ~AC_MASK);
1959		if (U.compareAndSwapLong(this, CTL, c, nc))
1960	<	return true; // no compensation
1960	>	return true; // no compensation
1961		}
1962	<	else if ((tc = u + pc) < MAX_CAP) {
1962	>	else if (tc + pc < MAX_CAP) {
1963		long nc = ((c + TC_UNIT) & TC_MASK) \| (c & ~TC_MASK);
1964		if (U.compareAndSwapLong(this, CTL, c, nc)) {
1965	+	ForkJoinWorkerThreadFactory fac;
1966		Throwable ex = null;
1967		ForkJoinWorkerThread wt = null;
1968		try {
1914	–	ForkJoinWorkerThreadFactory fac;
1969		if ((fac = factory) != null &&
1970		(wt = fac.newThread(this)) != null) {
1971		wt.start();
#	Line 1920 \| Line 1974 \| public class ForkJoinPool extends Abstra
1974		} catch (Throwable rex) {
1975		ex = rex;
1976		}
1977	<	deregisterWorker(wt, ex); // adjust counts etc
1977	>	deregisterWorker(wt, ex); // clean up and return false
1978		}
1979		}
1980		}
#	Line 1936 \| Line 1990 \| public class ForkJoinPool extends Abstra
1990		*/
1991		final int awaitJoin(WorkQueue joiner, ForkJoinTask<?> task) {
1992		int s = 0;
1993	<	if (joiner != null && task != null && (s = task.status) >= 0) {
1993	>	if (task != null && (s = task.status) >= 0 && joiner != null) {
1994		ForkJoinTask<?> prevJoin = joiner.currentJoin;
1995		joiner.currentJoin = task;
1996	<	do {} while ((s = task.status) >= 0 &&
1997	<	joiner.queueSize() > 0 &&
1998	<	joiner.tryRemoveAndExec(task)); // process local tasks
1999	<	if (s >= 0 && (s = task.status) >= 0 &&
2000	<	(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
1947	<	(task instanceof CountedCompleter))
1948	<	s = helpComplete(task, LIFO_QUEUE);
1996	>	do {} while (joiner.tryRemoveAndExec(task) && // process local tasks
1997	>	(s = task.status) >= 0);
1998	>	if (s >= 0 && (task instanceof CountedCompleter))
1999	>	s = helpComplete(joiner, (CountedCompleter<?>)task);
2000	>	long cc = 0; // for stability checks
2001		while (s >= 0 && (s = task.status) >= 0) {
2002	<	if ((joiner.queueSize() > 0 \|\| // try helping
2003	<	(s = tryHelpStealer(joiner, task)) == 0) &&
2004	<	(s = task.status) >= 0 && tryCompensate()) {
2005	<	if (task.trySetSignal() && (s = task.status) >= 0) {
2006	<	synchronized (task) {
2007	<	if (task.status >= 0) {
2008	<	try { // see ForkJoinTask
2009	<	task.wait(); // for explanation
2010	<	} catch (InterruptedException ie) {
2002	>	if ((s = tryHelpStealer(joiner, task)) == 0 &&
2003	>	(s = task.status) >= 0) {
2004	>	if (!tryCompensate(cc))
2005	>	cc = ctl;
2006	>	else {
2007	>	if (task.trySetSignal() && (s = task.status) >= 0) {
2008	>	synchronized (task) {
2009	>	if (task.status >= 0) {
2010	>	try { // see ForkJoinTask
2011	>	task.wait(); // for explanation
2012	>	} catch (InterruptedException ie) {
2013	>	}
2014		}
2015	+	else
2016	+	task.notifyAll();
2017		}
1961	–	else
1962	–	task.notifyAll();
2018		}
2019	+	long c; // reactivate
2020	+	do {} while (!U.compareAndSwapLong
2021	+	(this, CTL, c = ctl,
2022	+	((c & ~AC_MASK) \|
2023	+	((c & AC_MASK) + AC_UNIT))));
2024		}
1965	–	long c; // re-activate
1966	–	do {} while (!U.compareAndSwapLong
1967	–	(this, CTL, c = ctl, c + AC_UNIT));
2025		}
2026		}
2027		joiner.currentJoin = prevJoin;
#	Line 1985 \| Line 2042 \| public class ForkJoinPool extends Abstra
2042		if (joiner != null && task != null && (s = task.status) >= 0) {
2043		ForkJoinTask<?> prevJoin = joiner.currentJoin;
2044		joiner.currentJoin = task;
2045	<	do {} while ((s = task.status) >= 0 &&
2046	<	joiner.queueSize() > 0 &&
2047	<	joiner.tryRemoveAndExec(task));
2048	<	if (s >= 0 && (s = task.status) >= 0 &&
2049	<	(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
1993	<	(task instanceof CountedCompleter))
1994	<	s = helpComplete(task, LIFO_QUEUE);
1995	<	if (s >= 0 && joiner.queueSize() == 0) {
2045	>	do {} while (joiner.tryRemoveAndExec(task) && // process local tasks
2046	>	(s = task.status) >= 0);
2047	>	if (s >= 0) {
2048	>	if (task instanceof CountedCompleter)
2049	>	helpComplete(joiner, (CountedCompleter<?>)task);
2050		do {} while (task.status >= 0 &&
2051		tryHelpStealer(joiner, task) > 0);
2052		}
#	Line 2002 \| Line 2056 \| public class ForkJoinPool extends Abstra
2056
2057		/**
2058		* Returns a (probably) non-empty steal queue, if one is found
2059	<	* during a random, then cyclic scan, else null. This method must
2060	<	* be retried by caller if, by the time it tries to use the queue,
2061	<	* it is empty.
2062	<	* @param r a (random) seed for scanning
2063	<	*/
2064	<	private WorkQueue findNonEmptyStealQueue(int r) {
2065	<	int step = (r >>> 16) \| 1;
2066	<	for (WorkQueue[] ws;;) {
2067	<	int ps = plock, m;
2068	<	if ((ws = workQueues) == null \|\| (m = ws.length - 1) < 1)
2069	<	return null;
2070	<	for (int j = (m + 1) << 2; ; r += step) {
2017	<	WorkQueue q = ws[((r << 1) \| 1) & m];
2018	<	if (q != null && q.queueSize() > 0)
2019	<	return q;
2020	<	else if (--j < 0) {
2021	<	if (plock == ps)
2022	<	return null;
2023	<	break;
2059	>	* during a scan, else null. This method must be retried by
2060	>	* caller if, by the time it tries to use the queue, it is empty.
2061	>	*/
2062	>	private WorkQueue findNonEmptyStealQueue() {
2063	>	int r = ThreadLocalRandom.current().nextInt();
2064	>	for (;;) {
2065	>	int ps = plock, m; WorkQueue[] ws; WorkQueue q;
2066	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
2067	>	for (int j = (m + 1) << 2; j >= 0; --j) {
2068	>	if ((q = ws[(((r - j) << 1) \| 1) & m]) != null &&
2069	>	q.base - q.top < 0)
2070	>	return q;
2071		}
2072		}
2073	+	if (plock == ps)
2074	+	return null;
2075		}
2076		}
2077
#	Line 2033 \| Line 2082 \| public class ForkJoinPool extends Abstra
2082		* find tasks either.
2083		*/
2084		final void helpQuiescePool(WorkQueue w) {
2085	+	ForkJoinTask<?> ps = w.currentSteal;
2086		for (boolean active = true;;) {
2087	<	ForkJoinTask<?> localTask; // exhaust local queue
2088	<	while ((localTask = w.nextLocalTask()) != null)
2089	<	localTask.doExec();
2090	<	// Similar to loop in scan(), but ignoring submissions
2041	<	WorkQueue q = findNonEmptyStealQueue(w.nextSeed());
2042	<	if (q != null) {
2043	<	ForkJoinTask<?> t; int b;
2087	>	long c; WorkQueue q; ForkJoinTask<?> t; int b;
2088	>	while ((t = w.nextLocalTask()) != null)
2089	>	t.doExec();
2090	>	if ((q = findNonEmptyStealQueue()) != null) {
2091		if (!active) { // re-establish active count
2045	–	long c;
2092		active = true;
2093		do {} while (!U.compareAndSwapLong
2094	<	(this, CTL, c = ctl, c + AC_UNIT));
2094	>	(this, CTL, c = ctl,
2095	>	((c & ~AC_MASK) \|
2096	>	((c & AC_MASK) + AC_UNIT))));
2097	>	}
2098	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) {
2099	>	(w.currentSteal = t).doExec();
2100	>	w.currentSteal = ps;
2101		}
2050	–	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2051	–	w.runSubtask(t);
2102		}
2103	<	else {
2104	<	long c;
2105	<	if (active) { // decrement active count without queuing
2103	>	else if (active) { // decrement active count without queuing
2104	>	long nc = ((c = ctl) & ~AC_MASK) \| ((c & AC_MASK) - AC_UNIT);
2105	>	if ((int)(nc >> AC_SHIFT) + parallelism == 0)
2106	>	break; // bypass decrement-then-increment
2107	>	if (U.compareAndSwapLong(this, CTL, c, nc))
2108		active = false;
2057	–	do {} while (!U.compareAndSwapLong
2058	–	(this, CTL, c = ctl, c -= AC_UNIT));
2059	–	}
2060	–	else
2061	–	c = ctl; // re-increment on exit
2062	–	if ((int)(c >> AC_SHIFT) + parallelism == 0) {
2063	–	do {} while (!U.compareAndSwapLong
2064	–	(this, CTL, c = ctl, c + AC_UNIT));
2065	–	break;
2066	–	}
2109		}
2110	+	else if ((int)((c = ctl) >> AC_SHIFT) + parallelism <= 0 &&
2111	+	U.compareAndSwapLong
2112	+	(this, CTL, c, ((c & ~AC_MASK) \|
2113	+	((c & AC_MASK) + AC_UNIT))))
2114	+	break;
2115		}
2116		}
2117
#	Line 2078 \| Line 2125 \| public class ForkJoinPool extends Abstra
2125		WorkQueue q; int b;
2126		if ((t = w.nextLocalTask()) != null)
2127		return t;
2128	<	if ((q = findNonEmptyStealQueue(w.nextSeed())) == null)
2128	>	if ((q = findNonEmptyStealQueue()) == null)
2129		return null;
2130		if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2131		return t;
#	Line 2110 \| Line 2157 \| public class ForkJoinPool extends Abstra
2157		* producing extra tasks amortizes the uncertainty of progress and
2158		* diffusion assumptions.
2159		*
2160	<	* So, users will want to use values larger, but not much larger
2160	>	* So, users will want to use values larger (but not much larger)
2161		* than 1 to both smooth over transient shortages and hedge
2162		* against uneven progress; as traded off against the cost of
2163		* extra task overhead. We leave the user to pick a threshold
#	Line 2134 \| Line 2181 \| public class ForkJoinPool extends Abstra
2181		static int getSurplusQueuedTaskCount() {
2182		Thread t; ForkJoinWorkerThread wt; ForkJoinPool pool; WorkQueue q;
2183		if (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)) {
2184	<	int b = (q = (wt = (ForkJoinWorkerThread)t).workQueue).base;
2185	<	int p = (pool = wt.pool).parallelism;
2184	>	int p = (pool = (wt = (ForkJoinWorkerThread)t).pool).parallelism;
2185	>	int n = (q = wt.workQueue).top - q.base;
2186		int a = (int)(pool.ctl >> AC_SHIFT) + p;
2187	<	return q.top - b - (a > (p >>>= 1) ? 0 :
2188	<	a > (p >>>= 1) ? 1 :
2189	<	a > (p >>>= 1) ? 2 :
2190	<	a > (p >>>= 1) ? 4 :
2191	<	8);
2187	>	return n - (a > (p >>>= 1) ? 0 :
2188	>	a > (p >>>= 1) ? 1 :
2189	>	a > (p >>>= 1) ? 2 :
2190	>	a > (p >>>= 1) ? 4 :
2191	>	8);
2192		}
2193		return 0;
2194		}
#	Line 2163 \| Line 2210 \| public class ForkJoinPool extends Abstra
2210		* @return true if now terminating or terminated
2211		*/
2212		private boolean tryTerminate(boolean now, boolean enable) {
2213	<	if (this == commonPool) // cannot shut down
2213	>	int ps;
2214	>	if (this == common) // cannot shut down
2215		return false;
2216	+	if ((ps = plock) >= 0) { // enable by setting plock
2217	+	if (!enable)
2218	+	return false;
2219	+	if ((ps & PL_LOCK) != 0 \|\|
2220	+	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
2221	+	ps = acquirePlock();
2222	+	int nps = ((ps + PL_LOCK) & ~SHUTDOWN) \| SHUTDOWN;
2223	+	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
2224	+	releasePlock(nps);
2225	+	}
2226		for (long c;;) {
2227	<	if (((c = ctl) & STOP_BIT) != 0) { // already terminating
2228	<	if ((short)(c >>> TC_SHIFT) == -parallelism) {
2227	>	if (((c = ctl) & STOP_BIT) != 0) { // already terminating
2228	>	if ((short)(c >>> TC_SHIFT) + parallelism <= 0) {
2229		synchronized (this) {
2230	<	notifyAll(); // signal when 0 workers
2230	>	notifyAll(); // signal when 0 workers
2231		}
2232		}
2233		return true;
2234		}
2235	<	if (plock >= 0) { // not yet enabled
2236	<	int ps;
2237	<	if (!enable)
2180	<	return false;
2181	<	if (((ps = plock) & PL_LOCK) != 0 \|\|
2182	<	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
2183	<	ps = acquirePlock();
2184	<	int nps = SHUTDOWN;
2185	<	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
2186	<	releasePlock(nps);
2187	<	}
2188	<	if (!now) { // check if idle & no tasks
2189	<	if ((int)(c >> AC_SHIFT) != -parallelism \|\|
2190	<	hasQueuedSubmissions())
2235	>	if (!now) { // check if idle & no tasks
2236	>	WorkQueue[] ws; WorkQueue w;
2237	>	if ((int)(c >> AC_SHIFT) + parallelism > 0)
2238		return false;
2239	<	// Check for unqueued inactive workers. One pass suffices.
2240	<	WorkQueue[] ws = workQueues; WorkQueue w;
2241	<	if (ws != null) {
2242	<	for (int i = 1; i < ws.length; i += 2) {
2243	<	if ((w = ws[i]) != null && w.eventCount >= 0)
2239	>	if ((ws = workQueues) != null) {
2240	>	for (int i = 0; i < ws.length; ++i) {
2241	>	if ((w = ws[i]) != null &&
2242	>	(!w.isEmpty() \|\|
2243	>	((i & 1) != 0 && w.eventCount >= 0))) {
2244	>	signalWork(ws, w);
2245		return false;
2246	+	}
2247		}
2248		}
2249		}
2250		if (U.compareAndSwapLong(this, CTL, c, c \| STOP_BIT)) {
2251		for (int pass = 0; pass < 3; ++pass) {
2252	<	WorkQueue[] ws = workQueues;
2253	<	if (ws != null) {
2205	<	WorkQueue w;
2252	>	WorkQueue[] ws; WorkQueue w; Thread wt;
2253	>	if ((ws = workQueues) != null) {
2254		int n = ws.length;
2255		for (int i = 0; i < n; ++i) {
2256		if ((w = ws[i]) != null) {
2257		w.qlock = -1;
2258		if (pass > 0) {
2259		w.cancelAll();
2260	<	if (pass > 1)
2261	<	w.interruptOwner();
2260	>	if (pass > 1 && (wt = w.owner) != null) {
2261	>	if (!wt.isInterrupted()) {
2262	>	try {
2263	>	wt.interrupt();
2264	>	} catch (Throwable ignore) {
2265	>	}
2266	>	}
2267	>	U.unpark(wt);
2268	>	}
2269		}
2270		}
2271		}
2272		// Wake up workers parked on event queue
2273		int i, e; long cc; Thread p;
2274		while ((e = (int)(cc = ctl) & E_MASK) != 0 &&
2275	<	(i = e & SMASK) < n &&
2275	>	(i = e & SMASK) < n && i >= 0 &&
2276		(w = ws[i]) != null) {
2277		long nc = ((long)(w.nextWait & E_MASK) \|
2278		((cc + AC_UNIT) & AC_MASK) \|
#	Line 2243 \| Line 2298 \| public class ForkJoinPool extends Abstra
2298		* least one task.
2299		*/
2300		static WorkQueue commonSubmitterQueue() {
2301	<	ForkJoinPool p; WorkQueue[] ws; int m; Submitter z;
2301	>	Submitter z; ForkJoinPool p; WorkQueue[] ws; int m, r;
2302		return ((z = submitters.get()) != null &&
2303	<	(p = commonPool) != null &&
2303	>	(p = common) != null &&
2304		(ws = p.workQueues) != null &&
2305		(m = ws.length - 1) >= 0) ?
2306		ws[m & z.seed & SQMASK] : null;
#	Line 2254 \| Line 2309 \| public class ForkJoinPool extends Abstra
2309		/**
2310		* Tries to pop the given task from submitter's queue in common pool.
2311		*/
2312	<	static boolean tryExternalUnpush(ForkJoinTask<?> t) {
2313	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q; Submitter z;
2314	<	ForkJoinTask<?>[] a; int m, s; long j;
2315	<	if ((z = submitters.get()) != null &&
2316	<	(p = commonPool) != null &&
2317	<	(ws = p.workQueues) != null &&
2318	<	(m = ws.length - 1) >= 0 &&
2319	<	(q = ws[m & z.seed & SQMASK]) != null &&
2320	<	(s = q.top) != q.base &&
2321	<	(a = q.array) != null &&
2322	<	U.getObjectVolatile
2323	<	(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
2324	<	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2325	<	if (q.array == a && q.top == s && // recheck
2326	<	U.compareAndSwapObject(a, j, t, null)) {
2327	<	q.top = s - 1;
2328	<	q.qlock = 0;
2329	<	return true;
2330	<	}
2331	<	q.qlock = 0;
2332	<	}
2333	<	return false;
2334	<	}
2335	<
2336	<	/**
2337	<	* Tries to pop and run local tasks within the same computation
2338	<	* as the given root. On failure, tries to help complete from
2339	<	* other queues via helpComplete.
2340	<	*/
2341	<	private void externalHelpComplete(WorkQueue q, ForkJoinTask<?> root) {
2342	<	ForkJoinTask<?>[] a; int m;
2343	<	if (q != null && (a = q.array) != null && (m = (a.length - 1)) >= 0 &&
2344	<	root != null && root.status >= 0) {
2345	<	for (;;) {
2346	<	int s; Object o; CountedCompleter<?> task = null;
2347	<	if ((s = q.top) - q.base > 0) {
2293	<	long j = ((m & (s - 1)) << ASHIFT) + ABASE;
2294	<	if ((o = U.getObject(a, j)) != null &&
2295	<	(o instanceof CountedCompleter)) {
2296	<	CountedCompleter<?> t = (CountedCompleter<?>)o, r = t;
2297	<	do {
2298	<	if (r == root) {
2299	<	if (U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2300	<	if (q.array == a && q.top == s &&
2301	<	U.compareAndSwapObject(a, j, t, null)) {
2302	<	q.top = s - 1;
2303	<	task = t;
2304	<	}
2305	<	q.qlock = 0;
2306	<	}
2307	<	break;
2308	<	}
2309	<	} while ((r = r.completer) != null);
2310	<	}
2311	<	}
2312	<	if (task != null)
2313	<	task.doExec();
2314	<	if (root.status < 0 \|\| (int)(ctl >> AC_SHIFT) >= 0)
2312	>	final boolean tryExternalUnpush(ForkJoinTask<?> task) {
2313	>	WorkQueue joiner; ForkJoinTask<?>[] a; int m, s;
2314	>	Submitter z = submitters.get();
2315	>	WorkQueue[] ws = workQueues;
2316	>	boolean popped = false;
2317	>	if (z != null && ws != null && (m = ws.length - 1) >= 0 &&
2318	>	(joiner = ws[z.seed & m & SQMASK]) != null &&
2319	>	joiner.base != (s = joiner.top) &&
2320	>	(a = joiner.array) != null) {
2321	>	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
2322	>	if (U.getObject(a, j) == task &&
2323	>	U.compareAndSwapInt(joiner, QLOCK, 0, 1)) {
2324	>	if (joiner.top == s && joiner.array == a &&
2325	>	U.compareAndSwapObject(a, j, task, null)) {
2326	>	joiner.top = s - 1;
2327	>	popped = true;
2328	>	}
2329	>	joiner.qlock = 0;
2330	>	}
2331	>	}
2332	>	return popped;
2333	>	}
2334	>
2335	>	final int externalHelpComplete(CountedCompleter<?> task) {
2336	>	WorkQueue joiner; int m, j;
2337	>	Submitter z = submitters.get();
2338	>	WorkQueue[] ws = workQueues;
2339	>	int s = 0;
2340	>	if (z != null && ws != null && (m = ws.length - 1) >= 0 &&
2341	>	(joiner = ws[(j = z.seed) & m & SQMASK]) != null && task != null) {
2342	>	int scans = m + m + 1;
2343	>	long c = 0L; // for stability check
2344	>	j \|= 1; // poll odd queues
2345	>	for (int k = scans; ; j += 2) {
2346	>	WorkQueue q;
2347	>	if ((s = task.status) < 0)
2348		break;
2349	<	if (task == null) {
2350	<	if (helpSignal(root, q.poolIndex) >= 0)
2351	<	helpComplete(root, SHARED_QUEUE);
2349	>	else if (joiner.externalPopAndExecCC(task))
2350	>	k = scans;
2351	>	else if ((s = task.status) < 0)
2352		break;
2353	+	else if ((q = ws[j & m]) != null && q.pollAndExecCC(task))
2354	+	k = scans;
2355	+	else if (--k < 0) {
2356	+	if (c == (c = ctl))
2357	+	break;
2358	+	k = scans;
2359		}
2360		}
2361		}
2362	<	}
2324	<
2325	<	/**
2326	<	* Tries to help execute or signal availability of the given task
2327	<	* from submitter's queue in common pool.
2328	<	*/
2329	<	static void externalHelpJoin(ForkJoinTask<?> t) {
2330	<	// Some hard-to-avoid overlap with tryExternalUnpush
2331	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q, w; Submitter z;
2332	<	ForkJoinTask<?>[] a; int m, s, n; long j;
2333	<	if (t != null && t.status >= 0 &&
2334	<	(z = submitters.get()) != null &&
2335	<	(p = commonPool) != null &&
2336	<	(ws = p.workQueues) != null &&
2337	<	(m = ws.length - 1) >= 0 &&
2338	<	(q = ws[m & z.seed & SQMASK]) != null &&
2339	<	(a = q.array) != null) {
2340	<	if ((s = q.top) != q.base &&
2341	<	U.getObjectVolatile
2342	<	(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
2343	<	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2344	<	if (q.array == a && q.top == s &&
2345	<	U.compareAndSwapObject(a, j, t, null)) {
2346	<	q.top = s - 1;
2347	<	q.qlock = 0;
2348	<	t.doExec();
2349	<	}
2350	<	else
2351	<	q.qlock = 0;
2352	<	}
2353	<	if (t.status >= 0) {
2354	<	if (t instanceof CountedCompleter)
2355	<	p.externalHelpComplete(q, t);
2356	<	else
2357	<	p.helpSignal(t, q.poolIndex);
2358	<	}
2359	<	}
2360	<	}
2361	<
2362	<	/**
2363	<	* Restricted version of helpQuiescePool for external callers
2364	<	*/
2365	<	static void externalHelpQuiescePool() {
2366	<	ForkJoinPool p; ForkJoinTask<?> t; WorkQueue q; int b;
2367	<	int r = ThreadLocalRandom.current().nextInt();
2368	<	if ((p = commonPool) != null &&
2369	<	(q = p.findNonEmptyStealQueue(r)) != null &&
2370	<	(b = q.base) - q.top < 0 &&
2371	<	(t = q.pollAt(b)) != null)
2372	<	t.doExec();
2362	>	return s;
2363		}
2364
2365		// Exported methods
#	Line 2388 \| Line 2378 \| public class ForkJoinPool extends Abstra
2378		* java.lang.RuntimePermission}{@code ("modifyThread")}
2379		*/
2380		public ForkJoinPool() {
2381	<	this(Runtime.getRuntime().availableProcessors(),
2381	>	this(Math.min(MAX_CAP, Runtime.getRuntime().availableProcessors()),
2382		defaultForkJoinWorkerThreadFactory, null, false);
2383		}
2384
#	Line 2436 \| Line 2426 \| public class ForkJoinPool extends Abstra
2426		*/
2427		public ForkJoinPool(int parallelism,
2428		ForkJoinWorkerThreadFactory factory,
2429	<	Thread.UncaughtExceptionHandler handler,
2429	>	UncaughtExceptionHandler handler,
2430		boolean asyncMode) {
2431	+	this(checkParallelism(parallelism),
2432	+	checkFactory(factory),
2433	+	handler,
2434	+	(asyncMode ? FIFO_QUEUE : LIFO_QUEUE),
2435	+	"ForkJoinPool-" + nextPoolId() + "-worker-");
2436		checkPermission();
2437	<	if (factory == null)
2438	<	throw new NullPointerException();
2437	>	}
2438	>
2439	>	private static int checkParallelism(int parallelism) {
2440		if (parallelism <= 0 \|\| parallelism > MAX_CAP)
2441		throw new IllegalArgumentException();
2442	<	this.parallelism = parallelism;
2443	<	this.factory = factory;
2444	<	this.ueh = handler;
2445	<	this.localMode = asyncMode ? FIFO_QUEUE : LIFO_QUEUE;
2446	<	long np = (long)(-parallelism); // offset ctl counts
2447	<	this.ctl = ((np << AC_SHIFT) & AC_MASK) \| ((np << TC_SHIFT) & TC_MASK);
2448	<	int pn = nextPoolId();
2449	<	StringBuilder sb = new StringBuilder("ForkJoinPool-");
2454	<	sb.append(Integer.toString(pn));
2455	<	sb.append("-worker-");
2456	<	this.workerNamePrefix = sb.toString();
2442	>	return parallelism;
2443	>	}
2444	>
2445	>	private static ForkJoinWorkerThreadFactory checkFactory
2446	>	(ForkJoinWorkerThreadFactory factory) {
2447	>	if (factory == null)
2448	>	throw new NullPointerException();
2449	>	return factory;
2450		}
2451
2452		/**
2453	<	* Constructor for common pool, suitable only for static initialization.
2454	<	* Basically the same as above, but uses smallest possible initial footprint.
2455	<	*/
2456	<	ForkJoinPool(int parallelism, long ctl,
2457	<	ForkJoinWorkerThreadFactory factory,
2458	<	Thread.UncaughtExceptionHandler handler) {
2459	<	this.parallelism = parallelism;
2460	<	this.ctl = ctl;
2453	>	* Creates a {@code ForkJoinPool} with the given parameters, without
2454	>	* any security checks or parameter validation. Invoked directly by
2455	>	* makeCommonPool.
2456	>	*/
2457	>	private ForkJoinPool(int parallelism,
2458	>	ForkJoinWorkerThreadFactory factory,
2459	>	UncaughtExceptionHandler handler,
2460	>	int mode,
2461	>	String workerNamePrefix) {
2462	>	this.workerNamePrefix = workerNamePrefix;
2463		this.factory = factory;
2464		this.ueh = handler;
2465	<	this.localMode = LIFO_QUEUE;
2466	<	this.workerNamePrefix = "ForkJoinPool.commonPool-worker-";
2465	>	this.mode = (short)mode;
2466	>	this.parallelism = (short)parallelism;
2467	>	long np = (long)(-parallelism); // offset ctl counts
2468	>	this.ctl = ((np << AC_SHIFT) & AC_MASK) \| ((np << TC_SHIFT) & TC_MASK);
2469		}
2470
2471		/**
2472	<	* Returns the common pool instance.
2472	>	* Returns the common pool instance. This pool is statically
2473	>	* constructed; its run state is unaffected by attempts to {@link
2474	>	* #shutdown} or {@link #shutdownNow}. However this pool and any
2475	>	* ongoing processing are automatically terminated upon program
2476	>	* {@link System#exit}. Any program that relies on asynchronous
2477	>	* task processing to complete before program termination should
2478	>	* invoke {@code commonPool().}{@link #awaitQuiescence awaitQuiescence},
2479	>	* before exit.
2480		*
2481		* @return the common pool instance
2482	+	* @since 1.8
2483		*/
2484		public static ForkJoinPool commonPool() {
2485	<	return commonPool; // cannot be null (if so, a static init error)
2485	>	// assert common != null : "static init error";
2486	>	return common;
2487		}
2488
2489		// Execution methods
#	Line 2493 \| Line 2499 \| public class ForkJoinPool extends Abstra
2499		* minimally only the latter.
2500		*
2501		* @param task the task
2502	+	* @param <T> the type of the task's result
2503		* @return the task's result
2504		* @throws NullPointerException if the task is null
2505		* @throws RejectedExecutionException if the task cannot be
#	Line 2533 \| Line 2540 \| public class ForkJoinPool extends Abstra
2540		if (task instanceof ForkJoinTask<?>) // avoid re-wrap
2541		job = (ForkJoinTask<?>) task;
2542		else
2543	<	job = new ForkJoinTask.AdaptedRunnableAction(task);
2543	>	job = new ForkJoinTask.RunnableExecuteAction(task);
2544		externalPush(job);
2545		}
2546
#	Line 2541 \| Line 2548 \| public class ForkJoinPool extends Abstra
2548		* Submits a ForkJoinTask for execution.
2549		*
2550		* @param task the task to submit
2551	+	* @param <T> the type of the task's result
2552		* @return the task
2553		* @throws NullPointerException if the task is null
2554		* @throws RejectedExecutionException if the task cannot be
#	Line 2600 \| Line 2608 \| public class ForkJoinPool extends Abstra
2608		// In previous versions of this class, this method constructed
2609		// a task to run ForkJoinTask.invokeAll, but now external
2610		// invocation of multiple tasks is at least as efficient.
2611	<	List<ForkJoinTask<T>> fs = new ArrayList<ForkJoinTask<T>>(tasks.size());
2604	<	// Workaround needed because method wasn't declared with
2605	<	// wildcards in return type but should have been.
2606	<	@SuppressWarnings({"unchecked", "rawtypes"})
2607	<	List<Future<T>> futures = (List<Future<T>>) (List) fs;
2611	>	ArrayList<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
2612
2613		boolean done = false;
2614		try {
2615		for (Callable<T> t : tasks) {
2616		ForkJoinTask<T> f = new ForkJoinTask.AdaptedCallable<T>(t);
2617	+	futures.add(f);
2618		externalPush(f);
2614	–	fs.add(f);
2619		}
2620	<	for (ForkJoinTask<T> f : fs)
2621	<	f.quietlyJoin();
2620	>	for (int i = 0, size = futures.size(); i < size; i++)
2621	>	((ForkJoinTask<?>)futures.get(i)).quietlyJoin();
2622		done = true;
2623		return futures;
2624		} finally {
2625		if (!done)
2626	<	for (ForkJoinTask<T> f : fs)
2627	<	f.cancel(false);
2626	>	for (int i = 0, size = futures.size(); i < size; i++)
2627	>	futures.get(i).cancel(false);
2628		}
2629		}
2630
#	Line 2639 \| Line 2643 \| public class ForkJoinPool extends Abstra
2643		*
2644		* @return the handler, or {@code null} if none
2645		*/
2646	<	public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
2646	>	public UncaughtExceptionHandler getUncaughtExceptionHandler() {
2647		return ueh;
2648		}
2649
#	Line 2649 \| Line 2653 \| public class ForkJoinPool extends Abstra
2653		* @return the targeted parallelism level of this pool
2654		*/
2655		public int getParallelism() {
2656	<	return parallelism;
2656	>	int par;
2657	>	return ((par = parallelism) > 0) ? par : 1;
2658		}
2659
2660		/**
2661		* Returns the targeted parallelism level of the common pool.
2662		*
2663		* @return the targeted parallelism level of the common pool
2664	+	* @since 1.8
2665		*/
2666		public static int getCommonPoolParallelism() {
2667	<	return commonPoolParallelism;
2667	>	return commonParallelism;
2668		}
2669
2670		/**
#	Line 2680 \| Line 2686 \| public class ForkJoinPool extends Abstra
2686		* @return {@code true} if this pool uses async mode
2687		*/
2688		public boolean getAsyncMode() {
2689	<	return localMode != 0;
2689	>	return mode == FIFO_QUEUE;
2690		}
2691
2692		/**
#	Line 2727 \| Line 2733 \| public class ForkJoinPool extends Abstra
2733		* @return {@code true} if all threads are currently idle
2734		*/
2735		public boolean isQuiescent() {
2736	<	return (int)(ctl >> AC_SHIFT) + parallelism == 0;
2736	>	return parallelism + (int)(ctl >> AC_SHIFT) <= 0;
2737		}
2738
2739		/**
#	Line 2804 \| Line 2810 \| public class ForkJoinPool extends Abstra
2810		WorkQueue[] ws; WorkQueue w;
2811		if ((ws = workQueues) != null) {
2812		for (int i = 0; i < ws.length; i += 2) {
2813	<	if ((w = ws[i]) != null && w.queueSize() != 0)
2813	>	if ((w = ws[i]) != null && !w.isEmpty())
2814		return true;
2815		}
2816		}
#	Line 2916 \| Line 2922 \| public class ForkJoinPool extends Abstra
2922		* Possibly initiates an orderly shutdown in which previously
2923		* submitted tasks are executed, but no new tasks will be
2924		* accepted. Invocation has no effect on execution state if this
2925	<	* is the {@link #commonPool}, and no additional effect if
2925	>	* is the {@link #commonPool()}, and no additional effect if
2926		* already shut down. Tasks that are in the process of being
2927		* submitted concurrently during the course of this method may or
2928		* may not be rejected.
#	Line 2934 \| Line 2940 \| public class ForkJoinPool extends Abstra
2940		/**
2941		* Possibly attempts to cancel and/or stop all tasks, and reject
2942		* all subsequently submitted tasks. Invocation has no effect on
2943	<	* execution state if this is the {@link #commonPool}, and no
2943	>	* execution state if this is the {@link #commonPool()}, and no
2944		* additional effect if already shut down. Otherwise, tasks that
2945		* are in the process of being submitted or executed concurrently
2946		* during the course of this method may or may not be
#	Line 2963 \| Line 2969 \| public class ForkJoinPool extends Abstra
2969		public boolean isTerminated() {
2970		long c = ctl;
2971		return ((c & STOP_BIT) != 0L &&
2972	<	(short)(c >>> TC_SHIFT) == -parallelism);
2972	>	(short)(c >>> TC_SHIFT) + parallelism <= 0);
2973		}
2974
2975		/**
#	Line 2971 \| Line 2977 \| public class ForkJoinPool extends Abstra
2977		* commenced but not yet completed. This method may be useful for
2978		* debugging. A return of {@code true} reported a sufficient
2979		* period after shutdown may indicate that submitted tasks have
2980	<	* ignored or suppressed interruption, or are waiting for IO,
2980	>	* ignored or suppressed interruption, or are waiting for I/O,
2981		* causing this executor not to properly terminate. (See the
2982		* advisory notes for class {@link ForkJoinTask} stating that
2983		* tasks should not normally entail blocking operations. But if
#	Line 2982 \| Line 2988 \| public class ForkJoinPool extends Abstra
2988		public boolean isTerminating() {
2989		long c = ctl;
2990		return ((c & STOP_BIT) != 0L &&
2991	<	(short)(c >>> TC_SHIFT) != -parallelism);
2991	>	(short)(c >>> TC_SHIFT) + parallelism > 0);
2992		}
2993
2994		/**
#	Line 2997 \| Line 3003 \| public class ForkJoinPool extends Abstra
3003		/**
3004		* Blocks until all tasks have completed execution after a
3005		* shutdown request, or the timeout occurs, or the current thread
3006	<	* is interrupted, whichever happens first. Note that the {@link
3007	<	* #commonPool()} never terminates until program shutdown so
3008	<	* this method will always time out.
3006	>	* is interrupted, whichever happens first. Because the {@link
3007	>	* #commonPool()} never terminates until program shutdown, when
3008	>	* applied to the common pool, this method is equivalent to {@link
3009	>	* #awaitQuiescence(long, TimeUnit)} but always returns {@code false}.
3010		*
3011		* @param timeout the maximum time to wait
3012		* @param unit the time unit of the timeout argument
#	Line 3009 \| Line 3016 \| public class ForkJoinPool extends Abstra
3016		*/
3017		public boolean awaitTermination(long timeout, TimeUnit unit)
3018		throws InterruptedException {
3019	+	if (Thread.interrupted())
3020	+	throw new InterruptedException();
3021	+	if (this == common) {
3022	+	awaitQuiescence(timeout, unit);
3023	+	return false;
3024	+	}
3025		long nanos = unit.toNanos(timeout);
3026		if (isTerminated())
3027		return true;
3028	<	long startTime = System.nanoTime();
3029	<	boolean terminated = false;
3028	>	if (nanos <= 0L)
3029	>	return false;
3030	>	long deadline = System.nanoTime() + nanos;
3031		synchronized (this) {
3032	<	for (long waitTime = nanos, millis = 0L;;) {
3033	<	if (terminated = isTerminated() \|\|
3034	<	waitTime <= 0L \|\|
3035	<	(millis = unit.toMillis(waitTime)) <= 0L)
3032	>	for (;;) {
3033	>	if (isTerminated())
3034	>	return true;
3035	>	if (nanos <= 0L)
3036	>	return false;
3037	>	long millis = TimeUnit.NANOSECONDS.toMillis(nanos);
3038	>	wait(millis > 0L ? millis : 1L);
3039	>	nanos = deadline - System.nanoTime();
3040	>	}
3041	>	}
3042	>	}
3043	>
3044	>	/**
3045	>	* If called by a ForkJoinTask operating in this pool, equivalent
3046	>	* in effect to {@link ForkJoinTask#helpQuiesce}. Otherwise,
3047	>	* waits and/or attempts to assist performing tasks until this
3048	>	* pool {@link #isQuiescent} or the indicated timeout elapses.
3049	>	*
3050	>	* @param timeout the maximum time to wait
3051	>	* @param unit the time unit of the timeout argument
3052	>	* @return {@code true} if quiescent; {@code false} if the
3053	>	* timeout elapsed.
3054	>	*/
3055	>	public boolean awaitQuiescence(long timeout, TimeUnit unit) {
3056	>	long nanos = unit.toNanos(timeout);
3057	>	ForkJoinWorkerThread wt;
3058	>	Thread thread = Thread.currentThread();
3059	>	if ((thread instanceof ForkJoinWorkerThread) &&
3060	>	(wt = (ForkJoinWorkerThread)thread).pool == this) {
3061	>	helpQuiescePool(wt.workQueue);
3062	>	return true;
3063	>	}
3064	>	long startTime = System.nanoTime();
3065	>	WorkQueue[] ws;
3066	>	int r = 0, m;
3067	>	boolean found = true;
3068	>	while (!isQuiescent() && (ws = workQueues) != null &&
3069	>	(m = ws.length - 1) >= 0) {
3070	>	if (!found) {
3071	>	if ((System.nanoTime() - startTime) > nanos)
3072	>	return false;
3073	>	Thread.yield(); // cannot block
3074	>	}
3075	>	found = false;
3076	>	for (int j = (m + 1) << 2; j >= 0; --j) {
3077	>	ForkJoinTask<?> t; WorkQueue q; int b;
3078	>	if ((q = ws[r++ & m]) != null && (b = q.base) - q.top < 0) {
3079	>	found = true;
3080	>	if ((t = q.pollAt(b)) != null)
3081	>	t.doExec();
3082		break;
3083	<	wait(millis);
3024	<	waitTime = nanos - (System.nanoTime() - startTime);
3083	>	}
3084		}
3085		}
3086	<	return terminated;
3086	>	return true;
3087	>	}
3088	>
3089	>	/**
3090	>	* Waits and/or attempts to assist performing tasks indefinitely
3091	>	* until the {@link #commonPool()} {@link #isQuiescent}.
3092	>	*/
3093	>	static void quiesceCommonPool() {
3094	>	common.awaitQuiescence(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
3095		}
3096
3097		/**
#	Line 3036 \| Line 3103 \| public class ForkJoinPool extends Abstra
3103		* not necessary. Method {@code block} blocks the current thread
3104		* if necessary (perhaps internally invoking {@code isReleasable}
3105		* before actually blocking). These actions are performed by any
3106	<	* thread invoking {@link ForkJoinPool#managedBlock}. The
3107	<	* unusual methods in this API accommodate synchronizers that may,
3108	<	* but don't usually, block for long periods. Similarly, they
3106	>	* thread invoking {@link ForkJoinPool#managedBlock(ManagedBlocker)}.
3107	>	* The unusual methods in this API accommodate synchronizers that
3108	>	* may, but don't usually, block for long periods. Similarly, they
3109		* allow more efficient internal handling of cases in which
3110		* additional workers may be, but usually are not, needed to
3111		* ensure sufficient parallelism. Toward this end,
#	Line 3096 \| Line 3163 \| public class ForkJoinPool extends Abstra
3163
3164		/**
3165		* Returns {@code true} if blocking is unnecessary.
3166	+	* @return {@code true} if blocking is unnecessary
3167		*/
3168		boolean isReleasable();
3169		}
#	Line 3125 \| Line 3193 \| public class ForkJoinPool extends Abstra
3193		Thread t = Thread.currentThread();
3194		if (t instanceof ForkJoinWorkerThread) {
3195		ForkJoinPool p = ((ForkJoinWorkerThread)t).pool;
3196	<	while (!blocker.isReleasable()) { // variant of helpSignal
3197	<	WorkQueue[] ws; WorkQueue q; int m, n;
3130	<	if ((ws = p.workQueues) != null && (m = ws.length - 1) >= 0) {
3131	<	for (int i = 0; i <= m; ++i) {
3132	<	if (blocker.isReleasable())
3133	<	return;
3134	<	if ((q = ws[i]) != null && (n = q.queueSize()) > 0) {
3135	<	p.signalWork(q, n);
3136	<	if ((int)(p.ctl >> AC_SHIFT) >= 0)
3137	<	break;
3138	<	}
3139	<	}
3140	<	}
3141	<	if (p.tryCompensate()) {
3196	>	while (!blocker.isReleasable()) {
3197	>	if (p.tryCompensate(p.ctl)) {
3198		try {
3199		do {} while (!blocker.isReleasable() &&
3200		!blocker.block());
#	Line 3176 \| Line 3232 \| public class ForkJoinPool extends Abstra
3232		private static final long STEALCOUNT;
3233		private static final long PLOCK;
3234		private static final long INDEXSEED;
3235	+	private static final long QBASE;
3236		private static final long QLOCK;
3237
3238		static {
3239	<	// Establish common pool parameters
3183	<	// TBD: limit or report ignored exceptions?
3184	<
3185	<	int par = 0;
3186	<	ForkJoinWorkerThreadFactory fac = null;
3187	<	Thread.UncaughtExceptionHandler handler = null;
3188	<	try {
3189	<	String pp = System.getProperty(propPrefix + "parallelism");
3190	<	String hp = System.getProperty(propPrefix + "exceptionHandler");
3191	<	String fp = System.getProperty(propPrefix + "threadFactory");
3192	<	if (fp != null)
3193	<	fac = ((ForkJoinWorkerThreadFactory)ClassLoader.
3194	<	getSystemClassLoader().loadClass(fp).newInstance());
3195	<	if (hp != null)
3196	<	handler = ((Thread.UncaughtExceptionHandler)ClassLoader.
3197	<	getSystemClassLoader().loadClass(hp).newInstance());
3198	<	if (pp != null)
3199	<	par = Integer.parseInt(pp);
3200	<	} catch (Exception ignore) {
3201	<	}
3202	<
3203	<	int s; // initialize field offsets for CAS etc
3239	>	// initialize field offsets for CAS etc
3240		try {
3241		U = getUnsafe();
3242		Class<?> k = ForkJoinPool.class;
#	Line 3216 \| Line 3252 \| public class ForkJoinPool extends Abstra
3252		PARKBLOCKER = U.objectFieldOffset
3253		(tk.getDeclaredField("parkBlocker"));
3254		Class<?> wk = WorkQueue.class;
3255	+	QBASE = U.objectFieldOffset
3256	+	(wk.getDeclaredField("base"));
3257		QLOCK = U.objectFieldOffset
3258		(wk.getDeclaredField("qlock"));
3259		Class<?> ak = ForkJoinTask[].class;
3260		ABASE = U.arrayBaseOffset(ak);
3261	<	s = U.arrayIndexScale(ak);
3262	<	ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
3261	>	int scale = U.arrayIndexScale(ak);
3262	>	if ((scale & (scale - 1)) != 0)
3263	>	throw new Error("data type scale not a power of two");
3264	>	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
3265		} catch (Exception e) {
3266		throw new Error(e);
3267		}
3228	–	if ((s & (s-1)) != 0)
3229	–	throw new Error("data type scale not a power of two");
3268
3269	<	/*
3270	<	* For extra caution, computations to set up pool state are
3233	<	* here; the constructor just assigns these values to fields.
3234	<	*/
3235	<	ForkJoinWorkerThreadFactory defaultFac =
3236	<	defaultForkJoinWorkerThreadFactory =
3269	>	submitters = new ThreadLocal<Submitter>();
3270	>	defaultForkJoinWorkerThreadFactory =
3271		new DefaultForkJoinWorkerThreadFactory();
3238	–	if (fac == null)
3239	–	fac = defaultFac;
3240	–	if (par <= 0)
3241	–	par = Runtime.getRuntime().availableProcessors();
3242	–	if (par > MAX_CAP)
3243	–	par = MAX_CAP;
3244	–	long np = (long)(-par); // precompute initial ctl value
3245	–	long ct = ((np << AC_SHIFT) & AC_MASK) \| ((np << TC_SHIFT) & TC_MASK);
3246	–
3247	–	commonPoolParallelism = par;
3248	–	commonPool = new ForkJoinPool(par, ct, fac, handler);
3272		modifyThreadPermission = new RuntimePermission("modifyThread");
3273	<	submitters = new ThreadLocal<Submitter>();
3273	>
3274	>	common = java.security.AccessController.doPrivileged
3275	>	(new java.security.PrivilegedAction<ForkJoinPool>() {
3276	>	public ForkJoinPool run() { return makeCommonPool(); }});
3277	>	int par = common.parallelism; // report 1 even if threads disabled
3278	>	commonParallelism = par > 0 ? par : 1;
3279	>	}
3280	>
3281	>	/**
3282	>	* Creates and returns the common pool, respecting user settings
3283	>	* specified via system properties.
3284	>	*/
3285	>	private static ForkJoinPool makeCommonPool() {
3286	>	int parallelism = -1;
3287	>	ForkJoinWorkerThreadFactory factory
3288	>	= defaultForkJoinWorkerThreadFactory;
3289	>	UncaughtExceptionHandler handler = null;
3290	>	try { // ignore exceptions in accessing/parsing properties
3291	>	String pp = System.getProperty
3292	>	("java.util.concurrent.ForkJoinPool.common.parallelism");
3293	>	String fp = System.getProperty
3294	>	("java.util.concurrent.ForkJoinPool.common.threadFactory");
3295	>	String hp = System.getProperty
3296	>	("java.util.concurrent.ForkJoinPool.common.exceptionHandler");
3297	>	if (pp != null)
3298	>	parallelism = Integer.parseInt(pp);
3299	>	if (fp != null)
3300	>	factory = ((ForkJoinWorkerThreadFactory)ClassLoader.
3301	>	getSystemClassLoader().loadClass(fp).newInstance());
3302	>	if (hp != null)
3303	>	handler = ((UncaughtExceptionHandler)ClassLoader.
3304	>	getSystemClassLoader().loadClass(hp).newInstance());
3305	>	} catch (Exception ignore) {
3306	>	}
3307	>
3308	>	if (parallelism < 0 && // default 1 less than #cores
3309	>	(parallelism = Runtime.getRuntime().availableProcessors() - 1) < 0)
3310	>	parallelism = 0;
3311	>	if (parallelism > MAX_CAP)
3312	>	parallelism = MAX_CAP;
3313	>	return new ForkJoinPool(parallelism, factory, handler, LIFO_QUEUE,
3314	>	"ForkJoinPool.commonPool-worker-");
3315		}
3316
3317		/**
#	Line 3260 \| Line 3324 \| public class ForkJoinPool extends Abstra
3324		private static sun.misc.Unsafe getUnsafe() {
3325		try {
3326		return sun.misc.Unsafe.getUnsafe();
3327	<	} catch (SecurityException se) {
3328	<	try {
3329	<	return java.security.AccessController.doPrivileged
3330	<	(new java.security
3331	<	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
3332	<	public sun.misc.Unsafe run() throws Exception {
3333	<	java.lang.reflect.Field f = sun.misc
3334	<	.Unsafe.class.getDeclaredField("theUnsafe");
3335	<	f.setAccessible(true);
3336	<	return (sun.misc.Unsafe) f.get(null);
3337	<	}});
3338	<	} catch (java.security.PrivilegedActionException e) {
3339	<	throw new RuntimeException("Could not initialize intrinsics",
3340	<	e.getCause());
3341	<	}
3327	>	} catch (SecurityException tryReflectionInstead) {}
3328	>	try {
3329	>	return java.security.AccessController.doPrivileged
3330	>	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
3331	>	public sun.misc.Unsafe run() throws Exception {
3332	>	Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
3333	>	for (java.lang.reflect.Field f : k.getDeclaredFields()) {
3334	>	f.setAccessible(true);
3335	>	Object x = f.get(null);
3336	>	if (k.isInstance(x))
3337	>	return k.cast(x);
3338	>	}
3339	>	throw new NoSuchFieldError("the Unsafe");
3340	>	}});
3341	>	} catch (java.security.PrivilegedActionException e) {
3342	>	throw new RuntimeException("Could not initialize intrinsics",
3343	>	e.getCause());
3344		}
3345		}
3280	–
3346		}

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Comparing jsr166/src/jsr166e/ForkJoinPool.java (file contents): Revision 1.15 by jsr166, Sun Nov 18 06:31:13 2012 UTC vs. Revision 1.66 by jsr166, Thu Nov 5 16:22:39 2015 UTC

Diff Legend

Comparing jsr166/src/jsr166e/ForkJoinPool.java (file contents):
Revision 1.15 by jsr166, Sun Nov 18 06:31:13 2012 UTC vs.
Revision 1.66 by jsr166, Thu Nov 5 16:22:39 2015 UTC