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

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.1 by dl, Tue Jan 6 14:30:31 2009 UTC vs.
Revision 1.32 by jsr166, Thu Jul 30 22:05:19 2009 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	<	import java.util.*;
8	>
9		import java.util.concurrent.*;
10	<	import java.util.concurrent.locks.*;
11	<	import java.util.concurrent.atomic.*;
12	<	import sun.misc.Unsafe;
13	<	import java.lang.reflect.*;
10	>
11	>	import java.util.ArrayList;
12	>	import java.util.Arrays;
13	>	import java.util.Collection;
14	>	import java.util.Collections;
15	>	import java.util.List;
16	>	import java.util.concurrent.locks.Condition;
17	>	import java.util.concurrent.locks.LockSupport;
18	>	import java.util.concurrent.locks.ReentrantLock;
19	>	import java.util.concurrent.atomic.AtomicInteger;
20	>	import java.util.concurrent.atomic.AtomicLong;
21
22		/**
23	<	* Host for a group of ForkJoinWorkerThreads.  A ForkJoinPool provides
24	<	* the entry point for tasks submitted from non-ForkJoinTasks, as well
25	<	* as management and monitoring operations.  Normally a single
26	<	* ForkJoinPool is used for a large number of submitted
27	<	* tasks. Otherwise, use would not usually outweigh the construction
28	<	* and bookkeeping overhead of creating a large set of threads.
23	>	* An {@link ExecutorService} for running {@link ForkJoinTask}s.
24	>	* A ForkJoinPool provides the entry point for submissions from
25	>	* non-ForkJoinTasks, as well as management and monitoring operations.
26	>	* Normally a single ForkJoinPool is used for a large number of
27	>	* submitted tasks. Otherwise, use would not usually outweigh the
28	>	* construction and bookkeeping overhead of creating a large set of
29	>	* threads.
30		*
31	<	* <p>ForkJoinPools differ from other kinds of Executor mainly in that
32	<	* they provide <em>work-stealing</em>: all threads in the pool
31	>	* <p>ForkJoinPools differ from other kinds of Executors mainly in
32	>	* that they provide <em>work-stealing</em>: all threads in the pool
33		* attempt to find and execute subtasks created by other active tasks
34		* (eventually blocking if none exist). This makes them efficient when
35	<	* most tasks spawn other subtasks (as do most ForkJoinTasks) but
36	<	* possibly less so otherwise. It is however fine to combine execution
37	<	* of some plain Runnable- or Callable- based activities with that of
38	<	* ForkJoinTasks.
35	>	* most tasks spawn other subtasks (as do most ForkJoinTasks), as well
36	>	* as the mixed execution of some plain Runnable- or Callable- based
37	>	* activities along with ForkJoinTasks. When setting {@linkplain
38	>	* #setAsyncMode async mode}, a ForkJoinPool may also be appropriate
39	>	* for use with fine-grained tasks that are never joined. Otherwise,
40	>	* other ExecutorService implementations are typically more
41	>	* appropriate choices.
42		*
43		* <p>A ForkJoinPool may be constructed with a given parallelism level
44		* (target pool size), which it attempts to maintain by dynamically
45	<	* adding, suspending, or resuming threads, even if some tasks have
46	<	* blocked waiting to join others. However, no such adjustments are
47	<	* performed in the face of blocked IO or other unmanaged
48	<	* synchronization. The nested ManagedBlocker interface enables
49	<	* extension of the kinds of synchronization accommodated.
50	<	*
51	<	* <p>The target parallelism level may also be set dynamically. You
52	<	* can limit the number of threads dynamically constructed using
53	<	* method <tt>setMaximumPoolSize</tt> and/or
43	<	* <tt>setMaintainParallelism</tt>.
45	>	* adding, suspending, or resuming threads, even if some tasks are
46	>	* waiting to join others. However, no such adjustments are performed
47	>	* in the face of blocked IO or other unmanaged synchronization. The
48	>	* nested {@link ManagedBlocker} interface enables extension of
49	>	* the kinds of synchronization accommodated.  The target parallelism
50	>	* level may also be changed dynamically ({@link #setParallelism})
51	>	* and thread construction can be limited using methods
52	>	* {@link #setMaximumPoolSize} and/or
53	>	* {@link #setMaintainsParallelism}.
54		*
55		* <p>In addition to execution and lifecycle control methods, this
56		* class provides status check methods (for example
57	<	* <tt>getStealCount</tt>) that are intended to aid in developing,
57	>	* {@link #getStealCount}) that are intended to aid in developing,
58		* tuning, and monitoring fork/join applications. Also, method
59	<	* <tt>toString</tt> returns indications of pool state in a convenient
60	<	* form for informal monitoring.
59	>	* {@link #toString} returns indications of pool state in a
60	>	* convenient form for informal monitoring.
61		*
62		* <p><b>Implementation notes</b>: This implementation restricts the
63	<	* maximum parallelism to 32767. Attempts to create pools with greater
64	<	* than the maximum result in IllegalArgumentExceptions.
63	>	* maximum number of running threads to 32767. Attempts to create
64	>	* pools with greater than the maximum result in
65	>	* IllegalArgumentExceptions.
66	>	*
67	>	* @since 1.7
68	>	* @author Doug Lea
69		*/
70	<	public class ForkJoinPool extends AbstractExecutorService
57	<	implements ExecutorService {
70	>	public class ForkJoinPool extends AbstractExecutorService {
71
72		/*
73		* See the extended comments interspersed below for design,
#	Line 78 | Line 91 | public class ForkJoinPool extends Abstra
91		* Returns a new worker thread operating in the given pool.
92		*
93		* @param pool the pool this thread works in
94	<	* @throws NullPointerException if pool is null;
94	>	* @throws NullPointerException if pool is null
95		*/
96		public ForkJoinWorkerThread newThread(ForkJoinPool pool);
97		}
98
99		/**
100	<	* Default ForkJoinWorkerThreadFactory implementation, creates a
100	>	* Default ForkJoinWorkerThreadFactory implementation; creates a
101		* new ForkJoinWorkerThread.
102		*/
103	<	public static class  DefaultForkJoinWorkerThreadFactory
103	>	static class  DefaultForkJoinWorkerThreadFactory
104		implements ForkJoinWorkerThreadFactory {
105		public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
106		try {
#	Line 99 | Line 112 | public class ForkJoinPool extends Abstra
112		}
113
114		/**
115	<	* The default ForkJoinWorkerThreadFactory, used unless overridden
116	<	* in ForkJoinPool constructors.
115	>	* Creates a new ForkJoinWorkerThread. This factory is used unless
116	>	* overridden in ForkJoinPool constructors.
117		*/
118	<	private static final DefaultForkJoinWorkerThreadFactory
118	>	public static final ForkJoinWorkerThreadFactory
119		defaultForkJoinWorkerThreadFactory =
120		new DefaultForkJoinWorkerThreadFactory();
121
109	–
122		/**
123		* Permission required for callers of methods that may start or
124		* kill threads.
#	Line 131 | Line 143 | public class ForkJoinPool extends Abstra
143		new AtomicInteger();
144
145		/**
146	<	* Array holding all worker threads in the pool. Array size must
147	<	* be a power of two.  Updates and replacements are protected by
148	<	* workerLock, but it is always kept in a consistent enough state
149	<	* to be randomly accessed without locking by workers performing
150	<	* work-stealing.
146	>	* Array holding all worker threads in the pool. Initialized upon
147	>	* first use. Array size must be a power of two.  Updates and
148	>	* replacements are protected by workerLock, but it is always kept
149	>	* in a consistent enough state to be randomly accessed without
150	>	* locking by workers performing work-stealing.
151		*/
152		volatile ForkJoinWorkerThread[] workers;
153
#	Line 151 | Line 163 | public class ForkJoinPool extends Abstra
163
164		/**
165		* The uncaught exception handler used when any worker
166	<	* abrupty terminates
166	>	* abruptly terminates
167		*/
168		private Thread.UncaughtExceptionHandler ueh;
169
#	Line 179 | Line 191 | public class ForkJoinPool extends Abstra
191		private final LinkedTransferQueue<ForkJoinTask<?>> submissionQueue;
192
193		/**
194	<	* Head of Treiber stack for barrier sync. See below for explanation
194	>	* Head of Treiber stack for barrier sync. See below for explanation.
195		*/
196	<	private volatile WaitQueueNode barrierStack;
196	>	private volatile WaitQueueNode syncStack;
197
198		/**
199		* The count for event barrier
#	Line 204 | Line 216 | public class ForkJoinPool extends Abstra
216		private volatile int parallelism;
217
218		/**
219	+	* True if use local fifo, not default lifo, for local polling
220	+	*/
221	+	private volatile boolean locallyFifo;
222	+
223	+	/**
224		* Holds number of total (i.e., created and not yet terminated)
225		* and running (i.e., not blocked on joins or other managed sync)
226		* threads, packed into one int to ensure consistent snapshot when
227		* making decisions about creating and suspending spare
228		* threads. Updated only by CAS.  Note: CASes in
229	<	* updateRunningCount and preJoin running active count is in low
230	<	* word, so need to be modified if this changes
229	>	* updateRunningCount and preJoin assume that running active count
230	>	* is in low word, so need to be modified if this changes.
231		*/
232		private volatile int workerCounts;
233
#	Line 219 | Line 236 | public class ForkJoinPool extends Abstra
236		private static int workerCountsFor(int t, int r) { return (t << 16) + r; }
237
238		/**
239	<	* Add delta (which may be negative) to running count.  This must
239	>	* Adds delta (which may be negative) to running count.  This must
240		* be called before (with negative arg) and after (with positive)
241	<	* any managed synchronization (i.e., mainly, joins)
241	>	* any managed synchronization (i.e., mainly, joins).
242	>	*
243		* @param delta the number to add
244		*/
245		final void updateRunningCount(int delta) {
246		int s;
247	<	do;while (!casWorkerCounts(s = workerCounts, s + delta));
247	>	do {} while (!casWorkerCounts(s = workerCounts, s + delta));
248		}
249
250		/**
251	<	* Add delta (which may be negative) to both total and running
251	>	* Adds delta (which may be negative) to both total and running
252		* count.  This must be called upon creation and termination of
253		* worker threads.
254	+	*
255		* @param delta the number to add
256		*/
257		private void updateWorkerCount(int delta) {
258		int d = delta + (delta << 16); // add to both lo and hi parts
259		int s;
260	<	do;while (!casWorkerCounts(s = workerCounts, s + d));
260	>	do {} while (!casWorkerCounts(s = workerCounts, s + d));
261		}
262
263		/**
#	Line 264 | Line 283 | public class ForkJoinPool extends Abstra
283		private static int runControlFor(int r, int a)   { return (r << 16) + a; }
284
285		/**
286	<	* Increment active count. Called by workers before/during
287	<	* executing tasks.
286	>	* Tries incrementing active count; fails on contention.
287	>	* Called by workers before/during executing tasks.
288	>	*
289	>	* @return true on success
290		*/
291	<	final void incrementActiveCount() {
292	<	int c;
293	<	do;while (!casRunControl(c = runControl, c+1));
291	>	final boolean tryIncrementActiveCount() {
292	>	int c = runControl;
293	>	return casRunControl(c, c+1);
294		}
295
296		/**
297	<	* Decrement active count; possibly trigger termination.
297	>	* Tries decrementing active count; fails on contention.
298	>	* Possibly triggers termination on success.
299		* Called by workers when they can't find tasks.
300	+	*
301	+	* @return true on success
302		*/
303	<	final void decrementActiveCount() {
304	<	int c, nextc;
305	<	do;while (!casRunControl(c = runControl, nextc = c-1));
303	>	final boolean tryDecrementActiveCount() {
304	>	int c = runControl;
305	>	int nextc = c - 1;
306	>	if (!casRunControl(c, nextc))
307	>	return false;
308		if (canTerminateOnShutdown(nextc))
309		terminateOnShutdown();
310	+	return true;
311		}
312
313		/**
314	<	* Return true if argument represents zero active count and
315	<	* nonzero runstate, which is the triggering condition for
314	>	* Returns {@code true} if argument represents zero active count
315	>	* and nonzero runstate, which is the triggering condition for
316		* terminating on shutdown.
317		*/
318		private static boolean canTerminateOnShutdown(int c) {
319	<	return ((c & -c) >>> 16) != 0; // i.e. least bit is nonzero runState bit
319	>	// i.e. least bit is nonzero runState bit
320	>	return ((c & -c) >>> 16) != 0;
321		}
322
323		/**
#	Line 315 | Line 343 | public class ForkJoinPool extends Abstra
343
344		/**
345		* Creates a ForkJoinPool with a pool size equal to the number of
346	<	* processors available on the system and using the default
347	<	* ForkJoinWorkerThreadFactory,
346	>	* processors available on the system, using the default
347	>	* ForkJoinWorkerThreadFactory.
348	>	*
349		* @throws SecurityException if a security manager exists and
350		*         the caller is not permitted to modify threads
351		*         because it does not hold {@link
352	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
352	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
353		*/
354		public ForkJoinPool() {
355		this(Runtime.getRuntime().availableProcessors(),
#	Line 328 | Line 357 | public class ForkJoinPool extends Abstra
357		}
358
359		/**
360	<	* Creates a ForkJoinPool with the indicated parellelism level
361	<	* threads, and using the default ForkJoinWorkerThreadFactory,
360	>	* Creates a ForkJoinPool with the indicated parallelism level
361	>	* threads and using the default ForkJoinWorkerThreadFactory.
362	>	*
363		* @param parallelism the number of worker threads
364		* @throws IllegalArgumentException if parallelism less than or
365		* equal to zero
366		* @throws SecurityException if a security manager exists and
367		*         the caller is not permitted to modify threads
368		*         because it does not hold {@link
369	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
369	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
370		*/
371		public ForkJoinPool(int parallelism) {
372		this(parallelism, defaultForkJoinWorkerThreadFactory);
373		}
374
375		/**
376	<	* Creates a ForkJoinPool with a pool size equal to the number of
376	>	* Creates a ForkJoinPool with parallelism equal to the number of
377		* processors available on the system and using the given
378	<	* ForkJoinWorkerThreadFactory,
378	>	* ForkJoinWorkerThreadFactory.
379	>	*
380		* @param factory the factory for creating new threads
381		* @throws NullPointerException if factory is null
382		* @throws SecurityException if a security manager exists and
383		*         the caller is not permitted to modify threads
384		*         because it does not hold {@link
385	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
385	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
386		*/
387		public ForkJoinPool(ForkJoinWorkerThreadFactory factory) {
388		this(Runtime.getRuntime().availableProcessors(), factory);
389		}
390
391		/**
392	<	* Creates a ForkJoinPool with the indicated target number of
362	<	* worker threads and the given factory.
392	>	* Creates a ForkJoinPool with the given parallelism and factory.
393		*
394		* @param parallelism the targeted number of worker threads
395		* @param factory the factory for creating new threads
396		* @throws IllegalArgumentException if parallelism less than or
397	<	* equal to zero, or greater than implementation limit.
397	>	* equal to zero, or greater than implementation limit
398		* @throws NullPointerException if factory is null
399		* @throws SecurityException if a security manager exists and
400		*         the caller is not permitted to modify threads
401		*         because it does not hold {@link
402	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
402	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
403		*/
404		public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) {
405		if (parallelism <= 0 || parallelism > MAX_THREADS)
#	Line 386 | Line 416 | public class ForkJoinPool extends Abstra
416		this.termination = workerLock.newCondition();
417		this.stealCount = new AtomicLong();
418		this.submissionQueue = new LinkedTransferQueue<ForkJoinTask<?>>();
419	<	createAndStartInitialWorkers(parallelism);
419	>	// worker array and workers are lazily constructed
420		}
421
422		/**
423	<	* Create new worker using factory.
423	>	* Creates a new worker thread using factory.
424	>	*
425		* @param index the index to assign worker
426		* @return new worker, or null of factory failed
427		*/
#	Line 400 | Line 431 | public class ForkJoinPool extends Abstra
431		if (w != null) {
432		w.poolIndex = index;
433		w.setDaemon(true);
434	+	w.setAsyncMode(locallyFifo);
435		w.setName("ForkJoinPool-" + poolNumber + "-worker-" + index);
436		if (h != null)
437		w.setUncaughtExceptionHandler(h);
#	Line 408 | Line 440 | public class ForkJoinPool extends Abstra
440		}
441
442		/**
443	<	* Return a good size for worker array given pool size.
443	>	* Returns a good size for worker array given pool size.
444		* Currently requires size to be a power of two.
445		*/
446	<	private static int arraySizeFor(int ps) {
447	<	return ps <= 1? 1 : (1 << (32 - Integer.numberOfLeadingZeros(ps-1)));
446	>	private static int arraySizeFor(int poolSize) {
447	>	return (poolSize <= 1) ? 1 :
448	>	(1 << (32 - Integer.numberOfLeadingZeros(poolSize-1)));
449		}
450
451		/**
452	<	* Create or resize array if necessary to hold newLength
452	>	* Creates or resizes array if necessary to hold newLength.
453	>	* Call only under exclusion.
454	>	*
455		* @return the array
456		*/
457		private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
#	Line 430 | Line 465 | public class ForkJoinPool extends Abstra
465		}
466
467		/**
468	<	* Try to shrink workers into smaller array after one or more terminate
468	>	* Tries to shrink workers into smaller array after one or more terminate.
469		*/
470		private void tryShrinkWorkerArray() {
471		ForkJoinWorkerThread[] ws = workers;
472	<	int len = ws.length;
473	<	int last = len - 1;
474	<	while (last >= 0 && ws[last] == null)
475	<	--last;
476	<	int newLength = arraySizeFor(last+1);
477	<	if (newLength < len)
478	<	workers = Arrays.copyOf(ws, newLength);
472	>	if (ws != null) {
473	>	int len = ws.length;
474	>	int last = len - 1;
475	>	while (last >= 0 && ws[last] == null)
476	>	--last;
477	>	int newLength = arraySizeFor(last+1);
478	>	if (newLength < len)
479	>	workers = Arrays.copyOf(ws, newLength);
480	>	}
481		}
482
483		/**
484	<	* Initial worker array and worker creation and startup. (This
448	<	* must be done under lock to avoid interference by some of the
449	<	* newly started threads while creating others.)
484	>	* Initializes workers if necessary.
485		*/
486	<	private void createAndStartInitialWorkers(int ps) {
487	<	final ReentrantLock lock = this.workerLock;
488	<	lock.lock();
489	<	try {
490	<	ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps);
491	<	for (int i = 0; i < ps; ++i) {
492	<	ForkJoinWorkerThread w = createWorker(i);
493	<	if (w != null) {
494	<	ws[i] = w;
495	<	w.start();
496	<	updateWorkerCount(1);
486	>	final void ensureWorkerInitialization() {
487	>	ForkJoinWorkerThread[] ws = workers;
488	>	if (ws == null) {
489	>	final ReentrantLock lock = this.workerLock;
490	>	lock.lock();
491	>	try {
492	>	ws = workers;
493	>	if (ws == null) {
494	>	int ps = parallelism;
495	>	ws = ensureWorkerArrayCapacity(ps);
496	>	for (int i = 0; i < ps; ++i) {
497	>	ForkJoinWorkerThread w = createWorker(i);
498	>	if (w != null) {
499	>	ws[i] = w;
500	>	w.start();
501	>	updateWorkerCount(1);
502	>	}
503	>	}
504		}
505	+	} finally {
506	+	lock.unlock();
507		}
464	–	} finally {
465	–	lock.unlock();
508		}
509		}
510
#	Line 500 | Line 542 | public class ForkJoinPool extends Abstra
542		}
543		}
544
503	–	/**
504	–	* Sets the handler for internal worker threads that terminate due
505	–	* to unrecoverable errors encountered while executing tasks.
506	–	* Unless set, the current default or ThreadGroup handler is used
507	–	* as handler.
508	–	*
509	–	* @param h the new handler
510	–	* @return the old handler, or null if none
511	–	* @throws SecurityException if a security manager exists and
512	–	*         the caller is not permitted to modify threads
513	–	*         because it does not hold {@link
514	–	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
515	–	*/
516	–	public Thread.UncaughtExceptionHandler
517	–	setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
518	–	checkPermission();
519	–	Thread.UncaughtExceptionHandler old = null;
520	–	final ReentrantLock lock = this.workerLock;
521	–	lock.lock();
522	–	try {
523	–	old = ueh;
524	–	ueh = h;
525	–	ForkJoinWorkerThread[] ws = workers;
526	–	for (int i = 0; i < ws.length; ++i) {
527	–	ForkJoinWorkerThread w = ws[i];
528	–	if (w != null)
529	–	w.setUncaughtExceptionHandler(h);
530	–	}
531	–	} finally {
532	–	lock.unlock();
533	–	}
534	–	return old;
535	–	}
536	–
537	–	/**
538	–	* Returns the handler for internal worker threads that terminate
539	–	* due to unrecoverable errors encountered while executing tasks.
540	–	* @return the handler, or null if none
541	–	*/
542	–	public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
543	–	Thread.UncaughtExceptionHandler h;
544	–	final ReentrantLock lock = this.workerLock;
545	–	lock.lock();
546	–	try {
547	–	h = ueh;
548	–	} finally {
549	–	lock.unlock();
550	–	}
551	–	return h;
552	–	}
553	–
545		// Execution methods
546
547		/**
548		* Common code for execute, invoke and submit
549		*/
550		private <T> void doSubmit(ForkJoinTask<T> task) {
551	+	if (task == null)
552	+	throw new NullPointerException();
553		if (isShutdown())
554		throw new RejectedExecutionException();
555	+	if (workers == null)
556	+	ensureWorkerInitialization();
557		submissionQueue.offer(task);
558	<	signalIdleWorkers(true);
558	>	signalIdleWorkers();
559		}
560
561		/**
562	<	* Performs the given task; returning its result upon completion
562	>	* Performs the given task, returning its result upon completion.
563	>	*
564		* @param task the task
565		* @return the task's result
566		* @throws NullPointerException if task is null
#	Line 577 | Line 573 | public class ForkJoinPool extends Abstra
573
574		/**
575		* Arranges for (asynchronous) execution of the given task.
576	+	*
577		* @param task the task
578		* @throws NullPointerException if task is null
579		* @throws RejectedExecutionException if pool is shut down
#	Line 588 | Line 585 | public class ForkJoinPool extends Abstra
585		// AbstractExecutorService methods
586
587		public void execute(Runnable task) {
588	<	doSubmit(new AdaptedRunnable<Void>(task, null));
588	>	ForkJoinTask<?> job;
589	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
590	>	job = (ForkJoinTask<?>) task;
591	>	else
592	>	job = new AdaptedRunnable<Void>(task, null);
593	>	doSubmit(job);
594		}
595
596		public <T> ForkJoinTask<T> submit(Callable<T> task) {
#	Line 604 | Line 606 | public class ForkJoinPool extends Abstra
606		}
607
608		public ForkJoinTask<?> submit(Runnable task) {
609	<	ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null);
609	>	ForkJoinTask<?> job;
610	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
611	>	job = (ForkJoinTask<?>) task;
612	>	else
613	>	job = new AdaptedRunnable<Void>(task, null);
614		doSubmit(job);
615		return job;
616		}
617
618	<	protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
619	<	return new AdaptedRunnable(runnable, value);
620	<	}
621	<
622	<	protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
623	<	return new AdaptedCallable(callable);
618	>	/**
619	>	* Submits a ForkJoinTask for execution.
620	>	*
621	>	* @param task the task to submit
622	>	* @return the task
623	>	* @throws RejectedExecutionException if the task cannot be
624	>	*         scheduled for execution
625	>	* @throws NullPointerException if the task is null
626	>	*/
627	>	public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) {
628	>	doSubmit(task);
629	>	return task;
630		}
631
632		/**
633		* Adaptor for Runnables. This implements RunnableFuture
634	<	* to be compliant with AbstractExecutorService constraints
634	>	* to be compliant with AbstractExecutorService constraints.
635		*/
636		static final class AdaptedRunnable<T> extends ForkJoinTask<T>
637		implements RunnableFuture<T> {
#	Line 639 | Line 651 | public class ForkJoinPool extends Abstra
651		return true;
652		}
653		public void run() { invoke(); }
654	+	private static final long serialVersionUID = 5232453952276885070L;
655		}
656
657		/**
#	Line 667 | Line 680 | public class ForkJoinPool extends Abstra
680		}
681		}
682		public void run() { invoke(); }
683	+	private static final long serialVersionUID = 2838392045355241008L;
684		}
685
686		public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) {
687	<	ArrayList<ForkJoinTask<T>> ts =
687	>	ArrayList<ForkJoinTask<T>> forkJoinTasks =
688		new ArrayList<ForkJoinTask<T>>(tasks.size());
689	<	for (Callable<T> c : tasks)
690	<	ts.add(new AdaptedCallable<T>(c));
691	<	invoke(new InvokeAll<T>(ts));
692	<	return (List<Future<T>>)(List)ts;
689	>	for (Callable<T> task : tasks)
690	>	forkJoinTasks.add(new AdaptedCallable<T>(task));
691	>	invoke(new InvokeAll<T>(forkJoinTasks));
692	>
693	>	@SuppressWarnings({"unchecked", "rawtypes"})
694	>	List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks;
695	>	return futures;
696		}
697
698		static final class InvokeAll<T> extends RecursiveAction {
699		final ArrayList<ForkJoinTask<T>> tasks;
700		InvokeAll(ArrayList<ForkJoinTask<T>> tasks) { this.tasks = tasks; }
701		public void compute() {
702	<	try { invokeAll(tasks); } catch(Exception ignore) {}
702	>	try { invokeAll(tasks); }
703	>	catch (Exception ignore) {}
704		}
705	+	private static final long serialVersionUID = -7914297376763021607L;
706		}
707
708		// Configuration and status settings and queries
709
710		/**
711	<	* Returns the factory used for constructing new workers
711	>	* Returns the factory used for constructing new workers.
712		*
713		* @return the factory used for constructing new workers
714		*/
#	Line 698 | Line 717 | public class ForkJoinPool extends Abstra
717		}
718
719		/**
720	<	* Sets the target paralleism level of this pool.
720	>	* Returns the handler for internal worker threads that terminate
721	>	* due to unrecoverable errors encountered while executing tasks.
722	>	*
723	>	* @return the handler, or {@code null} if none
724	>	*/
725	>	public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
726	>	Thread.UncaughtExceptionHandler h;
727	>	final ReentrantLock lock = this.workerLock;
728	>	lock.lock();
729	>	try {
730	>	h = ueh;
731	>	} finally {
732	>	lock.unlock();
733	>	}
734	>	return h;
735	>	}
736	>
737	>	/**
738	>	* Sets the handler for internal worker threads that terminate due
739	>	* to unrecoverable errors encountered while executing tasks.
740	>	* Unless set, the current default or ThreadGroup handler is used
741	>	* as handler.
742	>	*
743	>	* @param h the new handler
744	>	* @return the old handler, or {@code null} if none
745	>	* @throws SecurityException if a security manager exists and
746	>	*         the caller is not permitted to modify threads
747	>	*         because it does not hold {@link
748	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
749	>	*/
750	>	public Thread.UncaughtExceptionHandler
751	>	setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
752	>	checkPermission();
753	>	Thread.UncaughtExceptionHandler old = null;
754	>	final ReentrantLock lock = this.workerLock;
755	>	lock.lock();
756	>	try {
757	>	old = ueh;
758	>	ueh = h;
759	>	ForkJoinWorkerThread[] ws = workers;
760	>	if (ws != null) {
761	>	for (int i = 0; i < ws.length; ++i) {
762	>	ForkJoinWorkerThread w = ws[i];
763	>	if (w != null)
764	>	w.setUncaughtExceptionHandler(h);
765	>	}
766	>	}
767	>	} finally {
768	>	lock.unlock();
769	>	}
770	>	return old;
771	>	}
772	>
773	>
774	>	/**
775	>	* Sets the target parallelism level of this pool.
776	>	*
777		* @param parallelism the target parallelism
778		* @throws IllegalArgumentException if parallelism less than or
779	<	* equal to zero or greater than maximum size bounds.
779	>	* equal to zero or greater than maximum size bounds
780		* @throws SecurityException if a security manager exists and
781		*         the caller is not permitted to modify threads
782		*         because it does not hold {@link
783	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
783	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
784		*/
785		public void setParallelism(int parallelism) {
786		checkPermission();
#	Line 725 | Line 800 | public class ForkJoinPool extends Abstra
800		} finally {
801		lock.unlock();
802		}
803	<	signalIdleWorkers(false);
803	>	signalIdleWorkers();
804		}
805
806		/**
807		* Returns the targeted number of worker threads in this pool.
733	–	* This value does not necessarily reflect transient changes as
734	–	* threads are added, removed, or abruptly terminate.
808		*
809		* @return the targeted number of worker threads in this pool
810		*/
#	Line 742 | Line 815 | public class ForkJoinPool extends Abstra
815		/**
816		* Returns the number of worker threads that have started but not
817		* yet terminated.  This result returned by this method may differ
818	<	* from <tt>getParallelism</tt> when threads are created to
818	>	* from {@link #getParallelism} when threads are created to
819		* maintain parallelism when others are cooperatively blocked.
820		*
821		* @return the number of worker threads
#	Line 754 | Line 827 | public class ForkJoinPool extends Abstra
827		/**
828		* Returns the maximum number of threads allowed to exist in the
829		* pool, even if there are insufficient unblocked running threads.
830	+	*
831		* @return the maximum
832		*/
833		public int getMaximumPoolSize() {
#	Line 765 | Line 839 | public class ForkJoinPool extends Abstra
839		* pool, even if there are insufficient unblocked running threads.
840		* Setting this value has no effect on current pool size. It
841		* controls construction of new threads.
842	+	*
843		* @throws IllegalArgumentException if negative or greater then
844	<	* internal implementation limit.
844	>	* internal implementation limit
845		*/
846		public void setMaximumPoolSize(int newMax) {
847		if (newMax < 0 || newMax > MAX_THREADS)
#	Line 776 | Line 851 | public class ForkJoinPool extends Abstra
851
852
853		/**
854	<	* Returns true if this pool dynamically maintains its target
855	<	* parallelism level. If false, new threads are added only to
856	<	* avoid possible starvation.
857	<	* This setting is by default true;
858	<	* @return true if maintains parallelism
854	>	* Returns {@code true} if this pool dynamically maintains its
855	>	* target parallelism level. If false, new threads are added only
856	>	* to avoid possible starvation.  This setting is by default true.
857	>	*
858	>	* @return {@code true} if maintains parallelism
859		*/
860		public boolean getMaintainsParallelism() {
861		return maintainsParallelism;
#	Line 790 | Line 865 | public class ForkJoinPool extends Abstra
865		* Sets whether this pool dynamically maintains its target
866		* parallelism level. If false, new threads are added only to
867		* avoid possible starvation.
868	<	* @param enable true to maintains parallelism
868	>	*
869	>	* @param enable {@code true} to maintain parallelism
870		*/
871		public void setMaintainsParallelism(boolean enable) {
872		maintainsParallelism = enable;
873		}
874
875		/**
876	<	* Returns the approximate number of worker threads that are not
877	<	* blocked waiting to join tasks or for other managed
876	>	* Establishes local first-in-first-out scheduling mode for forked
877	>	* tasks that are never joined. This mode may be more appropriate
878	>	* than default locally stack-based mode in applications in which
879	>	* worker threads only process asynchronous tasks.  This method is
880	>	* designed to be invoked only when the pool is quiescent, and
881	>	* typically only before any tasks are submitted. The effects of
882	>	* invocations at other times may be unpredictable.
883	>	*
884	>	* @param async if {@code true}, use locally FIFO scheduling
885	>	* @return the previous mode
886	>	* @see #getAsyncMode
887	>	*/
888	>	public boolean setAsyncMode(boolean async) {
889	>	boolean oldMode = locallyFifo;
890	>	locallyFifo = async;
891	>	ForkJoinWorkerThread[] ws = workers;
892	>	if (ws != null) {
893	>	for (int i = 0; i < ws.length; ++i) {
894	>	ForkJoinWorkerThread t = ws[i];
895	>	if (t != null)
896	>	t.setAsyncMode(async);
897	>	}
898	>	}
899	>	return oldMode;
900	>	}
901	>
902	>	/**
903	>	* Returns {@code true} if this pool uses local first-in-first-out
904	>	* scheduling mode for forked tasks that are never joined.
905	>	*
906	>	* @return {@code true} if this pool uses async mode
907	>	* @see #setAsyncMode
908	>	*/
909	>	public boolean getAsyncMode() {
910	>	return locallyFifo;
911	>	}
912	>
913	>	/**
914	>	* Returns an estimate of the number of worker threads that are
915	>	* not blocked waiting to join tasks or for other managed
916		* synchronization.
917		*
918		* @return the number of worker threads
#	Line 808 | Line 922 | public class ForkJoinPool extends Abstra
922		}
923
924		/**
925	<	* Returns the approximate number of threads that are currently
925	>	* Returns an estimate of the number of threads that are currently
926		* stealing or executing tasks. This method may overestimate the
927		* number of active threads.
928	<	* @return the number of active threads.
928	>	*
929	>	* @return the number of active threads
930		*/
931		public int getActiveThreadCount() {
932		return activeCountOf(runControl);
933		}
934
935		/**
936	<	* Returns the approximate number of threads that are currently
936	>	* Returns an estimate of the number of threads that are currently
937		* idle waiting for tasks. This method may underestimate the
938		* number of idle threads.
939	<	* @return the number of idle threads.
939	>	*
940	>	* @return the number of idle threads
941		*/
942		final int getIdleThreadCount() {
943		int c = runningCountOf(workerCounts) - activeCountOf(runControl);
944	<	return (c <= 0)? 0 : c;
944	>	return (c <= 0) ? 0 : c;
945		}
946
947		/**
948	<	* Returns true if all worker threads are currently idle. An idle
949	<	* worker is one that cannot obtain a task to execute because none
950	<	* are available to steal from other threads, and there are no
951	<	* pending submissions to the pool. This method is conservative:
952	<	* It might not return true immediately upon idleness of all
953	<	* threads, but will eventually become true if threads remain
954	<	* inactive.
955	<	* @return true if all threads are currently idle
948	>	* Returns {@code true} if all worker threads are currently idle.
949	>	* An idle worker is one that cannot obtain a task to execute
950	>	* because none are available to steal from other threads, and
951	>	* there are no pending submissions to the pool. This method is
952	>	* conservative; it might not return {@code true} immediately upon
953	>	* idleness of all threads, but will eventually become true if
954	>	* threads remain inactive.
955	>	*
956	>	* @return {@code true} if all threads are currently idle
957		*/
958		public boolean isQuiescent() {
959		return activeCountOf(runControl) == 0;
#	Line 847 | Line 964 | public class ForkJoinPool extends Abstra
964		* one thread's work queue by another. The reported value
965		* underestimates the actual total number of steals when the pool
966		* is not quiescent. This value may be useful for monitoring and
967	<	* tuning fork/join programs: In general, steal counts should be
967	>	* tuning fork/join programs: in general, steal counts should be
968		* high enough to keep threads busy, but low enough to avoid
969		* overhead and contention across threads.
970	<	* @return the number of steals.
970	>	*
971	>	* @return the number of steals
972		*/
973		public long getStealCount() {
974		return stealCount.get();
975		}
976
977		/**
978	<	* Accumulate steal count from a worker. Call only
979	<	* when worker known to be idle.
978	>	* Accumulates steal count from a worker.
979	>	* Call only when worker known to be idle.
980		*/
981		private void updateStealCount(ForkJoinWorkerThread w) {
982		int sc = w.getAndClearStealCount();
#	Line 867 | Line 985 | public class ForkJoinPool extends Abstra
985		}
986
987		/**
988	<	* Returns the total number of tasks currently held in queues by
989	<	* worker threads (but not including tasks submitted to the pool
990	<	* that have not begun executing). This value is only an
991	<	* approximation, obtained by iterating across all threads in the
992	<	* pool. This method may be useful for tuning task granularities.
993	<	* @return the number of queued tasks.
988	>	* Returns an estimate of the total number of tasks currently held
989	>	* in queues by worker threads (but not including tasks submitted
990	>	* to the pool that have not begun executing). This value is only
991	>	* an approximation, obtained by iterating across all threads in
992	>	* the pool. This method may be useful for tuning task
993	>	* granularities.
994	>	*
995	>	* @return the number of queued tasks
996		*/
997		public long getQueuedTaskCount() {
998		long count = 0;
999		ForkJoinWorkerThread[] ws = workers;
1000	<	for (int i = 0; i < ws.length; ++i) {
1001	<	ForkJoinWorkerThread t = ws[i];
1002	<	if (t != null)
1003	<	count += t.getQueueSize();
1000	>	if (ws != null) {
1001	>	for (int i = 0; i < ws.length; ++i) {
1002	>	ForkJoinWorkerThread t = ws[i];
1003	>	if (t != null)
1004	>	count += t.getQueueSize();
1005	>	}
1006		}
1007		return count;
1008		}
1009
1010		/**
1011	<	* Returns the approximate number tasks submitted to this pool
1011	>	* Returns an estimate of the number tasks submitted to this pool
1012		* that have not yet begun executing. This method takes time
1013		* proportional to the number of submissions.
1014	<	* @return the number of queued submissions.
1014	>	*
1015	>	* @return the number of queued submissions
1016		*/
1017		public int getQueuedSubmissionCount() {
1018		return submissionQueue.size();
1019		}
1020
1021		/**
1022	<	* Returns true if there are any tasks submitted to this pool
1023	<	* that have not yet begun executing.
1024	<	* @return <tt>true</tt> if there are any queued submissions.
1022	>	* Returns {@code true} if there are any tasks submitted to this
1023	>	* pool that have not yet begun executing.
1024	>	*
1025	>	* @return {@code true} if there are any queued submissions
1026		*/
1027		public boolean hasQueuedSubmissions() {
1028		return !submissionQueue.isEmpty();
#	Line 908 | Line 1032 | public class ForkJoinPool extends Abstra
1032		* Removes and returns the next unexecuted submission if one is
1033		* available.  This method may be useful in extensions to this
1034		* class that re-assign work in systems with multiple pools.
1035	<	* @return the next submission, or null if none
1035	>	*
1036	>	* @return the next submission, or {@code null} if none
1037		*/
1038		protected ForkJoinTask<?> pollSubmission() {
1039		return submissionQueue.poll();
1040		}
1041
1042		/**
1043	+	* Removes all available unexecuted submitted and forked tasks
1044	+	* from scheduling queues and adds them to the given collection,
1045	+	* without altering their execution status. These may include
1046	+	* artificially generated or wrapped tasks. This method is designed
1047	+	* to be invoked only when the pool is known to be
1048	+	* quiescent. Invocations at other times may not remove all
1049	+	* tasks. A failure encountered while attempting to add elements
1050	+	* to collection {@code c} may result in elements being in
1051	+	* neither, either or both collections when the associated
1052	+	* exception is thrown.  The behavior of this operation is
1053	+	* undefined if the specified collection is modified while the
1054	+	* operation is in progress.
1055	+	*
1056	+	* @param c the collection to transfer elements into
1057	+	* @return the number of elements transferred
1058	+	*/
1059	+	protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) {
1060	+	int n = submissionQueue.drainTo(c);
1061	+	ForkJoinWorkerThread[] ws = workers;
1062	+	if (ws != null) {
1063	+	for (int i = 0; i < ws.length; ++i) {
1064	+	ForkJoinWorkerThread w = ws[i];
1065	+	if (w != null)
1066	+	n += w.drainTasksTo(c);
1067	+	}
1068	+	}
1069	+	return n;
1070	+	}
1071	+
1072	+	/**
1073		* Returns a string identifying this pool, as well as its state,
1074		* including indications of run state, parallelism level, and
1075		* worker and task counts.
#	Line 958 | Line 1113 | public class ForkJoinPool extends Abstra
1113		* Invocation has no additional effect if already shut down.
1114		* Tasks that are in the process of being submitted concurrently
1115		* during the course of this method may or may not be rejected.
1116	+	*
1117		* @throws SecurityException if a security manager exists and
1118		*         the caller is not permitted to modify threads
1119		*         because it does not hold {@link
1120	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
1120	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1121		*/
1122		public void shutdown() {
1123		checkPermission();
1124		transitionRunStateTo(SHUTDOWN);
1125	<	if (canTerminateOnShutdown(runControl))
1125	>	if (canTerminateOnShutdown(runControl)) {
1126	>	if (workers == null) { // shutting down before workers created
1127	>	final ReentrantLock lock = this.workerLock;
1128	>	lock.lock();
1129	>	try {
1130	>	if (workers == null) {
1131	>	terminate();
1132	>	transitionRunStateTo(TERMINATED);
1133	>	termination.signalAll();
1134	>	}
1135	>	} finally {
1136	>	lock.unlock();
1137	>	}
1138	>	}
1139		terminateOnShutdown();
1140	+	}
1141		}
1142
1143		/**
#	Line 975 | Line 1145 | public class ForkJoinPool extends Abstra
1145		* waiting tasks.  Tasks that are in the process of being
1146		* submitted or executed concurrently during the course of this
1147		* method may or may not be rejected. Unlike some other executors,
1148	<	* this method cancels rather than collects non-executed tasks,
1149	<	* so always returns an empty list.
1148	>	* this method cancels rather than collects non-executed tasks
1149	>	* upon termination, so always returns an empty list. However, you
1150	>	* can use method {@link #drainTasksTo} before invoking this
1151	>	* method to transfer unexecuted tasks to another collection.
1152	>	*
1153		* @return an empty list
1154		* @throws SecurityException if a security manager exists and
1155		*         the caller is not permitted to modify threads
1156		*         because it does not hold {@link
1157	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
1157	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1158		*/
1159		public List<Runnable> shutdownNow() {
1160		checkPermission();
#	Line 990 | Line 1163 | public class ForkJoinPool extends Abstra
1163		}
1164
1165		/**
1166	<	* Returns <tt>true</tt> if all tasks have completed following shut down.
1166	>	* Returns {@code true} if all tasks have completed following shut down.
1167		*
1168	<	* @return <tt>true</tt> if all tasks have completed following shut down
1168	>	* @return {@code true} if all tasks have completed following shut down
1169		*/
1170		public boolean isTerminated() {
1171		return runStateOf(runControl) == TERMINATED;
1172		}
1173
1174		/**
1175	<	* Returns <tt>true</tt> if the process of termination has
1175	>	* Returns {@code true} if the process of termination has
1176		* commenced but possibly not yet completed.
1177		*
1178	<	* @return <tt>true</tt> if terminating
1178	>	* @return {@code true} if terminating
1179		*/
1180		public boolean isTerminating() {
1181		return runStateOf(runControl) >= TERMINATING;
1182		}
1183
1184		/**
1185	<	* Returns <tt>true</tt> if this pool has been shut down.
1185	>	* Returns {@code true} if this pool has been shut down.
1186		*
1187	<	* @return <tt>true</tt> if this pool has been shut down
1187	>	* @return {@code true} if this pool has been shut down
1188		*/
1189		public boolean isShutdown() {
1190		return runStateOf(runControl) >= SHUTDOWN;
#	Line 1024 | Line 1197 | public class ForkJoinPool extends Abstra
1197		*
1198		* @param timeout the maximum time to wait
1199		* @param unit the time unit of the timeout argument
1200	<	* @return <tt>true</tt> if this executor terminated and
1201	<	*         <tt>false</tt> if the timeout elapsed before termination
1200	>	* @return {@code true} if this executor terminated and
1201	>	*         {@code false} if the timeout elapsed before termination
1202		* @throws InterruptedException if interrupted while waiting
1203		*/
1204		public boolean awaitTermination(long timeout, TimeUnit unit)
#	Line 1049 | Line 1222 | public class ForkJoinPool extends Abstra
1222		// Shutdown and termination support
1223
1224		/**
1225	<	* Callback from terminating worker. Null out the corresponding
1226	<	* workers slot, and if terminating, try to terminate, else try to
1227	<	* shrink workers array.
1225	>	* Callback from terminating worker. Nulls out the corresponding
1226	>	* workers slot, and if terminating, tries to terminate; else
1227	>	* tries to shrink workers array.
1228	>	*
1229		* @param w the worker
1230		*/
1231		final void workerTerminated(ForkJoinWorkerThread w) {
#	Line 1061 | Line 1235 | public class ForkJoinPool extends Abstra
1235		lock.lock();
1236		try {
1237		ForkJoinWorkerThread[] ws = workers;
1238	<	int idx = w.poolIndex;
1239	<	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1240	<	ws[idx] = null;
1241	<	if (totalCountOf(workerCounts) == 0) {
1242	<	terminate(); // no-op if already terminating
1243	<	transitionRunStateTo(TERMINATED);
1244	<	termination.signalAll();
1245	<	}
1246	<	else if (!isTerminating()) {
1247	<	tryShrinkWorkerArray();
1248	<	tryResumeSpare(true); // allow replacement
1238	>	if (ws != null) {
1239	>	int idx = w.poolIndex;
1240	>	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1241	>	ws[idx] = null;
1242	>	if (totalCountOf(workerCounts) == 0) {
1243	>	terminate(); // no-op if already terminating
1244	>	transitionRunStateTo(TERMINATED);
1245	>	termination.signalAll();
1246	>	}
1247	>	else if (!isTerminating()) {
1248	>	tryShrinkWorkerArray();
1249	>	tryResumeSpare(true); // allow replacement
1250	>	}
1251		}
1252		} finally {
1253		lock.unlock();
1254		}
1255	<	signalIdleWorkers(false);
1255	>	signalIdleWorkers();
1256		}
1257
1258		/**
1259	<	* Initiate termination.
1259	>	* Initiates termination.
1260		*/
1261		private void terminate() {
1262		if (transitionRunStateTo(TERMINATING)) {
1263		stopAllWorkers();
1264		resumeAllSpares();
1265	<	signalIdleWorkers(true);
1265	>	signalIdleWorkers();
1266		cancelQueuedSubmissions();
1267		cancelQueuedWorkerTasks();
1268		interruptUnterminatedWorkers();
1269	<	signalIdleWorkers(true); // resignal after interrupt
1269	>	signalIdleWorkers(); // resignal after interrupt
1270		}
1271		}
1272
1273		/**
1274	<	* Possibly terminate when on shutdown state
1274	>	* Possibly terminates when on shutdown state.
1275		*/
1276		private void terminateOnShutdown() {
1277		if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
#	Line 1103 | Line 1279 | public class ForkJoinPool extends Abstra
1279		}
1280
1281		/**
1282	<	* Clear out and cancel submissions
1282	>	* Clears out and cancels submissions.
1283		*/
1284		private void cancelQueuedSubmissions() {
1285		ForkJoinTask<?> task;
#	Line 1112 | Line 1288 | public class ForkJoinPool extends Abstra
1288		}
1289
1290		/**
1291	<	* Clean out worker queues.
1291	>	* Cleans out worker queues.
1292		*/
1293		private void cancelQueuedWorkerTasks() {
1294		final ReentrantLock lock = this.workerLock;
1295		lock.lock();
1296		try {
1297		ForkJoinWorkerThread[] ws = workers;
1298	<	for (int i = 0; i < ws.length; ++i) {
1299	<	ForkJoinWorkerThread t = ws[i];
1300	<	if (t != null)
1301	<	t.cancelTasks();
1298	>	if (ws != null) {
1299	>	for (int i = 0; i < ws.length; ++i) {
1300	>	ForkJoinWorkerThread t = ws[i];
1301	>	if (t != null)
1302	>	t.cancelTasks();
1303	>	}
1304		}
1305		} finally {
1306		lock.unlock();
#	Line 1130 | Line 1308 | public class ForkJoinPool extends Abstra
1308		}
1309
1310		/**
1311	<	* Set each worker's status to terminating. Requires lock to avoid
1312	<	* conflicts with add/remove
1311	>	* Sets each worker's status to terminating. Requires lock to avoid
1312	>	* conflicts with add/remove.
1313		*/
1314		private void stopAllWorkers() {
1315		final ReentrantLock lock = this.workerLock;
1316		lock.lock();
1317		try {
1318		ForkJoinWorkerThread[] ws = workers;
1319	<	for (int i = 0; i < ws.length; ++i) {
1320	<	ForkJoinWorkerThread t = ws[i];
1321	<	if (t != null)
1322	<	t.shutdownNow();
1319	>	if (ws != null) {
1320	>	for (int i = 0; i < ws.length; ++i) {
1321	>	ForkJoinWorkerThread t = ws[i];
1322	>	if (t != null)
1323	>	t.shutdownNow();
1324	>	}
1325		}
1326		} finally {
1327		lock.unlock();
#	Line 1149 | Line 1329 | public class ForkJoinPool extends Abstra
1329		}
1330
1331		/**
1332	<	* Interrupt all unterminated workers.  This is not required for
1332	>	* Interrupts all unterminated workers.  This is not required for
1333		* sake of internal control, but may help unstick user code during
1334		* shutdown.
1335		*/
#	Line 1158 | Line 1338 | public class ForkJoinPool extends Abstra
1338		lock.lock();
1339		try {
1340		ForkJoinWorkerThread[] ws = workers;
1341	<	for (int i = 0; i < ws.length; ++i) {
1342	<	ForkJoinWorkerThread t = ws[i];
1343	<	if (t != null && !t.isTerminated()) {
1344	<	try {
1345	<	t.interrupt();
1346	<	} catch (SecurityException ignore) {
1341	>	if (ws != null) {
1342	>	for (int i = 0; i < ws.length; ++i) {
1343	>	ForkJoinWorkerThread t = ws[i];
1344	>	if (t != null && !t.isTerminated()) {
1345	>	try {
1346	>	t.interrupt();
1347	>	} catch (SecurityException ignore) {
1348	>	}
1349		}
1350		}
1351		}
#	Line 1174 | Line 1356 | public class ForkJoinPool extends Abstra
1356
1357
1358		/*
1359	<	* Nodes for event barrier to manage idle threads.
1359	>	* Nodes for event barrier to manage idle threads.  Queue nodes
1360	>	* are basic Treiber stack nodes, also used for spare stack.
1361		*
1362		* The event barrier has an event count and a wait queue (actually
1363		* a Treiber stack).  Workers are enabled to look for work when
1364	<	* the eventCount is incremented. If they fail to find some,
1365	<	* they may wait for next count. Synchronization events occur only
1366	<	* in enough contexts to maintain overall liveness:
1364	>	* the eventCount is incremented. If they fail to find work, they
1365	>	* may wait for next count. Upon release, threads help others wake
1366	>	* up.
1367	>	*
1368	>	* Synchronization events occur only in enough contexts to
1369	>	* maintain overall liveness:
1370		*
1371		*   - Submission of a new task to the pool
1372	<	*   - Creation or termination of a worker
1372	>	*   - Resizes or other changes to the workers array
1373		*   - pool termination
1374		*   - A worker pushing a task on an empty queue
1375		*
1376	<	* The last case (pushing a task) occurs often enough, and is
1377	<	* heavy enough compared to simple stack pushes to require some
1378	<	* special handling: Method signalNonEmptyWorkerQueue returns
1379	<	* without advancing count if the queue appears to be empty.  This
1380	<	* would ordinarily result in races causing some queued waiters
1381	<	* not to be woken up. To avoid this, a worker in sync
1382	<	* rescans for tasks after being enqueued if it was the first to
1383	<	* enqueue, and aborts the wait if finding one, also helping to
1384	<	* signal others. This works well because the worker has nothing
1385	<	* better to do anyway, and so might as well help alleviate the
1386	<	* overhead and contention on the threads actually doing work.
1387	<	*
1388	<	* Queue nodes are basic Treiber stack nodes, also used for spare
1389	<	* stack.
1376	>	* The case of pushing a task occurs often enough, and is heavy
1377	>	* enough compared to simple stack pushes, to require special
1378	>	* handling: Method signalWork returns without advancing count if
1379	>	* the queue appears to be empty.  This would ordinarily result in
1380	>	* races causing some queued waiters not to be woken up. To avoid
1381	>	* this, the first worker enqueued in method sync (see
1382	>	* syncIsReleasable) rescans for tasks after being enqueued, and
1383	>	* helps signal if any are found. This works well because the
1384	>	* worker has nothing better to do, and so might as well help
1385	>	* alleviate the overhead and contention on the threads actually
1386	>	* doing work.  Also, since event counts increments on task
1387	>	* availability exist to maintain liveness (rather than to force
1388	>	* refreshes etc), it is OK for callers to exit early if
1389	>	* contending with another signaller.
1390		*/
1391		static final class WaitQueueNode {
1392		WaitQueueNode next; // only written before enqueued
1393		volatile ForkJoinWorkerThread thread; // nulled to cancel wait
1394		final long count; // unused for spare stack
1395	<	WaitQueueNode(ForkJoinWorkerThread w, long c) {
1395	>
1396	>	WaitQueueNode(long c, ForkJoinWorkerThread w) {
1397		count = c;
1398		thread = w;
1399		}
1400	<	final boolean signal() {
1400	>
1401	>	/**
1402	>	* Wakes up waiter, returning false if known to already
1403	>	*/
1404	>	boolean signal() {
1405		ForkJoinWorkerThread t = thread;
1406	+	if (t == null)
1407	+	return false;
1408		thread = null;
1409	<	if (t != null) {
1410	<	LockSupport.unpark(t);
1411	<	return true;
1409	>	LockSupport.unpark(t);
1410	>	return true;
1411	>	}
1412	>
1413	>	/**
1414	>	* Awaits release on sync.
1415	>	*/
1416	>	void awaitSyncRelease(ForkJoinPool p) {
1417	>	while (thread != null && !p.syncIsReleasable(this))
1418	>	LockSupport.park(this);
1419	>	}
1420	>
1421	>	/**
1422	>	* Awaits resumption as spare.
1423	>	*/
1424	>	void awaitSpareRelease() {
1425	>	while (thread != null) {
1426	>	if (!Thread.interrupted())
1427	>	LockSupport.park(this);
1428		}
1220	–	return false;
1429		}
1430		}
1431
1432		/**
1433	<	* Release at least one thread waiting for event count to advance,
1434	<	* if one exists. If initial attempt fails, release all threads.
1435	<	* @param all if false, at first try to only release one thread
1436	<	* @return current event
1433	>	* Ensures that no thread is waiting for count to advance from the
1434	>	* current value of eventCount read on entry to this method, by
1435	>	* releasing waiting threads if necessary.
1436	>	*
1437	>	* @return the count
1438		*/
1439	<	private long releaseIdleWorkers(boolean all) {
1440	<	long c;
1441	<	for (;;) {
1442	<	WaitQueueNode q = barrierStack;
1443	<	c = eventCount;
1235	<	long qc;
1236	<	if (q == null || (qc = q.count) >= c)
1237	<	break;
1238	<	if (!all) {
1239	<	if (casBarrierStack(q, q.next) && q.signal())
1240	<	break;
1241	<	all = true;
1242	<	}
1243	<	else if (casBarrierStack(q, null)) {
1439	>	final long ensureSync() {
1440	>	long c = eventCount;
1441	>	WaitQueueNode q;
1442	>	while ((q = syncStack) != null && q.count < c) {
1443	>	if (casBarrierStack(q, null)) {
1444		do {
1445	<	q.signal();
1445	>	q.signal();
1446		} while ((q = q.next) != null);
1447		break;
1448		}
#	Line 1251 | Line 1451 | public class ForkJoinPool extends Abstra
1451		}
1452
1453		/**
1454	<	* Returns current barrier event count
1255	<	* @return current barrier event count
1256	<	*/
1257	<	final long getEventCount() {
1258	<	long ec = eventCount;
1259	<	releaseIdleWorkers(true); // release to ensure accurate result
1260	<	return ec;
1261	<	}
1262	<
1263	<	/**
1264	<	* Increment event count and release at least one waiting thread,
1265	<	* if one exists (released threads will in turn wake up others).
1266	<	* @param all if true, try to wake up all
1454	>	* Increments event count and releases waiting threads.
1455		*/
1456	<	final void signalIdleWorkers(boolean all) {
1456	>	private void signalIdleWorkers() {
1457		long c;
1458	<	do;while (!casEventCount(c = eventCount, c+1));
1459	<	releaseIdleWorkers(all);
1458	>	do {} while (!casEventCount(c = eventCount, c+1));
1459	>	ensureSync();
1460		}
1461
1462		/**
1463	<	* Wake up threads waiting to steal a task. Because method
1464	<	* sync rechecks availability, it is OK to only proceed if
1465	<	* queue appears to be non-empty.
1463	>	* Signals threads waiting to poll a task. Because method sync
1464	>	* rechecks availability, it is OK to only proceed if queue
1465	>	* appears to be non-empty, and OK to skip under contention to
1466	>	* increment count (since some other thread succeeded).
1467		*/
1468	<	final void signalNonEmptyWorkerQueue() {
1280	<	// If CAS fails another signaller must have succeeded
1468	>	final void signalWork() {
1469		long c;
1470	<	if (barrierStack != null && casEventCount(c = eventCount, c+1))
1471	<	releaseIdleWorkers(false);
1470	>	WaitQueueNode q;
1471	>	if (syncStack != null &&
1472	>	casEventCount(c = eventCount, c+1) &&
1473	>	(((q = syncStack) != null && q.count <= c) &&
1474	>	(!casBarrierStack(q, q.next) || !q.signal())))
1475	>	ensureSync();
1476		}
1477
1478		/**
1479	<	* Waits until event count advances from count, or some thread is
1480	<	* waiting on a previous count, or there is stealable work
1481	<	* available. Help wake up others on release.
1479	>	* Waits until event count advances from last value held by
1480	>	* caller, or if excess threads, caller is resumed as spare, or
1481	>	* caller or pool is terminating. Updates caller's event on exit.
1482	>	*
1483		* @param w the calling worker thread
1291	–	* @param prev previous value returned by sync (or 0)
1292	–	* @return current event count
1484		*/
1485	<	final long sync(ForkJoinWorkerThread w, long prev) {
1486	<	updateStealCount(w);
1485	>	final void sync(ForkJoinWorkerThread w) {
1486	>	updateStealCount(w); // Transfer w's count while it is idle
1487
1488	<	while (!w.isShutdown() && !isTerminating() &&
1489	<	(parallelism >= runningCountOf(workerCounts) ||
1299	<	!suspendIfSpare(w))) { // prefer suspend to waiting here
1488	>	while (!w.isShutdown() && !isTerminating() && !suspendIfSpare(w)) {
1489	>	long prev = w.lastEventCount;
1490		WaitQueueNode node = null;
1491	<	boolean queued = false;
1492	<	for (;;) {
1493	<	if (!queued) {
1494	<	if (eventCount != prev)
1495	<	break;
1496	<	WaitQueueNode h = barrierStack;
1497	<	if (h != null && h.count != prev)
1308	<	break; // release below and maybe retry
1309	<	if (node == null)
1310	<	node = new WaitQueueNode(w, prev);
1311	<	queued = casBarrierStack(node.next = h, node);
1312	<	}
1313	<	else if (Thread.interrupted() ||
1314	<	node.thread == null ||
1315	<	(node.next == null && w.prescan()) ||
1316	<	eventCount != prev) {
1317	<	node.thread = null;
1318	<	if (eventCount == prev) // help trigger
1319	<	casEventCount(prev, prev+1);
1491	>	WaitQueueNode h;
1492	>	while (eventCount == prev &&
1493	>	((h = syncStack) == null || h.count == prev)) {
1494	>	if (node == null)
1495	>	node = new WaitQueueNode(prev, w);
1496	>	if (casBarrierStack(node.next = h, node)) {
1497	>	node.awaitSyncRelease(this);
1498		break;
1499		}
1322	–	else
1323	–	LockSupport.park(this);
1500		}
1501	+	long ec = ensureSync();
1502	+	if (ec != prev) {
1503	+	w.lastEventCount = ec;
1504	+	break;
1505	+	}
1506	+	}
1507	+	}
1508	+
1509	+	/**
1510	+	* Returns {@code true} if worker waiting on sync can proceed:
1511	+	*  - on signal (thread == null)
1512	+	*  - on event count advance (winning race to notify vs signaller)
1513	+	*  - on interrupt
1514	+	*  - if the first queued node, we find work available
1515	+	* If node was not signalled and event count not advanced on exit,
1516	+	* then we also help advance event count.
1517	+	*
1518	+	* @return {@code true} if node can be released
1519	+	*/
1520	+	final boolean syncIsReleasable(WaitQueueNode node) {
1521	+	long prev = node.count;
1522	+	if (!Thread.interrupted() && node.thread != null &&
1523	+	(node.next != null ||
1524	+	!ForkJoinWorkerThread.hasQueuedTasks(workers)) &&
1525	+	eventCount == prev)
1526	+	return false;
1527	+	if (node.thread != null) {
1528	+	node.thread = null;
1529		long ec = eventCount;
1530	<	if (releaseIdleWorkers(false) != prev)
1531	<	return ec;
1530	>	if (prev <= ec) // help signal
1531	>	casEventCount(ec, ec+1);
1532		}
1533	<	return prev; // return old count if aborted
1533	>	return true;
1534	>	}
1535	>
1536	>	/**
1537	>	* Returns {@code true} if a new sync event occurred since last
1538	>	* call to sync or this method, if so, updating caller's count.
1539	>	*/
1540	>	final boolean hasNewSyncEvent(ForkJoinWorkerThread w) {
1541	>	long lc = w.lastEventCount;
1542	>	long ec = ensureSync();
1543	>	if (ec == lc)
1544	>	return false;
1545	>	w.lastEventCount = ec;
1546	>	return true;
1547		}
1548
1549		//  Parallelism maintenance
1550
1551		/**
1552	<	* Decrement running count; if too low, add spare.
1552	>	* Decrements running count; if too low, adds spare.
1553		*
1554		* Conceptually, all we need to do here is add or resume a
1555		* spare thread when one is about to block (and remove or
1556		* suspend it later when unblocked -- see suspendIfSpare).
1557		* However, implementing this idea requires coping with
1558	<	* several problems: We have imperfect information about the
1558	>	* several problems: we have imperfect information about the
1559		* states of threads. Some count updates can and usually do
1560		* lag run state changes, despite arrangements to keep them
1561		* accurate (for example, when possible, updating counts
#	Line 1352 | Line 1569 | public class ForkJoinPool extends Abstra
1569		* only be suspended or removed when they are idle, not
1570		* immediately when they aren't needed. So adding threads will
1571		* raise parallelism level for longer than necessary.  Also,
1572	<	* FJ applications often enounter highly transient peaks when
1572	>	* FJ applications often encounter highly transient peaks when
1573		* many threads are blocked joining, but for less time than it
1574		* takes to create or resume spares.
1575		*
#	Line 1361 | Line 1578 | public class ForkJoinPool extends Abstra
1578		* target counts, else create only to avoid starvation
1579		* @return true if joinMe known to be done
1580		*/
1581	<	final boolean preJoin(ForkJoinTask<?> joinMe, boolean maintainParallelism) {
1581	>	final boolean preJoin(ForkJoinTask<?> joinMe,
1582	>	boolean maintainParallelism) {
1583		maintainParallelism &= maintainsParallelism; // overrride
1584		boolean dec = false;  // true when running count decremented
1585		while (spareStack == null || !tryResumeSpare(dec)) {
1586		int counts = workerCounts;
1587	<	if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat
1587	>	if (dec || (dec = casWorkerCounts(counts, --counts))) {
1588	>	// CAS cheat
1589		if (!needSpare(counts, maintainParallelism))
1590		break;
1591		if (joinMe.status < 0)
#	Line 1381 | Line 1600 | public class ForkJoinPool extends Abstra
1600		/**
1601		* Same idea as preJoin
1602		*/
1603	<	final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){
1603	>	final boolean preBlock(ManagedBlocker blocker,
1604	>	boolean maintainParallelism) {
1605		maintainParallelism &= maintainsParallelism;
1606		boolean dec = false;
1607		while (spareStack == null || !tryResumeSpare(dec)) {
#	Line 1399 | Line 1619 | public class ForkJoinPool extends Abstra
1619		}
1620
1621		/**
1622	<	* Returns true if a spare thread appears to be needed.  If
1623	<	* maintaining parallelism, returns true when the deficit in
1622	>	* Returns {@code true} if a spare thread appears to be needed.
1623	>	* If maintaining parallelism, returns true when the deficit in
1624		* running threads is more than the surplus of total threads, and
1625		* there is apparently some work to do.  This self-limiting rule
1626		* means that the more threads that have already been added, the
1627		* less parallelism we will tolerate before adding another.
1628	+	*
1629		* @param counts current worker counts
1630		* @param maintainParallelism try to maintain parallelism
1631		*/
#	Line 1417 | Line 1638 | public class ForkJoinPool extends Abstra
1638		return (tc < maxPoolSize &&
1639		(rc == 0 || totalSurplus < 0 ||
1640		(maintainParallelism &&
1641	<	runningDeficit > totalSurplus && mayHaveQueuedWork())));
1641	>	runningDeficit > totalSurplus &&
1642	>	ForkJoinWorkerThread.hasQueuedTasks(workers))));
1643		}
1644
1645		/**
1646	<	* Returns true if at least one worker queue appears to be
1647	<	* nonempty. This is expensive but not often called. It is not
1648	<	* critical that this be accurate, but if not, more or fewer
1427	<	* running threads than desired might be maintained.
1428	<	*/
1429	<	private boolean mayHaveQueuedWork() {
1430	<	ForkJoinWorkerThread[] ws = workers;
1431	<	int len = ws.length;
1432	<	ForkJoinWorkerThread v;
1433	<	for (int i = 0; i < len; ++i) {
1434	<	if ((v = ws[i]) != null && v.getRawQueueSize() > 0) {
1435	<	releaseIdleWorkers(false); // help wake up stragglers
1436	<	return true;
1437	<	}
1438	<	}
1439	<	return false;
1440	<	}
1441	<
1442	<	/**
1443	<	* Add a spare worker if lock available and no more than the
1444	<	* expected numbers of threads exist
1646	>	* Adds a spare worker if lock available and no more than the
1647	>	* expected numbers of threads exist.
1648	>	*
1649		* @return true if successful
1650		*/
1651		private boolean tryAddSpare(int expectedCounts) {
#	Line 1474 | Line 1678 | public class ForkJoinPool extends Abstra
1678		}
1679
1680		/**
1681	<	* Add the kth spare worker. On entry, pool coounts are already
1681	>	* Adds the kth spare worker. On entry, pool counts are already
1682		* adjusted to reflect addition.
1683		*/
1684		private void createAndStartSpare(int k) {
#	Line 1486 | Line 1690 | public class ForkJoinPool extends Abstra
1690		for (k = 0; k < len && ws[k] != null; ++k)
1691		;
1692		}
1693	<	if (k < len && (w = createWorker(k)) != null) {
1693	>	if (k < len && !isTerminating() && (w = createWorker(k)) != null) {
1694		ws[k] = w;
1695		w.start();
1696		}
1697		else
1698		updateWorkerCount(-1); // adjust on failure
1699	<	signalIdleWorkers(false);
1699	>	signalIdleWorkers();
1700		}
1701
1702		/**
1703	<	* Suspend calling thread w if there are excess threads.  Called
1704	<	* only from sync.  Spares are enqueued in a Treiber stack
1705	<	* using the same WaitQueueNodes as barriers.  They are resumed
1706	<	* mainly in preJoin, but are also woken on pool events that
1707	<	* require all threads to check run state.
1703	>	* Suspends calling thread w if there are excess threads.  Called
1704	>	* only from sync.  Spares are enqueued in a Treiber stack using
1705	>	* the same WaitQueueNodes as barriers.  They are resumed mainly
1706	>	* in preJoin, but are also woken on pool events that require all
1707	>	* threads to check run state.
1708	>	*
1709		* @param w the caller
1710		*/
1711		private boolean suspendIfSpare(ForkJoinWorkerThread w) {
#	Line 1508 | Line 1713 | public class ForkJoinPool extends Abstra
1713		int s;
1714		while (parallelism < runningCountOf(s = workerCounts)) {
1715		if (node == null)
1716	<	node = new WaitQueueNode(w, 0);
1716	>	node = new WaitQueueNode(0, w);
1717		if (casWorkerCounts(s, s-1)) { // representation-dependent
1718		// push onto stack
1719	<	do;while (!casSpareStack(node.next = spareStack, node));
1515	<
1719	>	do {} while (!casSpareStack(node.next = spareStack, node));
1720		// block until released by resumeSpare
1721	<	while (node.thread != null) {
1518	<	if (!Thread.interrupted())
1519	<	LockSupport.park(this);
1520	<	}
1521	<	w.activate(); // help warm up
1721	>	node.awaitSpareRelease();
1722		return true;
1723		}
1724		}
#	Line 1526 | Line 1726 | public class ForkJoinPool extends Abstra
1726		}
1727
1728		/**
1729	<	* Try to pop and resume a spare thread.
1729	>	* Tries to pop and resume a spare thread.
1730	>	*
1731		* @param updateCount if true, increment running count on success
1732		* @return true if successful
1733		*/
#	Line 1544 | Line 1745 | public class ForkJoinPool extends Abstra
1745		}
1746
1747		/**
1748	<	* Pop and resume all spare threads. Same idea as
1749	<	* releaseIdleWorkers.
1748	>	* Pops and resumes all spare threads. Same idea as ensureSync.
1749	>	*
1750		* @return true if any spares released
1751		*/
1752		private boolean resumeAllSpares() {
#	Line 1563 | Line 1764 | public class ForkJoinPool extends Abstra
1764		}
1765
1766		/**
1767	<	* Pop and shutdown excessive spare threads. Call only while
1767	>	* Pops and shuts down excessive spare threads. Call only while
1768		* holding lock. This is not guaranteed to eliminate all excess
1769		* threads, only those suspended as spares, which are the ones
1770		* unlikely to be needed in the future.
#	Line 1586 | Line 1787 | public class ForkJoinPool extends Abstra
1787		}
1788
1789		/**
1589	–	* Returns approximate number of spares, just for diagnostics.
1590	–	*/
1591	–	private int countSpares() {
1592	–	int sum = 0;
1593	–	for (WaitQueueNode q = spareStack; q != null; q = q.next)
1594	–	++sum;
1595	–	return sum;
1596	–	}
1597	–
1598	–	/**
1790		* Interface for extending managed parallelism for tasks running
1791		* in ForkJoinPools. A ManagedBlocker provides two methods.
1792	<	* Method <tt>isReleasable</tt> must return true if blocking is not
1793	<	* necessary. Method <tt>block</tt> blocks the current thread
1794	<	* if necessary (perhaps internally invoking isReleasable before
1795	<	* actually blocking.).
1792	>	* Method {@code isReleasable} must return {@code true} if
1793	>	* blocking is not necessary. Method {@code block} blocks the
1794	>	* current thread if necessary (perhaps internally invoking
1795	>	* {@code isReleasable} before actually blocking.).
1796	>	*
1797		* <p>For example, here is a ManagedBlocker based on a
1798		* ReentrantLock:
1799	<	* <pre>
1800	<	*   class ManagedLocker implements ManagedBlocker {
1801	<	*     final ReentrantLock lock;
1802	<	*     boolean hasLock = false;
1803	<	*     ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1804	<	*     public boolean block() {
1805	<	*        if (!hasLock)
1806	<	*           lock.lock();
1807	<	*        return true;
1808	<	*     }
1809	<	*     public boolean isReleasable() {
1810	<	*        return hasLock || (hasLock = lock.tryLock());
1619	<	*     }
1799	>	*  <pre> {@code
1800	>	* class ManagedLocker implements ManagedBlocker {
1801	>	*   final ReentrantLock lock;
1802	>	*   boolean hasLock = false;
1803	>	*   ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1804	>	*   public boolean block() {
1805	>	*     if (!hasLock)
1806	>	*       lock.lock();
1807	>	*     return true;
1808	>	*   }
1809	>	*   public boolean isReleasable() {
1810	>	*     return hasLock || (hasLock = lock.tryLock());
1811		*   }
1812	<	* </pre>
1812	>	* }}</pre>
1813		*/
1814		public static interface ManagedBlocker {
1815		/**
1816		* Possibly blocks the current thread, for example waiting for
1817		* a lock or condition.
1818	<	* @return true if no additional blocking is necessary (i.e.,
1819	<	* if isReleasable would return true).
1818	>	*
1819	>	* @return {@code true} if no additional blocking is necessary
1820	>	* (i.e., if isReleasable would return true)
1821		* @throws InterruptedException if interrupted while waiting
1822	<	* (the method is not required to do so, but is allowe to).
1822	>	* (the method is not required to do so, but is allowed to)
1823		*/
1824		boolean block() throws InterruptedException;
1825
1826		/**
1827	<	* Returns true if blocking is unnecessary.
1827	>	* Returns {@code true} if blocking is unnecessary.
1828		*/
1829		boolean isReleasable();
1830		}
#	Line 1642 | Line 1834 | public class ForkJoinPool extends Abstra
1834		* is a ForkJoinWorkerThread, this method possibly arranges for a
1835		* spare thread to be activated if necessary to ensure parallelism
1836		* while the current thread is blocked.  If
1837	<	* <tt>maintainParallelism</tt> is true and the pool supports it
1838	<	* (see <tt>getMaintainsParallelism</tt>), this method attempts to
1839	<	* maintain the pool's nominal parallelism. Otherwise if activates
1837	>	* {@code maintainParallelism} is {@code true} and the pool supports
1838	>	* it ({@link #getMaintainsParallelism}), this method attempts to
1839	>	* maintain the pool's nominal parallelism. Otherwise it activates
1840		* a thread only if necessary to avoid complete starvation. This
1841		* option may be preferable when blockages use timeouts, or are
1842		* almost always brief.
1843		*
1844		* <p> If the caller is not a ForkJoinTask, this method is behaviorally
1845		* equivalent to
1846	<	* <pre>
1847	<	*   while (!blocker.isReleasable())
1848	<	*      if (blocker.block())
1849	<	*         return;
1850	<	* </pre>
1846	>	*  <pre> {@code
1847	>	* while (!blocker.isReleasable())
1848	>	*   if (blocker.block())
1849	>	*     return;
1850	>	* }</pre>
1851		* If the caller is a ForkJoinTask, then the pool may first
1852		* be expanded to ensure parallelism, and later adjusted.
1853		*
1854		* @param blocker the blocker
1855	<	* @param maintainParallelism if true and supported by this pool,
1856	<	* attempt to maintain the pool's nominal parallelism; otherwise
1857	<	* activate a thread only if necessary to avoid complete
1858	<	* starvation.
1859	<	* @throws InterruptedException if blocker.block did so.
1855	>	* @param maintainParallelism if {@code true} and supported by
1856	>	* this pool, attempt to maintain the pool's nominal parallelism;
1857	>	* otherwise activate a thread only if necessary to avoid
1858	>	* complete starvation.
1859	>	* @throws InterruptedException if blocker.block did so
1860		*/
1861		public static void managedBlock(ManagedBlocker blocker,
1862		boolean maintainParallelism)
1863		throws InterruptedException {
1864		Thread t = Thread.currentThread();
1865	<	ForkJoinPool pool = (t instanceof ForkJoinWorkerThread?
1866	<	((ForkJoinWorkerThread)t).pool : null);
1865	>	ForkJoinPool pool = ((t instanceof ForkJoinWorkerThread) ?
1866	>	((ForkJoinWorkerThread) t).pool : null);
1867		if (!blocker.isReleasable()) {
1868		try {
1869		if (pool == null ||
#	Line 1686 | Line 1878 | public class ForkJoinPool extends Abstra
1878
1879		private static void awaitBlocker(ManagedBlocker blocker)
1880		throws InterruptedException {
1881	<	do;while (!blocker.isReleasable() && !blocker.block());
1881	>	do {} while (!blocker.isReleasable() && !blocker.block());
1882		}
1883
1884	+	// AbstractExecutorService overrides
1885
1886	<	// Temporary Unsafe mechanics for preliminary release
1887	<
1888	<	static final Unsafe _unsafe;
1696	<	static final long eventCountOffset;
1697	<	static final long workerCountsOffset;
1698	<	static final long runControlOffset;
1699	<	static final long barrierStackOffset;
1700	<	static final long spareStackOffset;
1886	>	protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
1887	>	return new AdaptedRunnable<T>(runnable, value);
1888	>	}
1889
1890	<	static {
1891	<	try {
1704	<	if (ForkJoinPool.class.getClassLoader() != null) {
1705	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1706	<	f.setAccessible(true);
1707	<	_unsafe = (Unsafe)f.get(null);
1708	<	}
1709	<	else
1710	<	_unsafe = Unsafe.getUnsafe();
1711	<	eventCountOffset = _unsafe.objectFieldOffset
1712	<	(ForkJoinPool.class.getDeclaredField("eventCount"));
1713	<	workerCountsOffset = _unsafe.objectFieldOffset
1714	<	(ForkJoinPool.class.getDeclaredField("workerCounts"));
1715	<	runControlOffset = _unsafe.objectFieldOffset
1716	<	(ForkJoinPool.class.getDeclaredField("runControl"));
1717	<	barrierStackOffset = _unsafe.objectFieldOffset
1718	<	(ForkJoinPool.class.getDeclaredField("barrierStack"));
1719	<	spareStackOffset = _unsafe.objectFieldOffset
1720	<	(ForkJoinPool.class.getDeclaredField("spareStack"));
1721	<	} catch (Exception e) {
1722	<	throw new RuntimeException("Could not initialize intrinsics", e);
1723	<	}
1890	>	protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
1891	>	return new AdaptedCallable<T>(callable);
1892		}
1893
1894	+	// Unsafe mechanics
1895	+
1896	+	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1897	+	private static final long eventCountOffset =
1898	+	objectFieldOffset("eventCount", ForkJoinPool.class);
1899	+	private static final long workerCountsOffset =
1900	+	objectFieldOffset("workerCounts", ForkJoinPool.class);
1901	+	private static final long runControlOffset =
1902	+	objectFieldOffset("runControl", ForkJoinPool.class);
1903	+	private static final long syncStackOffset =
1904	+	objectFieldOffset("syncStack",ForkJoinPool.class);
1905	+	private static final long spareStackOffset =
1906	+	objectFieldOffset("spareStack", ForkJoinPool.class);
1907	+
1908		private boolean casEventCount(long cmp, long val) {
1909	<	return _unsafe.compareAndSwapLong(this, eventCountOffset, cmp, val);
1909	>	return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
1910		}
1911		private boolean casWorkerCounts(int cmp, int val) {
1912	<	return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1912	>	return UNSAFE.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1913		}
1914		private boolean casRunControl(int cmp, int val) {
1915	<	return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val);
1915	>	return UNSAFE.compareAndSwapInt(this, runControlOffset, cmp, val);
1916		}
1917		private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) {
1918	<	return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val);
1918	>	return UNSAFE.compareAndSwapObject(this, spareStackOffset, cmp, val);
1919		}
1920		private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1921	<	return _unsafe.compareAndSwapObject(this, barrierStackOffset, cmp, val);
1921	>	return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val);
1922	>	}
1923	>
1924	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1925	>	try {
1926	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1927	>	} catch (NoSuchFieldException e) {
1928	>	// Convert Exception to corresponding Error
1929	>	NoSuchFieldError error = new NoSuchFieldError(field);
1930	>	error.initCause(e);
1931	>	throw error;
1932	>	}
1933	>	}
1934	>
1935	>	/**
1936	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1937	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1938	>	* into a jdk.
1939	>	*
1940	>	* @return a sun.misc.Unsafe
1941	>	*/
1942	>	private static sun.misc.Unsafe getUnsafe() {
1943	>	try {
1944	>	return sun.misc.Unsafe.getUnsafe();
1945	>	} catch (SecurityException se) {
1946	>	try {
1947	>	return java.security.AccessController.doPrivileged
1948	>	(new java.security
1949	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1950	>	public sun.misc.Unsafe run() throws Exception {
1951	>	java.lang.reflect.Field f = sun.misc
1952	>	.Unsafe.class.getDeclaredField("theUnsafe");
1953	>	f.setAccessible(true);
1954	>	return (sun.misc.Unsafe) f.get(null);
1955	>	}});
1956	>	} catch (java.security.PrivilegedActionException e) {
1957	>	throw new RuntimeException("Could not initialize intrinsics",
1958	>	e.getCause());
1959	>	}
1960	>	}
1961		}
1962		}

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