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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 1.16 by jsr166, Thu Jul 23 19:44:46 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
220		* making decisions about creating and suspending spare
221		* threads. Updated only by CAS.  Note: CASes in
222	<	* updateRunningCount and preJoin running active count is in low
223	<	* word, so need to be modified if this changes
222	>	* updateRunningCount and preJoin assume that running active count
223	>	* is in low word, so need to be modified if this changes.
224		*/
225		private volatile int workerCounts;
226
#	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.
437	>	*
438		* @return the array
439		*/
440		private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
#	Line 439 | Line 452 | public class ForkJoinPool extends Abstra
452		*/
453		private void tryShrinkWorkerArray() {
454		ForkJoinWorkerThread[] ws = workers;
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);
455	>	if (ws != null) {
456	>	int len = ws.length;
457	>	int last = len - 1;
458	>	while (last >= 0 && ws[last] == null)
459	>	--last;
460	>	int newLength = arraySizeFor(last+1);
461	>	if (newLength < len)
462	>	workers = Arrays.copyOf(ws, newLength);
463	>	}
464		}
465
466		/**
467	<	* 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.)
467	>	* Initialize workers if necessary
468		*/
469	<	private void createAndStartInitialWorkers(int ps) {
470	<	final ReentrantLock lock = this.workerLock;
471	<	lock.lock();
472	<	try {
473	<	ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps);
474	<	for (int i = 0; i < ps; ++i) {
475	<	ForkJoinWorkerThread w = createWorker(i);
476	<	if (w != null) {
477	<	ws[i] = w;
478	<	w.start();
479	<	updateWorkerCount(1);
469	>	final void ensureWorkerInitialization() {
470	>	ForkJoinWorkerThread[] ws = workers;
471	>	if (ws == null) {
472	>	final ReentrantLock lock = this.workerLock;
473	>	lock.lock();
474	>	try {
475	>	ws = workers;
476	>	if (ws == null) {
477	>	int ps = parallelism;
478	>	ws = ensureWorkerArrayCapacity(ps);
479	>	for (int i = 0; i < ps; ++i) {
480	>	ForkJoinWorkerThread w = createWorker(i);
481	>	if (w != null) {
482	>	ws[i] = w;
483	>	w.start();
484	>	updateWorkerCount(1);
485	>	}
486	>	}
487		}
488	+	} finally {
489	+	lock.unlock();
490		}
469	–	} finally {
470	–	lock.unlock();
491		}
492		}
493
#	Line 513 | Line 533 | public class ForkJoinPool extends Abstra
533		private <T> void doSubmit(ForkJoinTask<T> task) {
534		if (isShutdown())
535		throw new RejectedExecutionException();
536	+	if (workers == null)
537	+	ensureWorkerInitialization();
538		submissionQueue.offer(task);
539		signalIdleWorkers();
540		}
#	Line 671 | Line 693 | public class ForkJoinPool extends Abstra
693		* @throws SecurityException if a security manager exists and
694		*         the caller is not permitted to modify threads
695		*         because it does not hold {@link
696	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
696	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
697		*/
698		public Thread.UncaughtExceptionHandler
699		setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
#	Line 683 | Line 705 | public class ForkJoinPool extends Abstra
705		old = ueh;
706		ueh = h;
707		ForkJoinWorkerThread[] ws = workers;
708	<	for (int i = 0; i < ws.length; ++i) {
709	<	ForkJoinWorkerThread w = ws[i];
710	<	if (w != null)
711	<	w.setUncaughtExceptionHandler(h);
708	>	if (ws != null) {
709	>	for (int i = 0; i < ws.length; ++i) {
710	>	ForkJoinWorkerThread w = ws[i];
711	>	if (w != null)
712	>	w.setUncaughtExceptionHandler(h);
713	>	}
714		}
715		} finally {
716		lock.unlock();
#	Line 696 | Line 720 | public class ForkJoinPool extends Abstra
720
721
722		/**
723	<	* Sets the target paralleism level of this pool.
723	>	* Sets the target parallelism level of this pool.
724		* @param parallelism the target parallelism
725		* @throws IllegalArgumentException if parallelism less than or
726	<	* equal to zero or greater than maximum size bounds.
726	>	* equal to zero or greater than maximum size bounds
727		* @throws SecurityException if a security manager exists and
728		*         the caller is not permitted to modify threads
729		*         because it does not hold {@link
730	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
730	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
731		*/
732		public void setParallelism(int parallelism) {
733		checkPermission();
#	Line 738 | Line 762 | public class ForkJoinPool extends Abstra
762		/**
763		* Returns the number of worker threads that have started but not
764		* yet terminated.  This result returned by this method may differ
765	<	* from <code>getParallelism</code> when threads are created to
765	>	* from {@code getParallelism} when threads are created to
766		* maintain parallelism when others are cooperatively blocked.
767		*
768		* @return the number of worker threads
#	Line 762 | Line 786 | public class ForkJoinPool extends Abstra
786		* Setting this value has no effect on current pool size. It
787		* controls construction of new threads.
788		* @throws IllegalArgumentException if negative or greater then
789	<	* internal implementation limit.
789	>	* internal implementation limit
790		*/
791		public void setMaximumPoolSize(int newMax) {
792		if (newMax < 0 || newMax > MAX_THREADS)
#	Line 793 | Line 817 | public class ForkJoinPool extends Abstra
817		}
818
819		/**
820	+	* Establishes local first-in-first-out scheduling mode for forked
821	+	* tasks that are never joined. This mode may be more appropriate
822	+	* than default locally stack-based mode in applications in which
823	+	* worker threads only process asynchronous tasks.  This method is
824	+	* designed to be invoked only when pool is quiescent, and
825	+	* typically only before any tasks are submitted. The effects of
826	+	* invocations at other times may be unpredictable.
827	+	*
828	+	* @param async if true, use locally FIFO scheduling
829	+	* @return the previous mode
830	+	*/
831	+	public boolean setAsyncMode(boolean async) {
832	+	boolean oldMode = locallyFifo;
833	+	locallyFifo = async;
834	+	ForkJoinWorkerThread[] ws = workers;
835	+	if (ws != null) {
836	+	for (int i = 0; i < ws.length; ++i) {
837	+	ForkJoinWorkerThread t = ws[i];
838	+	if (t != null)
839	+	t.setAsyncMode(async);
840	+	}
841	+	}
842	+	return oldMode;
843	+	}
844	+
845	+	/**
846	+	* Returns true if this pool uses local first-in-first-out
847	+	* scheduling mode for forked tasks that are never joined.
848	+	*
849	+	* @return true if this pool uses async mode
850	+	*/
851	+	public boolean getAsyncMode() {
852	+	return locallyFifo;
853	+	}
854	+
855	+	/**
856		* Returns an estimate of the number of worker threads that are
857		* not blocked waiting to join tasks or for other managed
858		* synchronization.
#	Line 807 | Line 867 | public class ForkJoinPool extends Abstra
867		* Returns an estimate of the number of threads that are currently
868		* stealing or executing tasks. This method may overestimate the
869		* number of active threads.
870	<	* @return the number of active threads.
870	>	* @return the number of active threads
871		*/
872		public int getActiveThreadCount() {
873		return activeCountOf(runControl);
#	Line 817 | Line 877 | public class ForkJoinPool extends Abstra
877		* Returns an estimate of the number of threads that are currently
878		* idle waiting for tasks. This method may underestimate the
879		* number of idle threads.
880	<	* @return the number of idle threads.
880	>	* @return the number of idle threads
881		*/
882		final int getIdleThreadCount() {
883		int c = runningCountOf(workerCounts) - activeCountOf(runControl);
#	Line 846 | Line 906 | public class ForkJoinPool extends Abstra
906		* tuning fork/join programs: In general, steal counts should be
907		* high enough to keep threads busy, but low enough to avoid
908		* overhead and contention across threads.
909	<	* @return the number of steals.
909	>	* @return the number of steals
910		*/
911		public long getStealCount() {
912		return stealCount.get();
#	Line 869 | Line 929 | public class ForkJoinPool extends Abstra
929		* an approximation, obtained by iterating across all threads in
930		* the pool. This method may be useful for tuning task
931		* granularities.
932	<	* @return the number of queued tasks.
932	>	* @return the number of queued tasks
933		*/
934		public long getQueuedTaskCount() {
935		long count = 0;
936		ForkJoinWorkerThread[] ws = workers;
937	<	for (int i = 0; i < ws.length; ++i) {
938	<	ForkJoinWorkerThread t = ws[i];
939	<	if (t != null)
940	<	count += t.getQueueSize();
937	>	if (ws != null) {
938	>	for (int i = 0; i < ws.length; ++i) {
939	>	ForkJoinWorkerThread t = ws[i];
940	>	if (t != null)
941	>	count += t.getQueueSize();
942	>	}
943		}
944		return count;
945		}
#	Line 886 | Line 948 | public class ForkJoinPool extends Abstra
948		* Returns an estimate of the number tasks submitted to this pool
949		* that have not yet begun executing. This method takes time
950		* proportional to the number of submissions.
951	<	* @return the number of queued submissions.
951	>	* @return the number of queued submissions
952		*/
953		public int getQueuedSubmissionCount() {
954		return submissionQueue.size();
#	Line 895 | Line 957 | public class ForkJoinPool extends Abstra
957		/**
958		* Returns true if there are any tasks submitted to this pool
959		* that have not yet begun executing.
960	<	* @return <code>true</code> if there are any queued submissions.
960	>	* @return {@code true} if there are any queued submissions
961		*/
962		public boolean hasQueuedSubmissions() {
963		return !submissionQueue.isEmpty();
#	Line 912 | Line 974 | public class ForkJoinPool extends Abstra
974		}
975
976		/**
977	+	* Removes all available unexecuted submitted and forked tasks
978	+	* from scheduling queues and adds them to the given collection,
979	+	* without altering their execution status. These may include
980	+	* artificially generated or wrapped tasks. This method is designed
981	+	* to be invoked only when the pool is known to be
982	+	* quiescent. Invocations at other times may not remove all
983	+	* tasks. A failure encountered while attempting to add elements
984	+	* to collection {@code c} may result in elements being in
985	+	* neither, either or both collections when the associated
986	+	* exception is thrown.  The behavior of this operation is
987	+	* undefined if the specified collection is modified while the
988	+	* operation is in progress.
989	+	* @param c the collection to transfer elements into
990	+	* @return the number of elements transferred
991	+	*/
992	+	protected int drainTasksTo(Collection<ForkJoinTask<?>> c) {
993	+	int n = submissionQueue.drainTo(c);
994	+	ForkJoinWorkerThread[] ws = workers;
995	+	if (ws != null) {
996	+	for (int i = 0; i < ws.length; ++i) {
997	+	ForkJoinWorkerThread w = ws[i];
998	+	if (w != null)
999	+	n += w.drainTasksTo(c);
1000	+	}
1001	+	}
1002	+	return n;
1003	+	}
1004	+
1005	+	/**
1006		* Returns a string identifying this pool, as well as its state,
1007		* including indications of run state, parallelism level, and
1008		* worker and task counts.
#	Line 958 | Line 1049 | public class ForkJoinPool extends Abstra
1049		* @throws SecurityException if a security manager exists and
1050		*         the caller is not permitted to modify threads
1051		*         because it does not hold {@link
1052	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1052	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
1053		*/
1054		public void shutdown() {
1055		checkPermission();
#	Line 972 | Line 1063 | public class ForkJoinPool extends Abstra
1063		* waiting tasks.  Tasks that are in the process of being
1064		* submitted or executed concurrently during the course of this
1065		* method may or may not be rejected. Unlike some other executors,
1066	<	* this method cancels rather than collects non-executed tasks,
1067	<	* so always returns an empty list.
1066	>	* this method cancels rather than collects non-executed tasks
1067	>	* upon termination, so always returns an empty list. However, you
1068	>	* can use method {@code drainTasksTo} before invoking this
1069	>	* method to transfer unexecuted tasks to another collection.
1070		* @return an empty list
1071		* @throws SecurityException if a security manager exists and
1072		*         the caller is not permitted to modify threads
1073		*         because it does not hold {@link
1074	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1074	>	*         java.lang.RuntimePermission}{@code ("modifyThread")},
1075		*/
1076		public List<Runnable> shutdownNow() {
1077		checkPermission();
#	Line 987 | Line 1080 | public class ForkJoinPool extends Abstra
1080		}
1081
1082		/**
1083	<	* Returns <code>true</code> if all tasks have completed following shut down.
1083	>	* Returns {@code true} if all tasks have completed following shut down.
1084		*
1085	<	* @return <code>true</code> if all tasks have completed following shut down
1085	>	* @return {@code true} if all tasks have completed following shut down
1086		*/
1087		public boolean isTerminated() {
1088		return runStateOf(runControl) == TERMINATED;
1089		}
1090
1091		/**
1092	<	* Returns <code>true</code> if the process of termination has
1092	>	* Returns {@code true} if the process of termination has
1093		* commenced but possibly not yet completed.
1094		*
1095	<	* @return <code>true</code> if terminating
1095	>	* @return {@code true} if terminating
1096		*/
1097		public boolean isTerminating() {
1098		return runStateOf(runControl) >= TERMINATING;
1099		}
1100
1101		/**
1102	<	* Returns <code>true</code> if this pool has been shut down.
1102	>	* Returns {@code true} if this pool has been shut down.
1103		*
1104	<	* @return <code>true</code> if this pool has been shut down
1104	>	* @return {@code true} if this pool has been shut down
1105		*/
1106		public boolean isShutdown() {
1107		return runStateOf(runControl) >= SHUTDOWN;
#	Line 1021 | Line 1114 | public class ForkJoinPool extends Abstra
1114		*
1115		* @param timeout the maximum time to wait
1116		* @param unit the time unit of the timeout argument
1117	<	* @return <code>true</code> if this executor terminated and
1118	<	*         <code>false</code> if the timeout elapsed before termination
1117	>	* @return {@code true} if this executor terminated and
1118	>	*         {@code false} if the timeout elapsed before termination
1119		* @throws InterruptedException if interrupted while waiting
1120		*/
1121		public boolean awaitTermination(long timeout, TimeUnit unit)
#	Line 1058 | Line 1151 | public class ForkJoinPool extends Abstra
1151		lock.lock();
1152		try {
1153		ForkJoinWorkerThread[] ws = workers;
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
1154	>	if (ws != null) {
1155	>	int idx = w.poolIndex;
1156	>	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1157	>	ws[idx] = null;
1158	>	if (totalCountOf(workerCounts) == 0) {
1159	>	terminate(); // no-op if already terminating
1160	>	transitionRunStateTo(TERMINATED);
1161	>	termination.signalAll();
1162	>	}
1163	>	else if (!isTerminating()) {
1164	>	tryShrinkWorkerArray();
1165	>	tryResumeSpare(true); // allow replacement
1166	>	}
1167		}
1168		} finally {
1169		lock.unlock();
#	Line 1092 | Line 1187 | public class ForkJoinPool extends Abstra
1187		}
1188
1189		/**
1190	<	* Possibly terminate when on shutdown state
1190	>	* Possibly terminates when on shutdown state.
1191		*/
1192		private void terminateOnShutdown() {
1193		if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
#	Line 1100 | Line 1195 | public class ForkJoinPool extends Abstra
1195		}
1196
1197		/**
1198	<	* Clear out and cancel submissions
1198	>	* Clears out and cancels submissions.
1199		*/
1200		private void cancelQueuedSubmissions() {
1201		ForkJoinTask<?> task;
#	Line 1109 | Line 1204 | public class ForkJoinPool extends Abstra
1204		}
1205
1206		/**
1207	<	* Clean out worker queues.
1207	>	* Cleans out worker queues.
1208		*/
1209		private void cancelQueuedWorkerTasks() {
1210		final ReentrantLock lock = this.workerLock;
1211		lock.lock();
1212		try {
1213		ForkJoinWorkerThread[] ws = workers;
1214	<	for (int i = 0; i < ws.length; ++i) {
1215	<	ForkJoinWorkerThread t = ws[i];
1216	<	if (t != null)
1217	<	t.cancelTasks();
1214	>	if (ws != null) {
1215	>	for (int i = 0; i < ws.length; ++i) {
1216	>	ForkJoinWorkerThread t = ws[i];
1217	>	if (t != null)
1218	>	t.cancelTasks();
1219	>	}
1220		}
1221		} finally {
1222		lock.unlock();
#	Line 1127 | Line 1224 | public class ForkJoinPool extends Abstra
1224		}
1225
1226		/**
1227	<	* Set each worker's status to terminating. Requires lock to avoid
1228	<	* conflicts with add/remove
1227	>	* Sets each worker's status to terminating. Requires lock to avoid
1228	>	* conflicts with add/remove.
1229		*/
1230		private void stopAllWorkers() {
1231		final ReentrantLock lock = this.workerLock;
1232		lock.lock();
1233		try {
1234		ForkJoinWorkerThread[] ws = workers;
1235	<	for (int i = 0; i < ws.length; ++i) {
1236	<	ForkJoinWorkerThread t = ws[i];
1237	<	if (t != null)
1238	<	t.shutdownNow();
1235	>	if (ws != null) {
1236	>	for (int i = 0; i < ws.length; ++i) {
1237	>	ForkJoinWorkerThread t = ws[i];
1238	>	if (t != null)
1239	>	t.shutdownNow();
1240	>	}
1241		}
1242		} finally {
1243		lock.unlock();
#	Line 1146 | Line 1245 | public class ForkJoinPool extends Abstra
1245		}
1246
1247		/**
1248	<	* Interrupt all unterminated workers.  This is not required for
1248	>	* Interrupts all unterminated workers.  This is not required for
1249		* sake of internal control, but may help unstick user code during
1250		* shutdown.
1251		*/
#	Line 1155 | Line 1254 | public class ForkJoinPool extends Abstra
1254		lock.lock();
1255		try {
1256		ForkJoinWorkerThread[] ws = workers;
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) {
1257	>	if (ws != null) {
1258	>	for (int i = 0; i < ws.length; ++i) {
1259	>	ForkJoinWorkerThread t = ws[i];
1260	>	if (t != null && !t.isTerminated()) {
1261	>	try {
1262	>	t.interrupt();
1263	>	} catch (SecurityException ignore) {
1264	>	}
1265		}
1266		}
1267		}
#	Line 1214 | Line 1315 | public class ForkJoinPool extends Abstra
1315		}
1316
1317		/**
1318	<	* Wake up waiter, returning false if known to already
1318	>	* Wakes up waiter, returning false if known to already
1319		*/
1320		boolean signal() {
1321		ForkJoinWorkerThread t = thread;
#	Line 1226 | Line 1327 | public class ForkJoinPool extends Abstra
1327		}
1328
1329		/**
1330	<	* Await release on sync
1330	>	* Awaits release on sync.
1331		*/
1332		void awaitSyncRelease(ForkJoinPool p) {
1333		while (thread != null && !p.syncIsReleasable(this))
#	Line 1234 | Line 1335 | public class ForkJoinPool extends Abstra
1335		}
1336
1337		/**
1338	<	* Await resumption as spare
1338	>	* Awaits resumption as spare.
1339		*/
1340		void awaitSpareRelease() {
1341		while (thread != null) {
#	Line 1274 | Line 1375 | public class ForkJoinPool extends Abstra
1375		}
1376
1377		/**
1378	<	* Signal threads waiting to poll a task. Because method sync
1378	>	* Signals threads waiting to poll a task. Because method sync
1379		* rechecks availability, it is OK to only proceed if queue
1380		* appears to be non-empty, and OK to skip under contention to
1381		* increment count (since some other thread succeeded).
#	Line 1361 | Line 1462 | public class ForkJoinPool extends Abstra
1462		//  Parallelism maintenance
1463
1464		/**
1465	<	* Decrement running count; if too low, add spare.
1465	>	* Decrements running count; if too low, adds spare.
1466		*
1467		* Conceptually, all we need to do here is add or resume a
1468		* spare thread when one is about to block (and remove or
#	Line 1381 | Line 1482 | public class ForkJoinPool extends Abstra
1482		* only be suspended or removed when they are idle, not
1483		* immediately when they aren't needed. So adding threads will
1484		* raise parallelism level for longer than necessary.  Also,
1485	<	* FJ applications often enounter highly transient peaks when
1485	>	* FJ applications often encounter highly transient peaks when
1486		* many threads are blocked joining, but for less time than it
1487		* takes to create or resume spares.
1488		*
#	Line 1451 | Line 1552 | public class ForkJoinPool extends Abstra
1552		}
1553
1554		/**
1555	<	* Add a spare worker if lock available and no more than the
1556	<	* expected numbers of threads exist
1555	>	* Adds a spare worker if lock available and no more than the
1556	>	* expected numbers of threads exist.
1557		* @return true if successful
1558		*/
1559		private boolean tryAddSpare(int expectedCounts) {
#	Line 1485 | Line 1586 | public class ForkJoinPool extends Abstra
1586		}
1587
1588		/**
1589	<	* Add the kth spare worker. On entry, pool coounts are already
1589	>	* Adds the kth spare worker. On entry, pool counts are already
1590		* adjusted to reflect addition.
1591		*/
1592		private void createAndStartSpare(int k) {
#	Line 1507 | Line 1608 | public class ForkJoinPool extends Abstra
1608		}
1609
1610		/**
1611	<	* Suspend calling thread w if there are excess threads.  Called
1612	<	* only from sync.  Spares are enqueued in a Treiber stack
1613	<	* using the same WaitQueueNodes as barriers.  They are resumed
1614	<	* mainly in preJoin, but are also woken on pool events that
1615	<	* require all threads to check run state.
1611	>	* Suspends calling thread w if there are excess threads.  Called
1612	>	* only from sync.  Spares are enqueued in a Treiber stack using
1613	>	* the same WaitQueueNodes as barriers.  They are resumed mainly
1614	>	* in preJoin, but are also woken on pool events that require all
1615	>	* threads to check run state.
1616		* @param w the caller
1617		*/
1618		private boolean suspendIfSpare(ForkJoinWorkerThread w) {
#	Line 1532 | Line 1633 | public class ForkJoinPool extends Abstra
1633		}
1634
1635		/**
1636	<	* Try to pop and resume a spare thread.
1636	>	* Tries to pop and resume a spare thread.
1637		* @param updateCount if true, increment running count on success
1638		* @return true if successful
1639		*/
#	Line 1550 | Line 1651 | public class ForkJoinPool extends Abstra
1651		}
1652
1653		/**
1654	<	* Pop and resume all spare threads. Same idea as ensureSync.
1654	>	* Pops and resumes all spare threads. Same idea as ensureSync.
1655		* @return true if any spares released
1656		*/
1657		private boolean resumeAllSpares() {
#	Line 1568 | Line 1669 | public class ForkJoinPool extends Abstra
1669		}
1670
1671		/**
1672	<	* Pop and shutdown excessive spare threads. Call only while
1672	>	* Pops and shuts down excessive spare threads. Call only while
1673		* holding lock. This is not guaranteed to eliminate all excess
1674		* threads, only those suspended as spares, which are the ones
1675		* unlikely to be needed in the future.
#	Line 1593 | Line 1694 | public class ForkJoinPool extends Abstra
1694		/**
1695		* Interface for extending managed parallelism for tasks running
1696		* in ForkJoinPools. A ManagedBlocker provides two methods.
1697	<	* Method <code>isReleasable</code> must return true if blocking is not
1698	<	* necessary. Method <code>block</code> blocks the current thread
1697	>	* Method {@code isReleasable} must return true if blocking is not
1698	>	* necessary. Method {@code block} blocks the current thread
1699		* if necessary (perhaps internally invoking isReleasable before
1700		* actually blocking.).
1701		* <p>For example, here is a ManagedBlocker based on a
#	Line 1620 | Line 1721 | public class ForkJoinPool extends Abstra
1721		* Possibly blocks the current thread, for example waiting for
1722		* a lock or condition.
1723		* @return true if no additional blocking is necessary (i.e.,
1724	<	* if isReleasable would return true).
1724	>	* if isReleasable would return true)
1725		* @throws InterruptedException if interrupted while waiting
1726	<	* (the method is not required to do so, but is allowe to).
1726	>	* (the method is not required to do so, but is allowed to).
1727		*/
1728		boolean block() throws InterruptedException;
1729
#	Line 1637 | Line 1738 | public class ForkJoinPool extends Abstra
1738		* is a ForkJoinWorkerThread, this method possibly arranges for a
1739		* spare thread to be activated if necessary to ensure parallelism
1740		* while the current thread is blocked.  If
1741	<	* <code>maintainParallelism</code> is true and the pool supports
1741	>	* {@code maintainParallelism} is true and the pool supports
1742		* it ({@link #getMaintainsParallelism}), this method attempts to
1743		* maintain the pool's nominal parallelism. Otherwise if activates
1744		* a thread only if necessary to avoid complete starvation. This
#	Line 1659 | Line 1760 | public class ForkJoinPool extends Abstra
1760		* attempt to maintain the pool's nominal parallelism; otherwise
1761		* activate a thread only if necessary to avoid complete
1762		* starvation.
1763	<	* @throws InterruptedException if blocker.block did so.
1763	>	* @throws InterruptedException if blocker.block did so
1764		*/
1765		public static void managedBlock(ManagedBlocker blocker,
1766		boolean maintainParallelism)
#	Line 1721 | Line 1822 | public class ForkJoinPool extends Abstra
1822
1823		private static long fieldOffset(String fieldName)
1824		throws NoSuchFieldException {
1825	<	return _unsafe.objectFieldOffset
1825	>	return UNSAFE.objectFieldOffset
1826		(ForkJoinPool.class.getDeclaredField(fieldName));
1827		}
1828
1829	<	static final Unsafe _unsafe;
1829	>	static final Unsafe UNSAFE;
1830		static final long eventCountOffset;
1831		static final long workerCountsOffset;
1832		static final long runControlOffset;
#	Line 1734 | Line 1835 | public class ForkJoinPool extends Abstra
1835
1836		static {
1837		try {
1838	<	_unsafe = getUnsafe();
1838	>	UNSAFE = getUnsafe();
1839		eventCountOffset = fieldOffset("eventCount");
1840		workerCountsOffset = fieldOffset("workerCounts");
1841		runControlOffset = fieldOffset("runControl");
#	Line 1746 | Line 1847 | public class ForkJoinPool extends Abstra
1847		}
1848
1849		private boolean casEventCount(long cmp, long val) {
1850	<	return _unsafe.compareAndSwapLong(this, eventCountOffset, cmp, val);
1850	>	return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
1851		}
1852		private boolean casWorkerCounts(int cmp, int val) {
1853	<	return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1853	>	return UNSAFE.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1854		}
1855		private boolean casRunControl(int cmp, int val) {
1856	<	return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val);
1856	>	return UNSAFE.compareAndSwapInt(this, runControlOffset, cmp, val);
1857		}
1858		private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) {
1859	<	return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val);
1859	>	return UNSAFE.compareAndSwapObject(this, spareStackOffset, cmp, val);
1860		}
1861		private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1862	<	return _unsafe.compareAndSwapObject(this, syncStackOffset, cmp, val);
1862	>	return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val);
1863		}
1864		}

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