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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 1.20 by jsr166, Fri Jul 24 22:05:22 2009 UTC

#	Line 13 | Line 13 | import sun.misc.Unsafe;
13		import java.lang.reflect.*;
14
15		/**
16	<	* Host for a group of ForkJoinWorkerThreads.  A ForkJoinPool provides
17	<	* the entry point for tasks submitted from non-ForkJoinTasks, as well
18	<	* as management and monitoring operations.  Normally a single
19	<	* ForkJoinPool is used for a large number of submitted
20	<	* tasks. Otherwise, use would not usually outweigh the construction
21	<	* and bookkeeping overhead of creating a large set of threads.
16	>	* An {@link ExecutorService} for running {@link ForkJoinTask}s.  A
17	>	* ForkJoinPool provides the entry point for submissions from
18	>	* non-ForkJoinTasks, as well as management and monitoring operations.
19	>	* Normally a single ForkJoinPool is used for a large number of
20	>	* submitted tasks. Otherwise, use would not usually outweigh the
21	>	* construction and bookkeeping overhead of creating a large set of
22	>	* threads.
23		*
24	<	* <p>ForkJoinPools differ from other kinds of Executor mainly in that
25	<	* they provide <em>work-stealing</em>: all threads in the pool
24	>	* <p>ForkJoinPools differ from other kinds of Executors mainly in
25	>	* that they provide <em>work-stealing</em>: all threads in the pool
26		* attempt to find and execute subtasks created by other active tasks
27		* (eventually blocking if none exist). This makes them efficient when
28	<	* most tasks spawn other subtasks (as do most ForkJoinTasks) but
29	<	* possibly less so otherwise. It is however fine to combine execution
30	<	* of some plain Runnable- or Callable- based activities with that of
31	<	* ForkJoinTasks.
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. 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		*
36		* <p>A ForkJoinPool may be constructed with a given parallelism level
37		* (target pool size), which it attempts to maintain by dynamically
38	<	* adding, suspending, or resuming threads, even if some tasks have
39	<	* blocked waiting to join others. However, no such adjustments are
40	<	* performed in the face of blocked IO or other unmanaged
41	<	* synchronization. The nested ManagedBlocker interface enables
42	<	* extension of the kinds of synchronization accommodated.
43	<	*
44	<	* <p>The target parallelism level may also be set dynamically. You
45	<	* can limit the number of threads dynamically constructed using
46	<	* method <tt>setMaximumPoolSize</tt> and/or
43	<	* <tt>setMaintainParallelism</tt>.
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} interface enables extension of
42	>	* the kinds of synchronization accommodated.  The target parallelism
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	<	* <tt>getStealCount</tt>) 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	<	* <tt>toString</tt> returns indications of pool state in a convenient
53	<	* form for informal monitoring.
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 parallelism to 32767. Attempts to create pools with greater
57	<	* than the maximum result in IllegalArgumentExceptions.
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
57	<	implements ExecutorService {
63	>	public class ForkJoinPool extends AbstractExecutorService {
64
65		/*
66		* See the extended comments interspersed below for design,
#	Line 78 | 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		}
91
92		/**
93	<	* Default ForkJoinWorkerThreadFactory implementation, creates a
93	>	* Default ForkJoinWorkerThreadFactory implementation; creates a
94		* new ForkJoinWorkerThread.
95		*/
96	<	public static class  DefaultForkJoinWorkerThreadFactory
96	>	static class  DefaultForkJoinWorkerThreadFactory
97		implements ForkJoinWorkerThreadFactory {
98		public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
99		try {
#	Line 99 | Line 105 | public class ForkJoinPool extends Abstra
105		}
106
107		/**
108	<	* The default ForkJoinWorkerThreadFactory, used unless overridden
109	<	* in ForkJoinPool constructors.
108	>	* Creates a new ForkJoinWorkerThread. This factory is used unless
109	>	* overridden in ForkJoinPool constructors.
110		*/
111	<	private static final DefaultForkJoinWorkerThreadFactory
111	>	public static final ForkJoinWorkerThreadFactory
112		defaultForkJoinWorkerThreadFactory =
113		new DefaultForkJoinWorkerThreadFactory();
114
109	–
115		/**
116		* Permission required for callers of methods that may start or
117		* kill threads.
#	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 179 | Line 184 | public class ForkJoinPool extends Abstra
184		private final LinkedTransferQueue<ForkJoinTask<?>> submissionQueue;
185
186		/**
187	<	* Head of Treiber stack for barrier sync. See below for explanation
187	>	* Head of Treiber stack for barrier sync. See below for explanation.
188		*/
189	<	private volatile WaitQueueNode barrierStack;
189	>	private volatile WaitQueueNode syncStack;
190
191		/**
192		* The count for event barrier
#	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	>	*
236		* @param delta the number to add
237		*/
238		final void updateRunningCount(int delta) {
239		int s;
240	<	do;while (!casWorkerCounts(s = workerCounts, s + delta));
240	>	do {} while (!casWorkerCounts(s = workerCounts, s + delta));
241		}
242
243		/**
244	<	* Add delta (which may be negative) to both total and running
244	>	* Adds delta (which may be negative) to both total and running
245		* count.  This must be called upon creation and termination of
246		* worker threads.
247	+	*
248		* @param delta the number to add
249		*/
250		private void updateWorkerCount(int delta) {
251		int d = delta + (delta << 16); // add to both lo and hi parts
252		int s;
253	<	do;while (!casWorkerCounts(s = workerCounts, s + d));
253	>	do {} while (!casWorkerCounts(s = workerCounts, s + d));
254		}
255
256		/**
#	Line 264 | Line 276 | public class ForkJoinPool extends Abstra
276		private static int runControlFor(int r, int a)   { return (r << 16) + a; }
277
278		/**
279	<	* Increment active count. Called by workers before/during
280	<	* executing tasks.
279	>	* Tries incrementing active count; fails on contention.
280	>	* Called by workers before/during executing tasks.
281	>	*
282	>	* @return true on success
283		*/
284	<	final void incrementActiveCount() {
285	<	int c;
286	<	do;while (!casRunControl(c = runControl, c+1));
284	>	final boolean tryIncrementActiveCount() {
285	>	int c = runControl;
286	>	return casRunControl(c, c+1);
287		}
288
289		/**
290	<	* Decrement active count; possibly trigger termination.
290	>	* Tries decrementing active count; fails on contention.
291	>	* Possibly triggers termination on success.
292		* Called by workers when they can't find tasks.
293	+	*
294	+	* @return true on success
295		*/
296	<	final void decrementActiveCount() {
297	<	int c, nextc;
298	<	do;while (!casRunControl(c = runControl, nextc = c-1));
296	>	final boolean tryDecrementActiveCount() {
297	>	int c = runControl;
298	>	int nextc = c - 1;
299	>	if (!casRunControl(c, nextc))
300	>	return false;
301		if (canTerminateOnShutdown(nextc))
302		terminateOnShutdown();
303	+	return true;
304		}
305
306		/**
307	<	* Return true if argument represents zero active count and
307	>	* Returns true if argument represents zero active count and
308		* nonzero runstate, which is the triggering condition for
309		* terminating on shutdown.
310		*/
311		private static boolean canTerminateOnShutdown(int c) {
312	<	return ((c & -c) >>> 16) != 0; // i.e. least bit is nonzero runState bit
312	>	// i.e. least bit is nonzero runState bit
313	>	return ((c & -c) >>> 16) != 0;
314		}
315
316		/**
#	Line 315 | Line 336 | public class ForkJoinPool extends Abstra
336
337		/**
338		* Creates a ForkJoinPool with a pool size equal to the number of
339	<	* processors available on the system and using the default
340	<	* ForkJoinWorkerThreadFactory,
339	>	* processors available on the system, using the default
340	>	* ForkJoinWorkerThreadFactory.
341	>	*
342		* @throws SecurityException if a security manager exists and
343		*         the caller is not permitted to modify threads
344		*         because it does not hold {@link
345	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
345	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
346		*/
347		public ForkJoinPool() {
348		this(Runtime.getRuntime().availableProcessors(),
#	Line 328 | Line 350 | public class ForkJoinPool extends Abstra
350		}
351
352		/**
353	<	* Creates a ForkJoinPool with the indicated parellelism level
354	<	* threads, and using the default ForkJoinWorkerThreadFactory,
353	>	* Creates a ForkJoinPool with the indicated parallelism level
354	>	* threads and using the default ForkJoinWorkerThreadFactory.
355	>	*
356		* @param parallelism the number of worker threads
357		* @throws IllegalArgumentException if parallelism less than or
358		* equal to zero
359		* @throws SecurityException if a security manager exists and
360		*         the caller is not permitted to modify threads
361		*         because it does not hold {@link
362	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
362	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
363		*/
364		public ForkJoinPool(int parallelism) {
365		this(parallelism, defaultForkJoinWorkerThreadFactory);
366		}
367
368		/**
369	<	* Creates a ForkJoinPool with a pool size equal to the number of
369	>	* Creates a ForkJoinPool with parallelism equal to the number of
370		* processors available on the system and using the given
371	<	* ForkJoinWorkerThreadFactory,
371	>	* ForkJoinWorkerThreadFactory.
372	>	*
373		* @param factory the factory for creating new threads
374		* @throws NullPointerException if factory is null
375		* @throws SecurityException if a security manager exists and
376		*         the caller is not permitted to modify threads
377		*         because it does not hold {@link
378	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
378	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
379		*/
380		public ForkJoinPool(ForkJoinWorkerThreadFactory factory) {
381		this(Runtime.getRuntime().availableProcessors(), factory);
382		}
383
384		/**
385	<	* Creates a ForkJoinPool with the indicated target number of
362	<	* worker threads and the given factory.
385	>	* Creates a ForkJoinPool with the given parallelism and factory.
386		*
387		* @param parallelism the targeted number of worker threads
388		* @param factory the factory for creating new threads
389		* @throws IllegalArgumentException if parallelism less than or
390	<	* equal to zero, or greater than implementation limit.
390	>	* equal to zero, or greater than implementation limit
391		* @throws NullPointerException if factory is null
392		* @throws SecurityException if a security manager exists and
393		*         the caller is not permitted to modify threads
394		*         because it does not hold {@link
395	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
395	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
396		*/
397		public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) {
398		if (parallelism <= 0 || parallelism > MAX_THREADS)
#	Line 386 | Line 409 | public class ForkJoinPool extends Abstra
409		this.termination = workerLock.newCondition();
410		this.stealCount = new AtomicLong();
411		this.submissionQueue = new LinkedTransferQueue<ForkJoinTask<?>>();
412	<	createAndStartInitialWorkers(parallelism);
412	>	// worker array and workers are lazily constructed
413		}
414
415		/**
416	<	* Create new worker using factory.
416	>	* Creates a new worker thread using factory.
417	>	*
418		* @param index the index to assign worker
419		* @return new worker, or null of factory failed
420		*/
#	Line 400 | Line 424 | public class ForkJoinPool extends Abstra
424		if (w != null) {
425		w.poolIndex = index;
426		w.setDaemon(true);
427	+	w.setAsyncMode(locallyFifo);
428		w.setName("ForkJoinPool-" + poolNumber + "-worker-" + index);
429		if (h != null)
430		w.setUncaughtExceptionHandler(h);
#	Line 408 | Line 433 | public class ForkJoinPool extends Abstra
433		}
434
435		/**
436	<	* Return a good size for worker array given pool size.
436	>	* Returns a good size for worker array given pool size.
437		* Currently requires size to be a power of two.
438		*/
439	<	private static int arraySizeFor(int ps) {
440	<	return ps <= 1? 1 : (1 << (32 - Integer.numberOfLeadingZeros(ps-1)));
439	>	private static int arraySizeFor(int poolSize) {
440	>	return (poolSize <= 1) ? 1 :
441	>	(1 << (32 - Integer.numberOfLeadingZeros(poolSize-1)));
442		}
443
444		/**
445	<	* Create or resize array if necessary to hold newLength
445	>	* Creates or resizes array if necessary to hold newLength.
446	>	* Call only under exclusion.
447	>	*
448		* @return the array
449		*/
450		private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
#	Line 430 | Line 458 | public class ForkJoinPool extends Abstra
458		}
459
460		/**
461	<	* Try to shrink workers into smaller array after one or more terminate
461	>	* Tries to shrink workers into smaller array after one or more terminate.
462		*/
463		private void tryShrinkWorkerArray() {
464		ForkJoinWorkerThread[] ws = workers;
465	<	int len = ws.length;
466	<	int last = len - 1;
467	<	while (last >= 0 && ws[last] == null)
468	<	--last;
469	<	int newLength = arraySizeFor(last+1);
470	<	if (newLength < len)
471	<	workers = Arrays.copyOf(ws, newLength);
465	>	if (ws != null) {
466	>	int len = ws.length;
467	>	int last = len - 1;
468	>	while (last >= 0 && ws[last] == null)
469	>	--last;
470	>	int newLength = arraySizeFor(last+1);
471	>	if (newLength < len)
472	>	workers = Arrays.copyOf(ws, newLength);
473	>	}
474		}
475
476		/**
477	<	* 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.)
477	>	* Initializes workers if necessary.
478		*/
479	<	private void createAndStartInitialWorkers(int ps) {
480	<	final ReentrantLock lock = this.workerLock;
481	<	lock.lock();
482	<	try {
483	<	ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps);
484	<	for (int i = 0; i < ps; ++i) {
485	<	ForkJoinWorkerThread w = createWorker(i);
486	<	if (w != null) {
487	<	ws[i] = w;
488	<	w.start();
489	<	updateWorkerCount(1);
479	>	final void ensureWorkerInitialization() {
480	>	ForkJoinWorkerThread[] ws = workers;
481	>	if (ws == null) {
482	>	final ReentrantLock lock = this.workerLock;
483	>	lock.lock();
484	>	try {
485	>	ws = workers;
486	>	if (ws == null) {
487	>	int ps = parallelism;
488	>	ws = ensureWorkerArrayCapacity(ps);
489	>	for (int i = 0; i < ps; ++i) {
490	>	ForkJoinWorkerThread w = createWorker(i);
491	>	if (w != null) {
492	>	ws[i] = w;
493	>	w.start();
494	>	updateWorkerCount(1);
495	>	}
496	>	}
497		}
498	+	} finally {
499	+	lock.unlock();
500		}
464	–	} finally {
465	–	lock.unlock();
501		}
502		}
503
#	Line 500 | Line 535 | public class ForkJoinPool extends Abstra
535		}
536		}
537
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	–
538		// Execution methods
539
540		/**
#	Line 559 | Line 543 | public class ForkJoinPool extends Abstra
543		private <T> void doSubmit(ForkJoinTask<T> task) {
544		if (isShutdown())
545		throw new RejectedExecutionException();
546	+	if (workers == null)
547	+	ensureWorkerInitialization();
548		submissionQueue.offer(task);
549	<	signalIdleWorkers(true);
549	>	signalIdleWorkers();
550		}
551
552		/**
553	<	* Performs the given task; returning its result upon completion
553	>	* Performs the given task, returning its result upon completion.
554	>	*
555		* @param task the task
556		* @return the task's result
557		* @throws NullPointerException if task is null
#	Line 577 | Line 564 | public class ForkJoinPool extends Abstra
564
565		/**
566		* Arranges for (asynchronous) execution of the given task.
567	+	*
568		* @param task the task
569		* @throws NullPointerException if task is null
570		* @throws RejectedExecutionException if pool is shut down
#	Line 609 | Line 597 | public class ForkJoinPool extends Abstra
597		return job;
598		}
599
612	–	protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
613	–	return new AdaptedRunnable(runnable, value);
614	–	}
615	–
616	–	protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
617	–	return new AdaptedCallable(callable);
618	–	}
619	–
600		/**
601		* Adaptor for Runnables. This implements RunnableFuture
602	<	* to be compliant with AbstractExecutorService constraints
602	>	* to be compliant with AbstractExecutorService constraints.
603		*/
604		static final class AdaptedRunnable<T> extends ForkJoinTask<T>
605		implements RunnableFuture<T> {
#	Line 639 | Line 619 | public class ForkJoinPool extends Abstra
619		return true;
620		}
621		public void run() { invoke(); }
622	+	private static final long serialVersionUID = 5232453952276885070L;
623		}
624
625		/**
#	Line 667 | Line 648 | public class ForkJoinPool extends Abstra
648		}
649		}
650		public void run() { invoke(); }
651	+	private static final long serialVersionUID = 2838392045355241008L;
652		}
653
654		public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) {
655	<	ArrayList<ForkJoinTask<T>> ts =
655	>	ArrayList<ForkJoinTask<T>> forkJoinTasks =
656		new ArrayList<ForkJoinTask<T>>(tasks.size());
657	<	for (Callable<T> c : tasks)
658	<	ts.add(new AdaptedCallable<T>(c));
659	<	invoke(new InvokeAll<T>(ts));
660	<	return (List<Future<T>>)(List)ts;
657	>	for (Callable<T> task : tasks)
658	>	forkJoinTasks.add(new AdaptedCallable<T>(task));
659	>	invoke(new InvokeAll<T>(forkJoinTasks));
660	>
661	>	@SuppressWarnings({"unchecked", "rawtypes"})
662	>	List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks;
663	>	return futures;
664		}
665
666		static final class InvokeAll<T> extends RecursiveAction {
667		final ArrayList<ForkJoinTask<T>> tasks;
668		InvokeAll(ArrayList<ForkJoinTask<T>> tasks) { this.tasks = tasks; }
669		public void compute() {
670	<	try { invokeAll(tasks); } catch(Exception ignore) {}
670	>	try { invokeAll(tasks); }
671	>	catch (Exception ignore) {}
672		}
673	+	private static final long serialVersionUID = -7914297376763021607L;
674		}
675
676		// Configuration and status settings and queries
677
678		/**
679	<	* Returns the factory used for constructing new workers
679	>	* Returns the factory used for constructing new workers.
680		*
681		* @return the factory used for constructing new workers
682		*/
#	Line 698 | Line 685 | public class ForkJoinPool extends Abstra
685		}
686
687		/**
688	<	* Sets the target paralleism level of this pool.
688	>	* Returns the handler for internal worker threads that terminate
689	>	* due to unrecoverable errors encountered while executing tasks.
690	>	*
691	>	* @return the handler, or null if none
692	>	*/
693	>	public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
694	>	Thread.UncaughtExceptionHandler h;
695	>	final ReentrantLock lock = this.workerLock;
696	>	lock.lock();
697	>	try {
698	>	h = ueh;
699	>	} finally {
700	>	lock.unlock();
701	>	}
702	>	return h;
703	>	}
704	>
705	>	/**
706	>	* Sets the handler for internal worker threads that terminate due
707	>	* to unrecoverable errors encountered while executing tasks.
708	>	* Unless set, the current default or ThreadGroup handler is used
709	>	* as handler.
710	>	*
711	>	* @param h the new handler
712	>	* @return the old handler, or null if none
713	>	* @throws SecurityException if a security manager exists and
714	>	*         the caller is not permitted to modify threads
715	>	*         because it does not hold {@link
716	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
717	>	*/
718	>	public Thread.UncaughtExceptionHandler
719	>	setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
720	>	checkPermission();
721	>	Thread.UncaughtExceptionHandler old = null;
722	>	final ReentrantLock lock = this.workerLock;
723	>	lock.lock();
724	>	try {
725	>	old = ueh;
726	>	ueh = h;
727	>	ForkJoinWorkerThread[] ws = workers;
728	>	if (ws != null) {
729	>	for (int i = 0; i < ws.length; ++i) {
730	>	ForkJoinWorkerThread w = ws[i];
731	>	if (w != null)
732	>	w.setUncaughtExceptionHandler(h);
733	>	}
734	>	}
735	>	} finally {
736	>	lock.unlock();
737	>	}
738	>	return old;
739	>	}
740	>
741	>
742	>	/**
743	>	* Sets the target parallelism level of this pool.
744	>	*
745		* @param parallelism the target parallelism
746		* @throws IllegalArgumentException if parallelism less than or
747	<	* equal to zero or greater than maximum size bounds.
747	>	* equal to zero or greater than maximum size bounds
748		* @throws SecurityException if a security manager exists and
749		*         the caller is not permitted to modify threads
750		*         because it does not hold {@link
751	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
751	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
752		*/
753		public void setParallelism(int parallelism) {
754		checkPermission();
#	Line 725 | Line 768 | public class ForkJoinPool extends Abstra
768		} finally {
769		lock.unlock();
770		}
771	<	signalIdleWorkers(false);
771	>	signalIdleWorkers();
772		}
773
774		/**
775		* 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.
776		*
777		* @return the targeted number of worker threads in this pool
778		*/
#	Line 742 | Line 783 | public class ForkJoinPool extends Abstra
783		/**
784		* Returns the number of worker threads that have started but not
785		* yet terminated.  This result returned by this method may differ
786	<	* from <tt>getParallelism</tt> when threads are created to
786	>	* from {@code getParallelism} when threads are created to
787		* maintain parallelism when others are cooperatively blocked.
788		*
789		* @return the number of worker threads
#	Line 754 | Line 795 | public class ForkJoinPool extends Abstra
795		/**
796		* Returns the maximum number of threads allowed to exist in the
797		* pool, even if there are insufficient unblocked running threads.
798	+	*
799		* @return the maximum
800		*/
801		public int getMaximumPoolSize() {
#	Line 765 | Line 807 | public class ForkJoinPool extends Abstra
807		* pool, even if there are insufficient unblocked running threads.
808		* Setting this value has no effect on current pool size. It
809		* controls construction of new threads.
810	+	*
811		* @throws IllegalArgumentException if negative or greater then
812	<	* internal implementation limit.
812	>	* internal implementation limit
813		*/
814		public void setMaximumPoolSize(int newMax) {
815		if (newMax < 0 || newMax > MAX_THREADS)
#	Line 779 | Line 822 | public class ForkJoinPool extends Abstra
822		* Returns true if this pool dynamically maintains its target
823		* parallelism level. If false, new threads are added only to
824		* avoid possible starvation.
825	<	* This setting is by default true;
825	>	* This setting is by default true.
826	>	*
827		* @return true if maintains parallelism
828		*/
829		public boolean getMaintainsParallelism() {
#	Line 790 | Line 834 | public class ForkJoinPool extends Abstra
834		* Sets whether this pool dynamically maintains its target
835		* parallelism level. If false, new threads are added only to
836		* avoid possible starvation.
837	+	*
838		* @param enable true to maintains parallelism
839		*/
840		public void setMaintainsParallelism(boolean enable) {
#	Line 797 | Line 842 | public class ForkJoinPool extends Abstra
842		}
843
844		/**
845	<	* Returns the approximate number of worker threads that are not
846	<	* blocked waiting to join tasks or for other managed
845	>	* Establishes local first-in-first-out scheduling mode for forked
846	>	* tasks that are never joined. This mode may be more appropriate
847	>	* than default locally stack-based mode in applications in which
848	>	* worker threads only process asynchronous tasks.  This method is
849	>	* designed to be invoked only when pool is quiescent, and
850	>	* typically only before any tasks are submitted. The effects of
851	>	* invocations at other times may be unpredictable.
852	>	*
853	>	* @param async if true, use locally FIFO scheduling
854	>	* @return the previous mode
855	>	*/
856	>	public boolean setAsyncMode(boolean async) {
857	>	boolean oldMode = locallyFifo;
858	>	locallyFifo = async;
859	>	ForkJoinWorkerThread[] ws = workers;
860	>	if (ws != null) {
861	>	for (int i = 0; i < ws.length; ++i) {
862	>	ForkJoinWorkerThread t = ws[i];
863	>	if (t != null)
864	>	t.setAsyncMode(async);
865	>	}
866	>	}
867	>	return oldMode;
868	>	}
869	>
870	>	/**
871	>	* Returns true if this pool uses local first-in-first-out
872	>	* scheduling mode for forked tasks that are never joined.
873	>	*
874	>	* @return true if this pool uses async mode
875	>	*/
876	>	public boolean getAsyncMode() {
877	>	return locallyFifo;
878	>	}
879	>
880	>	/**
881	>	* Returns an estimate of the number of worker threads that are
882	>	* not blocked waiting to join tasks or for other managed
883		* synchronization.
884		*
885		* @return the number of worker threads
#	Line 808 | Line 889 | public class ForkJoinPool extends Abstra
889		}
890
891		/**
892	<	* Returns the approximate number of threads that are currently
892	>	* Returns an estimate of the number of threads that are currently
893		* stealing or executing tasks. This method may overestimate the
894		* number of active threads.
895	<	* @return the number of active threads.
895	>	*
896	>	* @return the number of active threads
897		*/
898		public int getActiveThreadCount() {
899		return activeCountOf(runControl);
900		}
901
902		/**
903	<	* Returns the approximate number of threads that are currently
903	>	* Returns an estimate of the number of threads that are currently
904		* idle waiting for tasks. This method may underestimate the
905		* number of idle threads.
906	<	* @return the number of idle threads.
906	>	*
907	>	* @return the number of idle threads
908		*/
909		final int getIdleThreadCount() {
910		int c = runningCountOf(workerCounts) - activeCountOf(runControl);
911	<	return (c <= 0)? 0 : c;
911	>	return (c <= 0) ? 0 : c;
912		}
913
914		/**
915		* Returns true if all worker threads are currently idle. An idle
916		* worker is one that cannot obtain a task to execute because none
917		* are available to steal from other threads, and there are no
918	<	* pending submissions to the pool. This method is conservative:
919	<	* It might not return true immediately upon idleness of all
918	>	* pending submissions to the pool. This method is conservative;
919	>	* it might not return true immediately upon idleness of all
920		* threads, but will eventually become true if threads remain
921		* inactive.
922	+	*
923		* @return true if all threads are currently idle
924		*/
925		public boolean isQuiescent() {
#	Line 847 | Line 931 | public class ForkJoinPool extends Abstra
931		* one thread's work queue by another. The reported value
932		* underestimates the actual total number of steals when the pool
933		* is not quiescent. This value may be useful for monitoring and
934	<	* tuning fork/join programs: In general, steal counts should be
934	>	* tuning fork/join programs: in general, steal counts should be
935		* high enough to keep threads busy, but low enough to avoid
936		* overhead and contention across threads.
937	<	* @return the number of steals.
937	>	*
938	>	* @return the number of steals
939		*/
940		public long getStealCount() {
941		return stealCount.get();
942		}
943
944		/**
945	<	* Accumulate steal count from a worker. Call only
946	<	* when worker known to be idle.
945	>	* Accumulates steal count from a worker.
946	>	* Call only when worker known to be idle.
947		*/
948		private void updateStealCount(ForkJoinWorkerThread w) {
949		int sc = w.getAndClearStealCount();
#	Line 867 | Line 952 | public class ForkJoinPool extends Abstra
952		}
953
954		/**
955	<	* Returns the total number of tasks currently held in queues by
956	<	* worker threads (but not including tasks submitted to the pool
957	<	* that have not begun executing). This value is only an
958	<	* approximation, obtained by iterating across all threads in the
959	<	* pool. This method may be useful for tuning task granularities.
960	<	* @return the number of queued tasks.
955	>	* Returns an estimate of the total number of tasks currently held
956	>	* in queues by worker threads (but not including tasks submitted
957	>	* to the pool that have not begun executing). This value is only
958	>	* an approximation, obtained by iterating across all threads in
959	>	* the pool. This method may be useful for tuning task
960	>	* granularities.
961	>	*
962	>	* @return the number of queued tasks
963		*/
964		public long getQueuedTaskCount() {
965		long count = 0;
966		ForkJoinWorkerThread[] ws = workers;
967	<	for (int i = 0; i < ws.length; ++i) {
968	<	ForkJoinWorkerThread t = ws[i];
969	<	if (t != null)
970	<	count += t.getQueueSize();
967	>	if (ws != null) {
968	>	for (int i = 0; i < ws.length; ++i) {
969	>	ForkJoinWorkerThread t = ws[i];
970	>	if (t != null)
971	>	count += t.getQueueSize();
972	>	}
973		}
974		return count;
975		}
976
977		/**
978	<	* Returns the approximate number tasks submitted to this pool
978	>	* Returns an estimate of the number tasks submitted to this pool
979		* that have not yet begun executing. This method takes time
980		* proportional to the number of submissions.
981	<	* @return the number of queued submissions.
981	>	*
982	>	* @return the number of queued submissions
983		*/
984		public int getQueuedSubmissionCount() {
985		return submissionQueue.size();
#	Line 898 | Line 988 | public class ForkJoinPool extends Abstra
988		/**
989		* Returns true if there are any tasks submitted to this pool
990		* that have not yet begun executing.
991	<	* @return <tt>true</tt> if there are any queued submissions.
991	>	*
992	>	* @return {@code true} if there are any queued submissions
993		*/
994		public boolean hasQueuedSubmissions() {
995		return !submissionQueue.isEmpty();
#	Line 908 | Line 999 | public class ForkJoinPool extends Abstra
999		* Removes and returns the next unexecuted submission if one is
1000		* available.  This method may be useful in extensions to this
1001		* class that re-assign work in systems with multiple pools.
1002	+	*
1003		* @return the next submission, or null if none
1004		*/
1005		protected ForkJoinTask<?> pollSubmission() {
#	Line 915 | Line 1007 | public class ForkJoinPool extends Abstra
1007		}
1008
1009		/**
1010	+	* Removes all available unexecuted submitted and forked tasks
1011	+	* from scheduling queues and adds them to the given collection,
1012	+	* without altering their execution status. These may include
1013	+	* artificially generated or wrapped tasks. This method is designed
1014	+	* to be invoked only when the pool is known to be
1015	+	* quiescent. Invocations at other times may not remove all
1016	+	* tasks. A failure encountered while attempting to add elements
1017	+	* to collection {@code c} may result in elements being in
1018	+	* neither, either or both collections when the associated
1019	+	* exception is thrown.  The behavior of this operation is
1020	+	* undefined if the specified collection is modified while the
1021	+	* operation is in progress.
1022	+	*
1023	+	* @param c the collection to transfer elements into
1024	+	* @return the number of elements transferred
1025	+	*/
1026	+	protected int drainTasksTo(Collection<ForkJoinTask<?>> c) {
1027	+	int n = submissionQueue.drainTo(c);
1028	+	ForkJoinWorkerThread[] ws = workers;
1029	+	if (ws != null) {
1030	+	for (int i = 0; i < ws.length; ++i) {
1031	+	ForkJoinWorkerThread w = ws[i];
1032	+	if (w != null)
1033	+	n += w.drainTasksTo(c);
1034	+	}
1035	+	}
1036	+	return n;
1037	+	}
1038	+
1039	+	/**
1040		* Returns a string identifying this pool, as well as its state,
1041		* including indications of run state, parallelism level, and
1042		* worker and task counts.
#	Line 958 | Line 1080 | public class ForkJoinPool extends Abstra
1080		* Invocation has no additional effect if already shut down.
1081		* Tasks that are in the process of being submitted concurrently
1082		* during the course of this method may or may not be rejected.
1083	+	*
1084		* @throws SecurityException if a security manager exists and
1085		*         the caller is not permitted to modify threads
1086		*         because it does not hold {@link
1087	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
1087	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1088		*/
1089		public void shutdown() {
1090		checkPermission();
#	Line 975 | Line 1098 | public class ForkJoinPool extends Abstra
1098		* waiting tasks.  Tasks that are in the process of being
1099		* submitted or executed concurrently during the course of this
1100		* method may or may not be rejected. Unlike some other executors,
1101	<	* this method cancels rather than collects non-executed tasks,
1102	<	* so always returns an empty list.
1101	>	* this method cancels rather than collects non-executed tasks
1102	>	* upon termination, so always returns an empty list. However, you
1103	>	* can use method {@code drainTasksTo} before invoking this
1104	>	* method to transfer unexecuted tasks to another collection.
1105	>	*
1106		* @return an empty list
1107		* @throws SecurityException if a security manager exists and
1108		*         the caller is not permitted to modify threads
1109		*         because it does not hold {@link
1110	<	*         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
1110	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1111		*/
1112		public List<Runnable> shutdownNow() {
1113		checkPermission();
#	Line 990 | Line 1116 | public class ForkJoinPool extends Abstra
1116		}
1117
1118		/**
1119	<	* Returns <tt>true</tt> if all tasks have completed following shut down.
1119	>	* Returns {@code true} if all tasks have completed following shut down.
1120		*
1121	<	* @return <tt>true</tt> if all tasks have completed following shut down
1121	>	* @return {@code true} if all tasks have completed following shut down
1122		*/
1123		public boolean isTerminated() {
1124		return runStateOf(runControl) == TERMINATED;
1125		}
1126
1127		/**
1128	<	* Returns <tt>true</tt> if the process of termination has
1128	>	* Returns {@code true} if the process of termination has
1129		* commenced but possibly not yet completed.
1130		*
1131	<	* @return <tt>true</tt> if terminating
1131	>	* @return {@code true} if terminating
1132		*/
1133		public boolean isTerminating() {
1134		return runStateOf(runControl) >= TERMINATING;
1135		}
1136
1137		/**
1138	<	* Returns <tt>true</tt> if this pool has been shut down.
1138	>	* Returns {@code true} if this pool has been shut down.
1139		*
1140	<	* @return <tt>true</tt> if this pool has been shut down
1140	>	* @return {@code true} if this pool has been shut down
1141		*/
1142		public boolean isShutdown() {
1143		return runStateOf(runControl) >= SHUTDOWN;
#	Line 1024 | Line 1150 | public class ForkJoinPool extends Abstra
1150		*
1151		* @param timeout the maximum time to wait
1152		* @param unit the time unit of the timeout argument
1153	<	* @return <tt>true</tt> if this executor terminated and
1154	<	*         <tt>false</tt> if the timeout elapsed before termination
1153	>	* @return {@code true} if this executor terminated and
1154	>	*         {@code false} if the timeout elapsed before termination
1155		* @throws InterruptedException if interrupted while waiting
1156		*/
1157		public boolean awaitTermination(long timeout, TimeUnit unit)
#	Line 1049 | Line 1175 | public class ForkJoinPool extends Abstra
1175		// Shutdown and termination support
1176
1177		/**
1178	<	* Callback from terminating worker. Null out the corresponding
1179	<	* workers slot, and if terminating, try to terminate, else try to
1180	<	* shrink workers array.
1178	>	* Callback from terminating worker. Nulls out the corresponding
1179	>	* workers slot, and if terminating, tries to terminate; else
1180	>	* tries to shrink workers array.
1181	>	*
1182		* @param w the worker
1183		*/
1184		final void workerTerminated(ForkJoinWorkerThread w) {
#	Line 1061 | Line 1188 | public class ForkJoinPool extends Abstra
1188		lock.lock();
1189		try {
1190		ForkJoinWorkerThread[] ws = workers;
1191	<	int idx = w.poolIndex;
1192	<	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1193	<	ws[idx] = null;
1194	<	if (totalCountOf(workerCounts) == 0) {
1195	<	terminate(); // no-op if already terminating
1196	<	transitionRunStateTo(TERMINATED);
1197	<	termination.signalAll();
1198	<	}
1199	<	else if (!isTerminating()) {
1200	<	tryShrinkWorkerArray();
1201	<	tryResumeSpare(true); // allow replacement
1191	>	if (ws != null) {
1192	>	int idx = w.poolIndex;
1193	>	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1194	>	ws[idx] = null;
1195	>	if (totalCountOf(workerCounts) == 0) {
1196	>	terminate(); // no-op if already terminating
1197	>	transitionRunStateTo(TERMINATED);
1198	>	termination.signalAll();
1199	>	}
1200	>	else if (!isTerminating()) {
1201	>	tryShrinkWorkerArray();
1202	>	tryResumeSpare(true); // allow replacement
1203	>	}
1204		}
1205		} finally {
1206		lock.unlock();
1207		}
1208	<	signalIdleWorkers(false);
1208	>	signalIdleWorkers();
1209		}
1210
1211		/**
1212	<	* Initiate termination.
1212	>	* Initiates termination.
1213		*/
1214		private void terminate() {
1215		if (transitionRunStateTo(TERMINATING)) {
1216		stopAllWorkers();
1217		resumeAllSpares();
1218	<	signalIdleWorkers(true);
1218	>	signalIdleWorkers();
1219		cancelQueuedSubmissions();
1220		cancelQueuedWorkerTasks();
1221		interruptUnterminatedWorkers();
1222	<	signalIdleWorkers(true); // resignal after interrupt
1222	>	signalIdleWorkers(); // resignal after interrupt
1223		}
1224		}
1225
1226		/**
1227	<	* Possibly terminate when on shutdown state
1227	>	* Possibly terminates when on shutdown state.
1228		*/
1229		private void terminateOnShutdown() {
1230		if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
#	Line 1103 | Line 1232 | public class ForkJoinPool extends Abstra
1232		}
1233
1234		/**
1235	<	* Clear out and cancel submissions
1235	>	* Clears out and cancels submissions.
1236		*/
1237		private void cancelQueuedSubmissions() {
1238		ForkJoinTask<?> task;
#	Line 1112 | Line 1241 | public class ForkJoinPool extends Abstra
1241		}
1242
1243		/**
1244	<	* Clean out worker queues.
1244	>	* Cleans out worker queues.
1245		*/
1246		private void cancelQueuedWorkerTasks() {
1247		final ReentrantLock lock = this.workerLock;
1248		lock.lock();
1249		try {
1250		ForkJoinWorkerThread[] ws = workers;
1251	<	for (int i = 0; i < ws.length; ++i) {
1252	<	ForkJoinWorkerThread t = ws[i];
1253	<	if (t != null)
1254	<	t.cancelTasks();
1251	>	if (ws != null) {
1252	>	for (int i = 0; i < ws.length; ++i) {
1253	>	ForkJoinWorkerThread t = ws[i];
1254	>	if (t != null)
1255	>	t.cancelTasks();
1256	>	}
1257		}
1258		} finally {
1259		lock.unlock();
#	Line 1130 | Line 1261 | public class ForkJoinPool extends Abstra
1261		}
1262
1263		/**
1264	<	* Set each worker's status to terminating. Requires lock to avoid
1265	<	* conflicts with add/remove
1264	>	* Sets each worker's status to terminating. Requires lock to avoid
1265	>	* conflicts with add/remove.
1266		*/
1267		private void stopAllWorkers() {
1268		final ReentrantLock lock = this.workerLock;
1269		lock.lock();
1270		try {
1271		ForkJoinWorkerThread[] ws = workers;
1272	<	for (int i = 0; i < ws.length; ++i) {
1273	<	ForkJoinWorkerThread t = ws[i];
1274	<	if (t != null)
1275	<	t.shutdownNow();
1272	>	if (ws != null) {
1273	>	for (int i = 0; i < ws.length; ++i) {
1274	>	ForkJoinWorkerThread t = ws[i];
1275	>	if (t != null)
1276	>	t.shutdownNow();
1277	>	}
1278		}
1279		} finally {
1280		lock.unlock();
#	Line 1149 | Line 1282 | public class ForkJoinPool extends Abstra
1282		}
1283
1284		/**
1285	<	* Interrupt all unterminated workers.  This is not required for
1285	>	* Interrupts all unterminated workers.  This is not required for
1286		* sake of internal control, but may help unstick user code during
1287		* shutdown.
1288		*/
#	Line 1158 | Line 1291 | public class ForkJoinPool extends Abstra
1291		lock.lock();
1292		try {
1293		ForkJoinWorkerThread[] ws = workers;
1294	<	for (int i = 0; i < ws.length; ++i) {
1295	<	ForkJoinWorkerThread t = ws[i];
1296	<	if (t != null && !t.isTerminated()) {
1297	<	try {
1298	<	t.interrupt();
1299	<	} catch (SecurityException ignore) {
1294	>	if (ws != null) {
1295	>	for (int i = 0; i < ws.length; ++i) {
1296	>	ForkJoinWorkerThread t = ws[i];
1297	>	if (t != null && !t.isTerminated()) {
1298	>	try {
1299	>	t.interrupt();
1300	>	} catch (SecurityException ignore) {
1301	>	}
1302		}
1303		}
1304		}
#	Line 1174 | Line 1309 | public class ForkJoinPool extends Abstra
1309
1310
1311		/*
1312	<	* Nodes for event barrier to manage idle threads.
1312	>	* Nodes for event barrier to manage idle threads.  Queue nodes
1313	>	* are basic Treiber stack nodes, also used for spare stack.
1314		*
1315		* The event barrier has an event count and a wait queue (actually
1316		* a Treiber stack).  Workers are enabled to look for work when
1317	<	* the eventCount is incremented. If they fail to find some,
1318	<	* they may wait for next count. Synchronization events occur only
1319	<	* in enough contexts to maintain overall liveness:
1317	>	* the eventCount is incremented. If they fail to find work, they
1318	>	* may wait for next count. Upon release, threads help others wake
1319	>	* up.
1320	>	*
1321	>	* Synchronization events occur only in enough contexts to
1322	>	* maintain overall liveness:
1323		*
1324		*   - Submission of a new task to the pool
1325	<	*   - Creation or termination of a worker
1325	>	*   - Resizes or other changes to the workers array
1326		*   - pool termination
1327		*   - A worker pushing a task on an empty queue
1328		*
1329	<	* The last case (pushing a task) occurs often enough, and is
1330	<	* heavy enough compared to simple stack pushes to require some
1331	<	* special handling: Method signalNonEmptyWorkerQueue returns
1332	<	* without advancing count if the queue appears to be empty.  This
1333	<	* would ordinarily result in races causing some queued waiters
1334	<	* not to be woken up. To avoid this, a worker in sync
1335	<	* rescans for tasks after being enqueued if it was the first to
1336	<	* enqueue, and aborts the wait if finding one, also helping to
1337	<	* signal others. This works well because the worker has nothing
1338	<	* better to do anyway, and so might as well help alleviate the
1339	<	* overhead and contention on the threads actually doing work.
1340	<	*
1341	<	* Queue nodes are basic Treiber stack nodes, also used for spare
1342	<	* stack.
1329	>	* The case of pushing a task occurs often enough, and is heavy
1330	>	* enough compared to simple stack pushes, to require special
1331	>	* handling: Method signalWork returns without advancing count if
1332	>	* the queue appears to be empty.  This would ordinarily result in
1333	>	* races causing some queued waiters not to be woken up. To avoid
1334	>	* this, the first worker enqueued in method sync (see
1335	>	* syncIsReleasable) rescans for tasks after being enqueued, and
1336	>	* helps signal if any are found. This works well because the
1337	>	* worker has nothing better to do, and so might as well help
1338	>	* alleviate the overhead and contention on the threads actually
1339	>	* doing work.  Also, since event counts increments on task
1340	>	* availability exist to maintain liveness (rather than to force
1341	>	* refreshes etc), it is OK for callers to exit early if
1342	>	* contending with another signaller.
1343		*/
1344		static final class WaitQueueNode {
1345		WaitQueueNode next; // only written before enqueued
1346		volatile ForkJoinWorkerThread thread; // nulled to cancel wait
1347		final long count; // unused for spare stack
1348	<	WaitQueueNode(ForkJoinWorkerThread w, long c) {
1348	>
1349	>	WaitQueueNode(long c, ForkJoinWorkerThread w) {
1350		count = c;
1351		thread = w;
1352		}
1353	<	final boolean signal() {
1353	>
1354	>	/**
1355	>	* Wakes up waiter, returning false if known to already
1356	>	*/
1357	>	boolean signal() {
1358		ForkJoinWorkerThread t = thread;
1359	+	if (t == null)
1360	+	return false;
1361		thread = null;
1362	<	if (t != null) {
1363	<	LockSupport.unpark(t);
1364	<	return true;
1362	>	LockSupport.unpark(t);
1363	>	return true;
1364	>	}
1365	>
1366	>	/**
1367	>	* Awaits release on sync.
1368	>	*/
1369	>	void awaitSyncRelease(ForkJoinPool p) {
1370	>	while (thread != null && !p.syncIsReleasable(this))
1371	>	LockSupport.park(this);
1372	>	}
1373	>
1374	>	/**
1375	>	* Awaits resumption as spare.
1376	>	*/
1377	>	void awaitSpareRelease() {
1378	>	while (thread != null) {
1379	>	if (!Thread.interrupted())
1380	>	LockSupport.park(this);
1381		}
1220	–	return false;
1382		}
1383		}
1384
1385		/**
1386	<	* Release at least one thread waiting for event count to advance,
1387	<	* if one exists. If initial attempt fails, release all threads.
1388	<	* @param all if false, at first try to only release one thread
1389	<	* @return current event
1386	>	* Ensures that no thread is waiting for count to advance from the
1387	>	* current value of eventCount read on entry to this method, by
1388	>	* releasing waiting threads if necessary.
1389	>	*
1390	>	* @return the count
1391		*/
1392	<	private long releaseIdleWorkers(boolean all) {
1393	<	long c;
1394	<	for (;;) {
1395	<	WaitQueueNode q = barrierStack;
1396	<	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)) {
1392	>	final long ensureSync() {
1393	>	long c = eventCount;
1394	>	WaitQueueNode q;
1395	>	while ((q = syncStack) != null && q.count < c) {
1396	>	if (casBarrierStack(q, null)) {
1397		do {
1398	<	q.signal();
1398	>	q.signal();
1399		} while ((q = q.next) != null);
1400		break;
1401		}
#	Line 1251 | Line 1404 | public class ForkJoinPool extends Abstra
1404		}
1405
1406		/**
1407	<	* 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
1407	>	* Increments event count and releases waiting threads.
1408		*/
1409	<	final void signalIdleWorkers(boolean all) {
1409	>	private void signalIdleWorkers() {
1410		long c;
1411	<	do;while (!casEventCount(c = eventCount, c+1));
1412	<	releaseIdleWorkers(all);
1411	>	do {} while (!casEventCount(c = eventCount, c+1));
1412	>	ensureSync();
1413		}
1414
1415		/**
1416	<	* Wake up threads waiting to steal a task. Because method
1417	<	* sync rechecks availability, it is OK to only proceed if
1418	<	* queue appears to be non-empty.
1416	>	* Signals threads waiting to poll a task. Because method sync
1417	>	* rechecks availability, it is OK to only proceed if queue
1418	>	* appears to be non-empty, and OK to skip under contention to
1419	>	* increment count (since some other thread succeeded).
1420		*/
1421	<	final void signalNonEmptyWorkerQueue() {
1280	<	// If CAS fails another signaller must have succeeded
1421	>	final void signalWork() {
1422		long c;
1423	<	if (barrierStack != null && casEventCount(c = eventCount, c+1))
1424	<	releaseIdleWorkers(false);
1423	>	WaitQueueNode q;
1424	>	if (syncStack != null &&
1425	>	casEventCount(c = eventCount, c+1) &&
1426	>	(((q = syncStack) != null && q.count <= c) &&
1427	>	(!casBarrierStack(q, q.next) || !q.signal())))
1428	>	ensureSync();
1429		}
1430
1431		/**
1432	<	* Waits until event count advances from count, or some thread is
1433	<	* waiting on a previous count, or there is stealable work
1434	<	* available. Help wake up others on release.
1432	>	* Waits until event count advances from last value held by
1433	>	* caller, or if excess threads, caller is resumed as spare, or
1434	>	* caller or pool is terminating. Updates caller's event on exit.
1435	>	*
1436		* @param w the calling worker thread
1291	–	* @param prev previous value returned by sync (or 0)
1292	–	* @return current event count
1437		*/
1438	<	final long sync(ForkJoinWorkerThread w, long prev) {
1439	<	updateStealCount(w);
1438	>	final void sync(ForkJoinWorkerThread w) {
1439	>	updateStealCount(w); // Transfer w's count while it is idle
1440
1441	<	while (!w.isShutdown() && !isTerminating() &&
1442	<	(parallelism >= runningCountOf(workerCounts) ||
1299	<	!suspendIfSpare(w))) { // prefer suspend to waiting here
1441	>	while (!w.isShutdown() && !isTerminating() && !suspendIfSpare(w)) {
1442	>	long prev = w.lastEventCount;
1443		WaitQueueNode node = null;
1444	<	boolean queued = false;
1445	<	for (;;) {
1446	<	if (!queued) {
1447	<	if (eventCount != prev)
1448	<	break;
1449	<	WaitQueueNode h = barrierStack;
1450	<	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);
1444	>	WaitQueueNode h;
1445	>	while (eventCount == prev &&
1446	>	((h = syncStack) == null || h.count == prev)) {
1447	>	if (node == null)
1448	>	node = new WaitQueueNode(prev, w);
1449	>	if (casBarrierStack(node.next = h, node)) {
1450	>	node.awaitSyncRelease(this);
1451		break;
1452		}
1322	–	else
1323	–	LockSupport.park(this);
1453		}
1454	+	long ec = ensureSync();
1455	+	if (ec != prev) {
1456	+	w.lastEventCount = ec;
1457	+	break;
1458	+	}
1459	+	}
1460	+	}
1461	+
1462	+	/**
1463	+	* Returns true if worker waiting on sync can proceed:
1464	+	*  - on signal (thread == null)
1465	+	*  - on event count advance (winning race to notify vs signaller)
1466	+	*  - on interrupt
1467	+	*  - if the first queued node, we find work available
1468	+	* If node was not signalled and event count not advanced on exit,
1469	+	* then we also help advance event count.
1470	+	*
1471	+	* @return true if node can be released
1472	+	*/
1473	+	final boolean syncIsReleasable(WaitQueueNode node) {
1474	+	long prev = node.count;
1475	+	if (!Thread.interrupted() && node.thread != null &&
1476	+	(node.next != null ||
1477	+	!ForkJoinWorkerThread.hasQueuedTasks(workers)) &&
1478	+	eventCount == prev)
1479	+	return false;
1480	+	if (node.thread != null) {
1481	+	node.thread = null;
1482		long ec = eventCount;
1483	<	if (releaseIdleWorkers(false) != prev)
1484	<	return ec;
1483	>	if (prev <= ec) // help signal
1484	>	casEventCount(ec, ec+1);
1485		}
1486	<	return prev; // return old count if aborted
1486	>	return true;
1487	>	}
1488	>
1489	>	/**
1490	>	* Returns true if a new sync event occurred since last call to
1491	>	* sync or this method, if so, updating caller's count.
1492	>	*/
1493	>	final boolean hasNewSyncEvent(ForkJoinWorkerThread w) {
1494	>	long lc = w.lastEventCount;
1495	>	long ec = ensureSync();
1496	>	if (ec == lc)
1497	>	return false;
1498	>	w.lastEventCount = ec;
1499	>	return true;
1500		}
1501
1502		//  Parallelism maintenance
1503
1504		/**
1505	<	* Decrement running count; if too low, add spare.
1505	>	* Decrements running count; if too low, adds spare.
1506		*
1507		* Conceptually, all we need to do here is add or resume a
1508		* spare thread when one is about to block (and remove or
1509		* suspend it later when unblocked -- see suspendIfSpare).
1510		* However, implementing this idea requires coping with
1511	<	* several problems: We have imperfect information about the
1511	>	* several problems: we have imperfect information about the
1512		* states of threads. Some count updates can and usually do
1513		* lag run state changes, despite arrangements to keep them
1514		* accurate (for example, when possible, updating counts
#	Line 1352 | Line 1522 | public class ForkJoinPool extends Abstra
1522		* only be suspended or removed when they are idle, not
1523		* immediately when they aren't needed. So adding threads will
1524		* raise parallelism level for longer than necessary.  Also,
1525	<	* FJ applications often enounter highly transient peaks when
1525	>	* FJ applications often encounter highly transient peaks when
1526		* many threads are blocked joining, but for less time than it
1527		* takes to create or resume spares.
1528		*
#	Line 1361 | Line 1531 | public class ForkJoinPool extends Abstra
1531		* target counts, else create only to avoid starvation
1532		* @return true if joinMe known to be done
1533		*/
1534	<	final boolean preJoin(ForkJoinTask<?> joinMe, boolean maintainParallelism) {
1534	>	final boolean preJoin(ForkJoinTask<?> joinMe,
1535	>	boolean maintainParallelism) {
1536		maintainParallelism &= maintainsParallelism; // overrride
1537		boolean dec = false;  // true when running count decremented
1538		while (spareStack == null || !tryResumeSpare(dec)) {
1539		int counts = workerCounts;
1540	<	if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat
1540	>	if (dec || (dec = casWorkerCounts(counts, --counts))) {
1541	>	// CAS cheat
1542		if (!needSpare(counts, maintainParallelism))
1543		break;
1544		if (joinMe.status < 0)
#	Line 1381 | Line 1553 | public class ForkJoinPool extends Abstra
1553		/**
1554		* Same idea as preJoin
1555		*/
1556	<	final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){
1556	>	final boolean preBlock(ManagedBlocker blocker,
1557	>	boolean maintainParallelism) {
1558		maintainParallelism &= maintainsParallelism;
1559		boolean dec = false;
1560		while (spareStack == null || !tryResumeSpare(dec)) {
#	Line 1405 | Line 1578 | public class ForkJoinPool extends Abstra
1578		* there is apparently some work to do.  This self-limiting rule
1579		* means that the more threads that have already been added, the
1580		* less parallelism we will tolerate before adding another.
1581	+	*
1582		* @param counts current worker counts
1583		* @param maintainParallelism try to maintain parallelism
1584		*/
#	Line 1417 | Line 1591 | public class ForkJoinPool extends Abstra
1591		return (tc < maxPoolSize &&
1592		(rc == 0 || totalSurplus < 0 ||
1593		(maintainParallelism &&
1594	<	runningDeficit > totalSurplus && mayHaveQueuedWork())));
1595	<	}
1422	<
1423	<	/**
1424	<	* Returns true if at least one worker queue appears to be
1425	<	* nonempty. This is expensive but not often called. It is not
1426	<	* 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;
1594	>	runningDeficit > totalSurplus &&
1595	>	ForkJoinWorkerThread.hasQueuedTasks(workers))));
1596		}
1597
1598		/**
1599	<	* Add a spare worker if lock available and no more than the
1600	<	* expected numbers of threads exist
1599	>	* Adds a spare worker if lock available and no more than the
1600	>	* expected numbers of threads exist.
1601	>	*
1602		* @return true if successful
1603		*/
1604		private boolean tryAddSpare(int expectedCounts) {
#	Line 1474 | Line 1631 | public class ForkJoinPool extends Abstra
1631		}
1632
1633		/**
1634	<	* Add the kth spare worker. On entry, pool coounts are already
1634	>	* Adds the kth spare worker. On entry, pool counts are already
1635		* adjusted to reflect addition.
1636		*/
1637		private void createAndStartSpare(int k) {
#	Line 1486 | Line 1643 | public class ForkJoinPool extends Abstra
1643		for (k = 0; k < len && ws[k] != null; ++k)
1644		;
1645		}
1646	<	if (k < len && (w = createWorker(k)) != null) {
1646	>	if (k < len && !isTerminating() && (w = createWorker(k)) != null) {
1647		ws[k] = w;
1648		w.start();
1649		}
1650		else
1651		updateWorkerCount(-1); // adjust on failure
1652	<	signalIdleWorkers(false);
1652	>	signalIdleWorkers();
1653		}
1654
1655		/**
1656	<	* Suspend calling thread w if there are excess threads.  Called
1657	<	* only from sync.  Spares are enqueued in a Treiber stack
1658	<	* using the same WaitQueueNodes as barriers.  They are resumed
1659	<	* mainly in preJoin, but are also woken on pool events that
1660	<	* require all threads to check run state.
1656	>	* Suspends calling thread w if there are excess threads.  Called
1657	>	* only from sync.  Spares are enqueued in a Treiber stack using
1658	>	* the same WaitQueueNodes as barriers.  They are resumed mainly
1659	>	* in preJoin, but are also woken on pool events that require all
1660	>	* threads to check run state.
1661	>	*
1662		* @param w the caller
1663		*/
1664		private boolean suspendIfSpare(ForkJoinWorkerThread w) {
#	Line 1508 | Line 1666 | public class ForkJoinPool extends Abstra
1666		int s;
1667		while (parallelism < runningCountOf(s = workerCounts)) {
1668		if (node == null)
1669	<	node = new WaitQueueNode(w, 0);
1669	>	node = new WaitQueueNode(0, w);
1670		if (casWorkerCounts(s, s-1)) { // representation-dependent
1671		// push onto stack
1672	<	do;while (!casSpareStack(node.next = spareStack, node));
1515	<
1672	>	do {} while (!casSpareStack(node.next = spareStack, node));
1673		// block until released by resumeSpare
1674	<	while (node.thread != null) {
1518	<	if (!Thread.interrupted())
1519	<	LockSupport.park(this);
1520	<	}
1521	<	w.activate(); // help warm up
1674	>	node.awaitSpareRelease();
1675		return true;
1676		}
1677		}
#	Line 1526 | Line 1679 | public class ForkJoinPool extends Abstra
1679		}
1680
1681		/**
1682	<	* Try to pop and resume a spare thread.
1682	>	* Tries to pop and resume a spare thread.
1683	>	*
1684		* @param updateCount if true, increment running count on success
1685		* @return true if successful
1686		*/
#	Line 1544 | Line 1698 | public class ForkJoinPool extends Abstra
1698		}
1699
1700		/**
1701	<	* Pop and resume all spare threads. Same idea as
1702	<	* releaseIdleWorkers.
1701	>	* Pops and resumes all spare threads. Same idea as ensureSync.
1702	>	*
1703		* @return true if any spares released
1704		*/
1705		private boolean resumeAllSpares() {
#	Line 1563 | Line 1717 | public class ForkJoinPool extends Abstra
1717		}
1718
1719		/**
1720	<	* Pop and shutdown excessive spare threads. Call only while
1720	>	* Pops and shuts down excessive spare threads. Call only while
1721		* holding lock. This is not guaranteed to eliminate all excess
1722		* threads, only those suspended as spares, which are the ones
1723		* unlikely to be needed in the future.
#	Line 1586 | Line 1740 | public class ForkJoinPool extends Abstra
1740		}
1741
1742		/**
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	–	/**
1743		* Interface for extending managed parallelism for tasks running
1744		* in ForkJoinPools. A ManagedBlocker provides two methods.
1745	<	* Method <tt>isReleasable</tt> must return true if blocking is not
1746	<	* necessary. Method <tt>block</tt> blocks the current thread
1747	<	* if necessary (perhaps internally invoking isReleasable before
1748	<	* actually blocking.).
1745	>	* Method {@code isReleasable} must return true if blocking is not
1746	>	* necessary. Method {@code block} blocks the current thread if
1747	>	* necessary (perhaps internally invoking {@code isReleasable}
1748	>	* before actually blocking.).
1749	>	*
1750		* <p>For example, here is a ManagedBlocker based on a
1751		* ReentrantLock:
1752	<	* <pre>
1753	<	*   class ManagedLocker implements ManagedBlocker {
1754	<	*     final ReentrantLock lock;
1755	<	*     boolean hasLock = false;
1756	<	*     ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1757	<	*     public boolean block() {
1758	<	*        if (!hasLock)
1759	<	*           lock.lock();
1760	<	*        return true;
1616	<	*     }
1617	<	*     public boolean isReleasable() {
1618	<	*        return hasLock || (hasLock = lock.tryLock());
1619	<	*     }
1752	>	*  <pre> {@code
1753	>	* class ManagedLocker implements ManagedBlocker {
1754	>	*   final ReentrantLock lock;
1755	>	*   boolean hasLock = false;
1756	>	*   ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1757	>	*   public boolean block() {
1758	>	*     if (!hasLock)
1759	>	*       lock.lock();
1760	>	*     return true;
1761		*   }
1762	<	* </pre>
1762	>	*   public boolean isReleasable() {
1763	>	*     return hasLock || (hasLock = lock.tryLock());
1764	>	*   }
1765	>	* }}</pre>
1766		*/
1767		public static interface ManagedBlocker {
1768		/**
1769		* Possibly blocks the current thread, for example waiting for
1770		* a lock or condition.
1771	+	*
1772		* @return true if no additional blocking is necessary (i.e.,
1773	<	* if isReleasable would return true).
1773	>	* if isReleasable would return true)
1774		* @throws InterruptedException if interrupted while waiting
1775	<	* (the method is not required to do so, but is allowe to).
1775	>	* (the method is not required to do so, but is allowed to)
1776		*/
1777		boolean block() throws InterruptedException;
1778
#	Line 1642 | Line 1787 | public class ForkJoinPool extends Abstra
1787		* is a ForkJoinWorkerThread, this method possibly arranges for a
1788		* spare thread to be activated if necessary to ensure parallelism
1789		* while the current thread is blocked.  If
1790	<	* <tt>maintainParallelism</tt> is true and the pool supports it
1791	<	* (see <tt>getMaintainsParallelism</tt>), this method attempts to
1792	<	* maintain the pool's nominal parallelism. Otherwise if activates
1790	>	* {@code maintainParallelism} is true and the pool supports
1791	>	* it ({@link #getMaintainsParallelism}), this method attempts to
1792	>	* maintain the pool's nominal parallelism. Otherwise it activates
1793		* a thread only if necessary to avoid complete starvation. This
1794		* option may be preferable when blockages use timeouts, or are
1795		* almost always brief.
1796		*
1797		* <p> If the caller is not a ForkJoinTask, this method is behaviorally
1798		* equivalent to
1799	<	* <pre>
1800	<	*   while (!blocker.isReleasable())
1801	<	*      if (blocker.block())
1802	<	*         return;
1803	<	* </pre>
1799	>	*  <pre> {@code
1800	>	* while (!blocker.isReleasable())
1801	>	*   if (blocker.block())
1802	>	*     return;
1803	>	* }</pre>
1804		* If the caller is a ForkJoinTask, then the pool may first
1805		* be expanded to ensure parallelism, and later adjusted.
1806		*
#	Line 1664 | Line 1809 | public class ForkJoinPool extends Abstra
1809		* attempt to maintain the pool's nominal parallelism; otherwise
1810		* activate a thread only if necessary to avoid complete
1811		* starvation.
1812	<	* @throws InterruptedException if blocker.block did so.
1812	>	* @throws InterruptedException if blocker.block did so
1813		*/
1814		public static void managedBlock(ManagedBlocker blocker,
1815		boolean maintainParallelism)
1816		throws InterruptedException {
1817		Thread t = Thread.currentThread();
1818	<	ForkJoinPool pool = (t instanceof ForkJoinWorkerThread?
1819	<	((ForkJoinWorkerThread)t).pool : null);
1818	>	ForkJoinPool pool = ((t instanceof ForkJoinWorkerThread) ?
1819	>	((ForkJoinWorkerThread) t).pool : null);
1820		if (!blocker.isReleasable()) {
1821		try {
1822		if (pool == null ||
#	Line 1686 | Line 1831 | public class ForkJoinPool extends Abstra
1831
1832		private static void awaitBlocker(ManagedBlocker blocker)
1833		throws InterruptedException {
1834	<	do;while (!blocker.isReleasable() && !blocker.block());
1834	>	do {} while (!blocker.isReleasable() && !blocker.block());
1835	>	}
1836	>
1837	>	// AbstractExecutorService overrides
1838	>
1839	>	protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
1840	>	return new AdaptedRunnable<T>(runnable, value);
1841	>	}
1842	>
1843	>	protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
1844	>	return new AdaptedCallable<T>(callable);
1845		}
1846
1847
1848		// Temporary Unsafe mechanics for preliminary release
1849	+	private static Unsafe getUnsafe() throws Throwable {
1850	+	try {
1851	+	return Unsafe.getUnsafe();
1852	+	} catch (SecurityException se) {
1853	+	try {
1854	+	return java.security.AccessController.doPrivileged
1855	+	(new java.security.PrivilegedExceptionAction<Unsafe>() {
1856	+	public Unsafe run() throws Exception {
1857	+	return getUnsafePrivileged();
1858	+	}});
1859	+	} catch (java.security.PrivilegedActionException e) {
1860	+	throw e.getCause();
1861	+	}
1862	+	}
1863	+	}
1864	+
1865	+	private static Unsafe getUnsafePrivileged()
1866	+	throws NoSuchFieldException, IllegalAccessException {
1867	+	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1868	+	f.setAccessible(true);
1869	+	return (Unsafe) f.get(null);
1870	+	}
1871	+
1872	+	private static long fieldOffset(String fieldName)
1873	+	throws NoSuchFieldException {
1874	+	return UNSAFE.objectFieldOffset
1875	+	(ForkJoinPool.class.getDeclaredField(fieldName));
1876	+	}
1877
1878	<	static final Unsafe _unsafe;
1878	>	static final Unsafe UNSAFE;
1879		static final long eventCountOffset;
1880		static final long workerCountsOffset;
1881		static final long runControlOffset;
1882	<	static final long barrierStackOffset;
1882	>	static final long syncStackOffset;
1883		static final long spareStackOffset;
1884
1885		static {
1886		try {
1887	<	if (ForkJoinPool.class.getClassLoader() != null) {
1888	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1889	<	f.setAccessible(true);
1890	<	_unsafe = (Unsafe)f.get(null);
1891	<	}
1892	<	else
1893	<	_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) {
1887	>	UNSAFE = getUnsafe();
1888	>	eventCountOffset = fieldOffset("eventCount");
1889	>	workerCountsOffset = fieldOffset("workerCounts");
1890	>	runControlOffset = fieldOffset("runControl");
1891	>	syncStackOffset = fieldOffset("syncStack");
1892	>	spareStackOffset = fieldOffset("spareStack");
1893	>	} catch (Throwable e) {
1894		throw new RuntimeException("Could not initialize intrinsics", e);
1895		}
1896		}
1897
1898		private boolean casEventCount(long cmp, long val) {
1899	<	return _unsafe.compareAndSwapLong(this, eventCountOffset, cmp, val);
1899	>	return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
1900		}
1901		private boolean casWorkerCounts(int cmp, int val) {
1902	<	return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1902	>	return UNSAFE.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1903		}
1904		private boolean casRunControl(int cmp, int val) {
1905	<	return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val);
1905	>	return UNSAFE.compareAndSwapInt(this, runControlOffset, cmp, val);
1906		}
1907		private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) {
1908	<	return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val);
1908	>	return UNSAFE.compareAndSwapObject(this, spareStackOffset, cmp, val);
1909		}
1910		private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1911	<	return _unsafe.compareAndSwapObject(this, barrierStackOffset, cmp, val);
1911	>	return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val);
1912		}
1913		}

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