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root/jsr166/jsr166/src/jsr166y/ForkJoinPool.java

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.5 by jsr166, Thu Mar 19 05:10:42 2009 UTC vs.
Revision 1.13 by jsr166, Wed Jul 22 01:36:51 2009 UTC

#	Line 27 | Line 27 | import java.lang.reflect.*;
27		* (eventually blocking if none exist). This makes them efficient when
28		* most tasks spawn other subtasks (as do most ForkJoinTasks), as well
29		* as the mixed execution of some plain Runnable- or Callable- based
30	<	* activities along with ForkJoinTasks. Otherwise, other
30	>	* activities along with ForkJoinTasks. When setting
31	>	* {@code setAsyncMode}, a ForkJoinPools may also be appropriate for
32	>	* use with fine-grained tasks that are never joined. Otherwise, other
33		* ExecutorService implementations are typically more appropriate
34		* choices.
35		*
#	Line 36 | Line 38 | import java.lang.reflect.*;
38		* adding, suspending, or resuming threads, even if some tasks are
39		* waiting to join others. However, no such adjustments are performed
40		* in the face of blocked IO or other unmanaged synchronization. The
41	<	* nested <code>ManagedBlocker</code> interface enables extension of
41	>	* nested {@code ManagedBlocker} interface enables extension of
42		* the kinds of synchronization accommodated.  The target parallelism
43	<	* level may also be changed dynamically (<code>setParallelism</code>)
44	<	* and dynamically thread construction can be limited using methods
45	<	* <code>setMaximumPoolSize</code> and/or
46	<	* <code>setMaintainsParallelism</code>.
43	>	* level may also be changed dynamically ({@code setParallelism})
44	>	* and thread construction can be limited using methods
45	>	* {@code setMaximumPoolSize} and/or
46	>	* {@code setMaintainsParallelism}.
47		*
48		* <p>In addition to execution and lifecycle control methods, this
49		* class provides status check methods (for example
50	<	* <code>getStealCount</code>) that are intended to aid in developing,
50	>	* {@code getStealCount}) that are intended to aid in developing,
51		* tuning, and monitoring fork/join applications. Also, method
52	<	* <code>toString</code> returns indications of pool state in a
52	>	* {@code toString} returns indications of pool state in a
53		* convenient form for informal monitoring.
54		*
55		* <p><b>Implementation notes</b>: This implementation restricts the
56		* maximum number of running threads to 32767. Attempts to create
57		* pools with greater than the maximum result in
58		* IllegalArgumentExceptions.
59	+	*
60	+	* @since 1.7
61	+	* @author Doug Lea
62		*/
63		public class ForkJoinPool extends AbstractExecutorService {
64
#	Line 79 | Line 84 | public class ForkJoinPool extends Abstra
84		* Returns a new worker thread operating in the given pool.
85		*
86		* @param pool the pool this thread works in
87	<	* @throws NullPointerException if pool is null;
87	>	* @throws NullPointerException if pool is null
88		*/
89		public ForkJoinWorkerThread newThread(ForkJoinPool pool);
90		}
#	Line 131 | Line 136 | public class ForkJoinPool extends Abstra
136		new AtomicInteger();
137
138		/**
139	<	* Array holding all worker threads in the pool. Array size must
140	<	* be a power of two.  Updates and replacements are protected by
141	<	* workerLock, but it is always kept in a consistent enough state
142	<	* to be randomly accessed without locking by workers performing
143	<	* work-stealing.
139	>	* Array holding all worker threads in the pool. Initialized upon
140	>	* first use. Array size must be a power of two.  Updates and
141	>	* replacements are protected by workerLock, but it is always kept
142	>	* in a consistent enough state to be randomly accessed without
143	>	* locking by workers performing work-stealing.
144		*/
145		volatile ForkJoinWorkerThread[] workers;
146
#	Line 151 | Line 156 | public class ForkJoinPool extends Abstra
156
157		/**
158		* The uncaught exception handler used when any worker
159	<	* abrupty terminates
159	>	* abruptly terminates
160		*/
161		private Thread.UncaughtExceptionHandler ueh;
162
#	Line 204 | Line 209 | public class ForkJoinPool extends Abstra
209		private volatile int parallelism;
210
211		/**
212	+	* True if use local fifo, not default lifo, for local polling
213	+	*/
214	+	private volatile boolean locallyFifo;
215	+
216	+	/**
217		* Holds number of total (i.e., created and not yet terminated)
218		* and running (i.e., not blocked on joins or other managed sync)
219		* threads, packed into one int to ensure consistent snapshot when
#	Line 219 | Line 229 | public class ForkJoinPool extends Abstra
229		private static int workerCountsFor(int t, int r) { return (t << 16) + r; }
230
231		/**
232	<	* Add delta (which may be negative) to running count.  This must
232	>	* Adds delta (which may be negative) to running count.  This must
233		* be called before (with negative arg) and after (with positive)
234	<	* any managed synchronization (i.e., mainly, joins)
234	>	* any managed synchronization (i.e., mainly, joins).
235		* @param delta the number to add
236		*/
237		final void updateRunningCount(int delta) {
#	Line 230 | Line 240 | public class ForkJoinPool extends Abstra
240		}
241
242		/**
243	<	* Add delta (which may be negative) to both total and running
243	>	* Adds delta (which may be negative) to both total and running
244		* count.  This must be called upon creation and termination of
245		* worker threads.
246		* @param delta the number to add
#	Line 266 | Line 276 | public class ForkJoinPool extends Abstra
276		/**
277		* Try incrementing active count; fail on contention. Called by
278		* workers before/during executing tasks.
279	<	* @return true on success;
279	>	* @return true on success
280		*/
281		final boolean tryIncrementActiveCount() {
282		int c = runControl;
#	Line 274 | Line 284 | public class ForkJoinPool extends Abstra
284		}
285
286		/**
287	<	* Try decrementing active count; fail on contention.
288	<	* Possibly trigger termination on success
287	>	* Tries decrementing active count; fails on contention.
288	>	* Possibly triggers termination on success.
289		* Called by workers when they can't find tasks.
290		* @return true on success
291		*/
#	Line 290 | Line 300 | public class ForkJoinPool extends Abstra
300		}
301
302		/**
303	<	* Return true if argument represents zero active count and
303	>	* Returns true if argument represents zero active count and
304		* nonzero runstate, which is the triggering condition for
305		* terminating on shutdown.
306		*/
#	Line 326 | Line 336 | public class ForkJoinPool extends Abstra
336		* @throws SecurityException if a security manager exists and
337		*         the caller is not permitted to modify threads
338		*         because it does not hold {@link
339	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
339	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
340		*/
341		public ForkJoinPool() {
342		this(Runtime.getRuntime().availableProcessors(),
#	Line 334 | Line 344 | public class ForkJoinPool extends Abstra
344		}
345
346		/**
347	<	* Creates a ForkJoinPool with the indicated parellelism level
347	>	* Creates a ForkJoinPool with the indicated parallelism level
348		* threads, and using the default ForkJoinWorkerThreadFactory,
349		* @param parallelism the number of worker threads
350		* @throws IllegalArgumentException if parallelism less than or
#	Line 342 | Line 352 | public class ForkJoinPool extends Abstra
352		* @throws SecurityException if a security manager exists and
353		*         the caller is not permitted to modify threads
354		*         because it does not hold {@link
355	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
355	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
356		*/
357		public ForkJoinPool(int parallelism) {
358		this(parallelism, defaultForkJoinWorkerThreadFactory);
#	Line 357 | Line 367 | public class ForkJoinPool extends Abstra
367		* @throws SecurityException if a security manager exists and
368		*         the caller is not permitted to modify threads
369		*         because it does not hold {@link
370	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
370	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
371		*/
372		public ForkJoinPool(ForkJoinWorkerThreadFactory factory) {
373		this(Runtime.getRuntime().availableProcessors(), factory);
#	Line 369 | Line 379 | public class ForkJoinPool extends Abstra
379		* @param parallelism the targeted number of worker threads
380		* @param factory the factory for creating new threads
381		* @throws IllegalArgumentException if parallelism less than or
382	<	* equal to zero, or greater than implementation limit.
382	>	* equal to zero, or greater than implementation limit
383		* @throws NullPointerException if factory is null
384		* @throws SecurityException if a security manager exists and
385		*         the caller is not permitted to modify threads
386		*         because it does not hold {@link
387	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
387	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
388		*/
389		public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) {
390		if (parallelism <= 0 || parallelism > MAX_THREADS)
#	Line 391 | Line 401 | public class ForkJoinPool extends Abstra
401		this.termination = workerLock.newCondition();
402		this.stealCount = new AtomicLong();
403		this.submissionQueue = new LinkedTransferQueue<ForkJoinTask<?>>();
404	<	createAndStartInitialWorkers(parallelism);
404	>	// worker array and workers are lazily constructed
405		}
406
407		/**
#	Line 405 | Line 415 | public class ForkJoinPool extends Abstra
415		if (w != null) {
416		w.poolIndex = index;
417		w.setDaemon(true);
418	+	w.setAsyncMode(locallyFifo);
419		w.setName("ForkJoinPool-" + poolNumber + "-worker-" + index);
420		if (h != null)
421		w.setUncaughtExceptionHandler(h);
#	Line 413 | Line 424 | public class ForkJoinPool extends Abstra
424		}
425
426		/**
427	<	* Return a good size for worker array given pool size.
427	>	* Returns a good size for worker array given pool size.
428		* Currently requires size to be a power of two.
429		*/
430		private static int arraySizeFor(int ps) {
#	Line 421 | Line 432 | public class ForkJoinPool extends Abstra
432		}
433
434		/**
435	<	* Create or resize array if necessary to hold newLength
435	>	* Creates or resizes array if necessary to hold newLength.
436	>	* Call only under exclusion or lock.
437		* @return the array
438		*/
439		private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
#	Line 439 | Line 451 | public class ForkJoinPool extends Abstra
451		*/
452		private void tryShrinkWorkerArray() {
453		ForkJoinWorkerThread[] ws = workers;
454	<	int len = ws.length;
455	<	int last = len - 1;
456	<	while (last >= 0 && ws[last] == null)
457	<	--last;
458	<	int newLength = arraySizeFor(last+1);
459	<	if (newLength < len)
460	<	workers = Arrays.copyOf(ws, newLength);
454	>	if (ws != null) {
455	>	int len = ws.length;
456	>	int last = len - 1;
457	>	while (last >= 0 && ws[last] == null)
458	>	--last;
459	>	int newLength = arraySizeFor(last+1);
460	>	if (newLength < len)
461	>	workers = Arrays.copyOf(ws, newLength);
462	>	}
463		}
464
465		/**
466	<	* Initial worker array and worker creation and startup. (This
453	<	* must be done under lock to avoid interference by some of the
454	<	* newly started threads while creating others.)
466	>	* Initialize workers if necessary
467		*/
468	<	private void createAndStartInitialWorkers(int ps) {
469	<	final ReentrantLock lock = this.workerLock;
470	<	lock.lock();
471	<	try {
472	<	ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps);
473	<	for (int i = 0; i < ps; ++i) {
474	<	ForkJoinWorkerThread w = createWorker(i);
475	<	if (w != null) {
476	<	ws[i] = w;
477	<	w.start();
478	<	updateWorkerCount(1);
468	>	final void ensureWorkerInitialization() {
469	>	ForkJoinWorkerThread[] ws = workers;
470	>	if (ws == null) {
471	>	final ReentrantLock lock = this.workerLock;
472	>	lock.lock();
473	>	try {
474	>	ws = workers;
475	>	if (ws == null) {
476	>	int ps = parallelism;
477	>	ws = ensureWorkerArrayCapacity(ps);
478	>	for (int i = 0; i < ps; ++i) {
479	>	ForkJoinWorkerThread w = createWorker(i);
480	>	if (w != null) {
481	>	ws[i] = w;
482	>	w.start();
483	>	updateWorkerCount(1);
484	>	}
485	>	}
486		}
487	+	} finally {
488	+	lock.unlock();
489		}
469	–	} finally {
470	–	lock.unlock();
490		}
491		}
492
#	Line 513 | Line 532 | public class ForkJoinPool extends Abstra
532		private <T> void doSubmit(ForkJoinTask<T> task) {
533		if (isShutdown())
534		throw new RejectedExecutionException();
535	+	if (workers == null)
536	+	ensureWorkerInitialization();
537		submissionQueue.offer(task);
538		signalIdleWorkers();
539		}
#	Line 671 | Line 692 | public class ForkJoinPool extends Abstra
692		* @throws SecurityException if a security manager exists and
693		*         the caller is not permitted to modify threads
694		*         because it does not hold {@link
695	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
695	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
696		*/
697		public Thread.UncaughtExceptionHandler
698		setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
#	Line 683 | Line 704 | public class ForkJoinPool extends Abstra
704		old = ueh;
705		ueh = h;
706		ForkJoinWorkerThread[] ws = workers;
707	<	for (int i = 0; i < ws.length; ++i) {
708	<	ForkJoinWorkerThread w = ws[i];
709	<	if (w != null)
710	<	w.setUncaughtExceptionHandler(h);
707	>	if (ws != null) {
708	>	for (int i = 0; i < ws.length; ++i) {
709	>	ForkJoinWorkerThread w = ws[i];
710	>	if (w != null)
711	>	w.setUncaughtExceptionHandler(h);
712	>	}
713		}
714		} finally {
715		lock.unlock();
#	Line 696 | Line 719 | public class ForkJoinPool extends Abstra
719
720
721		/**
722	<	* Sets the target paralleism level of this pool.
722	>	* Sets the target parallelism level of this pool.
723		* @param parallelism the target parallelism
724		* @throws IllegalArgumentException if parallelism less than or
725	<	* equal to zero or greater than maximum size bounds.
725	>	* equal to zero or greater than maximum size bounds
726		* @throws SecurityException if a security manager exists and
727		*         the caller is not permitted to modify threads
728		*         because it does not hold {@link
729	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
729	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
730		*/
731		public void setParallelism(int parallelism) {
732		checkPermission();
#	Line 738 | Line 761 | public class ForkJoinPool extends Abstra
761		/**
762		* Returns the number of worker threads that have started but not
763		* yet terminated.  This result returned by this method may differ
764	<	* from <code>getParallelism</code> when threads are created to
764	>	* from {@code getParallelism} when threads are created to
765		* maintain parallelism when others are cooperatively blocked.
766		*
767		* @return the number of worker threads
#	Line 762 | Line 785 | public class ForkJoinPool extends Abstra
785		* Setting this value has no effect on current pool size. It
786		* controls construction of new threads.
787		* @throws IllegalArgumentException if negative or greater then
788	<	* internal implementation limit.
788	>	* internal implementation limit
789		*/
790		public void setMaximumPoolSize(int newMax) {
791		if (newMax < 0 || newMax > MAX_THREADS)
#	Line 793 | Line 816 | public class ForkJoinPool extends Abstra
816		}
817
818		/**
819	+	* Establishes local first-in-first-out scheduling mode for forked
820	+	* tasks that are never joined. This mode may be more appropriate
821	+	* than default locally stack-based mode in applications in which
822	+	* worker threads only process asynchronous tasks.  This method is
823	+	* designed to be invoked only when pool is quiescent, and
824	+	* typically only before any tasks are submitted. The effects of
825	+	* invocations at other times may be unpredictable.
826	+	*
827	+	* @param async if true, use locally FIFO scheduling
828	+	* @return the previous mode
829	+	*/
830	+	public boolean setAsyncMode(boolean async) {
831	+	boolean oldMode = locallyFifo;
832	+	locallyFifo = async;
833	+	ForkJoinWorkerThread[] ws = workers;
834	+	if (ws != null) {
835	+	for (int i = 0; i < ws.length; ++i) {
836	+	ForkJoinWorkerThread t = ws[i];
837	+	if (t != null)
838	+	t.setAsyncMode(async);
839	+	}
840	+	}
841	+	return oldMode;
842	+	}
843	+
844	+	/**
845	+	* Returns true if this pool uses local first-in-first-out
846	+	* scheduling mode for forked tasks that are never joined.
847	+	*
848	+	* @return true if this pool uses async mode
849	+	*/
850	+	public boolean getAsyncMode() {
851	+	return locallyFifo;
852	+	}
853	+
854	+	/**
855		* Returns an estimate of the number of worker threads that are
856		* not blocked waiting to join tasks or for other managed
857		* synchronization.
#	Line 807 | Line 866 | public class ForkJoinPool extends Abstra
866		* Returns an estimate of the number of threads that are currently
867		* stealing or executing tasks. This method may overestimate the
868		* number of active threads.
869	<	* @return the number of active threads.
869	>	* @return the number of active threads
870		*/
871		public int getActiveThreadCount() {
872		return activeCountOf(runControl);
#	Line 817 | Line 876 | public class ForkJoinPool extends Abstra
876		* Returns an estimate of the number of threads that are currently
877		* idle waiting for tasks. This method may underestimate the
878		* number of idle threads.
879	<	* @return the number of idle threads.
879	>	* @return the number of idle threads
880		*/
881		final int getIdleThreadCount() {
882		int c = runningCountOf(workerCounts) - activeCountOf(runControl);
#	Line 846 | Line 905 | public class ForkJoinPool extends Abstra
905		* tuning fork/join programs: In general, steal counts should be
906		* high enough to keep threads busy, but low enough to avoid
907		* overhead and contention across threads.
908	<	* @return the number of steals.
908	>	* @return the number of steals
909		*/
910		public long getStealCount() {
911		return stealCount.get();
#	Line 869 | Line 928 | public class ForkJoinPool extends Abstra
928		* an approximation, obtained by iterating across all threads in
929		* the pool. This method may be useful for tuning task
930		* granularities.
931	<	* @return the number of queued tasks.
931	>	* @return the number of queued tasks
932		*/
933		public long getQueuedTaskCount() {
934		long count = 0;
935		ForkJoinWorkerThread[] ws = workers;
936	<	for (int i = 0; i < ws.length; ++i) {
937	<	ForkJoinWorkerThread t = ws[i];
938	<	if (t != null)
939	<	count += t.getQueueSize();
936	>	if (ws != null) {
937	>	for (int i = 0; i < ws.length; ++i) {
938	>	ForkJoinWorkerThread t = ws[i];
939	>	if (t != null)
940	>	count += t.getQueueSize();
941	>	}
942		}
943		return count;
944		}
#	Line 886 | Line 947 | public class ForkJoinPool extends Abstra
947		* Returns an estimate of the number tasks submitted to this pool
948		* that have not yet begun executing. This method takes time
949		* proportional to the number of submissions.
950	<	* @return the number of queued submissions.
950	>	* @return the number of queued submissions
951		*/
952		public int getQueuedSubmissionCount() {
953		return submissionQueue.size();
#	Line 895 | Line 956 | public class ForkJoinPool extends Abstra
956		/**
957		* Returns true if there are any tasks submitted to this pool
958		* that have not yet begun executing.
959	<	* @return <code>true</code> if there are any queued submissions.
959	>	* @return {@code true} if there are any queued submissions
960		*/
961		public boolean hasQueuedSubmissions() {
962		return !submissionQueue.isEmpty();
#	Line 912 | Line 973 | public class ForkJoinPool extends Abstra
973		}
974
975		/**
976	+	* Removes all available unexecuted submitted and forked tasks
977	+	* from scheduling queues and adds them to the given collection,
978	+	* without altering their execution status. These may include
979	+	* artificially generated or wrapped tasks. This method is designed
980	+	* to be invoked only when the pool is known to be
981	+	* quiescent. Invocations at other times may not remove all
982	+	* tasks. A failure encountered while attempting to add elements
983	+	* to collection {@code c} may result in elements being in
984	+	* neither, either or both collections when the associated
985	+	* exception is thrown.  The behavior of this operation is
986	+	* undefined if the specified collection is modified while the
987	+	* operation is in progress.
988	+	* @param c the collection to transfer elements into
989	+	* @return the number of elements transferred
990	+	*/
991	+	protected int drainTasksTo(Collection<ForkJoinTask<?>> c) {
992	+	int n = submissionQueue.drainTo(c);
993	+	ForkJoinWorkerThread[] ws = workers;
994	+	if (ws != null) {
995	+	for (int i = 0; i < ws.length; ++i) {
996	+	ForkJoinWorkerThread w = ws[i];
997	+	if (w != null)
998	+	n += w.drainTasksTo(c);
999	+	}
1000	+	}
1001	+	return n;
1002	+	}
1003	+
1004	+	/**
1005		* Returns a string identifying this pool, as well as its state,
1006		* including indications of run state, parallelism level, and
1007		* worker and task counts.
#	Line 958 | Line 1048 | public class ForkJoinPool extends Abstra
1048		* @throws SecurityException if a security manager exists and
1049		*         the caller is not permitted to modify threads
1050		*         because it does not hold {@link
1051	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1051	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
1052		*/
1053		public void shutdown() {
1054		checkPermission();
#	Line 972 | Line 1062 | public class ForkJoinPool extends Abstra
1062		* waiting tasks.  Tasks that are in the process of being
1063		* submitted or executed concurrently during the course of this
1064		* method may or may not be rejected. Unlike some other executors,
1065	<	* this method cancels rather than collects non-executed tasks,
1066	<	* so always returns an empty list.
1065	>	* this method cancels rather than collects non-executed tasks
1066	>	* upon termination, so always returns an empty list. However, you
1067	>	* can use method {@code drainTasksTo} before invoking this
1068	>	* method to transfer unexecuted tasks to another collection.
1069		* @return an empty list
1070		* @throws SecurityException if a security manager exists and
1071		*         the caller is not permitted to modify threads
1072		*         because it does not hold {@link
1073	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1073	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
1074		*/
1075		public List<Runnable> shutdownNow() {
1076		checkPermission();
#	Line 987 | Line 1079 | public class ForkJoinPool extends Abstra
1079		}
1080
1081		/**
1082	<	* Returns <code>true</code> if all tasks have completed following shut down.
1082	>	* Returns {@code true} if all tasks have completed following shut down.
1083		*
1084	<	* @return <code>true</code> if all tasks have completed following shut down
1084	>	* @return {@code true} if all tasks have completed following shut down
1085		*/
1086		public boolean isTerminated() {
1087		return runStateOf(runControl) == TERMINATED;
1088		}
1089
1090		/**
1091	<	* Returns <code>true</code> if the process of termination has
1091	>	* Returns {@code true} if the process of termination has
1092		* commenced but possibly not yet completed.
1093		*
1094	<	* @return <code>true</code> if terminating
1094	>	* @return {@code true} if terminating
1095		*/
1096		public boolean isTerminating() {
1097		return runStateOf(runControl) >= TERMINATING;
1098		}
1099
1100		/**
1101	<	* Returns <code>true</code> if this pool has been shut down.
1101	>	* Returns {@code true} if this pool has been shut down.
1102		*
1103	<	* @return <code>true</code> if this pool has been shut down
1103	>	* @return {@code true} if this pool has been shut down
1104		*/
1105		public boolean isShutdown() {
1106		return runStateOf(runControl) >= SHUTDOWN;
#	Line 1021 | Line 1113 | public class ForkJoinPool extends Abstra
1113		*
1114		* @param timeout the maximum time to wait
1115		* @param unit the time unit of the timeout argument
1116	<	* @return <code>true</code> if this executor terminated and
1117	<	*         <code>false</code> if the timeout elapsed before termination
1116	>	* @return {@code true} if this executor terminated and
1117	>	*         {@code false} if the timeout elapsed before termination
1118		* @throws InterruptedException if interrupted while waiting
1119		*/
1120		public boolean awaitTermination(long timeout, TimeUnit unit)
#	Line 1058 | Line 1150 | public class ForkJoinPool extends Abstra
1150		lock.lock();
1151		try {
1152		ForkJoinWorkerThread[] ws = workers;
1153	<	int idx = w.poolIndex;
1154	<	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1155	<	ws[idx] = null;
1156	<	if (totalCountOf(workerCounts) == 0) {
1157	<	terminate(); // no-op if already terminating
1158	<	transitionRunStateTo(TERMINATED);
1159	<	termination.signalAll();
1160	<	}
1161	<	else if (!isTerminating()) {
1162	<	tryShrinkWorkerArray();
1163	<	tryResumeSpare(true); // allow replacement
1153	>	if (ws != null) {
1154	>	int idx = w.poolIndex;
1155	>	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1156	>	ws[idx] = null;
1157	>	if (totalCountOf(workerCounts) == 0) {
1158	>	terminate(); // no-op if already terminating
1159	>	transitionRunStateTo(TERMINATED);
1160	>	termination.signalAll();
1161	>	}
1162	>	else if (!isTerminating()) {
1163	>	tryShrinkWorkerArray();
1164	>	tryResumeSpare(true); // allow replacement
1165	>	}
1166		}
1167		} finally {
1168		lock.unlock();
#	Line 1092 | Line 1186 | public class ForkJoinPool extends Abstra
1186		}
1187
1188		/**
1189	<	* Possibly terminate when on shutdown state
1189	>	* Possibly terminates when on shutdown state.
1190		*/
1191		private void terminateOnShutdown() {
1192		if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
#	Line 1100 | Line 1194 | public class ForkJoinPool extends Abstra
1194		}
1195
1196		/**
1197	<	* Clear out and cancel submissions
1197	>	* Clears out and cancels submissions.
1198		*/
1199		private void cancelQueuedSubmissions() {
1200		ForkJoinTask<?> task;
#	Line 1109 | Line 1203 | public class ForkJoinPool extends Abstra
1203		}
1204
1205		/**
1206	<	* Clean out worker queues.
1206	>	* Cleans out worker queues.
1207		*/
1208		private void cancelQueuedWorkerTasks() {
1209		final ReentrantLock lock = this.workerLock;
1210		lock.lock();
1211		try {
1212		ForkJoinWorkerThread[] ws = workers;
1213	<	for (int i = 0; i < ws.length; ++i) {
1214	<	ForkJoinWorkerThread t = ws[i];
1215	<	if (t != null)
1216	<	t.cancelTasks();
1213	>	if (ws != null) {
1214	>	for (int i = 0; i < ws.length; ++i) {
1215	>	ForkJoinWorkerThread t = ws[i];
1216	>	if (t != null)
1217	>	t.cancelTasks();
1218	>	}
1219		}
1220		} finally {
1221		lock.unlock();
#	Line 1127 | Line 1223 | public class ForkJoinPool extends Abstra
1223		}
1224
1225		/**
1226	<	* Set each worker's status to terminating. Requires lock to avoid
1227	<	* conflicts with add/remove
1226	>	* Sets each worker's status to terminating. Requires lock to avoid
1227	>	* conflicts with add/remove.
1228		*/
1229		private void stopAllWorkers() {
1230		final ReentrantLock lock = this.workerLock;
1231		lock.lock();
1232		try {
1233		ForkJoinWorkerThread[] ws = workers;
1234	<	for (int i = 0; i < ws.length; ++i) {
1235	<	ForkJoinWorkerThread t = ws[i];
1236	<	if (t != null)
1237	<	t.shutdownNow();
1234	>	if (ws != null) {
1235	>	for (int i = 0; i < ws.length; ++i) {
1236	>	ForkJoinWorkerThread t = ws[i];
1237	>	if (t != null)
1238	>	t.shutdownNow();
1239	>	}
1240		}
1241		} finally {
1242		lock.unlock();
#	Line 1146 | Line 1244 | public class ForkJoinPool extends Abstra
1244		}
1245
1246		/**
1247	<	* Interrupt all unterminated workers.  This is not required for
1247	>	* Interrupts all unterminated workers.  This is not required for
1248		* sake of internal control, but may help unstick user code during
1249		* shutdown.
1250		*/
#	Line 1155 | Line 1253 | public class ForkJoinPool extends Abstra
1253		lock.lock();
1254		try {
1255		ForkJoinWorkerThread[] ws = workers;
1256	<	for (int i = 0; i < ws.length; ++i) {
1257	<	ForkJoinWorkerThread t = ws[i];
1258	<	if (t != null && !t.isTerminated()) {
1259	<	try {
1260	<	t.interrupt();
1261	<	} catch (SecurityException ignore) {
1256	>	if (ws != null) {
1257	>	for (int i = 0; i < ws.length; ++i) {
1258	>	ForkJoinWorkerThread t = ws[i];
1259	>	if (t != null && !t.isTerminated()) {
1260	>	try {
1261	>	t.interrupt();
1262	>	} catch (SecurityException ignore) {
1263	>	}
1264		}
1265		}
1266		}
#	Line 1214 | Line 1314 | public class ForkJoinPool extends Abstra
1314		}
1315
1316		/**
1317	<	* Wake up waiter, returning false if known to already
1317	>	* Wakes up waiter, returning false if known to already
1318		*/
1319		boolean signal() {
1320		ForkJoinWorkerThread t = thread;
#	Line 1226 | Line 1326 | public class ForkJoinPool extends Abstra
1326		}
1327
1328		/**
1329	<	* Await release on sync
1329	>	* Awaits release on sync.
1330		*/
1331		void awaitSyncRelease(ForkJoinPool p) {
1332		while (thread != null && !p.syncIsReleasable(this))
#	Line 1234 | Line 1334 | public class ForkJoinPool extends Abstra
1334		}
1335
1336		/**
1337	<	* Await resumption as spare
1337	>	* Awaits resumption as spare.
1338		*/
1339		void awaitSpareRelease() {
1340		while (thread != null) {
#	Line 1274 | Line 1374 | public class ForkJoinPool extends Abstra
1374		}
1375
1376		/**
1377	<	* Signal threads waiting to poll a task. Because method sync
1377	>	* Signals threads waiting to poll a task. Because method sync
1378		* rechecks availability, it is OK to only proceed if queue
1379		* appears to be non-empty, and OK to skip under contention to
1380		* increment count (since some other thread succeeded).
#	Line 1361 | Line 1461 | public class ForkJoinPool extends Abstra
1461		//  Parallelism maintenance
1462
1463		/**
1464	<	* Decrement running count; if too low, add spare.
1464	>	* Decrements running count; if too low, adds spare.
1465		*
1466		* Conceptually, all we need to do here is add or resume a
1467		* spare thread when one is about to block (and remove or
#	Line 1381 | Line 1481 | public class ForkJoinPool extends Abstra
1481		* only be suspended or removed when they are idle, not
1482		* immediately when they aren't needed. So adding threads will
1483		* raise parallelism level for longer than necessary.  Also,
1484	<	* FJ applications often enounter highly transient peaks when
1484	>	* FJ applications often encounter highly transient peaks when
1485		* many threads are blocked joining, but for less time than it
1486		* takes to create or resume spares.
1487		*
#	Line 1451 | Line 1551 | public class ForkJoinPool extends Abstra
1551		}
1552
1553		/**
1554	<	* Add a spare worker if lock available and no more than the
1555	<	* expected numbers of threads exist
1554	>	* Adds a spare worker if lock available and no more than the
1555	>	* expected numbers of threads exist.
1556		* @return true if successful
1557		*/
1558		private boolean tryAddSpare(int expectedCounts) {
#	Line 1485 | Line 1585 | public class ForkJoinPool extends Abstra
1585		}
1586
1587		/**
1588	<	* Add the kth spare worker. On entry, pool coounts are already
1588	>	* Adds the kth spare worker. On entry, pool counts are already
1589		* adjusted to reflect addition.
1590		*/
1591		private void createAndStartSpare(int k) {
#	Line 1507 | Line 1607 | public class ForkJoinPool extends Abstra
1607		}
1608
1609		/**
1610	<	* Suspend calling thread w if there are excess threads.  Called
1611	<	* only from sync.  Spares are enqueued in a Treiber stack
1612	<	* using the same WaitQueueNodes as barriers.  They are resumed
1613	<	* mainly in preJoin, but are also woken on pool events that
1614	<	* require all threads to check run state.
1610	>	* Suspends calling thread w if there are excess threads.  Called
1611	>	* only from sync.  Spares are enqueued in a Treiber stack using
1612	>	* the same WaitQueueNodes as barriers.  They are resumed mainly
1613	>	* in preJoin, but are also woken on pool events that require all
1614	>	* threads to check run state.
1615		* @param w the caller
1616		*/
1617		private boolean suspendIfSpare(ForkJoinWorkerThread w) {
#	Line 1532 | Line 1632 | public class ForkJoinPool extends Abstra
1632		}
1633
1634		/**
1635	<	* Try to pop and resume a spare thread.
1635	>	* Tries to pop and resume a spare thread.
1636		* @param updateCount if true, increment running count on success
1637		* @return true if successful
1638		*/
#	Line 1550 | Line 1650 | public class ForkJoinPool extends Abstra
1650		}
1651
1652		/**
1653	<	* Pop and resume all spare threads. Same idea as ensureSync.
1653	>	* Pops and resumes all spare threads. Same idea as ensureSync.
1654		* @return true if any spares released
1655		*/
1656		private boolean resumeAllSpares() {
#	Line 1568 | Line 1668 | public class ForkJoinPool extends Abstra
1668		}
1669
1670		/**
1671	<	* Pop and shutdown excessive spare threads. Call only while
1671	>	* Pops and shuts down excessive spare threads. Call only while
1672		* holding lock. This is not guaranteed to eliminate all excess
1673		* threads, only those suspended as spares, which are the ones
1674		* unlikely to be needed in the future.
#	Line 1593 | Line 1693 | public class ForkJoinPool extends Abstra
1693		/**
1694		* Interface for extending managed parallelism for tasks running
1695		* in ForkJoinPools. A ManagedBlocker provides two methods.
1696	<	* Method <code>isReleasable</code> must return true if blocking is not
1697	<	* necessary. Method <code>block</code> blocks the current thread
1696	>	* Method {@code isReleasable} must return true if blocking is not
1697	>	* necessary. Method {@code block} blocks the current thread
1698		* if necessary (perhaps internally invoking isReleasable before
1699		* actually blocking.).
1700		* <p>For example, here is a ManagedBlocker based on a
#	Line 1620 | Line 1720 | public class ForkJoinPool extends Abstra
1720		* Possibly blocks the current thread, for example waiting for
1721		* a lock or condition.
1722		* @return true if no additional blocking is necessary (i.e.,
1723	<	* if isReleasable would return true).
1723	>	* if isReleasable would return true)
1724		* @throws InterruptedException if interrupted while waiting
1725	<	* (the method is not required to do so, but is allowe to).
1725	>	* (the method is not required to do so, but is allowed to).
1726		*/
1727		boolean block() throws InterruptedException;
1728
#	Line 1637 | Line 1737 | public class ForkJoinPool extends Abstra
1737		* is a ForkJoinWorkerThread, this method possibly arranges for a
1738		* spare thread to be activated if necessary to ensure parallelism
1739		* while the current thread is blocked.  If
1740	<	* <code>maintainParallelism</code> is true and the pool supports
1740	>	* {@code maintainParallelism} is true and the pool supports
1741		* it ({@link #getMaintainsParallelism}), this method attempts to
1742		* maintain the pool's nominal parallelism. Otherwise if activates
1743		* a thread only if necessary to avoid complete starvation. This
#	Line 1659 | Line 1759 | public class ForkJoinPool extends Abstra
1759		* attempt to maintain the pool's nominal parallelism; otherwise
1760		* activate a thread only if necessary to avoid complete
1761		* starvation.
1762	<	* @throws InterruptedException if blocker.block did so.
1762	>	* @throws InterruptedException if blocker.block did so
1763		*/
1764		public static void managedBlock(ManagedBlocker blocker,
1765		boolean maintainParallelism)
#	Line 1721 | Line 1821 | public class ForkJoinPool extends Abstra
1821
1822		private static long fieldOffset(String fieldName)
1823		throws NoSuchFieldException {
1824	<	return _unsafe.objectFieldOffset
1824	>	return UNSAFE.objectFieldOffset
1825		(ForkJoinPool.class.getDeclaredField(fieldName));
1826		}
1827
1828	<	static final Unsafe _unsafe;
1828	>	static final Unsafe UNSAFE;
1829		static final long eventCountOffset;
1830		static final long workerCountsOffset;
1831		static final long runControlOffset;
#	Line 1734 | Line 1834 | public class ForkJoinPool extends Abstra
1834
1835		static {
1836		try {
1837	<	_unsafe = getUnsafe();
1837	>	UNSAFE = getUnsafe();
1838		eventCountOffset = fieldOffset("eventCount");
1839		workerCountsOffset = fieldOffset("workerCounts");
1840		runControlOffset = fieldOffset("runControl");
#	Line 1746 | Line 1846 | public class ForkJoinPool extends Abstra
1846		}
1847
1848		private boolean casEventCount(long cmp, long val) {
1849	<	return _unsafe.compareAndSwapLong(this, eventCountOffset, cmp, val);
1849	>	return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
1850		}
1851		private boolean casWorkerCounts(int cmp, int val) {
1852	<	return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1852	>	return UNSAFE.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1853		}
1854		private boolean casRunControl(int cmp, int val) {
1855	<	return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val);
1855	>	return UNSAFE.compareAndSwapInt(this, runControlOffset, cmp, val);
1856		}
1857		private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) {
1858	<	return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val);
1858	>	return UNSAFE.compareAndSwapObject(this, spareStackOffset, cmp, val);
1859		}
1860		private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1861	<	return _unsafe.compareAndSwapObject(this, syncStackOffset, cmp, val);
1861	>	return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val);
1862		}
1863		}

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