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

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.5 by jsr166, Thu Mar 19 05:10:42 2009 UTC vs.
Revision 1.24 by dl, Sat Jul 25 17:49:01 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
#	Line 27 | Line 34 | import java.lang.reflect.*;
34		* (eventually blocking if none exist). This makes them efficient when
35		* most tasks spawn other subtasks (as do most ForkJoinTasks), as well
36		* as the mixed execution of some plain Runnable- or Callable- based
37	<	* activities along with ForkJoinTasks. Otherwise, other
37	>	* activities along with ForkJoinTasks. When setting
38	>	* {@code setAsyncMode}, a ForkJoinPools may also be appropriate for
39	>	* use with fine-grained tasks that are never joined. Otherwise, other
40		* ExecutorService implementations are typically more appropriate
41		* choices.
42		*
#	Line 36 | Line 45 | import java.lang.reflect.*;
45		* adding, suspending, or resuming threads, even if some tasks are
46		* waiting to join others. However, no such adjustments are performed
47		* in the face of blocked IO or other unmanaged synchronization. The
48	<	* nested <code>ManagedBlocker</code> interface enables extension of
48	>	* nested {@code ManagedBlocker} interface enables extension of
49		* the kinds of synchronization accommodated.  The target parallelism
50	<	* level may also be changed dynamically (<code>setParallelism</code>)
51	<	* and dynamically thread construction can be limited using methods
52	<	* <code>setMaximumPoolSize</code> and/or
53	<	* <code>setMaintainsParallelism</code>.
50	>	* level may also be changed dynamically ({@code setParallelism})
51	>	* and thread construction can be limited using methods
52	>	* {@code setMaximumPoolSize} and/or
53	>	* {@code setMaintainsParallelism}.
54		*
55		* <p>In addition to execution and lifecycle control methods, this
56		* class provides status check methods (for example
57	<	* <code>getStealCount</code>) that are intended to aid in developing,
57	>	* {@code getStealCount}) that are intended to aid in developing,
58		* tuning, and monitoring fork/join applications. Also, method
59	<	* <code>toString</code> returns indications of pool state in a
59	>	* {@code toString} returns indications of pool state in a
60		* convenient form for informal monitoring.
61		*
62		* <p><b>Implementation notes</b>: This implementation restricts the
63		* maximum number of running threads to 32767. Attempts to create
64		* pools with greater than the maximum result in
65		* IllegalArgumentExceptions.
66	+	*
67	+	* @since 1.7
68	+	* @author Doug Lea
69		*/
70		public class ForkJoinPool extends AbstractExecutorService {
71
#	Line 79 | Line 91 | public class ForkJoinPool extends Abstra
91		* Returns a new worker thread operating in the given pool.
92		*
93		* @param pool the pool this thread works in
94	<	* @throws NullPointerException if pool is null;
94	>	* @throws NullPointerException if pool is null
95		*/
96		public ForkJoinWorkerThread newThread(ForkJoinPool pool);
97		}
98
99		/**
100	<	* Default ForkJoinWorkerThreadFactory implementation, creates a
100	>	* Default ForkJoinWorkerThreadFactory implementation; creates a
101		* new ForkJoinWorkerThread.
102		*/
103		static class  DefaultForkJoinWorkerThreadFactory
#	Line 131 | Line 143 | public class ForkJoinPool extends Abstra
143		new AtomicInteger();
144
145		/**
146	<	* Array holding all worker threads in the pool. Array size must
147	<	* be a power of two.  Updates and replacements are protected by
148	<	* workerLock, but it is always kept in a consistent enough state
149	<	* to be randomly accessed without locking by workers performing
150	<	* work-stealing.
146	>	* Array holding all worker threads in the pool. Initialized upon
147	>	* first use. Array size must be a power of two.  Updates and
148	>	* replacements are protected by workerLock, but it is always kept
149	>	* in a consistent enough state to be randomly accessed without
150	>	* locking by workers performing work-stealing.
151		*/
152		volatile ForkJoinWorkerThread[] workers;
153
#	Line 151 | Line 163 | public class ForkJoinPool extends Abstra
163
164		/**
165		* The uncaught exception handler used when any worker
166	<	* abrupty terminates
166	>	* abruptly terminates
167		*/
168		private Thread.UncaughtExceptionHandler ueh;
169
#	Line 179 | Line 191 | public class ForkJoinPool extends Abstra
191		private final LinkedTransferQueue<ForkJoinTask<?>> submissionQueue;
192
193		/**
194	<	* Head of Treiber stack for barrier sync. See below for explanation
194	>	* Head of Treiber stack for barrier sync. See below for explanation.
195		*/
196		private volatile WaitQueueNode syncStack;
197
#	Line 204 | Line 216 | public class ForkJoinPool extends Abstra
216		private volatile int parallelism;
217
218		/**
219	+	* True if use local fifo, not default lifo, for local polling
220	+	*/
221	+	private volatile boolean locallyFifo;
222	+
223	+	/**
224		* Holds number of total (i.e., created and not yet terminated)
225		* and running (i.e., not blocked on joins or other managed sync)
226		* threads, packed into one int to ensure consistent snapshot when
227		* making decisions about creating and suspending spare
228		* threads. Updated only by CAS.  Note: CASes in
229	<	* updateRunningCount and preJoin running active count is in low
230	<	* word, so need to be modified if this changes
229	>	* updateRunningCount and preJoin assume that running active count
230	>	* is in low word, so need to be modified if this changes.
231		*/
232		private volatile int workerCounts;
233
#	Line 219 | Line 236 | public class ForkJoinPool extends Abstra
236		private static int workerCountsFor(int t, int r) { return (t << 16) + r; }
237
238		/**
239	<	* Add delta (which may be negative) to running count.  This must
239	>	* Adds delta (which may be negative) to running count.  This must
240		* be called before (with negative arg) and after (with positive)
241	<	* any managed synchronization (i.e., mainly, joins)
241	>	* any managed synchronization (i.e., mainly, joins).
242	>	*
243		* @param delta the number to add
244		*/
245		final void updateRunningCount(int delta) {
246		int s;
247	<	do;while (!casWorkerCounts(s = workerCounts, s + delta));
247	>	do {} while (!casWorkerCounts(s = workerCounts, s + delta));
248		}
249
250		/**
251	<	* Add delta (which may be negative) to both total and running
251	>	* Adds delta (which may be negative) to both total and running
252		* count.  This must be called upon creation and termination of
253		* worker threads.
254	+	*
255		* @param delta the number to add
256		*/
257		private void updateWorkerCount(int delta) {
258		int d = delta + (delta << 16); // add to both lo and hi parts
259		int s;
260	<	do;while (!casWorkerCounts(s = workerCounts, s + d));
260	>	do {} while (!casWorkerCounts(s = workerCounts, s + d));
261		}
262
263		/**
#	Line 264 | Line 283 | public class ForkJoinPool extends Abstra
283		private static int runControlFor(int r, int a)   { return (r << 16) + a; }
284
285		/**
286	<	* Try incrementing active count; fail on contention. Called by
287	<	* workers before/during executing tasks.
288	<	* @return true on success;
286	>	* Tries incrementing active count; fails on contention.
287	>	* Called by workers before/during executing tasks.
288	>	*
289	>	* @return true on success
290		*/
291		final boolean tryIncrementActiveCount() {
292		int c = runControl;
#	Line 274 | Line 294 | public class ForkJoinPool extends Abstra
294		}
295
296		/**
297	<	* Try decrementing active count; fail on contention.
298	<	* Possibly trigger termination on success
297	>	* Tries decrementing active count; fails on contention.
298	>	* Possibly triggers termination on success.
299		* Called by workers when they can't find tasks.
300	+	*
301		* @return true on success
302		*/
303		final boolean tryDecrementActiveCount() {
#	Line 290 | Line 311 | public class ForkJoinPool extends Abstra
311		}
312
313		/**
314	<	* Return true if argument represents zero active count and
314	>	* Returns true if argument represents zero active count and
315		* nonzero runstate, which is the triggering condition for
316		* terminating on shutdown.
317		*/
318		private static boolean canTerminateOnShutdown(int c) {
319	<	return ((c & -c) >>> 16) != 0; // i.e. least bit is nonzero runState bit
319	>	// i.e. least bit is nonzero runState bit
320	>	return ((c & -c) >>> 16) != 0;
321		}
322
323		/**
#	Line 321 | Line 343 | public class ForkJoinPool extends Abstra
343
344		/**
345		* Creates a ForkJoinPool with a pool size equal to the number of
346	<	* processors available on the system and using the default
347	<	* ForkJoinWorkerThreadFactory,
346	>	* processors available on the system, using the default
347	>	* ForkJoinWorkerThreadFactory.
348	>	*
349		* @throws SecurityException if a security manager exists and
350		*         the caller is not permitted to modify threads
351		*         because it does not hold {@link
352	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
352	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
353		*/
354		public ForkJoinPool() {
355		this(Runtime.getRuntime().availableProcessors(),
#	Line 334 | Line 357 | public class ForkJoinPool extends Abstra
357		}
358
359		/**
360	<	* Creates a ForkJoinPool with the indicated parellelism level
361	<	* threads, and using the default ForkJoinWorkerThreadFactory,
360	>	* Creates a ForkJoinPool with the indicated parallelism level
361	>	* threads and using the default ForkJoinWorkerThreadFactory.
362	>	*
363		* @param parallelism the number of worker threads
364		* @throws IllegalArgumentException if parallelism less than or
365		* equal to zero
366		* @throws SecurityException if a security manager exists and
367		*         the caller is not permitted to modify threads
368		*         because it does not hold {@link
369	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
369	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
370		*/
371		public ForkJoinPool(int parallelism) {
372		this(parallelism, defaultForkJoinWorkerThreadFactory);
#	Line 351 | Line 375 | public class ForkJoinPool extends Abstra
375		/**
376		* Creates a ForkJoinPool with parallelism equal to the number of
377		* processors available on the system and using the given
378	<	* ForkJoinWorkerThreadFactory,
378	>	* ForkJoinWorkerThreadFactory.
379	>	*
380		* @param factory the factory for creating new threads
381		* @throws NullPointerException if factory is null
382		* @throws SecurityException if a security manager exists and
383		*         the caller is not permitted to modify threads
384		*         because it does not hold {@link
385	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
385	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
386		*/
387		public ForkJoinPool(ForkJoinWorkerThreadFactory factory) {
388		this(Runtime.getRuntime().availableProcessors(), factory);
#	Line 369 | Line 394 | public class ForkJoinPool extends Abstra
394		* @param parallelism the targeted number of worker threads
395		* @param factory the factory for creating new threads
396		* @throws IllegalArgumentException if parallelism less than or
397	<	* equal to zero, or greater than implementation limit.
397	>	* equal to zero, or greater than implementation limit
398		* @throws NullPointerException if factory is null
399		* @throws SecurityException if a security manager exists and
400		*         the caller is not permitted to modify threads
401		*         because it does not hold {@link
402	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
402	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
403		*/
404		public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) {
405		if (parallelism <= 0 || parallelism > MAX_THREADS)
#	Line 391 | Line 416 | public class ForkJoinPool extends Abstra
416		this.termination = workerLock.newCondition();
417		this.stealCount = new AtomicLong();
418		this.submissionQueue = new LinkedTransferQueue<ForkJoinTask<?>>();
419	<	createAndStartInitialWorkers(parallelism);
419	>	// worker array and workers are lazily constructed
420		}
421
422		/**
423	<	* Create new worker using factory.
423	>	* Creates a new worker thread using factory.
424	>	*
425		* @param index the index to assign worker
426		* @return new worker, or null of factory failed
427		*/
#	Line 405 | Line 431 | public class ForkJoinPool extends Abstra
431		if (w != null) {
432		w.poolIndex = index;
433		w.setDaemon(true);
434	+	w.setAsyncMode(locallyFifo);
435		w.setName("ForkJoinPool-" + poolNumber + "-worker-" + index);
436		if (h != null)
437		w.setUncaughtExceptionHandler(h);
#	Line 413 | Line 440 | public class ForkJoinPool extends Abstra
440		}
441
442		/**
443	<	* Return a good size for worker array given pool size.
443	>	* Returns a good size for worker array given pool size.
444		* Currently requires size to be a power of two.
445		*/
446	<	private static int arraySizeFor(int ps) {
447	<	return ps <= 1? 1 : (1 << (32 - Integer.numberOfLeadingZeros(ps-1)));
446	>	private static int arraySizeFor(int poolSize) {
447	>	return (poolSize <= 1) ? 1 :
448	>	(1 << (32 - Integer.numberOfLeadingZeros(poolSize-1)));
449		}
450
451		/**
452	<	* Create or resize array if necessary to hold newLength
452	>	* Creates or resizes array if necessary to hold newLength.
453	>	* Call only under exclusion.
454	>	*
455		* @return the array
456		*/
457		private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
#	Line 435 | Line 465 | public class ForkJoinPool extends Abstra
465		}
466
467		/**
468	<	* Try to shrink workers into smaller array after one or more terminate
468	>	* Tries to shrink workers into smaller array after one or more terminate.
469		*/
470		private void tryShrinkWorkerArray() {
471		ForkJoinWorkerThread[] ws = workers;
472	<	int len = ws.length;
473	<	int last = len - 1;
474	<	while (last >= 0 && ws[last] == null)
475	<	--last;
476	<	int newLength = arraySizeFor(last+1);
477	<	if (newLength < len)
478	<	workers = Arrays.copyOf(ws, newLength);
472	>	if (ws != null) {
473	>	int len = ws.length;
474	>	int last = len - 1;
475	>	while (last >= 0 && ws[last] == null)
476	>	--last;
477	>	int newLength = arraySizeFor(last+1);
478	>	if (newLength < len)
479	>	workers = Arrays.copyOf(ws, newLength);
480	>	}
481		}
482
483		/**
484	<	* Initial worker array and worker creation and startup. (This
453	<	* must be done under lock to avoid interference by some of the
454	<	* newly started threads while creating others.)
484	>	* Initializes workers if necessary.
485		*/
486	<	private void createAndStartInitialWorkers(int ps) {
487	<	final ReentrantLock lock = this.workerLock;
488	<	lock.lock();
489	<	try {
490	<	ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps);
491	<	for (int i = 0; i < ps; ++i) {
492	<	ForkJoinWorkerThread w = createWorker(i);
493	<	if (w != null) {
494	<	ws[i] = w;
495	<	w.start();
496	<	updateWorkerCount(1);
486	>	final void ensureWorkerInitialization() {
487	>	ForkJoinWorkerThread[] ws = workers;
488	>	if (ws == null) {
489	>	final ReentrantLock lock = this.workerLock;
490	>	lock.lock();
491	>	try {
492	>	ws = workers;
493	>	if (ws == null) {
494	>	int ps = parallelism;
495	>	ws = ensureWorkerArrayCapacity(ps);
496	>	for (int i = 0; i < ps; ++i) {
497	>	ForkJoinWorkerThread w = createWorker(i);
498	>	if (w != null) {
499	>	ws[i] = w;
500	>	w.start();
501	>	updateWorkerCount(1);
502	>	}
503	>	}
504		}
505	+	} finally {
506	+	lock.unlock();
507		}
469	–	} finally {
470	–	lock.unlock();
508		}
509		}
510
#	Line 511 | Line 548 | public class ForkJoinPool extends Abstra
548		* Common code for execute, invoke and submit
549		*/
550		private <T> void doSubmit(ForkJoinTask<T> task) {
551	+	if (task == null)
552	+	throw new NullPointerException();
553		if (isShutdown())
554		throw new RejectedExecutionException();
555	+	if (workers == null)
556	+	ensureWorkerInitialization();
557		submissionQueue.offer(task);
558		signalIdleWorkers();
559		}
560
561		/**
562	<	* Performs the given task; returning its result upon completion
562	>	* Performs the given task, returning its result upon completion.
563	>	*
564		* @param task the task
565		* @return the task's result
566		* @throws NullPointerException if task is null
#	Line 531 | Line 573 | public class ForkJoinPool extends Abstra
573
574		/**
575		* Arranges for (asynchronous) execution of the given task.
576	+	*
577		* @param task the task
578		* @throws NullPointerException if task is null
579		* @throws RejectedExecutionException if pool is shut down
#	Line 542 | Line 585 | public class ForkJoinPool extends Abstra
585		// AbstractExecutorService methods
586
587		public void execute(Runnable task) {
588	<	doSubmit(new AdaptedRunnable<Void>(task, null));
588	>	ForkJoinTask<?> job;
589	>	if (task instanceof ForkJoinTask) // avoid re-wrap
590	>	job = (ForkJoinTask<?>)task;
591	>	else
592	>	job = new AdaptedRunnable<Void>(task, null);
593	>	doSubmit(job);
594		}
595
596		public <T> ForkJoinTask<T> submit(Callable<T> task) {
#	Line 558 | Line 606 | public class ForkJoinPool extends Abstra
606		}
607
608		public ForkJoinTask<?> submit(Runnable task) {
609	<	ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null);
609	>	ForkJoinTask<?> job;
610	>	if (task instanceof ForkJoinTask) // avoid re-wrap
611	>	job = (ForkJoinTask<?>)task;
612	>	else
613	>	job = new AdaptedRunnable<Void>(task, null);
614		doSubmit(job);
615		return job;
616		}
617
618		/**
619	+	* Submits a ForkJoinTask for execution.
620	+	*
621	+	* @param task the task to submit
622	+	* @return the task
623	+	* @throws RejectedExecutionException if the task cannot be
624	+	*         scheduled for execution
625	+	* @throws NullPointerException if the task is null
626	+	*/
627	+	public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) {
628	+	doSubmit(task);
629	+	return task;
630	+	}
631	+
632	+	/**
633		* Adaptor for Runnables. This implements RunnableFuture
634	<	* to be compliant with AbstractExecutorService constraints
634	>	* to be compliant with AbstractExecutorService constraints.
635		*/
636		static final class AdaptedRunnable<T> extends ForkJoinTask<T>
637		implements RunnableFuture<T> {
#	Line 585 | Line 651 | public class ForkJoinPool extends Abstra
651		return true;
652		}
653		public void run() { invoke(); }
654	+	private static final long serialVersionUID = 5232453952276885070L;
655		}
656
657		/**
#	Line 613 | Line 680 | public class ForkJoinPool extends Abstra
680		}
681		}
682		public void run() { invoke(); }
683	+	private static final long serialVersionUID = 2838392045355241008L;
684		}
685
686		public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) {
687	<	ArrayList<ForkJoinTask<T>> ts =
687	>	ArrayList<ForkJoinTask<T>> forkJoinTasks =
688		new ArrayList<ForkJoinTask<T>>(tasks.size());
689	<	for (Callable<T> c : tasks)
690	<	ts.add(new AdaptedCallable<T>(c));
691	<	invoke(new InvokeAll<T>(ts));
692	<	return (List<Future<T>>)(List)ts;
689	>	for (Callable<T> task : tasks)
690	>	forkJoinTasks.add(new AdaptedCallable<T>(task));
691	>	invoke(new InvokeAll<T>(forkJoinTasks));
692	>
693	>	@SuppressWarnings({"unchecked", "rawtypes"})
694	>	List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks;
695	>	return futures;
696		}
697
698		static final class InvokeAll<T> extends RecursiveAction {
699		final ArrayList<ForkJoinTask<T>> tasks;
700		InvokeAll(ArrayList<ForkJoinTask<T>> tasks) { this.tasks = tasks; }
701		public void compute() {
702	<	try { invokeAll(tasks); } catch(Exception ignore) {}
702	>	try { invokeAll(tasks); }
703	>	catch (Exception ignore) {}
704		}
705	+	private static final long serialVersionUID = -7914297376763021607L;
706		}
707
708		// Configuration and status settings and queries
709
710		/**
711	<	* Returns the factory used for constructing new workers
711	>	* Returns the factory used for constructing new workers.
712		*
713		* @return the factory used for constructing new workers
714		*/
#	Line 646 | Line 719 | public class ForkJoinPool extends Abstra
719		/**
720		* Returns the handler for internal worker threads that terminate
721		* due to unrecoverable errors encountered while executing tasks.
722	+	*
723		* @return the handler, or null if none
724		*/
725		public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
#	Line 671 | Line 745 | public class ForkJoinPool extends Abstra
745		* @throws SecurityException if a security manager exists and
746		*         the caller is not permitted to modify threads
747		*         because it does not hold {@link
748	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
748	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
749		*/
750		public Thread.UncaughtExceptionHandler
751		setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
#	Line 683 | Line 757 | public class ForkJoinPool extends Abstra
757		old = ueh;
758		ueh = h;
759		ForkJoinWorkerThread[] ws = workers;
760	<	for (int i = 0; i < ws.length; ++i) {
761	<	ForkJoinWorkerThread w = ws[i];
762	<	if (w != null)
763	<	w.setUncaughtExceptionHandler(h);
760	>	if (ws != null) {
761	>	for (int i = 0; i < ws.length; ++i) {
762	>	ForkJoinWorkerThread w = ws[i];
763	>	if (w != null)
764	>	w.setUncaughtExceptionHandler(h);
765	>	}
766		}
767		} finally {
768		lock.unlock();
#	Line 696 | Line 772 | public class ForkJoinPool extends Abstra
772
773
774		/**
775	<	* Sets the target paralleism level of this pool.
775	>	* Sets the target parallelism level of this pool.
776	>	*
777		* @param parallelism the target parallelism
778		* @throws IllegalArgumentException if parallelism less than or
779	<	* equal to zero or greater than maximum size bounds.
779	>	* equal to zero or greater than maximum size bounds
780		* @throws SecurityException if a security manager exists and
781		*         the caller is not permitted to modify threads
782		*         because it does not hold {@link
783	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
783	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
784		*/
785		public void setParallelism(int parallelism) {
786		checkPermission();
#	Line 738 | Line 815 | public class ForkJoinPool extends Abstra
815		/**
816		* Returns the number of worker threads that have started but not
817		* yet terminated.  This result returned by this method may differ
818	<	* from <code>getParallelism</code> when threads are created to
818	>	* from {@code getParallelism} when threads are created to
819		* maintain parallelism when others are cooperatively blocked.
820		*
821		* @return the number of worker threads
#	Line 750 | Line 827 | public class ForkJoinPool extends Abstra
827		/**
828		* Returns the maximum number of threads allowed to exist in the
829		* pool, even if there are insufficient unblocked running threads.
830	+	*
831		* @return the maximum
832		*/
833		public int getMaximumPoolSize() {
#	Line 761 | Line 839 | public class ForkJoinPool extends Abstra
839		* pool, even if there are insufficient unblocked running threads.
840		* Setting this value has no effect on current pool size. It
841		* controls construction of new threads.
842	+	*
843		* @throws IllegalArgumentException if negative or greater then
844	<	* internal implementation limit.
844	>	* internal implementation limit
845		*/
846		public void setMaximumPoolSize(int newMax) {
847		if (newMax < 0 || newMax > MAX_THREADS)
#	Line 775 | Line 854 | public class ForkJoinPool extends Abstra
854		* Returns true if this pool dynamically maintains its target
855		* parallelism level. If false, new threads are added only to
856		* avoid possible starvation.
857	<	* This setting is by default true;
857	>	* This setting is by default true.
858	>	*
859		* @return true if maintains parallelism
860		*/
861		public boolean getMaintainsParallelism() {
#	Line 786 | Line 866 | public class ForkJoinPool extends Abstra
866		* Sets whether this pool dynamically maintains its target
867		* parallelism level. If false, new threads are added only to
868		* avoid possible starvation.
869	+	*
870		* @param enable true to maintains parallelism
871		*/
872		public void setMaintainsParallelism(boolean enable) {
#	Line 793 | Line 874 | public class ForkJoinPool extends Abstra
874		}
875
876		/**
877	+	* Establishes local first-in-first-out scheduling mode for forked
878	+	* tasks that are never joined. This mode may be more appropriate
879	+	* than default locally stack-based mode in applications in which
880	+	* worker threads only process asynchronous tasks.  This method is
881	+	* designed to be invoked only when pool is quiescent, and
882	+	* typically only before any tasks are submitted. The effects of
883	+	* invocations at other times may be unpredictable.
884	+	*
885	+	* @param async if true, use locally FIFO scheduling
886	+	* @return the previous mode
887	+	*/
888	+	public boolean setAsyncMode(boolean async) {
889	+	boolean oldMode = locallyFifo;
890	+	locallyFifo = async;
891	+	ForkJoinWorkerThread[] ws = workers;
892	+	if (ws != null) {
893	+	for (int i = 0; i < ws.length; ++i) {
894	+	ForkJoinWorkerThread t = ws[i];
895	+	if (t != null)
896	+	t.setAsyncMode(async);
897	+	}
898	+	}
899	+	return oldMode;
900	+	}
901	+
902	+	/**
903	+	* Returns true if this pool uses local first-in-first-out
904	+	* scheduling mode for forked tasks that are never joined.
905	+	*
906	+	* @return true if this pool uses async mode
907	+	*/
908	+	public boolean getAsyncMode() {
909	+	return locallyFifo;
910	+	}
911	+
912	+	/**
913		* Returns an estimate of the number of worker threads that are
914		* not blocked waiting to join tasks or for other managed
915		* synchronization.
#	Line 807 | Line 924 | public class ForkJoinPool extends Abstra
924		* Returns an estimate of the number of threads that are currently
925		* stealing or executing tasks. This method may overestimate the
926		* number of active threads.
927	<	* @return the number of active threads.
927	>	*
928	>	* @return the number of active threads
929		*/
930		public int getActiveThreadCount() {
931		return activeCountOf(runControl);
#	Line 817 | Line 935 | public class ForkJoinPool extends Abstra
935		* Returns an estimate of the number of threads that are currently
936		* idle waiting for tasks. This method may underestimate the
937		* number of idle threads.
938	<	* @return the number of idle threads.
938	>	*
939	>	* @return the number of idle threads
940		*/
941		final int getIdleThreadCount() {
942		int c = runningCountOf(workerCounts) - activeCountOf(runControl);
943	<	return (c <= 0)? 0 : c;
943	>	return (c <= 0) ? 0 : c;
944		}
945
946		/**
947		* Returns true if all worker threads are currently idle. An idle
948		* worker is one that cannot obtain a task to execute because none
949		* are available to steal from other threads, and there are no
950	<	* pending submissions to the pool. This method is conservative:
951	<	* It might not return true immediately upon idleness of all
950	>	* pending submissions to the pool. This method is conservative;
951	>	* it might not return true immediately upon idleness of all
952		* threads, but will eventually become true if threads remain
953		* inactive.
954	+	*
955		* @return true if all threads are currently idle
956		*/
957		public boolean isQuiescent() {
#	Line 843 | Line 963 | public class ForkJoinPool extends Abstra
963		* one thread's work queue by another. The reported value
964		* underestimates the actual total number of steals when the pool
965		* is not quiescent. This value may be useful for monitoring and
966	<	* tuning fork/join programs: In general, steal counts should be
966	>	* tuning fork/join programs: in general, steal counts should be
967		* high enough to keep threads busy, but low enough to avoid
968		* overhead and contention across threads.
969	<	* @return the number of steals.
969	>	*
970	>	* @return the number of steals
971		*/
972		public long getStealCount() {
973		return stealCount.get();
974		}
975
976		/**
977	<	* Accumulate steal count from a worker. Call only
978	<	* when worker known to be idle.
977	>	* Accumulates steal count from a worker.
978	>	* Call only when worker known to be idle.
979		*/
980		private void updateStealCount(ForkJoinWorkerThread w) {
981		int sc = w.getAndClearStealCount();
#	Line 869 | Line 990 | public class ForkJoinPool extends Abstra
990		* an approximation, obtained by iterating across all threads in
991		* the pool. This method may be useful for tuning task
992		* granularities.
993	<	* @return the number of queued tasks.
993	>	*
994	>	* @return the number of queued tasks
995		*/
996		public long getQueuedTaskCount() {
997		long count = 0;
998		ForkJoinWorkerThread[] ws = workers;
999	<	for (int i = 0; i < ws.length; ++i) {
1000	<	ForkJoinWorkerThread t = ws[i];
1001	<	if (t != null)
1002	<	count += t.getQueueSize();
999	>	if (ws != null) {
1000	>	for (int i = 0; i < ws.length; ++i) {
1001	>	ForkJoinWorkerThread t = ws[i];
1002	>	if (t != null)
1003	>	count += t.getQueueSize();
1004	>	}
1005		}
1006		return count;
1007		}
#	Line 886 | Line 1010 | public class ForkJoinPool extends Abstra
1010		* Returns an estimate of the number tasks submitted to this pool
1011		* that have not yet begun executing. This method takes time
1012		* proportional to the number of submissions.
1013	<	* @return the number of queued submissions.
1013	>	*
1014	>	* @return the number of queued submissions
1015		*/
1016		public int getQueuedSubmissionCount() {
1017		return submissionQueue.size();
#	Line 895 | Line 1020 | public class ForkJoinPool extends Abstra
1020		/**
1021		* Returns true if there are any tasks submitted to this pool
1022		* that have not yet begun executing.
1023	<	* @return <code>true</code> if there are any queued submissions.
1023	>	*
1024	>	* @return {@code true} if there are any queued submissions
1025		*/
1026		public boolean hasQueuedSubmissions() {
1027		return !submissionQueue.isEmpty();
#	Line 905 | Line 1031 | public class ForkJoinPool extends Abstra
1031		* Removes and returns the next unexecuted submission if one is
1032		* available.  This method may be useful in extensions to this
1033		* class that re-assign work in systems with multiple pools.
1034	+	*
1035		* @return the next submission, or null if none
1036		*/
1037		protected ForkJoinTask<?> pollSubmission() {
#	Line 912 | Line 1039 | public class ForkJoinPool extends Abstra
1039		}
1040
1041		/**
1042	+	* Removes all available unexecuted submitted and forked tasks
1043	+	* from scheduling queues and adds them to the given collection,
1044	+	* without altering their execution status. These may include
1045	+	* artificially generated or wrapped tasks. This method is designed
1046	+	* to be invoked only when the pool is known to be
1047	+	* quiescent. Invocations at other times may not remove all
1048	+	* tasks. A failure encountered while attempting to add elements
1049	+	* to collection {@code c} may result in elements being in
1050	+	* neither, either or both collections when the associated
1051	+	* exception is thrown.  The behavior of this operation is
1052	+	* undefined if the specified collection is modified while the
1053	+	* operation is in progress.
1054	+	*
1055	+	* @param c the collection to transfer elements into
1056	+	* @return the number of elements transferred
1057	+	*/
1058	+	protected int drainTasksTo(Collection<ForkJoinTask<?>> c) {
1059	+	int n = submissionQueue.drainTo(c);
1060	+	ForkJoinWorkerThread[] ws = workers;
1061	+	if (ws != null) {
1062	+	for (int i = 0; i < ws.length; ++i) {
1063	+	ForkJoinWorkerThread w = ws[i];
1064	+	if (w != null)
1065	+	n += w.drainTasksTo(c);
1066	+	}
1067	+	}
1068	+	return n;
1069	+	}
1070	+
1071	+	/**
1072		* Returns a string identifying this pool, as well as its state,
1073		* including indications of run state, parallelism level, and
1074		* worker and task counts.
#	Line 955 | Line 1112 | public class ForkJoinPool extends Abstra
1112		* Invocation has no additional effect if already shut down.
1113		* Tasks that are in the process of being submitted concurrently
1114		* during the course of this method may or may not be rejected.
1115	+	*
1116		* @throws SecurityException if a security manager exists and
1117		*         the caller is not permitted to modify threads
1118		*         because it does not hold {@link
1119	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1119	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1120		*/
1121		public void shutdown() {
1122		checkPermission();
#	Line 972 | Line 1130 | public class ForkJoinPool extends Abstra
1130		* waiting tasks.  Tasks that are in the process of being
1131		* submitted or executed concurrently during the course of this
1132		* method may or may not be rejected. Unlike some other executors,
1133	<	* this method cancels rather than collects non-executed tasks,
1134	<	* so always returns an empty list.
1133	>	* this method cancels rather than collects non-executed tasks
1134	>	* upon termination, so always returns an empty list. However, you
1135	>	* can use method {@code drainTasksTo} before invoking this
1136	>	* method to transfer unexecuted tasks to another collection.
1137	>	*
1138		* @return an empty list
1139		* @throws SecurityException if a security manager exists and
1140		*         the caller is not permitted to modify threads
1141		*         because it does not hold {@link
1142	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1142	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1143		*/
1144		public List<Runnable> shutdownNow() {
1145		checkPermission();
#	Line 987 | Line 1148 | public class ForkJoinPool extends Abstra
1148		}
1149
1150		/**
1151	<	* Returns <code>true</code> if all tasks have completed following shut down.
1151	>	* Returns {@code true} if all tasks have completed following shut down.
1152		*
1153	<	* @return <code>true</code> if all tasks have completed following shut down
1153	>	* @return {@code true} if all tasks have completed following shut down
1154		*/
1155		public boolean isTerminated() {
1156		return runStateOf(runControl) == TERMINATED;
1157		}
1158
1159		/**
1160	<	* Returns <code>true</code> if the process of termination has
1160	>	* Returns {@code true} if the process of termination has
1161		* commenced but possibly not yet completed.
1162		*
1163	<	* @return <code>true</code> if terminating
1163	>	* @return {@code true} if terminating
1164		*/
1165		public boolean isTerminating() {
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;
#	Line 1021 | Line 1182 | public class ForkJoinPool extends Abstra
1182		*
1183		* @param timeout the maximum time to wait
1184		* @param unit the time unit of the timeout argument
1185	<	* @return <code>true</code> if this executor terminated and
1186	<	*         <code>false</code> if the timeout elapsed before termination
1185	>	* @return {@code true} if this executor terminated and
1186	>	*         {@code false} if the timeout elapsed before termination
1187		* @throws InterruptedException if interrupted while waiting
1188		*/
1189		public boolean awaitTermination(long timeout, TimeUnit unit)
#	Line 1046 | Line 1207 | public class ForkJoinPool extends Abstra
1207		// Shutdown and termination support
1208
1209		/**
1210	<	* Callback from terminating worker. Null out the corresponding
1211	<	* workers slot, and if terminating, try to terminate, else try to
1212	<	* shrink workers array.
1210	>	* Callback from terminating worker. Nulls out the corresponding
1211	>	* workers slot, and if terminating, tries to terminate; else
1212	>	* tries to shrink workers array.
1213	>	*
1214		* @param w the worker
1215		*/
1216		final void workerTerminated(ForkJoinWorkerThread w) {
#	Line 1058 | Line 1220 | public class ForkJoinPool extends Abstra
1220		lock.lock();
1221		try {
1222		ForkJoinWorkerThread[] ws = workers;
1223	<	int idx = w.poolIndex;
1224	<	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1225	<	ws[idx] = null;
1226	<	if (totalCountOf(workerCounts) == 0) {
1227	<	terminate(); // no-op if already terminating
1228	<	transitionRunStateTo(TERMINATED);
1229	<	termination.signalAll();
1230	<	}
1231	<	else if (!isTerminating()) {
1232	<	tryShrinkWorkerArray();
1233	<	tryResumeSpare(true); // allow replacement
1223	>	if (ws != null) {
1224	>	int idx = w.poolIndex;
1225	>	if (idx >= 0 && idx < ws.length && ws[idx] == w)
1226	>	ws[idx] = null;
1227	>	if (totalCountOf(workerCounts) == 0) {
1228	>	terminate(); // no-op if already terminating
1229	>	transitionRunStateTo(TERMINATED);
1230	>	termination.signalAll();
1231	>	}
1232	>	else if (!isTerminating()) {
1233	>	tryShrinkWorkerArray();
1234	>	tryResumeSpare(true); // allow replacement
1235	>	}
1236		}
1237		} finally {
1238		lock.unlock();
#	Line 1077 | Line 1241 | public class ForkJoinPool extends Abstra
1241		}
1242
1243		/**
1244	<	* Initiate termination.
1244	>	* Initiates termination.
1245		*/
1246		private void terminate() {
1247		if (transitionRunStateTo(TERMINATING)) {
#	Line 1092 | Line 1256 | public class ForkJoinPool extends Abstra
1256		}
1257
1258		/**
1259	<	* Possibly terminate when on shutdown state
1259	>	* Possibly terminates when on shutdown state.
1260		*/
1261		private void terminateOnShutdown() {
1262		if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
#	Line 1100 | Line 1264 | public class ForkJoinPool extends Abstra
1264		}
1265
1266		/**
1267	<	* Clear out and cancel submissions
1267	>	* Clears out and cancels submissions.
1268		*/
1269		private void cancelQueuedSubmissions() {
1270		ForkJoinTask<?> task;
#	Line 1109 | Line 1273 | public class ForkJoinPool extends Abstra
1273		}
1274
1275		/**
1276	<	* Clean out worker queues.
1276	>	* Cleans out worker queues.
1277		*/
1278		private void cancelQueuedWorkerTasks() {
1279		final ReentrantLock lock = this.workerLock;
1280		lock.lock();
1281		try {
1282		ForkJoinWorkerThread[] ws = workers;
1283	<	for (int i = 0; i < ws.length; ++i) {
1284	<	ForkJoinWorkerThread t = ws[i];
1285	<	if (t != null)
1286	<	t.cancelTasks();
1283	>	if (ws != null) {
1284	>	for (int i = 0; i < ws.length; ++i) {
1285	>	ForkJoinWorkerThread t = ws[i];
1286	>	if (t != null)
1287	>	t.cancelTasks();
1288	>	}
1289		}
1290		} finally {
1291		lock.unlock();
#	Line 1127 | Line 1293 | public class ForkJoinPool extends Abstra
1293		}
1294
1295		/**
1296	<	* Set each worker's status to terminating. Requires lock to avoid
1297	<	* conflicts with add/remove
1296	>	* Sets each worker's status to terminating. Requires lock to avoid
1297	>	* conflicts with add/remove.
1298		*/
1299		private void stopAllWorkers() {
1300		final ReentrantLock lock = this.workerLock;
1301		lock.lock();
1302		try {
1303		ForkJoinWorkerThread[] ws = workers;
1304	<	for (int i = 0; i < ws.length; ++i) {
1305	<	ForkJoinWorkerThread t = ws[i];
1306	<	if (t != null)
1307	<	t.shutdownNow();
1304	>	if (ws != null) {
1305	>	for (int i = 0; i < ws.length; ++i) {
1306	>	ForkJoinWorkerThread t = ws[i];
1307	>	if (t != null)
1308	>	t.shutdownNow();
1309	>	}
1310		}
1311		} finally {
1312		lock.unlock();
#	Line 1146 | Line 1314 | public class ForkJoinPool extends Abstra
1314		}
1315
1316		/**
1317	<	* Interrupt all unterminated workers.  This is not required for
1317	>	* Interrupts all unterminated workers.  This is not required for
1318		* sake of internal control, but may help unstick user code during
1319		* shutdown.
1320		*/
#	Line 1155 | Line 1323 | public class ForkJoinPool extends Abstra
1323		lock.lock();
1324		try {
1325		ForkJoinWorkerThread[] ws = workers;
1326	<	for (int i = 0; i < ws.length; ++i) {
1327	<	ForkJoinWorkerThread t = ws[i];
1328	<	if (t != null && !t.isTerminated()) {
1329	<	try {
1330	<	t.interrupt();
1331	<	} catch (SecurityException ignore) {
1326	>	if (ws != null) {
1327	>	for (int i = 0; i < ws.length; ++i) {
1328	>	ForkJoinWorkerThread t = ws[i];
1329	>	if (t != null && !t.isTerminated()) {
1330	>	try {
1331	>	t.interrupt();
1332	>	} catch (SecurityException ignore) {
1333	>	}
1334		}
1335		}
1336		}
#	Line 1214 | Line 1384 | public class ForkJoinPool extends Abstra
1384		}
1385
1386		/**
1387	<	* Wake up waiter, returning false if known to already
1387	>	* Wakes up waiter, returning false if known to already
1388		*/
1389		boolean signal() {
1390		ForkJoinWorkerThread t = thread;
#	Line 1226 | Line 1396 | public class ForkJoinPool extends Abstra
1396		}
1397
1398		/**
1399	<	* Await release on sync
1399	>	* Awaits release on sync.
1400		*/
1401		void awaitSyncRelease(ForkJoinPool p) {
1402		while (thread != null && !p.syncIsReleasable(this))
#	Line 1234 | Line 1404 | public class ForkJoinPool extends Abstra
1404		}
1405
1406		/**
1407	<	* Await resumption as spare
1407	>	* Awaits resumption as spare.
1408		*/
1409		void awaitSpareRelease() {
1410		while (thread != null) {
#	Line 1248 | Line 1418 | public class ForkJoinPool extends Abstra
1418		* Ensures that no thread is waiting for count to advance from the
1419		* current value of eventCount read on entry to this method, by
1420		* releasing waiting threads if necessary.
1421	+	*
1422		* @return the count
1423		*/
1424		final long ensureSync() {
#	Line 1269 | Line 1440 | public class ForkJoinPool extends Abstra
1440		*/
1441		private void signalIdleWorkers() {
1442		long c;
1443	<	do;while (!casEventCount(c = eventCount, c+1));
1443	>	do {} while (!casEventCount(c = eventCount, c+1));
1444		ensureSync();
1445		}
1446
1447		/**
1448	<	* Signal threads waiting to poll a task. Because method sync
1448	>	* Signals threads waiting to poll a task. Because method sync
1449		* rechecks availability, it is OK to only proceed if queue
1450		* appears to be non-empty, and OK to skip under contention to
1451		* increment count (since some other thread succeeded).
#	Line 1293 | Line 1464 | public class ForkJoinPool extends Abstra
1464		* Waits until event count advances from last value held by
1465		* caller, or if excess threads, caller is resumed as spare, or
1466		* caller or pool is terminating. Updates caller's event on exit.
1467	+	*
1468		* @param w the calling worker thread
1469		*/
1470		final void sync(ForkJoinWorkerThread w) {
#	Line 1323 | Line 1495 | public class ForkJoinPool extends Abstra
1495		* Returns true if worker waiting on sync can proceed:
1496		*  - on signal (thread == null)
1497		*  - on event count advance (winning race to notify vs signaller)
1498	<	*  - on Interrupt
1498	>	*  - on interrupt
1499		*  - if the first queued node, we find work available
1500		* If node was not signalled and event count not advanced on exit,
1501		* then we also help advance event count.
1502	+	*
1503		* @return true if node can be released
1504		*/
1505		final boolean syncIsReleasable(WaitQueueNode node) {
#	Line 1361 | Line 1534 | public class ForkJoinPool extends Abstra
1534		//  Parallelism maintenance
1535
1536		/**
1537	<	* Decrement running count; if too low, add spare.
1537	>	* Decrements running count; if too low, adds spare.
1538		*
1539		* Conceptually, all we need to do here is add or resume a
1540		* spare thread when one is about to block (and remove or
1541		* suspend it later when unblocked -- see suspendIfSpare).
1542		* However, implementing this idea requires coping with
1543	<	* several problems: We have imperfect information about the
1543	>	* several problems: we have imperfect information about the
1544		* states of threads. Some count updates can and usually do
1545		* lag run state changes, despite arrangements to keep them
1546		* accurate (for example, when possible, updating counts
#	Line 1381 | Line 1554 | public class ForkJoinPool extends Abstra
1554		* only be suspended or removed when they are idle, not
1555		* immediately when they aren't needed. So adding threads will
1556		* raise parallelism level for longer than necessary.  Also,
1557	<	* FJ applications often enounter highly transient peaks when
1557	>	* FJ applications often encounter highly transient peaks when
1558		* many threads are blocked joining, but for less time than it
1559		* takes to create or resume spares.
1560		*
#	Line 1390 | Line 1563 | public class ForkJoinPool extends Abstra
1563		* target counts, else create only to avoid starvation
1564		* @return true if joinMe known to be done
1565		*/
1566	<	final boolean preJoin(ForkJoinTask<?> joinMe, boolean maintainParallelism) {
1566	>	final boolean preJoin(ForkJoinTask<?> joinMe,
1567	>	boolean maintainParallelism) {
1568		maintainParallelism &= maintainsParallelism; // overrride
1569		boolean dec = false;  // true when running count decremented
1570		while (spareStack == null || !tryResumeSpare(dec)) {
1571		int counts = workerCounts;
1572	<	if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat
1572	>	if (dec || (dec = casWorkerCounts(counts, --counts))) {
1573	>	// CAS cheat
1574		if (!needSpare(counts, maintainParallelism))
1575		break;
1576		if (joinMe.status < 0)
#	Line 1410 | Line 1585 | public class ForkJoinPool extends Abstra
1585		/**
1586		* Same idea as preJoin
1587		*/
1588	<	final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){
1588	>	final boolean preBlock(ManagedBlocker blocker,
1589	>	boolean maintainParallelism) {
1590		maintainParallelism &= maintainsParallelism;
1591		boolean dec = false;
1592		while (spareStack == null || !tryResumeSpare(dec)) {
#	Line 1434 | Line 1610 | public class ForkJoinPool extends Abstra
1610		* there is apparently some work to do.  This self-limiting rule
1611		* means that the more threads that have already been added, the
1612		* less parallelism we will tolerate before adding another.
1613	+	*
1614		* @param counts current worker counts
1615		* @param maintainParallelism try to maintain parallelism
1616		*/
#	Line 1451 | Line 1628 | public class ForkJoinPool extends Abstra
1628		}
1629
1630		/**
1631	<	* Add a spare worker if lock available and no more than the
1632	<	* expected numbers of threads exist
1631	>	* Adds a spare worker if lock available and no more than the
1632	>	* expected numbers of threads exist.
1633	>	*
1634		* @return true if successful
1635		*/
1636		private boolean tryAddSpare(int expectedCounts) {
#	Line 1485 | Line 1663 | public class ForkJoinPool extends Abstra
1663		}
1664
1665		/**
1666	<	* Add the kth spare worker. On entry, pool coounts are already
1666	>	* Adds the kth spare worker. On entry, pool counts are already
1667		* adjusted to reflect addition.
1668		*/
1669		private void createAndStartSpare(int k) {
#	Line 1507 | Line 1685 | public class ForkJoinPool extends Abstra
1685		}
1686
1687		/**
1688	<	* Suspend calling thread w if there are excess threads.  Called
1689	<	* only from sync.  Spares are enqueued in a Treiber stack
1690	<	* using the same WaitQueueNodes as barriers.  They are resumed
1691	<	* mainly in preJoin, but are also woken on pool events that
1692	<	* require all threads to check run state.
1688	>	* Suspends calling thread w if there are excess threads.  Called
1689	>	* only from sync.  Spares are enqueued in a Treiber stack using
1690	>	* the same WaitQueueNodes as barriers.  They are resumed mainly
1691	>	* in preJoin, but are also woken on pool events that require all
1692	>	* threads to check run state.
1693	>	*
1694		* @param w the caller
1695		*/
1696		private boolean suspendIfSpare(ForkJoinWorkerThread w) {
#	Line 1522 | Line 1701 | public class ForkJoinPool extends Abstra
1701		node = new WaitQueueNode(0, w);
1702		if (casWorkerCounts(s, s-1)) { // representation-dependent
1703		// push onto stack
1704	<	do;while (!casSpareStack(node.next = spareStack, node));
1704	>	do {} while (!casSpareStack(node.next = spareStack, node));
1705		// block until released by resumeSpare
1706		node.awaitSpareRelease();
1707		return true;
#	Line 1532 | Line 1711 | public class ForkJoinPool extends Abstra
1711		}
1712
1713		/**
1714	<	* Try to pop and resume a spare thread.
1714	>	* Tries to pop and resume a spare thread.
1715	>	*
1716		* @param updateCount if true, increment running count on success
1717		* @return true if successful
1718		*/
#	Line 1550 | Line 1730 | public class ForkJoinPool extends Abstra
1730		}
1731
1732		/**
1733	<	* Pop and resume all spare threads. Same idea as ensureSync.
1733	>	* Pops and resumes all spare threads. Same idea as ensureSync.
1734	>	*
1735		* @return true if any spares released
1736		*/
1737		private boolean resumeAllSpares() {
#	Line 1568 | Line 1749 | public class ForkJoinPool extends Abstra
1749		}
1750
1751		/**
1752	<	* Pop and shutdown excessive spare threads. Call only while
1752	>	* Pops and shuts down excessive spare threads. Call only while
1753		* holding lock. This is not guaranteed to eliminate all excess
1754		* threads, only those suspended as spares, which are the ones
1755		* unlikely to be needed in the future.
#	Line 1593 | Line 1774 | public class ForkJoinPool extends Abstra
1774		/**
1775		* Interface for extending managed parallelism for tasks running
1776		* in ForkJoinPools. A ManagedBlocker provides two methods.
1777	<	* Method <code>isReleasable</code> must return true if blocking is not
1778	<	* necessary. Method <code>block</code> blocks the current thread
1779	<	* if necessary (perhaps internally invoking isReleasable before
1780	<	* actually blocking.).
1777	>	* Method {@code isReleasable} must return true if blocking is not
1778	>	* necessary. Method {@code block} blocks the current thread if
1779	>	* necessary (perhaps internally invoking {@code isReleasable}
1780	>	* before actually blocking.).
1781	>	*
1782		* <p>For example, here is a ManagedBlocker based on a
1783		* ReentrantLock:
1784	<	* <pre>
1785	<	*   class ManagedLocker implements ManagedBlocker {
1786	<	*     final ReentrantLock lock;
1787	<	*     boolean hasLock = false;
1788	<	*     ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1789	<	*     public boolean block() {
1790	<	*        if (!hasLock)
1791	<	*           lock.lock();
1792	<	*        return true;
1793	<	*     }
1794	<	*     public boolean isReleasable() {
1795	<	*        return hasLock || (hasLock = lock.tryLock());
1614	<	*     }
1784	>	*  <pre> {@code
1785	>	* class ManagedLocker implements ManagedBlocker {
1786	>	*   final ReentrantLock lock;
1787	>	*   boolean hasLock = false;
1788	>	*   ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1789	>	*   public boolean block() {
1790	>	*     if (!hasLock)
1791	>	*       lock.lock();
1792	>	*     return true;
1793	>	*   }
1794	>	*   public boolean isReleasable() {
1795	>	*     return hasLock || (hasLock = lock.tryLock());
1796		*   }
1797	<	* </pre>
1797	>	* }}</pre>
1798		*/
1799		public static interface ManagedBlocker {
1800		/**
1801		* Possibly blocks the current thread, for example waiting for
1802		* a lock or condition.
1803	+	*
1804		* @return true if no additional blocking is necessary (i.e.,
1805	<	* if isReleasable would return true).
1805	>	* if isReleasable would return true)
1806		* @throws InterruptedException if interrupted while waiting
1807	<	* (the method is not required to do so, but is allowe to).
1807	>	* (the method is not required to do so, but is allowed to)
1808		*/
1809		boolean block() throws InterruptedException;
1810
#	Line 1637 | Line 1819 | public class ForkJoinPool extends Abstra
1819		* is a ForkJoinWorkerThread, this method possibly arranges for a
1820		* spare thread to be activated if necessary to ensure parallelism
1821		* while the current thread is blocked.  If
1822	<	* <code>maintainParallelism</code> is true and the pool supports
1822	>	* {@code maintainParallelism} is true and the pool supports
1823		* it ({@link #getMaintainsParallelism}), this method attempts to
1824	<	* maintain the pool's nominal parallelism. Otherwise if activates
1824	>	* maintain the pool's nominal parallelism. Otherwise it activates
1825		* a thread only if necessary to avoid complete starvation. This
1826		* option may be preferable when blockages use timeouts, or are
1827		* almost always brief.
1828		*
1829		* <p> If the caller is not a ForkJoinTask, this method is behaviorally
1830		* equivalent to
1831	<	* <pre>
1832	<	*   while (!blocker.isReleasable())
1833	<	*      if (blocker.block())
1834	<	*         return;
1835	<	* </pre>
1831	>	*  <pre> {@code
1832	>	* while (!blocker.isReleasable())
1833	>	*   if (blocker.block())
1834	>	*     return;
1835	>	* }</pre>
1836		* If the caller is a ForkJoinTask, then the pool may first
1837		* be expanded to ensure parallelism, and later adjusted.
1838		*
#	Line 1659 | Line 1841 | public class ForkJoinPool extends Abstra
1841		* attempt to maintain the pool's nominal parallelism; otherwise
1842		* activate a thread only if necessary to avoid complete
1843		* starvation.
1844	<	* @throws InterruptedException if blocker.block did so.
1844	>	* @throws InterruptedException if blocker.block did so
1845		*/
1846		public static void managedBlock(ManagedBlocker blocker,
1847		boolean maintainParallelism)
1848		throws InterruptedException {
1849		Thread t = Thread.currentThread();
1850	<	ForkJoinPool pool = (t instanceof ForkJoinWorkerThread?
1851	<	((ForkJoinWorkerThread)t).pool : null);
1850	>	ForkJoinPool pool = ((t instanceof ForkJoinWorkerThread) ?
1851	>	((ForkJoinWorkerThread) t).pool : null);
1852		if (!blocker.isReleasable()) {
1853		try {
1854		if (pool == null ||
#	Line 1681 | Line 1863 | public class ForkJoinPool extends Abstra
1863
1864		private static void awaitBlocker(ManagedBlocker blocker)
1865		throws InterruptedException {
1866	<	do;while (!blocker.isReleasable() && !blocker.block());
1866	>	do {} while (!blocker.isReleasable() && !blocker.block());
1867		}
1868
1869		// AbstractExecutorService overrides
1870
1871		protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
1872	<	return new AdaptedRunnable(runnable, value);
1872	>	return new AdaptedRunnable<T>(runnable, value);
1873		}
1874
1875		protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
1876	<	return new AdaptedCallable(callable);
1876	>	return new AdaptedCallable<T>(callable);
1877		}
1878
1879
1880	<	// Temporary Unsafe mechanics for preliminary release
1881	<	private static Unsafe getUnsafe() throws Throwable {
1880	>	// Unsafe mechanics for jsr166y 3rd party package.
1881	>	private static sun.misc.Unsafe getUnsafe() {
1882		try {
1883	<	return Unsafe.getUnsafe();
1883	>	return sun.misc.Unsafe.getUnsafe();
1884		} catch (SecurityException se) {
1885		try {
1886		return java.security.AccessController.doPrivileged
1887	<	(new java.security.PrivilegedExceptionAction<Unsafe>() {
1888	<	public Unsafe run() throws Exception {
1889	<	return getUnsafePrivileged();
1887	>	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1888	>	public sun.misc.Unsafe run() throws Exception {
1889	>	return getUnsafeByReflection();
1890		}});
1891		} catch (java.security.PrivilegedActionException e) {
1892	<	throw e.getCause();
1892	>	throw new RuntimeException("Could not initialize intrinsics",
1893	>	e.getCause());
1894		}
1895		}
1896		}
1897
1898	<	private static Unsafe getUnsafePrivileged()
1898	>	private static sun.misc.Unsafe getUnsafeByReflection()
1899		throws NoSuchFieldException, IllegalAccessException {
1900	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1900	>	java.lang.reflect.Field f =
1901	>	sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
1902		f.setAccessible(true);
1903	<	return (Unsafe) f.get(null);
1903	>	return (sun.misc.Unsafe) f.get(null);
1904		}
1905
1906	<	private static long fieldOffset(String fieldName)
1723	<	throws NoSuchFieldException {
1724	<	return _unsafe.objectFieldOffset
1725	<	(ForkJoinPool.class.getDeclaredField(fieldName));
1726	<	}
1727	<
1728	<	static final Unsafe _unsafe;
1729	<	static final long eventCountOffset;
1730	<	static final long workerCountsOffset;
1731	<	static final long runControlOffset;
1732	<	static final long syncStackOffset;
1733	<	static final long spareStackOffset;
1734	<
1735	<	static {
1906	>	private static long fieldOffset(String fieldName, Class<?> klazz) {
1907		try {
1908	<	_unsafe = getUnsafe();
1909	<	eventCountOffset = fieldOffset("eventCount");
1910	<	workerCountsOffset = fieldOffset("workerCounts");
1911	<	runControlOffset = fieldOffset("runControl");
1912	<	syncStackOffset = fieldOffset("syncStack");
1913	<	spareStackOffset = fieldOffset("spareStack");
1743	<	} catch (Throwable e) {
1744	<	throw new RuntimeException("Could not initialize intrinsics", e);
1908	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(fieldName));
1909	>	} catch (NoSuchFieldException e) {
1910	>	// Convert Exception to Error
1911	>	NoSuchFieldError error = new NoSuchFieldError(fieldName);
1912	>	error.initCause(e);
1913	>	throw error;
1914		}
1915		}
1916
1917	+	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1918	+	static final long eventCountOffset =
1919	+	fieldOffset("eventCount", ForkJoinPool.class);
1920	+	static final long workerCountsOffset =
1921	+	fieldOffset("workerCounts", ForkJoinPool.class);
1922	+	static final long runControlOffset =
1923	+	fieldOffset("runControl", ForkJoinPool.class);
1924	+	static final long syncStackOffset =
1925	+	fieldOffset("syncStack",ForkJoinPool.class);
1926	+	static final long spareStackOffset =
1927	+	fieldOffset("spareStack", ForkJoinPool.class);
1928	+
1929		private boolean casEventCount(long cmp, long val) {
1930	<	return _unsafe.compareAndSwapLong(this, eventCountOffset, cmp, val);
1930	>	return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
1931		}
1932		private boolean casWorkerCounts(int cmp, int val) {
1933	<	return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1933	>	return UNSAFE.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1934		}
1935		private boolean casRunControl(int cmp, int val) {
1936	<	return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val);
1936	>	return UNSAFE.compareAndSwapInt(this, runControlOffset, cmp, val);
1937		}
1938		private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) {
1939	<	return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val);
1939	>	return UNSAFE.compareAndSwapObject(this, spareStackOffset, cmp, val);
1940		}
1941		private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1942	<	return _unsafe.compareAndSwapObject(this, syncStackOffset, cmp, val);
1942	>	return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val);
1943		}
1944		}

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