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

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.2 by dl, Wed Jan 7 16:07:37 2009 UTC vs.
Revision 1.47 by jsr166, Wed Aug 5 15:40:09 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	<	* An {@link ExecutorService} for running {@link ForkJoinTask}s.  A
24	<	* 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
20	<	* submitted tasks. Otherwise, use would not usually outweigh the
21	<	* construction and bookkeeping overhead of creating a large set of
22	<	* threads.
23	>	* An {@link ExecutorService} for running {@link ForkJoinTask}s.
24	>	* A {@code ForkJoinPool} provides the entry point for submissions
25	>	* from non-{@code ForkJoinTask}s, as well as management and
26	>	* monitoring operations.
27		*
28	<	* <p>ForkJoinPools differ from other kinds of Executors mainly in
29	<	* that they provide <em>work-stealing</em>: all threads in the pool
30	<	* attempt to find and execute subtasks created by other active tasks
31	<	* (eventually blocking if none exist). This makes them efficient when
32	<	* most tasks spawn other subtasks (as do most ForkJoinTasks), as well
33	<	* as the mixed execution of some plain Runnable- or Callable- based
34	<	* activities along with ForkJoinTasks. Otherwise, other
35	<	* ExecutorService implementations are typically more appropriate
36	<	* choices.
28	>	* <p>A {@code ForkJoinPool} differs from other kinds of {@link
29	>	* ExecutorService} mainly by virtue of employing
30	>	* <em>work-stealing</em>: all threads in the pool attempt to find and
31	>	* execute subtasks created by other active tasks (eventually blocking
32	>	* waiting for work if none exist). This enables efficient processing
33	>	* when most tasks spawn other subtasks (as do most {@code
34	>	* ForkJoinTask}s). A {@code ForkJoinPool} may also be used for mixed
35	>	* execution of some plain {@code Runnable}- or {@code Callable}-
36	>	* based activities along with {@code ForkJoinTask}s. When setting
37	>	* {@linkplain #setAsyncMode async mode}, a {@code ForkJoinPool} may
38	>	* also be appropriate for use with fine-grained tasks of any form
39	>	* that are never joined. Otherwise, other {@code ExecutorService}
40	>	* implementations are typically more appropriate choices.
41		*
42	<	* <p>A ForkJoinPool may be constructed with a given parallelism level
43	<	* (target pool size), which it attempts to maintain by dynamically
44	<	* adding, suspending, or resuming threads, even if some tasks are
45	<	* waiting to join others. However, no such adjustments are performed
46	<	* in the face of blocked IO or other unmanaged synchronization. The
47	<	* nested <code>ManagedBlocker</code> interface enables extension of
48	<	* the kinds of synchronization accommodated.  The target parallelism
49	<	* level may also be changed dynamically (<code>setParallelism</code>)
50	<	* and dynamically thread construction can be limited using methods
51	<	* <code>setMaximumPoolSize</code> and/or
52	<	* <code>setMaintainsParallelism</code>.
42	>	* <p>A {@code ForkJoinPool} is constructed with a given target
43	>	* parallelism level; by default, equal to the number of available
44	>	* processors. Unless configured otherwise via {@link
45	>	* #setMaintainsParallelism}, the pool attempts to maintain this
46	>	* number of active (or available) threads by dynamically adding,
47	>	* suspending, or resuming internal worker threads, even if some tasks
48	>	* are stalled waiting to join others. However, no such adjustments
49	>	* are performed in the face of blocked IO or other unmanaged
50	>	* synchronization. The nested {@link ManagedBlocker} interface
51	>	* enables extension of the kinds of synchronization accommodated.
52	>	* The target parallelism level may also be changed dynamically
53	>	* ({@link #setParallelism}). The total number of threads may be
54	>	* limited using method {@link #setMaximumPoolSize}, in which case it
55	>	* may become possible for the activities of a pool to stall due to
56	>	* the lack of available threads to process new tasks.
57		*
58		* <p>In addition to execution and lifecycle control methods, this
59		* class provides status check methods (for example
60	<	* <code>getStealCount</code>) that are intended to aid in developing,
60	>	* {@link #getStealCount}) that are intended to aid in developing,
61		* tuning, and monitoring fork/join applications. Also, method
62	<	* <code>toString</code> returns indications of pool state in a
62	>	* {@link #toString} returns indications of pool state in a
63		* convenient form for informal monitoring.
64		*
65	+	* <p><b>Sample Usage.</b> Normally a single {@code ForkJoinPool} is
66	+	* used for all parallel task execution in a program or subsystem.
67	+	* Otherwise, use would not usually outweigh the construction and
68	+	* bookkeeping overhead of creating a large set of threads. For
69	+	* example, a common pool could be used for the {@code SortTasks}
70	+	* illustrated in {@link RecursiveAction}. Because {@code
71	+	* ForkJoinPool} uses threads in {@linkplain java.lang.Thread#isDaemon
72	+	* daemon} mode, there is typically no need to explicitly {@link
73	+	* #shutdown} such a pool upon program exit.
74	+	*
75	+	* <pre>
76	+	* static final ForkJoinPool mainPool = new ForkJoinPool();
77	+	* ...
78	+	* public void sort(long[] array) {
79	+	*   mainPool.invoke(new SortTask(array, 0, array.length));
80	+	* }
81	+	* </pre>
82	+	*
83		* <p><b>Implementation notes</b>: This implementation restricts the
84		* maximum number of running threads to 32767. Attempts to create
85		* pools with greater than the maximum result in
86	<	* IllegalArgumentExceptions.
86	>	* {@code IllegalArgumentException}.
87	>	*
88	>	* @since 1.7
89	>	* @author Doug Lea
90		*/
91		public class ForkJoinPool extends AbstractExecutorService {
92
#	Line 69 | Line 102 | public class ForkJoinPool extends Abstra
102		private static final int MAX_THREADS =  0x7FFF;
103
104		/**
105	<	* Factory for creating new ForkJoinWorkerThreads.  A
106	<	* ForkJoinWorkerThreadFactory must be defined and used for
107	<	* ForkJoinWorkerThread subclasses that extend base functionality
108	<	* or initialize threads with different contexts.
105	>	* Factory for creating new {@link ForkJoinWorkerThread}s.
106	>	* A {@code ForkJoinWorkerThreadFactory} must be defined and used
107	>	* for {@code ForkJoinWorkerThread} subclasses that extend base
108	>	* functionality or initialize threads with different contexts.
109		*/
110		public static interface ForkJoinWorkerThreadFactory {
111		/**
112		* Returns a new worker thread operating in the given pool.
113		*
114		* @param pool the pool this thread works in
115	<	* @throws NullPointerException if pool is null;
115	>	* @throws NullPointerException if pool is null
116		*/
117		public ForkJoinWorkerThread newThread(ForkJoinPool pool);
118		}
119
120		/**
121	<	* Default ForkJoinWorkerThreadFactory implementation, creates a
121	>	* Default ForkJoinWorkerThreadFactory implementation; creates a
122		* new ForkJoinWorkerThread.
123		*/
124		static class  DefaultForkJoinWorkerThreadFactory
#	Line 131 | Line 164 | public class ForkJoinPool extends Abstra
164		new AtomicInteger();
165
166		/**
167	<	* Array holding all worker threads in the pool. Array size must
168	<	* be a power of two.  Updates and replacements are protected by
169	<	* workerLock, but it is always kept in a consistent enough state
170	<	* to be randomly accessed without locking by workers performing
171	<	* work-stealing.
167	>	* Array holding all worker threads in the pool. Initialized upon
168	>	* first use. Array size must be a power of two.  Updates and
169	>	* replacements are protected by workerLock, but it is always kept
170	>	* in a consistent enough state to be randomly accessed without
171	>	* locking by workers performing work-stealing.
172		*/
173		volatile ForkJoinWorkerThread[] workers;
174
#	Line 151 | Line 184 | public class ForkJoinPool extends Abstra
184
185		/**
186		* The uncaught exception handler used when any worker
187	<	* abrupty terminates
187	>	* abruptly terminates
188		*/
189		private Thread.UncaughtExceptionHandler ueh;
190
#	Line 179 | Line 212 | public class ForkJoinPool extends Abstra
212		private final LinkedTransferQueue<ForkJoinTask<?>> submissionQueue;
213
214		/**
215	<	* Head of Treiber stack for barrier sync. See below for explanation
215	>	* Head of Treiber stack for barrier sync. See below for explanation.
216		*/
217	<	private volatile WaitQueueNode barrierStack;
217	>	private volatile WaitQueueNode syncStack;
218
219		/**
220		* The count for event barrier
#	Line 204 | Line 237 | public class ForkJoinPool extends Abstra
237		private volatile int parallelism;
238
239		/**
240	+	* True if use local fifo, not default lifo, for local polling
241	+	*/
242	+	private volatile boolean locallyFifo;
243	+
244	+	/**
245		* Holds number of total (i.e., created and not yet terminated)
246		* and running (i.e., not blocked on joins or other managed sync)
247		* threads, packed into one int to ensure consistent snapshot when
248		* making decisions about creating and suspending spare
249		* threads. Updated only by CAS.  Note: CASes in
250	<	* updateRunningCount and preJoin running active count is in low
251	<	* word, so need to be modified if this changes
250	>	* updateRunningCount and preJoin assume that running active count
251	>	* is in low word, so need to be modified if this changes.
252		*/
253		private volatile int workerCounts;
254
#	Line 219 | Line 257 | public class ForkJoinPool extends Abstra
257		private static int workerCountsFor(int t, int r) { return (t << 16) + r; }
258
259		/**
260	<	* Add delta (which may be negative) to running count.  This must
260	>	* Adds delta (which may be negative) to running count.  This must
261		* be called before (with negative arg) and after (with positive)
262	<	* any managed synchronization (i.e., mainly, joins)
262	>	* any managed synchronization (i.e., mainly, joins).
263	>	*
264		* @param delta the number to add
265		*/
266		final void updateRunningCount(int delta) {
267		int s;
268	<	do;while (!casWorkerCounts(s = workerCounts, s + delta));
268	>	do {} while (!casWorkerCounts(s = workerCounts, s + delta));
269		}
270
271		/**
272	<	* Add delta (which may be negative) to both total and running
272	>	* Adds delta (which may be negative) to both total and running
273		* count.  This must be called upon creation and termination of
274		* worker threads.
275	+	*
276		* @param delta the number to add
277		*/
278		private void updateWorkerCount(int delta) {
279		int d = delta + (delta << 16); // add to both lo and hi parts
280		int s;
281	<	do;while (!casWorkerCounts(s = workerCounts, s + d));
281	>	do {} while (!casWorkerCounts(s = workerCounts, s + d));
282		}
283
284		/**
#	Line 264 | Line 304 | public class ForkJoinPool extends Abstra
304		private static int runControlFor(int r, int a)   { return (r << 16) + a; }
305
306		/**
307	<	* Increment active count. Called by workers before/during
308	<	* executing tasks.
307	>	* Tries incrementing active count; fails on contention.
308	>	* Called by workers before/during executing tasks.
309	>	*
310	>	* @return true on success
311		*/
312	<	final void incrementActiveCount() {
313	<	int c;
314	<	do;while (!casRunControl(c = runControl, c+1));
312	>	final boolean tryIncrementActiveCount() {
313	>	int c = runControl;
314	>	return casRunControl(c, c+1);
315		}
316
317		/**
318	<	* Decrement active count; possibly trigger termination.
318	>	* Tries decrementing active count; fails on contention.
319	>	* Possibly triggers termination on success.
320		* Called by workers when they can't find tasks.
321	+	*
322	+	* @return true on success
323		*/
324	<	final void decrementActiveCount() {
325	<	int c, nextc;
326	<	do;while (!casRunControl(c = runControl, nextc = c-1));
324	>	final boolean tryDecrementActiveCount() {
325	>	int c = runControl;
326	>	int nextc = c - 1;
327	>	if (!casRunControl(c, nextc))
328	>	return false;
329		if (canTerminateOnShutdown(nextc))
330		terminateOnShutdown();
331	+	return true;
332		}
333
334		/**
335	<	* Return true if argument represents zero active count and
336	<	* nonzero runstate, which is the triggering condition for
335	>	* Returns {@code true} if argument represents zero active count
336	>	* and nonzero runstate, which is the triggering condition for
337		* terminating on shutdown.
338		*/
339		private static boolean canTerminateOnShutdown(int c) {
340	<	return ((c & -c) >>> 16) != 0; // i.e. least bit is nonzero runState bit
340	>	// i.e. least bit is nonzero runState bit
341	>	return ((c & -c) >>> 16) != 0;
342		}
343
344		/**
#	Line 314 | Line 363 | public class ForkJoinPool extends Abstra
363		// Constructors
364
365		/**
366	<	* Creates a ForkJoinPool with a pool size equal to the number of
367	<	* processors available on the system and using the default
368	<	* ForkJoinWorkerThreadFactory,
366	>	* Creates a {@code ForkJoinPool} with parallelism equal to {@link
367	>	* java.lang.Runtime#availableProcessors}, and using the {@linkplain
368	>	* #defaultForkJoinWorkerThreadFactory default thread factory}.
369	>	*
370		* @throws SecurityException if a security manager exists and
371		*         the caller is not permitted to modify threads
372		*         because it does not hold {@link
373	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
373	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
374		*/
375		public ForkJoinPool() {
376		this(Runtime.getRuntime().availableProcessors(),
#	Line 328 | Line 378 | public class ForkJoinPool extends Abstra
378		}
379
380		/**
381	<	* Creates a ForkJoinPool with the indicated parellelism level
382	<	* threads, and using the default ForkJoinWorkerThreadFactory,
383	<	* @param parallelism the number of worker threads
381	>	* Creates a {@code ForkJoinPool} with the indicated parallelism
382	>	* level and using the {@linkplain
383	>	* #defaultForkJoinWorkerThreadFactory default thread factory}.
384	>	*
385	>	* @param parallelism the parallelism level
386		* @throws IllegalArgumentException if parallelism less than or
387	<	* equal to zero
387	>	*         equal to zero, or greater than implementation limit
388		* @throws SecurityException if a security manager exists and
389		*         the caller is not permitted to modify threads
390		*         because it does not hold {@link
391	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
391	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
392		*/
393		public ForkJoinPool(int parallelism) {
394		this(parallelism, defaultForkJoinWorkerThreadFactory);
395		}
396
397		/**
398	<	* Creates a ForkJoinPool with parallelism equal to the number of
399	<	* processors available on the system and using the given
400	<	* ForkJoinWorkerThreadFactory,
398	>	* Creates a {@code ForkJoinPool} with parallelism equal to {@link
399	>	* java.lang.Runtime#availableProcessors}, and using the given
400	>	* thread factory.
401	>	*
402		* @param factory the factory for creating new threads
403		* @throws NullPointerException if factory is null
404		* @throws SecurityException if a security manager exists and
405		*         the caller is not permitted to modify threads
406		*         because it does not hold {@link
407	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
407	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
408		*/
409		public ForkJoinPool(ForkJoinWorkerThreadFactory factory) {
410		this(Runtime.getRuntime().availableProcessors(), factory);
411		}
412
413		/**
414	<	* Creates a ForkJoinPool with the given parallelism and factory.
414	>	* Creates a {@code ForkJoinPool} with the given parallelism and
415	>	* thread factory.
416		*
417	<	* @param parallelism the targeted number of worker threads
417	>	* @param parallelism the parallelism level
418		* @param factory the factory for creating new threads
419		* @throws IllegalArgumentException if parallelism less than or
420	<	* equal to zero, or greater than implementation limit.
420	>	*         equal to zero, or greater than implementation limit
421		* @throws NullPointerException if factory is null
422		* @throws SecurityException if a security manager exists and
423		*         the caller is not permitted to modify threads
424		*         because it does not hold {@link
425	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
425	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
426		*/
427		public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) {
428		if (parallelism <= 0 || parallelism > MAX_THREADS)
#	Line 385 | Line 439 | public class ForkJoinPool extends Abstra
439		this.termination = workerLock.newCondition();
440		this.stealCount = new AtomicLong();
441		this.submissionQueue = new LinkedTransferQueue<ForkJoinTask<?>>();
442	<	createAndStartInitialWorkers(parallelism);
442	>	// worker array and workers are lazily constructed
443		}
444
445		/**
446	<	* Create new worker using factory.
446	>	* Creates a new worker thread using factory.
447	>	*
448		* @param index the index to assign worker
449	<	* @return new worker, or null of factory failed
449	>	* @return new worker, or null if factory failed
450		*/
451		private ForkJoinWorkerThread createWorker(int index) {
452		Thread.UncaughtExceptionHandler h = ueh;
#	Line 399 | Line 454 | public class ForkJoinPool extends Abstra
454		if (w != null) {
455		w.poolIndex = index;
456		w.setDaemon(true);
457	+	w.setAsyncMode(locallyFifo);
458		w.setName("ForkJoinPool-" + poolNumber + "-worker-" + index);
459		if (h != null)
460		w.setUncaughtExceptionHandler(h);
#	Line 407 | Line 463 | public class ForkJoinPool extends Abstra
463		}
464
465		/**
466	<	* Return a good size for worker array given pool size.
466	>	* Returns a good size for worker array given pool size.
467		* Currently requires size to be a power of two.
468		*/
469	<	private static int arraySizeFor(int ps) {
470	<	return ps <= 1? 1 : (1 << (32 - Integer.numberOfLeadingZeros(ps-1)));
469	>	private static int arraySizeFor(int poolSize) {
470	>	if (poolSize <= 1)
471	>	return 1;
472	>	// See Hackers Delight, sec 3.2
473	>	int c = poolSize >= MAX_THREADS ? MAX_THREADS : (poolSize - 1);
474	>	c |= c >>>  1;
475	>	c |= c >>>  2;
476	>	c |= c >>>  4;
477	>	c |= c >>>  8;
478	>	c |= c >>> 16;
479	>	return c + 1;
480		}
481
482		/**
483	<	* Create or resize array if necessary to hold newLength
483	>	* Creates or resizes array if necessary to hold newLength.
484	>	* Call only under exclusion.
485	>	*
486		* @return the array
487		*/
488		private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
#	Line 429 | Line 496 | public class ForkJoinPool extends Abstra
496		}
497
498		/**
499	<	* Try to shrink workers into smaller array after one or more terminate
499	>	* Tries to shrink workers into smaller array after one or more terminate.
500		*/
501		private void tryShrinkWorkerArray() {
502		ForkJoinWorkerThread[] ws = workers;
503	<	int len = ws.length;
504	<	int last = len - 1;
505	<	while (last >= 0 && ws[last] == null)
506	<	--last;
507	<	int newLength = arraySizeFor(last+1);
508	<	if (newLength < len)
509	<	workers = Arrays.copyOf(ws, newLength);
503	>	if (ws != null) {
504	>	int len = ws.length;
505	>	int last = len - 1;
506	>	while (last >= 0 && ws[last] == null)
507	>	--last;
508	>	int newLength = arraySizeFor(last+1);
509	>	if (newLength < len)
510	>	workers = Arrays.copyOf(ws, newLength);
511	>	}
512		}
513
514		/**
515	<	* Initial worker array and worker creation and startup. (This
447	<	* must be done under lock to avoid interference by some of the
448	<	* newly started threads while creating others.)
515	>	* Initializes workers if necessary.
516		*/
517	<	private void createAndStartInitialWorkers(int ps) {
518	<	final ReentrantLock lock = this.workerLock;
519	<	lock.lock();
520	<	try {
521	<	ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps);
522	<	for (int i = 0; i < ps; ++i) {
523	<	ForkJoinWorkerThread w = createWorker(i);
524	<	if (w != null) {
525	<	ws[i] = w;
526	<	w.start();
527	<	updateWorkerCount(1);
517	>	final void ensureWorkerInitialization() {
518	>	ForkJoinWorkerThread[] ws = workers;
519	>	if (ws == null) {
520	>	final ReentrantLock lock = this.workerLock;
521	>	lock.lock();
522	>	try {
523	>	ws = workers;
524	>	if (ws == null) {
525	>	int ps = parallelism;
526	>	ws = ensureWorkerArrayCapacity(ps);
527	>	for (int i = 0; i < ps; ++i) {
528	>	ForkJoinWorkerThread w = createWorker(i);
529	>	if (w != null) {
530	>	ws[i] = w;
531	>	w.start();
532	>	updateWorkerCount(1);
533	>	}
534	>	}
535		}
536	+	} finally {
537	+	lock.unlock();
538		}
463	–	} finally {
464	–	lock.unlock();
539		}
540		}
541
#	Line 505 | Line 579 | public class ForkJoinPool extends Abstra
579		* Common code for execute, invoke and submit
580		*/
581		private <T> void doSubmit(ForkJoinTask<T> task) {
582	+	if (task == null)
583	+	throw new NullPointerException();
584		if (isShutdown())
585		throw new RejectedExecutionException();
586	+	if (workers == null)
587	+	ensureWorkerInitialization();
588		submissionQueue.offer(task);
589	<	signalIdleWorkers(true);
589	>	signalIdleWorkers();
590		}
591
592		/**
593	<	* Performs the given task; returning its result upon completion
593	>	* Performs the given task, returning its result upon completion.
594	>	*
595		* @param task the task
596		* @return the task's result
597		* @throws NullPointerException if task is null
#	Line 525 | Line 604 | public class ForkJoinPool extends Abstra
604
605		/**
606		* Arranges for (asynchronous) execution of the given task.
607	+	*
608		* @param task the task
609		* @throws NullPointerException if task is null
610		* @throws RejectedExecutionException if pool is shut down
611		*/
612	<	public <T> void execute(ForkJoinTask<T> task) {
612	>	public void execute(ForkJoinTask<?> task) {
613		doSubmit(task);
614		}
615
616		// AbstractExecutorService methods
617
618		public void execute(Runnable task) {
619	<	doSubmit(new AdaptedRunnable<Void>(task, null));
619	>	ForkJoinTask<?> job;
620	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
621	>	job = (ForkJoinTask<?>) task;
622	>	else
623	>	job = ForkJoinTask.adapt(task, null);
624	>	doSubmit(job);
625		}
626
627		public <T> ForkJoinTask<T> submit(Callable<T> task) {
628	<	ForkJoinTask<T> job = new AdaptedCallable<T>(task);
628	>	ForkJoinTask<T> job = ForkJoinTask.adapt(task);
629		doSubmit(job);
630		return job;
631		}
632
633		public <T> ForkJoinTask<T> submit(Runnable task, T result) {
634	<	ForkJoinTask<T> job = new AdaptedRunnable<T>(task, result);
634	>	ForkJoinTask<T> job = ForkJoinTask.adapt(task, result);
635		doSubmit(job);
636		return job;
637		}
638
639		public ForkJoinTask<?> submit(Runnable task) {
640	<	ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null);
640	>	ForkJoinTask<?> job;
641	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
642	>	job = (ForkJoinTask<?>) task;
643	>	else
644	>	job = ForkJoinTask.adapt(task, null);
645		doSubmit(job);
646		return job;
647		}
648
649		/**
650	<	* Adaptor for Runnables. This implements RunnableFuture
651	<	* to be compliant with AbstractExecutorService constraints
650	>	* Submits a ForkJoinTask for execution.
651	>	*
652	>	* @param task the task to submit
653	>	* @return the task
654	>	* @throws RejectedExecutionException if the task cannot be
655	>	*         scheduled for execution
656	>	* @throws NullPointerException if the task is null
657		*/
658	<	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
659	<	implements RunnableFuture<T> {
660	<	final Runnable runnable;
567	<	final T resultOnCompletion;
568	<	T result;
569	<	AdaptedRunnable(Runnable runnable, T result) {
570	<	if (runnable == null) throw new NullPointerException();
571	<	this.runnable = runnable;
572	<	this.resultOnCompletion = result;
573	<	}
574	<	public T getRawResult() { return result; }
575	<	public void setRawResult(T v) { result = v; }
576	<	public boolean exec() {
577	<	runnable.run();
578	<	result = resultOnCompletion;
579	<	return true;
580	<	}
581	<	public void run() { invoke(); }
658	>	public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) {
659	>	doSubmit(task);
660	>	return task;
661		}
662
584	–	/**
585	–	* Adaptor for Callables
586	–	*/
587	–	static final class AdaptedCallable<T> extends ForkJoinTask<T>
588	–	implements RunnableFuture<T> {
589	–	final Callable<T> callable;
590	–	T result;
591	–	AdaptedCallable(Callable<T> callable) {
592	–	if (callable == null) throw new NullPointerException();
593	–	this.callable = callable;
594	–	}
595	–	public T getRawResult() { return result; }
596	–	public void setRawResult(T v) { result = v; }
597	–	public boolean exec() {
598	–	try {
599	–	result = callable.call();
600	–	return true;
601	–	} catch (Error err) {
602	–	throw err;
603	–	} catch (RuntimeException rex) {
604	–	throw rex;
605	–	} catch (Exception ex) {
606	–	throw new RuntimeException(ex);
607	–	}
608	–	}
609	–	public void run() { invoke(); }
610	–	}
663
664		public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) {
665	<	ArrayList<ForkJoinTask<T>> ts =
665	>	ArrayList<ForkJoinTask<T>> forkJoinTasks =
666		new ArrayList<ForkJoinTask<T>>(tasks.size());
667	<	for (Callable<T> c : tasks)
668	<	ts.add(new AdaptedCallable<T>(c));
669	<	invoke(new InvokeAll<T>(ts));
670	<	return (List<Future<T>>)(List)ts;
667	>	for (Callable<T> task : tasks)
668	>	forkJoinTasks.add(ForkJoinTask.adapt(task));
669	>	invoke(new InvokeAll<T>(forkJoinTasks));
670	>
671	>	@SuppressWarnings({"unchecked", "rawtypes"})
672	>	List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks;
673	>	return futures;
674		}
675
676		static final class InvokeAll<T> extends RecursiveAction {
677		final ArrayList<ForkJoinTask<T>> tasks;
678		InvokeAll(ArrayList<ForkJoinTask<T>> tasks) { this.tasks = tasks; }
679		public void compute() {
680	<	try { invokeAll(tasks); } catch(Exception ignore) {}
680	>	try { invokeAll(tasks); }
681	>	catch (Exception ignore) {}
682		}
683	+	private static final long serialVersionUID = -7914297376763021607L;
684		}
685
686		// Configuration and status settings and queries
687
688		/**
689	<	* Returns the factory used for constructing new workers
689	>	* Returns the factory used for constructing new workers.
690		*
691		* @return the factory used for constructing new workers
692		*/
#	Line 640 | Line 697 | public class ForkJoinPool extends Abstra
697		/**
698		* Returns the handler for internal worker threads that terminate
699		* due to unrecoverable errors encountered while executing tasks.
700	<	* @return the handler, or null if none
700	>	*
701	>	* @return the handler, or {@code null} if none
702		*/
703		public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
704		Thread.UncaughtExceptionHandler h;
#	Line 661 | Line 719 | public class ForkJoinPool extends Abstra
719		* as handler.
720		*
721		* @param h the new handler
722	<	* @return the old handler, or null if none
722	>	* @return the old handler, or {@code null} if none
723		* @throws SecurityException if a security manager exists and
724		*         the caller is not permitted to modify threads
725		*         because it does not hold {@link
726	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
726	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
727		*/
728		public Thread.UncaughtExceptionHandler
729		setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
#	Line 677 | Line 735 | public class ForkJoinPool extends Abstra
735		old = ueh;
736		ueh = h;
737		ForkJoinWorkerThread[] ws = workers;
738	<	for (int i = 0; i < ws.length; ++i) {
739	<	ForkJoinWorkerThread w = ws[i];
740	<	if (w != null)
741	<	w.setUncaughtExceptionHandler(h);
738	>	if (ws != null) {
739	>	for (int i = 0; i < ws.length; ++i) {
740	>	ForkJoinWorkerThread w = ws[i];
741	>	if (w != null)
742	>	w.setUncaughtExceptionHandler(h);
743	>	}
744		}
745		} finally {
746		lock.unlock();
#	Line 690 | Line 750 | public class ForkJoinPool extends Abstra
750
751
752		/**
753	<	* Sets the target paralleism level of this pool.
753	>	* Sets the target parallelism level of this pool.
754	>	*
755		* @param parallelism the target parallelism
756		* @throws IllegalArgumentException if parallelism less than or
757	<	* equal to zero or greater than maximum size bounds.
757	>	* equal to zero or greater than maximum size bounds
758		* @throws SecurityException if a security manager exists and
759		*         the caller is not permitted to modify threads
760		*         because it does not hold {@link
761	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
761	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
762		*/
763		public void setParallelism(int parallelism) {
764		checkPermission();
#	Line 706 | Line 767 | public class ForkJoinPool extends Abstra
767		final ReentrantLock lock = this.workerLock;
768		lock.lock();
769		try {
770	<	if (!isTerminating()) {
770	>	if (isProcessingTasks()) {
771		int p = this.parallelism;
772		this.parallelism = parallelism;
773		if (parallelism > p)
#	Line 717 | Line 778 | public class ForkJoinPool extends Abstra
778		} finally {
779		lock.unlock();
780		}
781	<	signalIdleWorkers(false);
781	>	signalIdleWorkers();
782		}
783
784		/**
785	<	* Returns the targeted number of worker threads in this pool.
785	>	* Returns the targeted parallelism level of this pool.
786		*
787	<	* @return the targeted number of worker threads in this pool
787	>	* @return the targeted parallelism level of this pool
788		*/
789		public int getParallelism() {
790		return parallelism;
#	Line 732 | Line 793 | public class ForkJoinPool extends Abstra
793		/**
794		* Returns the number of worker threads that have started but not
795		* yet terminated.  This result returned by this method may differ
796	<	* from <code>getParallelism</code> when threads are created to
796	>	* from {@link #getParallelism} when threads are created to
797		* maintain parallelism when others are cooperatively blocked.
798		*
799		* @return the number of worker threads
#	Line 743 | Line 804 | public class ForkJoinPool extends Abstra
804
805		/**
806		* Returns the maximum number of threads allowed to exist in the
807	<	* pool, even if there are insufficient unblocked running threads.
807	>	* pool. Unless set using {@link #setMaximumPoolSize}, the
808	>	* maximum is an implementation-defined value designed only to
809	>	* prevent runaway growth.
810	>	*
811		* @return the maximum
812		*/
813		public int getMaximumPoolSize() {
#	Line 752 | Line 816 | public class ForkJoinPool extends Abstra
816
817		/**
818		* Sets the maximum number of threads allowed to exist in the
819	<	* pool, even if there are insufficient unblocked running threads.
820	<	* Setting this value has no effect on current pool size. It
821	<	* controls construction of new threads.
822	<	* @throws IllegalArgumentException if negative or greater then
823	<	* internal implementation limit.
819	>	* pool. The given value should normally be greater than or equal
820	>	* to the {@link #getParallelism parallelism} level. Setting this
821	>	* value has no effect on current pool size. It controls
822	>	* construction of new threads.
823	>	*
824	>	* @throws IllegalArgumentException if negative or greater than
825	>	* internal implementation limit
826		*/
827		public void setMaximumPoolSize(int newMax) {
828		if (newMax < 0 || newMax > MAX_THREADS)
#	Line 766 | Line 832 | public class ForkJoinPool extends Abstra
832
833
834		/**
835	<	* Returns true if this pool dynamically maintains its target
836	<	* parallelism level. If false, new threads are added only to
837	<	* avoid possible starvation.
838	<	* This setting is by default true;
839	<	* @return true if maintains parallelism
835	>	* Returns {@code true} if this pool dynamically maintains its
836	>	* target parallelism level. If false, new threads are added only
837	>	* to avoid possible starvation.  This setting is by default true.
838	>	*
839	>	* @return {@code true} if maintains parallelism
840		*/
841		public boolean getMaintainsParallelism() {
842		return maintainsParallelism;
#	Line 780 | Line 846 | public class ForkJoinPool extends Abstra
846		* Sets whether this pool dynamically maintains its target
847		* parallelism level. If false, new threads are added only to
848		* avoid possible starvation.
849	<	* @param enable true to maintains parallelism
849	>	*
850	>	* @param enable {@code true} to maintain parallelism
851		*/
852		public void setMaintainsParallelism(boolean enable) {
853		maintainsParallelism = enable;
854		}
855
856		/**
857	+	* Establishes local first-in-first-out scheduling mode for forked
858	+	* tasks that are never joined. This mode may be more appropriate
859	+	* than default locally stack-based mode in applications in which
860	+	* worker threads only process asynchronous tasks.  This method is
861	+	* designed to be invoked only when the pool is quiescent, and
862	+	* typically only before any tasks are submitted. The effects of
863	+	* invocations at other times may be unpredictable.
864	+	*
865	+	* @param async if {@code true}, use locally FIFO scheduling
866	+	* @return the previous mode
867	+	* @see #getAsyncMode
868	+	*/
869	+	public boolean setAsyncMode(boolean async) {
870	+	boolean oldMode = locallyFifo;
871	+	locallyFifo = async;
872	+	ForkJoinWorkerThread[] ws = workers;
873	+	if (ws != null) {
874	+	for (int i = 0; i < ws.length; ++i) {
875	+	ForkJoinWorkerThread t = ws[i];
876	+	if (t != null)
877	+	t.setAsyncMode(async);
878	+	}
879	+	}
880	+	return oldMode;
881	+	}
882	+
883	+	/**
884	+	* Returns {@code true} if this pool uses local first-in-first-out
885	+	* scheduling mode for forked tasks that are never joined.
886	+	*
887	+	* @return {@code true} if this pool uses async mode
888	+	* @see #setAsyncMode
889	+	*/
890	+	public boolean getAsyncMode() {
891	+	return locallyFifo;
892	+	}
893	+
894	+	/**
895		* Returns an estimate of the number of worker threads that are
896		* not blocked waiting to join tasks or for other managed
897		* synchronization.
#	Line 801 | Line 906 | public class ForkJoinPool extends Abstra
906		* Returns an estimate of the number of threads that are currently
907		* stealing or executing tasks. This method may overestimate the
908		* number of active threads.
909	<	* @return the number of active threads.
909	>	*
910	>	* @return the number of active threads
911		*/
912		public int getActiveThreadCount() {
913		return activeCountOf(runControl);
#	Line 811 | Line 917 | public class ForkJoinPool extends Abstra
917		* Returns an estimate of the number of threads that are currently
918		* idle waiting for tasks. This method may underestimate the
919		* number of idle threads.
920	<	* @return the number of idle threads.
920	>	*
921	>	* @return the number of idle threads
922		*/
923		final int getIdleThreadCount() {
924		int c = runningCountOf(workerCounts) - activeCountOf(runControl);
925	<	return (c <= 0)? 0 : c;
925	>	return (c <= 0) ? 0 : c;
926		}
927
928		/**
929	<	* Returns true if all worker threads are currently idle. An idle
930	<	* worker is one that cannot obtain a task to execute because none
931	<	* are available to steal from other threads, and there are no
932	<	* pending submissions to the pool. This method is conservative:
933	<	* It might not return true immediately upon idleness of all
934	<	* threads, but will eventually become true if threads remain
935	<	* inactive.
936	<	* @return true if all threads are currently idle
929	>	* Returns {@code true} if all worker threads are currently idle.
930	>	* An idle worker is one that cannot obtain a task to execute
931	>	* because none are available to steal from other threads, and
932	>	* there are no pending submissions to the pool. This method is
933	>	* conservative; it might not return {@code true} immediately upon
934	>	* idleness of all threads, but will eventually become true if
935	>	* threads remain inactive.
936	>	*
937	>	* @return {@code true} if all threads are currently idle
938		*/
939		public boolean isQuiescent() {
940		return activeCountOf(runControl) == 0;
#	Line 837 | Line 945 | public class ForkJoinPool extends Abstra
945		* one thread's work queue by another. The reported value
946		* underestimates the actual total number of steals when the pool
947		* is not quiescent. This value may be useful for monitoring and
948	<	* tuning fork/join programs: In general, steal counts should be
948	>	* tuning fork/join programs: in general, steal counts should be
949		* high enough to keep threads busy, but low enough to avoid
950		* overhead and contention across threads.
951	<	* @return the number of steals.
951	>	*
952	>	* @return the number of steals
953		*/
954		public long getStealCount() {
955		return stealCount.get();
956		}
957
958		/**
959	<	* Accumulate steal count from a worker. Call only
960	<	* when worker known to be idle.
959	>	* Accumulates steal count from a worker.
960	>	* Call only when worker known to be idle.
961		*/
962		private void updateStealCount(ForkJoinWorkerThread w) {
963		int sc = w.getAndClearStealCount();
#	Line 863 | Line 972 | public class ForkJoinPool extends Abstra
972		* an approximation, obtained by iterating across all threads in
973		* the pool. This method may be useful for tuning task
974		* granularities.
975	<	* @return the number of queued tasks.
975	>	*
976	>	* @return the number of queued tasks
977		*/
978		public long getQueuedTaskCount() {
979		long count = 0;
980		ForkJoinWorkerThread[] ws = workers;
981	<	for (int i = 0; i < ws.length; ++i) {
982	<	ForkJoinWorkerThread t = ws[i];
983	<	if (t != null)
984	<	count += t.getQueueSize();
981	>	if (ws != null) {
982	>	for (int i = 0; i < ws.length; ++i) {
983	>	ForkJoinWorkerThread t = ws[i];
984	>	if (t != null)
985	>	count += t.getQueueSize();
986	>	}
987		}
988		return count;
989		}
990
991		/**
992	<	* Returns an estimate of the number tasks submitted to this pool
993	<	* that have not yet begun executing. This method takes time
992	>	* Returns an estimate of the number of tasks submitted to this
993	>	* pool that have not yet begun executing.  This method takes time
994		* proportional to the number of submissions.
995	<	* @return the number of queued submissions.
995	>	*
996	>	* @return the number of queued submissions
997		*/
998		public int getQueuedSubmissionCount() {
999		return submissionQueue.size();
1000		}
1001
1002		/**
1003	<	* Returns true if there are any tasks submitted to this pool
1004	<	* that have not yet begun executing.
1005	<	* @return <code>true</code> if there are any queued submissions.
1003	>	* Returns {@code true} if there are any tasks submitted to this
1004	>	* pool that have not yet begun executing.
1005	>	*
1006	>	* @return {@code true} if there are any queued submissions
1007		*/
1008		public boolean hasQueuedSubmissions() {
1009		return !submissionQueue.isEmpty();
#	Line 899 | Line 1013 | public class ForkJoinPool extends Abstra
1013		* Removes and returns the next unexecuted submission if one is
1014		* available.  This method may be useful in extensions to this
1015		* class that re-assign work in systems with multiple pools.
1016	<	* @return the next submission, or null if none
1016	>	*
1017	>	* @return the next submission, or {@code null} if none
1018		*/
1019		protected ForkJoinTask<?> pollSubmission() {
1020		return submissionQueue.poll();
1021		}
1022
1023		/**
1024	+	* Removes all available unexecuted submitted and forked tasks
1025	+	* from scheduling queues and adds them to the given collection,
1026	+	* without altering their execution status. These may include
1027	+	* artificially generated or wrapped tasks. This method is
1028	+	* designed to be invoked only when the pool is known to be
1029	+	* quiescent. Invocations at other times may not remove all
1030	+	* tasks. A failure encountered while attempting to add elements
1031	+	* to collection {@code c} may result in elements being in
1032	+	* neither, either or both collections when the associated
1033	+	* exception is thrown.  The behavior of this operation is
1034	+	* undefined if the specified collection is modified while the
1035	+	* operation is in progress.
1036	+	*
1037	+	* @param c the collection to transfer elements into
1038	+	* @return the number of elements transferred
1039	+	*/
1040	+	protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) {
1041	+	int n = submissionQueue.drainTo(c);
1042	+	ForkJoinWorkerThread[] ws = workers;
1043	+	if (ws != null) {
1044	+	for (int i = 0; i < ws.length; ++i) {
1045	+	ForkJoinWorkerThread w = ws[i];
1046	+	if (w != null)
1047	+	n += w.drainTasksTo(c);
1048	+	}
1049	+	}
1050	+	return n;
1051	+	}
1052	+
1053	+	/**
1054		* Returns a string identifying this pool, as well as its state,
1055		* including indications of run state, parallelism level, and
1056		* worker and task counts.
#	Line 949 | Line 1094 | public class ForkJoinPool extends Abstra
1094		* Invocation has no additional effect if already shut down.
1095		* Tasks that are in the process of being submitted concurrently
1096		* during the course of this method may or may not be rejected.
1097	+	*
1098		* @throws SecurityException if a security manager exists and
1099		*         the caller is not permitted to modify threads
1100		*         because it does not hold {@link
1101	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1101	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1102		*/
1103		public void shutdown() {
1104		checkPermission();
1105		transitionRunStateTo(SHUTDOWN);
1106	<	if (canTerminateOnShutdown(runControl))
1106	>	if (canTerminateOnShutdown(runControl)) {
1107	>	if (workers == null) { // shutting down before workers created
1108	>	final ReentrantLock lock = this.workerLock;
1109	>	lock.lock();
1110	>	try {
1111	>	if (workers == null) {
1112	>	terminate();
1113	>	transitionRunStateTo(TERMINATED);
1114	>	termination.signalAll();
1115	>	}
1116	>	} finally {
1117	>	lock.unlock();
1118	>	}
1119	>	}
1120		terminateOnShutdown();
1121	+	}
1122		}
1123
1124		/**
1125	<	* Attempts to stop all actively executing tasks, and cancels all
1126	<	* waiting tasks.  Tasks that are in the process of being
1127	<	* submitted or executed concurrently during the course of this
1128	<	* method may or may not be rejected. Unlike some other executors,
1129	<	* this method cancels rather than collects non-executed tasks,
1130	<	* so always returns an empty list.
1125	>	* Attempts to cancel and/or stop all tasks, and reject all
1126	>	* subsequently submitted tasks.  Tasks that are in the process of
1127	>	* being submitted or executed concurrently during the course of
1128	>	* this method may or may not be rejected. This method cancels
1129	>	* both existing and unexecuted tasks, in order to permit
1130	>	* termination in the presence of task dependencies. So the method
1131	>	* always returns an empty list (unlike the case for some other
1132	>	* Executors).
1133	>	*
1134		* @return an empty list
1135		* @throws SecurityException if a security manager exists and
1136		*         the caller is not permitted to modify threads
1137		*         because it does not hold {@link
1138	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1138	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1139		*/
1140		public List<Runnable> shutdownNow() {
1141		checkPermission();
#	Line 981 | Line 1144 | public class ForkJoinPool extends Abstra
1144		}
1145
1146		/**
1147	<	* Returns <code>true</code> if all tasks have completed following shut down.
1147	>	* Returns {@code true} if all tasks have completed following shut down.
1148		*
1149	<	* @return <code>true</code> if all tasks have completed following shut down
1149	>	* @return {@code true} if all tasks have completed following shut down
1150		*/
1151		public boolean isTerminated() {
1152		return runStateOf(runControl) == TERMINATED;
1153		}
1154
1155		/**
1156	<	* Returns <code>true</code> if the process of termination has
1157	<	* commenced but possibly not yet completed.
1156	>	* Returns {@code true} if the process of termination has
1157	>	* commenced but not yet completed.  This method may be useful for
1158	>	* debugging. A return of {@code true} reported a sufficient
1159	>	* period after shutdown may indicate that submitted tasks have
1160	>	* ignored or suppressed interruption, causing this executor not
1161	>	* to properly terminate.
1162		*
1163	<	* @return <code>true</code> if terminating
1163	>	* @return {@code true} if terminating but not yet terminated
1164		*/
1165		public boolean isTerminating() {
1166	<	return runStateOf(runControl) >= TERMINATING;
1166	>	return runStateOf(runControl) == TERMINATING;
1167		}
1168
1169		/**
1170	<	* Returns <code>true</code> if this pool has been shut down.
1170	>	* Returns {@code true} if this pool has been shut down.
1171		*
1172	<	* @return <code>true</code> if this pool has been shut down
1172	>	* @return {@code true} if this pool has been shut down
1173		*/
1174		public boolean isShutdown() {
1175		return runStateOf(runControl) >= SHUTDOWN;
1176		}
1177
1178		/**
1179	+	* Returns true if pool is not terminating or terminated.
1180	+	* Used internally to suppress execution when terminating.
1181	+	*/
1182	+	final boolean isProcessingTasks() {
1183	+	return runStateOf(runControl) < TERMINATING;
1184	+	}
1185	+
1186	+	/**
1187		* Blocks until all tasks have completed execution after a shutdown
1188		* request, or the timeout occurs, or the current thread is
1189		* interrupted, whichever happens first.
1190		*
1191		* @param timeout the maximum time to wait
1192		* @param unit the time unit of the timeout argument
1193	<	* @return <code>true</code> if this executor terminated and
1194	<	*         <code>false</code> if the timeout elapsed before termination
1193	>	* @return {@code true} if this executor terminated and
1194	>	*         {@code false} if the timeout elapsed before termination
1195		* @throws InterruptedException if interrupted while waiting
1196		*/
1197		public boolean awaitTermination(long timeout, TimeUnit unit)
#	Line 1040 | Line 1215 | public class ForkJoinPool extends Abstra
1215		// Shutdown and termination support
1216
1217		/**
1218	<	* Callback from terminating worker. Null out the corresponding
1219	<	* workers slot, and if terminating, try to terminate, else try to
1220	<	* shrink workers array.
1218	>	* Callback from terminating worker. Nulls out the corresponding
1219	>	* workers slot, and if terminating, tries to terminate; else
1220	>	* tries to shrink workers array.
1221	>	*
1222		* @param w the worker
1223		*/
1224		final void workerTerminated(ForkJoinWorkerThread w) {
#	Line 1052 | Line 1228 | public class ForkJoinPool extends Abstra
1228		lock.lock();
1229		try {
1230		ForkJoinWorkerThread[] ws = workers;
1231	<	int idx = w.poolIndex;
1232	<	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1233	<	ws[idx] = null;
1234	<	if (totalCountOf(workerCounts) == 0) {
1235	<	terminate(); // no-op if already terminating
1236	<	transitionRunStateTo(TERMINATED);
1237	<	termination.signalAll();
1238	<	}
1239	<	else if (!isTerminating()) {
1240	<	tryShrinkWorkerArray();
1241	<	tryResumeSpare(true); // allow replacement
1231	>	if (ws != null) {
1232	>	int idx = w.poolIndex;
1233	>	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1234	>	ws[idx] = null;
1235	>	if (totalCountOf(workerCounts) == 0) {
1236	>	terminate(); // no-op if already terminating
1237	>	transitionRunStateTo(TERMINATED);
1238	>	termination.signalAll();
1239	>	}
1240	>	else if (isProcessingTasks()) {
1241	>	tryShrinkWorkerArray();
1242	>	tryResumeSpare(true); // allow replacement
1243	>	}
1244		}
1245		} finally {
1246		lock.unlock();
1247		}
1248	<	signalIdleWorkers(false);
1248	>	signalIdleWorkers();
1249		}
1250
1251		/**
1252	<	* Initiate termination.
1252	>	* Initiates termination.
1253		*/
1254		private void terminate() {
1255		if (transitionRunStateTo(TERMINATING)) {
1256		stopAllWorkers();
1257		resumeAllSpares();
1258	<	signalIdleWorkers(true);
1258	>	signalIdleWorkers();
1259		cancelQueuedSubmissions();
1260		cancelQueuedWorkerTasks();
1261		interruptUnterminatedWorkers();
1262	<	signalIdleWorkers(true); // resignal after interrupt
1262	>	signalIdleWorkers(); // resignal after interrupt
1263		}
1264		}
1265
1266		/**
1267	<	* Possibly terminate when on shutdown state
1267	>	* Possibly terminates when on shutdown state.
1268		*/
1269		private void terminateOnShutdown() {
1270		if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
#	Line 1094 | Line 1272 | public class ForkJoinPool extends Abstra
1272		}
1273
1274		/**
1275	<	* Clear out and cancel submissions
1275	>	* Clears out and cancels submissions.
1276		*/
1277		private void cancelQueuedSubmissions() {
1278		ForkJoinTask<?> task;
#	Line 1103 | Line 1281 | public class ForkJoinPool extends Abstra
1281		}
1282
1283		/**
1284	<	* Clean out worker queues.
1284	>	* Cleans out worker queues.
1285		*/
1286		private void cancelQueuedWorkerTasks() {
1287		final ReentrantLock lock = this.workerLock;
1288		lock.lock();
1289		try {
1290		ForkJoinWorkerThread[] ws = workers;
1291	<	for (int i = 0; i < ws.length; ++i) {
1292	<	ForkJoinWorkerThread t = ws[i];
1293	<	if (t != null)
1294	<	t.cancelTasks();
1291	>	if (ws != null) {
1292	>	for (int i = 0; i < ws.length; ++i) {
1293	>	ForkJoinWorkerThread t = ws[i];
1294	>	if (t != null)
1295	>	t.cancelTasks();
1296	>	}
1297		}
1298		} finally {
1299		lock.unlock();
#	Line 1121 | Line 1301 | public class ForkJoinPool extends Abstra
1301		}
1302
1303		/**
1304	<	* Set each worker's status to terminating. Requires lock to avoid
1305	<	* conflicts with add/remove
1304	>	* Sets each worker's status to terminating. Requires lock to avoid
1305	>	* conflicts with add/remove.
1306		*/
1307		private void stopAllWorkers() {
1308		final ReentrantLock lock = this.workerLock;
1309		lock.lock();
1310		try {
1311		ForkJoinWorkerThread[] ws = workers;
1312	<	for (int i = 0; i < ws.length; ++i) {
1313	<	ForkJoinWorkerThread t = ws[i];
1314	<	if (t != null)
1315	<	t.shutdownNow();
1312	>	if (ws != null) {
1313	>	for (int i = 0; i < ws.length; ++i) {
1314	>	ForkJoinWorkerThread t = ws[i];
1315	>	if (t != null)
1316	>	t.shutdownNow();
1317	>	}
1318		}
1319		} finally {
1320		lock.unlock();
#	Line 1140 | Line 1322 | public class ForkJoinPool extends Abstra
1322		}
1323
1324		/**
1325	<	* Interrupt all unterminated workers.  This is not required for
1325	>	* Interrupts all unterminated workers.  This is not required for
1326		* sake of internal control, but may help unstick user code during
1327		* shutdown.
1328		*/
#	Line 1149 | Line 1331 | public class ForkJoinPool extends Abstra
1331		lock.lock();
1332		try {
1333		ForkJoinWorkerThread[] ws = workers;
1334	<	for (int i = 0; i < ws.length; ++i) {
1335	<	ForkJoinWorkerThread t = ws[i];
1336	<	if (t != null && !t.isTerminated()) {
1337	<	try {
1338	<	t.interrupt();
1339	<	} catch (SecurityException ignore) {
1334	>	if (ws != null) {
1335	>	for (int i = 0; i < ws.length; ++i) {
1336	>	ForkJoinWorkerThread t = ws[i];
1337	>	if (t != null && !t.isTerminated()) {
1338	>	try {
1339	>	t.interrupt();
1340	>	} catch (SecurityException ignore) {
1341	>	}
1342		}
1343		}
1344		}
#	Line 1165 | Line 1349 | public class ForkJoinPool extends Abstra
1349
1350
1351		/*
1352	<	* Nodes for event barrier to manage idle threads.
1352	>	* Nodes for event barrier to manage idle threads.  Queue nodes
1353	>	* are basic Treiber stack nodes, also used for spare stack.
1354		*
1355		* The event barrier has an event count and a wait queue (actually
1356		* a Treiber stack).  Workers are enabled to look for work when
1357	<	* the eventCount is incremented. If they fail to find some,
1358	<	* they may wait for next count. Synchronization events occur only
1359	<	* in enough contexts to maintain overall liveness:
1357	>	* the eventCount is incremented. If they fail to find work, they
1358	>	* may wait for next count. Upon release, threads help others wake
1359	>	* up.
1360	>	*
1361	>	* Synchronization events occur only in enough contexts to
1362	>	* maintain overall liveness:
1363		*
1364		*   - Submission of a new task to the pool
1365	<	*   - Creation or termination of a worker
1365	>	*   - Resizes or other changes to the workers array
1366		*   - pool termination
1367		*   - A worker pushing a task on an empty queue
1368		*
1369	<	* The last case (pushing a task) occurs often enough, and is
1370	<	* heavy enough compared to simple stack pushes to require some
1371	<	* special handling: Method signalNonEmptyWorkerQueue returns
1372	<	* without advancing count if the queue appears to be empty.  This
1373	<	* would ordinarily result in races causing some queued waiters
1374	<	* not to be woken up. To avoid this, a worker in sync
1375	<	* rescans for tasks after being enqueued if it was the first to
1376	<	* enqueue, and aborts the wait if finding one, also helping to
1377	<	* signal others. This works well because the worker has nothing
1378	<	* better to do anyway, and so might as well help alleviate the
1379	<	* overhead and contention on the threads actually doing work.
1380	<	*
1381	<	* Queue nodes are basic Treiber stack nodes, also used for spare
1382	<	* stack.
1369	>	* The case of pushing a task occurs often enough, and is heavy
1370	>	* enough compared to simple stack pushes, to require special
1371	>	* handling: Method signalWork returns without advancing count if
1372	>	* the queue appears to be empty.  This would ordinarily result in
1373	>	* races causing some queued waiters not to be woken up. To avoid
1374	>	* this, the first worker enqueued in method sync (see
1375	>	* syncIsReleasable) rescans for tasks after being enqueued, and
1376	>	* helps signal if any are found. This works well because the
1377	>	* worker has nothing better to do, and so might as well help
1378	>	* alleviate the overhead and contention on the threads actually
1379	>	* doing work.  Also, since event counts increments on task
1380	>	* availability exist to maintain liveness (rather than to force
1381	>	* refreshes etc), it is OK for callers to exit early if
1382	>	* contending with another signaller.
1383		*/
1384		static final class WaitQueueNode {
1385		WaitQueueNode next; // only written before enqueued
1386		volatile ForkJoinWorkerThread thread; // nulled to cancel wait
1387		final long count; // unused for spare stack
1388	<	WaitQueueNode(ForkJoinWorkerThread w, long c) {
1388	>
1389	>	WaitQueueNode(long c, ForkJoinWorkerThread w) {
1390		count = c;
1391		thread = w;
1392		}
1393	<	final boolean signal() {
1393	>
1394	>	/**
1395	>	* Wakes up waiter, returning false if known to already
1396	>	*/
1397	>	boolean signal() {
1398		ForkJoinWorkerThread t = thread;
1399	+	if (t == null)
1400	+	return false;
1401		thread = null;
1402	<	if (t != null) {
1403	<	LockSupport.unpark(t);
1404	<	return true;
1402	>	LockSupport.unpark(t);
1403	>	return true;
1404	>	}
1405	>
1406	>	/**
1407	>	* Awaits release on sync.
1408	>	*/
1409	>	void awaitSyncRelease(ForkJoinPool p) {
1410	>	while (thread != null && !p.syncIsReleasable(this))
1411	>	LockSupport.park(this);
1412	>	}
1413	>
1414	>	/**
1415	>	* Awaits resumption as spare.
1416	>	*/
1417	>	void awaitSpareRelease() {
1418	>	while (thread != null) {
1419	>	if (!Thread.interrupted())
1420	>	LockSupport.park(this);
1421		}
1211	–	return false;
1422		}
1423		}
1424
1425		/**
1426	<	* Release at least one thread waiting for event count to advance,
1427	<	* if one exists. If initial attempt fails, release all threads.
1428	<	* @param all if false, at first try to only release one thread
1429	<	* @return current event
1426	>	* Ensures that no thread is waiting for count to advance from the
1427	>	* current value of eventCount read on entry to this method, by
1428	>	* releasing waiting threads if necessary.
1429	>	*
1430	>	* @return the count
1431		*/
1432	<	private long releaseIdleWorkers(boolean all) {
1433	<	long c;
1434	<	for (;;) {
1435	<	WaitQueueNode q = barrierStack;
1436	<	c = eventCount;
1226	<	long qc;
1227	<	if (q == null || (qc = q.count) >= c)
1228	<	break;
1229	<	if (!all) {
1230	<	if (casBarrierStack(q, q.next) && q.signal())
1231	<	break;
1232	<	all = true;
1233	<	}
1234	<	else if (casBarrierStack(q, null)) {
1432	>	final long ensureSync() {
1433	>	long c = eventCount;
1434	>	WaitQueueNode q;
1435	>	while ((q = syncStack) != null && q.count < c) {
1436	>	if (casBarrierStack(q, null)) {
1437		do {
1438	<	q.signal();
1438	>	q.signal();
1439		} while ((q = q.next) != null);
1440		break;
1441		}
#	Line 1242 | Line 1444 | public class ForkJoinPool extends Abstra
1444		}
1445
1446		/**
1447	<	* Returns current barrier event count
1246	<	* @return current barrier event count
1247	<	*/
1248	<	final long getEventCount() {
1249	<	long ec = eventCount;
1250	<	releaseIdleWorkers(true); // release to ensure accurate result
1251	<	return ec;
1252	<	}
1253	<
1254	<	/**
1255	<	* Increment event count and release at least one waiting thread,
1256	<	* if one exists (released threads will in turn wake up others).
1257	<	* @param all if true, try to wake up all
1447	>	* Increments event count and releases waiting threads.
1448		*/
1449	<	final void signalIdleWorkers(boolean all) {
1449	>	private void signalIdleWorkers() {
1450		long c;
1451	<	do;while (!casEventCount(c = eventCount, c+1));
1452	<	releaseIdleWorkers(all);
1451	>	do {} while (!casEventCount(c = eventCount, c+1));
1452	>	ensureSync();
1453		}
1454
1455		/**
1456	<	* Wake up threads waiting to steal a task. Because method
1457	<	* sync rechecks availability, it is OK to only proceed if
1458	<	* queue appears to be non-empty.
1456	>	* Signals threads waiting to poll a task. Because method sync
1457	>	* rechecks availability, it is OK to only proceed if queue
1458	>	* appears to be non-empty, and OK to skip under contention to
1459	>	* increment count (since some other thread succeeded).
1460		*/
1461	<	final void signalNonEmptyWorkerQueue() {
1271	<	// If CAS fails another signaller must have succeeded
1461	>	final void signalWork() {
1462		long c;
1463	<	if (barrierStack != null && casEventCount(c = eventCount, c+1))
1464	<	releaseIdleWorkers(false);
1463	>	WaitQueueNode q;
1464	>	if (syncStack != null &&
1465	>	casEventCount(c = eventCount, c+1) &&
1466	>	(((q = syncStack) != null && q.count <= c) &&
1467	>	(!casBarrierStack(q, q.next) || !q.signal())))
1468	>	ensureSync();
1469		}
1470
1471		/**
1472	<	* Waits until event count advances from count, or some thread is
1473	<	* waiting on a previous count, or there is stealable work
1474	<	* available. Help wake up others on release.
1472	>	* Waits until event count advances from last value held by
1473	>	* caller, or if excess threads, caller is resumed as spare, or
1474	>	* caller or pool is terminating. Updates caller's event on exit.
1475	>	*
1476		* @param w the calling worker thread
1282	–	* @param prev previous value returned by sync (or 0)
1283	–	* @return current event count
1477		*/
1478	<	final long sync(ForkJoinWorkerThread w, long prev) {
1479	<	updateStealCount(w);
1478	>	final void sync(ForkJoinWorkerThread w) {
1479	>	updateStealCount(w); // Transfer w's count while it is idle
1480
1481	<	while (!w.isShutdown() && !isTerminating() &&
1482	<	(parallelism >= runningCountOf(workerCounts) ||
1290	<	!suspendIfSpare(w))) { // prefer suspend to waiting here
1481	>	while (!w.isShutdown() && isProcessingTasks() && !suspendIfSpare(w)) {
1482	>	long prev = w.lastEventCount;
1483		WaitQueueNode node = null;
1484	<	boolean queued = false;
1485	<	for (;;) {
1486	<	if (!queued) {
1487	<	if (eventCount != prev)
1488	<	break;
1489	<	WaitQueueNode h = barrierStack;
1490	<	if (h != null && h.count != prev)
1299	<	break; // release below and maybe retry
1300	<	if (node == null)
1301	<	node = new WaitQueueNode(w, prev);
1302	<	queued = casBarrierStack(node.next = h, node);
1303	<	}
1304	<	else if (Thread.interrupted() ||
1305	<	node.thread == null ||
1306	<	(node.next == null && w.prescan()) ||
1307	<	eventCount != prev) {
1308	<	node.thread = null;
1309	<	if (eventCount == prev) // help trigger
1310	<	casEventCount(prev, prev+1);
1484	>	WaitQueueNode h;
1485	>	while (eventCount == prev &&
1486	>	((h = syncStack) == null || h.count == prev)) {
1487	>	if (node == null)
1488	>	node = new WaitQueueNode(prev, w);
1489	>	if (casBarrierStack(node.next = h, node)) {
1490	>	node.awaitSyncRelease(this);
1491		break;
1492		}
1313	–	else
1314	–	LockSupport.park(this);
1493		}
1494	+	long ec = ensureSync();
1495	+	if (ec != prev) {
1496	+	w.lastEventCount = ec;
1497	+	break;
1498	+	}
1499	+	}
1500	+	}
1501	+
1502	+	/**
1503	+	* Returns {@code true} if worker waiting on sync can proceed:
1504	+	*  - on signal (thread == null)
1505	+	*  - on event count advance (winning race to notify vs signaller)
1506	+	*  - on interrupt
1507	+	*  - if the first queued node, we find work available
1508	+	* If node was not signalled and event count not advanced on exit,
1509	+	* then we also help advance event count.
1510	+	*
1511	+	* @return {@code true} if node can be released
1512	+	*/
1513	+	final boolean syncIsReleasable(WaitQueueNode node) {
1514	+	long prev = node.count;
1515	+	if (!Thread.interrupted() && node.thread != null &&
1516	+	(node.next != null ||
1517	+	!ForkJoinWorkerThread.hasQueuedTasks(workers)) &&
1518	+	eventCount == prev)
1519	+	return false;
1520	+	if (node.thread != null) {
1521	+	node.thread = null;
1522		long ec = eventCount;
1523	<	if (releaseIdleWorkers(false) != prev)
1524	<	return ec;
1523	>	if (prev <= ec) // help signal
1524	>	casEventCount(ec, ec+1);
1525		}
1526	<	return prev; // return old count if aborted
1526	>	return true;
1527	>	}
1528	>
1529	>	/**
1530	>	* Returns {@code true} if a new sync event occurred since last
1531	>	* call to sync or this method, if so, updating caller's count.
1532	>	*/
1533	>	final boolean hasNewSyncEvent(ForkJoinWorkerThread w) {
1534	>	long lc = w.lastEventCount;
1535	>	long ec = ensureSync();
1536	>	if (ec == lc)
1537	>	return false;
1538	>	w.lastEventCount = ec;
1539	>	return true;
1540		}
1541
1542		//  Parallelism maintenance
1543
1544		/**
1545	<	* Decrement running count; if too low, add spare.
1545	>	* Decrements running count; if too low, adds spare.
1546		*
1547		* Conceptually, all we need to do here is add or resume a
1548		* spare thread when one is about to block (and remove or
1549		* suspend it later when unblocked -- see suspendIfSpare).
1550		* However, implementing this idea requires coping with
1551	<	* several problems: We have imperfect information about the
1551	>	* several problems: we have imperfect information about the
1552		* states of threads. Some count updates can and usually do
1553		* lag run state changes, despite arrangements to keep them
1554		* accurate (for example, when possible, updating counts
#	Line 1343 | Line 1562 | public class ForkJoinPool extends Abstra
1562		* only be suspended or removed when they are idle, not
1563		* immediately when they aren't needed. So adding threads will
1564		* raise parallelism level for longer than necessary.  Also,
1565	<	* FJ applications often enounter highly transient peaks when
1565	>	* FJ applications often encounter highly transient peaks when
1566		* many threads are blocked joining, but for less time than it
1567		* takes to create or resume spares.
1568		*
#	Line 1352 | Line 1571 | public class ForkJoinPool extends Abstra
1571		* target counts, else create only to avoid starvation
1572		* @return true if joinMe known to be done
1573		*/
1574	<	final boolean preJoin(ForkJoinTask<?> joinMe, boolean maintainParallelism) {
1574	>	final boolean preJoin(ForkJoinTask<?> joinMe,
1575	>	boolean maintainParallelism) {
1576		maintainParallelism &= maintainsParallelism; // overrride
1577		boolean dec = false;  // true when running count decremented
1578		while (spareStack == null || !tryResumeSpare(dec)) {
1579		int counts = workerCounts;
1580	<	if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat
1580	>	if (dec || (dec = casWorkerCounts(counts, --counts))) {
1581		if (!needSpare(counts, maintainParallelism))
1582		break;
1583		if (joinMe.status < 0)
#	Line 1372 | Line 1592 | public class ForkJoinPool extends Abstra
1592		/**
1593		* Same idea as preJoin
1594		*/
1595	<	final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){
1595	>	final boolean preBlock(ManagedBlocker blocker,
1596	>	boolean maintainParallelism) {
1597		maintainParallelism &= maintainsParallelism;
1598		boolean dec = false;
1599		while (spareStack == null || !tryResumeSpare(dec)) {
#	Line 1390 | Line 1611 | public class ForkJoinPool extends Abstra
1611		}
1612
1613		/**
1614	<	* Returns true if a spare thread appears to be needed.  If
1615	<	* maintaining parallelism, returns true when the deficit in
1614	>	* Returns {@code true} if a spare thread appears to be needed.
1615	>	* If maintaining parallelism, returns true when the deficit in
1616		* running threads is more than the surplus of total threads, and
1617		* there is apparently some work to do.  This self-limiting rule
1618		* means that the more threads that have already been added, the
1619		* less parallelism we will tolerate before adding another.
1620	+	*
1621		* @param counts current worker counts
1622		* @param maintainParallelism try to maintain parallelism
1623		*/
#	Line 1408 | Line 1630 | public class ForkJoinPool extends Abstra
1630		return (tc < maxPoolSize &&
1631		(rc == 0 || totalSurplus < 0 ||
1632		(maintainParallelism &&
1633	<	runningDeficit > totalSurplus && mayHaveQueuedWork())));
1634	<	}
1413	<
1414	<	/**
1415	<	* Returns true if at least one worker queue appears to be
1416	<	* nonempty. This is expensive but not often called. It is not
1417	<	* critical that this be accurate, but if not, more or fewer
1418	<	* running threads than desired might be maintained.
1419	<	*/
1420	<	private boolean mayHaveQueuedWork() {
1421	<	ForkJoinWorkerThread[] ws = workers;
1422	<	int len = ws.length;
1423	<	ForkJoinWorkerThread v;
1424	<	for (int i = 0; i < len; ++i) {
1425	<	if ((v = ws[i]) != null && v.getRawQueueSize() > 0) {
1426	<	releaseIdleWorkers(false); // help wake up stragglers
1427	<	return true;
1428	<	}
1429	<	}
1430	<	return false;
1633	>	runningDeficit > totalSurplus &&
1634	>	ForkJoinWorkerThread.hasQueuedTasks(workers))));
1635		}
1636
1637		/**
1638	<	* Add a spare worker if lock available and no more than the
1639	<	* expected numbers of threads exist
1638	>	* Adds a spare worker if lock available and no more than the
1639	>	* expected numbers of threads exist.
1640	>	*
1641		* @return true if successful
1642		*/
1643		private boolean tryAddSpare(int expectedCounts) {
#	Line 1465 | Line 1670 | public class ForkJoinPool extends Abstra
1670		}
1671
1672		/**
1673	<	* Add the kth spare worker. On entry, pool coounts are already
1673	>	* Adds the kth spare worker. On entry, pool counts are already
1674		* adjusted to reflect addition.
1675		*/
1676		private void createAndStartSpare(int k) {
#	Line 1477 | Line 1682 | public class ForkJoinPool extends Abstra
1682		for (k = 0; k < len && ws[k] != null; ++k)
1683		;
1684		}
1685	<	if (k < len && (w = createWorker(k)) != null) {
1685	>	if (k < len && isProcessingTasks() && (w = createWorker(k)) != null) {
1686		ws[k] = w;
1687		w.start();
1688		}
1689		else
1690		updateWorkerCount(-1); // adjust on failure
1691	<	signalIdleWorkers(false);
1691	>	signalIdleWorkers();
1692		}
1693
1694		/**
1695	<	* Suspend calling thread w if there are excess threads.  Called
1696	<	* only from sync.  Spares are enqueued in a Treiber stack
1697	<	* using the same WaitQueueNodes as barriers.  They are resumed
1698	<	* mainly in preJoin, but are also woken on pool events that
1699	<	* require all threads to check run state.
1695	>	* Suspends calling thread w if there are excess threads.  Called
1696	>	* only from sync.  Spares are enqueued in a Treiber stack using
1697	>	* the same WaitQueueNodes as barriers.  They are resumed mainly
1698	>	* in preJoin, but are also woken on pool events that require all
1699	>	* threads to check run state.
1700	>	*
1701		* @param w the caller
1702		*/
1703		private boolean suspendIfSpare(ForkJoinWorkerThread w) {
#	Line 1499 | Line 1705 | public class ForkJoinPool extends Abstra
1705		int s;
1706		while (parallelism < runningCountOf(s = workerCounts)) {
1707		if (node == null)
1708	<	node = new WaitQueueNode(w, 0);
1708	>	node = new WaitQueueNode(0, w);
1709		if (casWorkerCounts(s, s-1)) { // representation-dependent
1710		// push onto stack
1711	<	do;while (!casSpareStack(node.next = spareStack, node));
1506	<
1711	>	do {} while (!casSpareStack(node.next = spareStack, node));
1712		// block until released by resumeSpare
1713	<	while (node.thread != null) {
1509	<	if (!Thread.interrupted())
1510	<	LockSupport.park(this);
1511	<	}
1512	<	w.activate(); // help warm up
1713	>	node.awaitSpareRelease();
1714		return true;
1715		}
1716		}
#	Line 1517 | Line 1718 | public class ForkJoinPool extends Abstra
1718		}
1719
1720		/**
1721	<	* Try to pop and resume a spare thread.
1721	>	* Tries to pop and resume a spare thread.
1722	>	*
1723		* @param updateCount if true, increment running count on success
1724		* @return true if successful
1725		*/
#	Line 1535 | Line 1737 | public class ForkJoinPool extends Abstra
1737		}
1738
1739		/**
1740	<	* Pop and resume all spare threads. Same idea as
1741	<	* releaseIdleWorkers.
1740	>	* Pops and resumes all spare threads. Same idea as ensureSync.
1741	>	*
1742		* @return true if any spares released
1743		*/
1744		private boolean resumeAllSpares() {
#	Line 1554 | Line 1756 | public class ForkJoinPool extends Abstra
1756		}
1757
1758		/**
1759	<	* Pop and shutdown excessive spare threads. Call only while
1759	>	* Pops and shuts down excessive spare threads. Call only while
1760		* holding lock. This is not guaranteed to eliminate all excess
1761		* threads, only those suspended as spares, which are the ones
1762		* unlikely to be needed in the future.
#	Line 1577 | Line 1779 | public class ForkJoinPool extends Abstra
1779		}
1780
1781		/**
1580	–	* Returns approximate number of spares, just for diagnostics.
1581	–	*/
1582	–	private int countSpares() {
1583	–	int sum = 0;
1584	–	for (WaitQueueNode q = spareStack; q != null; q = q.next)
1585	–	++sum;
1586	–	return sum;
1587	–	}
1588	–
1589	–	/**
1782		* Interface for extending managed parallelism for tasks running
1783	<	* in ForkJoinPools. A ManagedBlocker provides two methods.
1784	<	* Method <code>isReleasable</code> must return true if blocking is not
1785	<	* necessary. Method <code>block</code> blocks the current thread
1786	<	* if necessary (perhaps internally invoking isReleasable before
1787	<	* actually blocking.).
1783	>	* in {@link ForkJoinPool}s.
1784	>	*
1785	>	* <p>A {@code ManagedBlocker} provides two methods.
1786	>	* Method {@code isReleasable} must return {@code true} if
1787	>	* blocking is not necessary. Method {@code block} blocks the
1788	>	* current thread if necessary (perhaps internally invoking
1789	>	* {@code isReleasable} before actually blocking).
1790	>	*
1791		* <p>For example, here is a ManagedBlocker based on a
1792		* ReentrantLock:
1793	<	* <pre>
1794	<	*   class ManagedLocker implements ManagedBlocker {
1795	<	*     final ReentrantLock lock;
1796	<	*     boolean hasLock = false;
1797	<	*     ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1798	<	*     public boolean block() {
1799	<	*        if (!hasLock)
1800	<	*           lock.lock();
1801	<	*        return true;
1607	<	*     }
1608	<	*     public boolean isReleasable() {
1609	<	*        return hasLock || (hasLock = lock.tryLock());
1610	<	*     }
1793	>	*  <pre> {@code
1794	>	* class ManagedLocker implements ManagedBlocker {
1795	>	*   final ReentrantLock lock;
1796	>	*   boolean hasLock = false;
1797	>	*   ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1798	>	*   public boolean block() {
1799	>	*     if (!hasLock)
1800	>	*       lock.lock();
1801	>	*     return true;
1802		*   }
1803	<	* </pre>
1803	>	*   public boolean isReleasable() {
1804	>	*     return hasLock || (hasLock = lock.tryLock());
1805	>	*   }
1806	>	* }}</pre>
1807		*/
1808		public static interface ManagedBlocker {
1809		/**
1810		* Possibly blocks the current thread, for example waiting for
1811		* a lock or condition.
1812	<	* @return true if no additional blocking is necessary (i.e.,
1813	<	* if isReleasable would return true).
1812	>	*
1813	>	* @return {@code true} if no additional blocking is necessary
1814	>	* (i.e., if isReleasable would return true)
1815		* @throws InterruptedException if interrupted while waiting
1816	<	* (the method is not required to do so, but is allowe to).
1816	>	* (the method is not required to do so, but is allowed to)
1817		*/
1818		boolean block() throws InterruptedException;
1819
1820		/**
1821	<	* Returns true if blocking is unnecessary.
1821	>	* Returns {@code true} if blocking is unnecessary.
1822		*/
1823		boolean isReleasable();
1824		}
1825
1826		/**
1827		* Blocks in accord with the given blocker.  If the current thread
1828	<	* is a ForkJoinWorkerThread, this method possibly arranges for a
1829	<	* spare thread to be activated if necessary to ensure parallelism
1830	<	* while the current thread is blocked.  If
1831	<	* <code>maintainParallelism</code> is true and the pool supports
1832	<	* it ({@link #getMaintainsParallelism}), this method attempts to
1833	<	* maintain the pool's nominal parallelism. Otherwise if activates
1834	<	* a thread only if necessary to avoid complete starvation. This
1835	<	* option may be preferable when blockages use timeouts, or are
1836	<	* almost always brief.
1837	<	*
1838	<	* <p> If the caller is not a ForkJoinTask, this method is behaviorally
1839	<	* equivalent to
1840	<	* <pre>
1841	<	*   while (!blocker.isReleasable())
1842	<	*      if (blocker.block())
1843	<	*         return;
1844	<	* </pre>
1845	<	* If the caller is a ForkJoinTask, then the pool may first
1846	<	* be expanded to ensure parallelism, and later adjusted.
1828	>	* is a {@link ForkJoinWorkerThread}, this method possibly
1829	>	* arranges for a spare thread to be activated if necessary to
1830	>	* ensure parallelism while the current thread is blocked.
1831	>	*
1832	>	* <p>If {@code maintainParallelism} is {@code true} and the pool
1833	>	* supports it ({@link #getMaintainsParallelism}), this method
1834	>	* attempts to maintain the pool's nominal parallelism. Otherwise
1835	>	* it activates a thread only if necessary to avoid complete
1836	>	* starvation. This option may be preferable when blockages use
1837	>	* timeouts, or are almost always brief.
1838	>	*
1839	>	* <p>If the caller is not a {@link ForkJoinTask}, this method is
1840	>	* behaviorally equivalent to
1841	>	*  <pre> {@code
1842	>	* while (!blocker.isReleasable())
1843	>	*   if (blocker.block())
1844	>	*     return;
1845	>	* }</pre>
1846	>	*
1847	>	* If the caller is a {@code ForkJoinTask}, then the pool may
1848	>	* first be expanded to ensure parallelism, and later adjusted.
1849		*
1850		* @param blocker the blocker
1851	<	* @param maintainParallelism if true and supported by this pool,
1852	<	* attempt to maintain the pool's nominal parallelism; otherwise
1853	<	* activate a thread only if necessary to avoid complete
1854	<	* starvation.
1855	<	* @throws InterruptedException if blocker.block did so.
1851	>	* @param maintainParallelism if {@code true} and supported by
1852	>	* this pool, attempt to maintain the pool's nominal parallelism;
1853	>	* otherwise activate a thread only if necessary to avoid
1854	>	* complete starvation.
1855	>	* @throws InterruptedException if blocker.block did so
1856		*/
1857		public static void managedBlock(ManagedBlocker blocker,
1858		boolean maintainParallelism)
1859		throws InterruptedException {
1860		Thread t = Thread.currentThread();
1861	<	ForkJoinPool pool = (t instanceof ForkJoinWorkerThread?
1862	<	((ForkJoinWorkerThread)t).pool : null);
1861	>	ForkJoinPool pool = ((t instanceof ForkJoinWorkerThread) ?
1862	>	((ForkJoinWorkerThread) t).pool : null);
1863		if (!blocker.isReleasable()) {
1864		try {
1865		if (pool == null ||
#	Line 1677 | Line 1874 | public class ForkJoinPool extends Abstra
1874
1875		private static void awaitBlocker(ManagedBlocker blocker)
1876		throws InterruptedException {
1877	<	do;while (!blocker.isReleasable() && !blocker.block());
1877	>	do {} while (!blocker.isReleasable() && !blocker.block());
1878		}
1879
1880	<	// AbstractExecutorService overrides
1880	>	// AbstractExecutorService overrides.  These rely on undocumented
1881	>	// fact that ForkJoinTask.adapt returns ForkJoinTasks that also
1882	>	// implement RunnableFuture.
1883
1884		protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
1885	<	return new AdaptedRunnable(runnable, value);
1885	>	return (RunnableFuture<T>) ForkJoinTask.adapt(runnable, value);
1886		}
1887
1888		protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
1889	<	return new AdaptedCallable(callable);
1889	>	return (RunnableFuture<T>) ForkJoinTask.adapt(callable);
1890		}
1891
1892	+	// Unsafe mechanics
1893
1894	<	// Temporary Unsafe mechanics for preliminary release
1895	<
1896	<	static final Unsafe _unsafe;
1897	<	static final long eventCountOffset;
1898	<	static final long workerCountsOffset;
1899	<	static final long runControlOffset;
1900	<	static final long barrierStackOffset;
1901	<	static final long spareStackOffset;
1902	<
1903	<	static {
1904	<	try {
1705	<	if (ForkJoinPool.class.getClassLoader() != null) {
1706	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1707	<	f.setAccessible(true);
1708	<	_unsafe = (Unsafe)f.get(null);
1709	<	}
1710	<	else
1711	<	_unsafe = Unsafe.getUnsafe();
1712	<	eventCountOffset = _unsafe.objectFieldOffset
1713	<	(ForkJoinPool.class.getDeclaredField("eventCount"));
1714	<	workerCountsOffset = _unsafe.objectFieldOffset
1715	<	(ForkJoinPool.class.getDeclaredField("workerCounts"));
1716	<	runControlOffset = _unsafe.objectFieldOffset
1717	<	(ForkJoinPool.class.getDeclaredField("runControl"));
1718	<	barrierStackOffset = _unsafe.objectFieldOffset
1719	<	(ForkJoinPool.class.getDeclaredField("barrierStack"));
1720	<	spareStackOffset = _unsafe.objectFieldOffset
1721	<	(ForkJoinPool.class.getDeclaredField("spareStack"));
1722	<	} catch (Exception e) {
1723	<	throw new RuntimeException("Could not initialize intrinsics", e);
1724	<	}
1725	<	}
1894	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1895	>	private static final long eventCountOffset =
1896	>	objectFieldOffset("eventCount", ForkJoinPool.class);
1897	>	private static final long workerCountsOffset =
1898	>	objectFieldOffset("workerCounts", ForkJoinPool.class);
1899	>	private static final long runControlOffset =
1900	>	objectFieldOffset("runControl", ForkJoinPool.class);
1901	>	private static final long syncStackOffset =
1902	>	objectFieldOffset("syncStack",ForkJoinPool.class);
1903	>	private static final long spareStackOffset =
1904	>	objectFieldOffset("spareStack", ForkJoinPool.class);
1905
1906		private boolean casEventCount(long cmp, long val) {
1907	<	return _unsafe.compareAndSwapLong(this, eventCountOffset, cmp, val);
1907	>	return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
1908		}
1909		private boolean casWorkerCounts(int cmp, int val) {
1910	<	return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1910	>	return UNSAFE.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1911		}
1912		private boolean casRunControl(int cmp, int val) {
1913	<	return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val);
1913	>	return UNSAFE.compareAndSwapInt(this, runControlOffset, cmp, val);
1914		}
1915		private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) {
1916	<	return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val);
1916	>	return UNSAFE.compareAndSwapObject(this, spareStackOffset, cmp, val);
1917		}
1918		private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1919	<	return _unsafe.compareAndSwapObject(this, barrierStackOffset, cmp, val);
1919	>	return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val);
1920	>	}
1921	>
1922	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1923	>	try {
1924	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1925	>	} catch (NoSuchFieldException e) {
1926	>	// Convert Exception to corresponding Error
1927	>	NoSuchFieldError error = new NoSuchFieldError(field);
1928	>	error.initCause(e);
1929	>	throw error;
1930	>	}
1931	>	}
1932	>
1933	>	/**
1934	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1935	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1936	>	* into a jdk.
1937	>	*
1938	>	* @return a sun.misc.Unsafe
1939	>	*/
1940	>	private static sun.misc.Unsafe getUnsafe() {
1941	>	try {
1942	>	return sun.misc.Unsafe.getUnsafe();
1943	>	} catch (SecurityException se) {
1944	>	try {
1945	>	return java.security.AccessController.doPrivileged
1946	>	(new java.security
1947	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1948	>	public sun.misc.Unsafe run() throws Exception {
1949	>	java.lang.reflect.Field f = sun.misc
1950	>	.Unsafe.class.getDeclaredField("theUnsafe");
1951	>	f.setAccessible(true);
1952	>	return (sun.misc.Unsafe) f.get(null);
1953	>	}});
1954	>	} catch (java.security.PrivilegedActionException e) {
1955	>	throw new RuntimeException("Could not initialize intrinsics",
1956	>	e.getCause());
1957	>	}
1958	>	}
1959		}
1960		}

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