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Comparing jsr166/src/jsr166e/ForkJoinPool.java (file contents):
Revision 1.57 by jsr166, Sat Feb 16 20:50:29 2013 UTC vs.
Revision 1.58 by dl, Wed Jun 19 14:55:40 2013 UTC

#	Line 6 | Line 6
6
7		package jsr166e;
8
9	+	import java.lang.Thread.UncaughtExceptionHandler;
10		import java.util.ArrayList;
11		import java.util.Arrays;
12		import java.util.Collection;
#	Line 17 | Line 18 | import java.util.concurrent.ExecutorServ
18		import java.util.concurrent.Future;
19		import java.util.concurrent.RejectedExecutionException;
20		import java.util.concurrent.RunnableFuture;
21	+	import java.util.concurrent.ThreadLocalRandom;
22		import java.util.concurrent.TimeUnit;
23
24		/**
#	Line 49 | Line 51 | import java.util.concurrent.TimeUnit;
51		* level; by default, equal to the number of available processors. The
52		* pool attempts to maintain enough active (or available) threads by
53		* dynamically adding, suspending, or resuming internal worker
54	<	* threads, even if some tasks are stalled waiting to join
55	<	* others. However, no such adjustments are guaranteed in the face of
56	<	* blocked I/O or other unmanaged synchronization. The nested {@link
54	>	* threads, even if some tasks are stalled waiting to join others.
55	>	* However, no such adjustments are guaranteed in the face of blocked
56	>	* I/O or other unmanaged synchronization. The nested {@link
57		* ManagedBlocker} interface enables extension of the kinds of
58		* synchronization accommodated.
59		*
#	Line 75 | Line 77 | import java.util.concurrent.TimeUnit;
77		* there is little difference among choice of methods.
78		*
79		* <table BORDER CELLPADDING=3 CELLSPACING=1>
80	+	* <caption>Summary of task execution methods</caption>
81		*  <tr>
82		*    <td></td>
83		*    <td ALIGN=CENTER> <b>Call from non-fork/join clients</b></td>
84		*    <td ALIGN=CENTER> <b>Call from within fork/join computations</b></td>
85		*  </tr>
86		*  <tr>
87	<	*    <td> <b>Arrange async execution</td>
87	>	*    <td> <b>Arrange async execution</b></td>
88		*    <td> {@link #execute(ForkJoinTask)}</td>
89		*    <td> {@link ForkJoinTask#fork}</td>
90		*  </tr>
91		*  <tr>
92	<	*    <td> <b>Await and obtain result</td>
92	>	*    <td> <b>Await and obtain result</b></td>
93		*    <td> {@link #invoke(ForkJoinTask)}</td>
94		*    <td> {@link ForkJoinTask#invoke}</td>
95		*  </tr>
96		*  <tr>
97	<	*    <td> <b>Arrange exec and obtain Future</td>
97	>	*    <td> <b>Arrange exec and obtain Future</b></td>
98		*    <td> {@link #submit(ForkJoinTask)}</td>
99		*    <td> {@link ForkJoinTask#fork} (ForkJoinTasks <em>are</em> Futures)</td>
100		*  </tr>
101		* </table>
102		*
103		* <p>The common pool is by default constructed with default
104	<	* parameters, but these may be controlled by setting three {@link
105	<	* System#getProperty system properties} with prefix {@code
106	<	* java.util.concurrent.ForkJoinPool.common}: {@code parallelism} --
107	<	* an integer greater than zero, {@code threadFactory} -- the class
108	<	* name of a {@link ForkJoinWorkerThreadFactory}, and {@code
109	<	* exceptionHandler} -- the class name of a {@link
110	<	* java.lang.Thread.UncaughtExceptionHandler
111	<	* Thread.UncaughtExceptionHandler}. Upon any error in establishing
112	<	* these settings, default parameters are used.
104	>	* parameters, but these may be controlled by setting three
105	>	* {@linkplain System#getProperty system properties}:
106	>	* <ul>
107	>	* <li>{@code java.util.concurrent.ForkJoinPool.common.parallelism}
108	>	* - the parallelism level, a non-negative integer
109	>	* <li>{@code java.util.concurrent.ForkJoinPool.common.threadFactory}
110	>	* - the class name of a {@link ForkJoinWorkerThreadFactory}
111	>	* <li>{@code java.util.concurrent.ForkJoinPool.common.exceptionHandler}
112	>	* - the class name of a {@link UncaughtExceptionHandler}
113	>	* </ul>
114	>	* The system class loader is used to load these classes.
115	>	* Upon any error in establishing these settings, default parameters
116	>	* are used. It is possible to disable or limit the use of threads in
117	>	* the common pool by setting the parallelism property to zero, and/or
118	>	* using a factory that may return {@code null}.
119		*
120		* <p><b>Implementation notes</b>: This implementation restricts the
121		* maximum number of running threads to 32767. Attempts to create
#	Line 152 | Line 161 | public class ForkJoinPool extends Abstra
161		* (http://research.sun.com/scalable/pubs/index.html) and
162		* "Idempotent work stealing" by Michael, Saraswat, and Vechev,
163		* PPoPP 2009 (http://portal.acm.org/citation.cfm?id=1504186).
164	<	* The main differences ultimately stem from GC requirements that
165	<	* we null out taken slots as soon as we can, to maintain as small
166	<	* a footprint as possible even in programs generating huge
167	<	* numbers of tasks. To accomplish this, we shift the CAS
168	<	* arbitrating pop vs poll (steal) from being on the indices
169	<	* ("base" and "top") to the slots themselves.  So, both a
170	<	* successful pop and poll mainly entail a CAS of a slot from
171	<	* non-null to null.  Because we rely on CASes of references, we
172	<	* do not need tag bits on base or top.  They are simple ints as
173	<	* used in any circular array-based queue (see for example
174	<	* ArrayDeque).  Updates to the indices must still be ordered in a
175	<	* way that guarantees that top == base means the queue is empty,
176	<	* but otherwise may err on the side of possibly making the queue
177	<	* appear nonempty when a push, pop, or poll have not fully
178	<	* committed. Note that this means that the poll operation,
179	<	* considered individually, is not wait-free. One thief cannot
180	<	* successfully continue until another in-progress one (or, if
181	<	* previously empty, a push) completes.  However, in the
182	<	* aggregate, we ensure at least probabilistic non-blockingness.
183	<	* If an attempted steal fails, a thief always chooses a different
184	<	* random victim target to try next. So, in order for one thief to
185	<	* progress, it suffices for any in-progress poll or new push on
186	<	* any empty queue to complete. (This is why we normally use
187	<	* method pollAt and its variants that try once at the apparent
188	<	* base index, else consider alternative actions, rather than
189	<	* method poll.)
164	>	* See also "Correct and Efficient Work-Stealing for Weak Memory
165	>	* Models" by Le, Pop, Cohen, and Nardelli, PPoPP 2013
166	>	* (http://www.di.ens.fr/~zappa/readings/ppopp13.pdf) for an
167	>	* analysis of memory ordering (atomic, volatile etc) issues.  The
168	>	* main differences ultimately stem from GC requirements that we
169	>	* null out taken slots as soon as we can, to maintain as small a
170	>	* footprint as possible even in programs generating huge numbers
171	>	* of tasks. To accomplish this, we shift the CAS arbitrating pop
172	>	* vs poll (steal) from being on the indices ("base" and "top") to
173	>	* the slots themselves.  So, both a successful pop and poll
174	>	* mainly entail a CAS of a slot from non-null to null.  Because
175	>	* we rely on CASes of references, we do not need tag bits on base
176	>	* or top.  They are simple ints as used in any circular
177	>	* array-based queue (see for example ArrayDeque).  Updates to the
178	>	* indices must still be ordered in a way that guarantees that top
179	>	* == base means the queue is empty, but otherwise may err on the
180	>	* side of possibly making the queue appear nonempty when a push,
181	>	* pop, or poll have not fully committed. Note that this means
182	>	* that the poll operation, considered individually, is not
183	>	* wait-free. One thief cannot successfully continue until another
184	>	* in-progress one (or, if previously empty, a push) completes.
185	>	* However, in the aggregate, we ensure at least probabilistic
186	>	* non-blockingness.  If an attempted steal fails, a thief always
187	>	* chooses a different random victim target to try next. So, in
188	>	* order for one thief to progress, it suffices for any
189	>	* in-progress poll or new push on any empty queue to
190	>	* complete. (This is why we normally use method pollAt and its
191	>	* variants that try once at the apparent base index, else
192	>	* consider alternative actions, rather than method poll.)
193		*
194		* This approach also enables support of a user mode in which local
195		* task processing is in FIFO, not LIFO order, simply by using
#	Line 196 | Line 208 | public class ForkJoinPool extends Abstra
208		* for work-stealing (this would contaminate lifo/fifo
209		* processing). Instead, we randomly associate submission queues
210		* with submitting threads, using a form of hashing.  The
211	<	* ThreadLocal Submitter class contains a value initially used as
212	<	* a hash code for choosing existing queues, but may be randomly
213	<	* repositioned upon contention with other submitters.  In
214	<	* essence, submitters act like workers except that they are
215	<	* restricted to executing local tasks that they submitted (or in
216	<	* the case of CountedCompleters, others with the same root task).
217	<	* However, because most shared/external queue operations are more
218	<	* expensive than internal, and because, at steady state, external
219	<	* submitters will compete for CPU with workers, ForkJoinTask.join
220	<	* and related methods disable them from repeatedly helping to
221	<	* process tasks if all workers are active.  Insertion of tasks in
222	<	* shared mode requires a lock (mainly to protect in the case of
211	>	* Submitter probe value serves as a hash code for
212	>	* choosing existing queues, and may be randomly repositioned upon
213	>	* contention with other submitters.  In essence, submitters act
214	>	* like workers except that they are restricted to executing local
215	>	* tasks that they submitted (or in the case of CountedCompleters,
216	>	* others with the same root task).  However, because most
217	>	* shared/external queue operations are more expensive than
218	>	* internal, and because, at steady state, external submitters
219	>	* will compete for CPU with workers, ForkJoinTask.join and
220	>	* related methods disable them from repeatedly helping to process
221	>	* tasks if all workers are active.  Insertion of tasks in shared
222	>	* mode requires a lock (mainly to protect in the case of
223		* resizing) but we use only a simple spinlock (using bits in
224		* field qlock), because submitters encountering a busy queue move
225		* on to try or create other queues -- they block only when
#	Line 297 | Line 309 | public class ForkJoinPool extends Abstra
309		* has not yet entered the wait queue. We solve this by requiring
310		* a full sweep of all workers (via repeated calls to method
311		* scan()) both before and after a newly waiting worker is added
312	<	* to the wait queue. During a rescan, the worker might release
313	<	* some other queued worker rather than itself, which has the same
314	<	* net effect. Because enqueued workers may actually be rescanning
315	<	* rather than waiting, we set and clear the "parker" field of
316	<	* WorkQueues to reduce unnecessary calls to unpark.  (This
317	<	* requires a secondary recheck to avoid missed signals.)  Note
318	<	* the unusual conventions about Thread.interrupts surrounding
319	<	* parking and other blocking: Because interrupts are used solely
320	<	* to alert threads to check termination, which is checked anyway
321	<	* upon blocking, we clear status (using Thread.interrupted)
322	<	* before any call to park, so that park does not immediately
311	<	* return due to status being set via some other unrelated call to
312	<	* interrupt in user code.
312	>	* to the wait queue.  Because enqueued workers may actually be
313	>	* rescanning rather than waiting, we set and clear the "parker"
314	>	* field of WorkQueues to reduce unnecessary calls to unpark.
315	>	* (This requires a secondary recheck to avoid missed signals.)
316	>	* Note the unusual conventions about Thread.interrupts
317	>	* surrounding parking and other blocking: Because interrupts are
318	>	* used solely to alert threads to check termination, which is
319	>	* checked anyway upon blocking, we clear status (using
320	>	* Thread.interrupted) before any call to park, so that park does
321	>	* not immediately return due to status being set via some other
322	>	* unrelated call to interrupt in user code.
323		*
324		* Signalling.  We create or wake up workers only when there
325		* appears to be at least one task they might be able to find and
326	<	* execute. However, many other threads may notice the same task
327	<	* and each signal to wake up a thread that might take it. So in
328	<	* general, pools will be over-signalled.  When a submission is
329	<	* added or another worker adds a task to a queue that has fewer
330	<	* than two tasks, they signal waiting workers (or trigger
331	<	* creation of new ones if fewer than the given parallelism level
332	<	* -- signalWork), and may leave a hint to the unparked worker to
333	<	* help signal others upon wakeup).  These primary signals are
324	<	* buttressed by others (see method helpSignal) whenever other
325	<	* threads scan for work or do not have a task to process.  On
326	<	* most platforms, signalling (unpark) overhead time is noticeably
326	>	* execute.  When a submission is added or another worker adds a
327	>	* task to a queue that has fewer than two tasks, they signal
328	>	* waiting workers (or trigger creation of new ones if fewer than
329	>	* the given parallelism level -- signalWork).  These primary
330	>	* signals are buttressed by others whenever other threads remove
331	>	* a task from a queue and notice that there are other tasks there
332	>	* as well.  So in general, pools will be over-signalled. On most
333	>	* platforms, signalling (unpark) overhead time is noticeably
334		* long, and the time between signalling a thread and it actually
335		* making progress can be very noticeably long, so it is worth
336		* offloading these delays from critical paths as much as
337	<	* possible.
337	>	* possible. Additionally, workers spin-down gradually, by staying
338	>	* alive so long as they see the ctl state changing.  Similar
339	>	* stability-sensing techniques are also used before blocking in
340	>	* awaitJoin and helpComplete.
341		*
342		* Trimming workers. To release resources after periods of lack of
343		* use, a worker starting to wait when the pool is quiescent will
#	Line 440 | Line 450 | public class ForkJoinPool extends Abstra
450		* Common Pool
451		* ===========
452		*
453	<	* The static common Pool always exists after static
453	>	* The static common pool always exists after static
454		* initialization.  Since it (or any other created pool) need
455		* never be used, we minimize initial construction overhead and
456		* footprint to the setup of about a dozen fields, with no nested
#	Line 448 | Line 458 | public class ForkJoinPool extends Abstra
458		* fullExternalPush during the first submission to the pool.
459		*
460		* When external threads submit to the common pool, they can
461	<	* perform some subtask processing (see externalHelpJoin and
462	<	* related methods).  We do not need to record whether these
461	>	* perform subtask processing (see externalHelpJoin and related
462	>	* methods).  This caller-helps policy makes it sensible to set
463	>	* common pool parallelism level to one (or more) less than the
464	>	* total number of available cores, or even zero for pure
465	>	* caller-runs.  We do not need to record whether external
466		* submissions are to the common pool -- if not, externalHelpJoin
467		* returns quickly (at the most helping to signal some common pool
468		* workers). These submitters would otherwise be blocked waiting
#	Line 519 | Line 532 | public class ForkJoinPool extends Abstra
532		*
533		* @param pool the pool this thread works in
534		* @throws NullPointerException if the pool is null
535	+	* @return the new worker thread
536		*/
537		public ForkJoinWorkerThread newThread(ForkJoinPool pool);
538		}
#	Line 535 | Line 549 | public class ForkJoinPool extends Abstra
549		}
550
551		/**
538	–	* Per-thread records for threads that submit to pools. Currently
539	–	* holds only pseudo-random seed / index that is used to choose
540	–	* submission queues in method externalPush. In the future, this may
541	–	* also incorporate a means to implement different task rejection
542	–	* and resubmission policies.
543	–	*
544	–	* Seeds for submitters and workers/workQueues work in basically
545	–	* the same way but are initialized and updated using slightly
546	–	* different mechanics. Both are initialized using the same
547	–	* approach as in class ThreadLocal, where successive values are
548	–	* unlikely to collide with previous values. Seeds are then
549	–	* randomly modified upon collisions using xorshifts, which
550	–	* requires a non-zero seed.
551	–	*/
552	–	static final class Submitter {
553	–	int seed;
554	–	Submitter(int s) { seed = s; }
555	–	}
556	–
557	–	/**
552		* Class for artificial tasks that are used to replace the target
553		* of local joins if they are removed from an interior queue slot
554		* in WorkQueue.tryRemoveAndExec. We don't need the proxy to
#	Line 613 | Line 607 | public class ForkJoinPool extends Abstra
607		* do not want multiple WorkQueue instances or multiple queue
608		* arrays sharing cache lines. (It would be best for queue objects
609		* and their arrays to share, but there is nothing available to
610	<	* help arrange that).  Unfortunately, because they are recorded
611	<	* in a common array, WorkQueue instances are often moved to be
618	<	* adjacent by garbage collectors. To reduce impact, we use field
619	<	* padding that works OK on common platforms; this effectively
620	<	* trades off slightly slower average field access for the sake of
621	<	* avoiding really bad worst-case access. (Until better JVM
622	<	* support is in place, this padding is dependent on transient
623	<	* properties of JVM field layout rules.) We also take care in
624	<	* allocating, sizing and resizing the array. Non-shared queue
625	<	* arrays are initialized by workers before use. Others are
626	<	* allocated on first use.
610	>	* help arrange that). The @Contended annotation alerts JVMs to
611	>	* try to keep instances apart.
612		*/
613		static final class WorkQueue {
614		/**
#	Line 649 | Line 634 | public class ForkJoinPool extends Abstra
634		// Heuristic padding to ameliorate unfortunate memory placements
635		volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
636
652	–	int seed;                  // for random scanning; initialize nonzero
637		volatile int eventCount;   // encoded inactivation count; < 0 if inactive
638		int nextWait;              // encoded record of next event waiter
655	–	int hint;                  // steal or signal hint (index)
656	–	int poolIndex;             // index of this queue in pool (or 0)
657	–	final int mode;            // 0: lifo, > 0: fifo, < 0: shared
639		int nsteals;               // number of steals
640	+	int hint;                  // steal index hint
641	+	short poolIndex;           // index of this queue in pool
642	+	final short mode;          // 0: lifo, > 0: fifo, < 0: shared
643		volatile int qlock;        // 1: locked, -1: terminate; else 0
644		volatile int base;         // index of next slot for poll
645		int top;                   // index of next slot for push
#	Line 673 | Line 657 | public class ForkJoinPool extends Abstra
657		int seed) {
658		this.pool = pool;
659		this.owner = owner;
660	<	this.mode = mode;
661	<	this.seed = seed;
660	>	this.mode = (short)mode;
661	>	this.hint = seed; // store initial seed for runWorker
662		// Place indices in the center of array (that is not yet allocated)
663		base = top = INITIAL_QUEUE_CAPACITY >>> 1;
664		}
#	Line 687 | Line 671 | public class ForkJoinPool extends Abstra
671		return (n >= 0) ? 0 : -n; // ignore transient negative
672		}
673
674	<	/**
674	>	/**
675		* Provides a more accurate estimate of whether this queue has
676		* any tasks than does queueSize, by checking whether a
677		* near-empty queue has at least one unclaimed task.
#	Line 712 | Line 696 | public class ForkJoinPool extends Abstra
696		*/
697		final void push(ForkJoinTask<?> task) {
698		ForkJoinTask<?>[] a; ForkJoinPool p;
699	<	int s = top, m, n;
699	>	int s = top, n;
700		if ((a = array) != null) {    // ignore if queue removed
701	<	int j = (((m = a.length - 1) & s) << ASHIFT) + ABASE;
702	<	U.putOrderedObject(a, j, task);
703	<	if ((n = (top = s + 1) - base) <= 2) {
704	<	if ((p = pool) != null)
721	<	p.signalWork(this);
722	<	}
701	>	int m = a.length - 1;
702	>	U.putOrderedObject(a, ((m & s) << ASHIFT) + ABASE, task);
703	>	if ((n = (top = s + 1) - base) <= 2)
704	>	(p = pool).signalWork(p.workQueues, this);
705		else if (n >= m)
706		growArray();
707		}
708		}
709
710	<	/**
710	>	/**
711		* Initializes or doubles the capacity of array. Call either
712		* by owner or with lock held -- it is OK for base, but not
713		* top, to move while resizings are in progress.
#	Line 783 | Line 765 | public class ForkJoinPool extends Abstra
765		if ((a = array) != null) {
766		int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
767		if ((t = (ForkJoinTask<?>)U.getObjectVolatile(a, j)) != null &&
768	<	base == b &&
769	<	U.compareAndSwapObject(a, j, t, null)) {
788	<	base = b + 1;
768	>	base == b && U.compareAndSwapObject(a, j, t, null)) {
769	>	U.putOrderedInt(this, QBASE, b + 1);
770		return t;
771		}
772		}
#	Line 801 | Line 782 | public class ForkJoinPool extends Abstra
782		int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
783		t = (ForkJoinTask<?>)U.getObjectVolatile(a, j);
784		if (t != null) {
785	<	if (base == b &&
786	<	U.compareAndSwapObject(a, j, t, null)) {
806	<	base = b + 1;
785	>	if (U.compareAndSwapObject(a, j, t, null)) {
786	>	U.putOrderedInt(this, QBASE, b + 1);
787		return t;
788		}
789		}
#	Line 860 | Line 840 | public class ForkJoinPool extends Abstra
840		ForkJoinTask.cancelIgnoringExceptions(t);
841		}
842
863	–	/**
864	–	* Computes next value for random probes.  Scans don't require
865	–	* a very high quality generator, but also not a crummy one.
866	–	* Marsaglia xor-shift is cheap and works well enough.  Note:
867	–	* This is manually inlined in its usages in ForkJoinPool to
868	–	* avoid writes inside busy scan loops.
869	–	*/
870	–	final int nextSeed() {
871	–	int r = seed;
872	–	r ^= r << 13;
873	–	r ^= r >>> 17;
874	–	return seed = r ^= r << 5;
875	–	}
876	–
843		// Specialized execution methods
844
845		/**
880	–	* Pops and runs tasks until empty.
881	–	*/
882	–	private void popAndExecAll() {
883	–	// A bit faster than repeated pop calls
884	–	ForkJoinTask<?>[] a; int m, s; long j; ForkJoinTask<?> t;
885	–	while ((a = array) != null && (m = a.length - 1) >= 0 &&
886	–	(s = top - 1) - base >= 0 &&
887	–	(t = ((ForkJoinTask<?>)
888	–	U.getObject(a, j = ((m & s) << ASHIFT) + ABASE)))
889	–	!= null) {
890	–	if (U.compareAndSwapObject(a, j, t, null)) {
891	–	top = s;
892	–	t.doExec();
893	–	}
894	–	}
895	–	}
896	–
897	–	/**
846		* Polls and runs tasks until empty.
847		*/
848	<	private void pollAndExecAll() {
848	>	final void pollAndExecAll() {
849		for (ForkJoinTask<?> t; (t = poll()) != null;)
850		t.doExec();
851		}
852
853		/**
854	+	* Executes a top-level task and any local tasks remaining
855	+	* after execution.
856	+	*/
857	+	final void runTask(ForkJoinTask<?> task) {
858	+	if ((currentSteal = task) != null) {
859	+	task.doExec();
860	+	ForkJoinTask<?>[] a = array;
861	+	int md = mode;
862	+	++nsteals;
863	+	currentSteal = null;
864	+	if (md != 0)
865	+	pollAndExecAll();
866	+	else if (a != null) {
867	+	int s, m = a.length - 1;
868	+	while ((s = top - 1) - base >= 0) {
869	+	long i = ((m & s) << ASHIFT) + ABASE;
870	+	ForkJoinTask<?> t = (ForkJoinTask<?>)U.getObject(a, i);
871	+	if (t == null)
872	+	break;
873	+	if (U.compareAndSwapObject(a, i, t, null)) {
874	+	top = s;
875	+	t.doExec();
876	+	}
877	+	}
878	+	}
879	+	}
880	+	}
881	+
882	+	/**
883		* If present, removes from queue and executes the given task,
884		* or any other cancelled task. Returns (true) on any CAS
885		* or consistency check failure so caller can retry.
#	Line 910 | Line 887 | public class ForkJoinPool extends Abstra
887		* @return false if no progress can be made, else true
888		*/
889		final boolean tryRemoveAndExec(ForkJoinTask<?> task) {
890	<	boolean stat = true, removed = false, empty = true;
890	>	boolean stat;
891		ForkJoinTask<?>[] a; int m, s, b, n;
892	<	if ((a = array) != null && (m = a.length - 1) >= 0 &&
892	>	if (task != null && (a = array) != null && (m = a.length - 1) >= 0 &&
893		(n = (s = top) - (b = base)) > 0) {
894	+	boolean removed = false, empty = true;
895	+	stat = true;
896		for (ForkJoinTask<?> t;;) {           // traverse from s to b
897	<	int j = ((--s & m) << ASHIFT) + ABASE;
898	<	t = (ForkJoinTask<?>)U.getObjectVolatile(a, j);
897	>	long j = ((--s & m) << ASHIFT) + ABASE;
898	>	t = (ForkJoinTask<?>)U.getObject(a, j);
899		if (t == null)                    // inconsistent length
900		break;
901		else if (t == task) {
#	Line 944 | Line 923 | public class ForkJoinPool extends Abstra
923		break;
924		}
925		}
926	+	if (removed)
927	+	task.doExec();
928		}
929	<	if (removed)
930	<	task.doExec();
929	>	else
930	>	stat = false;
931		return stat;
932		}
933
934		/**
935	<	* Polls for and executes the given task or any other task in
936	<	* its CountedCompleter computation.
935	>	* Tries to poll for and execute the given task or any other
936	>	* task in its CountedCompleter computation.
937		*/
938	<	final boolean pollAndExecCC(ForkJoinTask<?> root) {
939	<	ForkJoinTask<?>[] a; int b; Object o;
940	<	outer: while ((b = base) - top < 0 && (a = array) != null) {
938	>	final boolean pollAndExecCC(CountedCompleter<?> root) {
939	>	ForkJoinTask<?>[] a; int b; Object o; CountedCompleter<?> t, r;
940	>	if ((b = base) - top < 0 && (a = array) != null) {
941		long j = (((a.length - 1) & b) << ASHIFT) + ABASE;
942	<	if ((o = U.getObject(a, j)) == null ||
943	<	!(o instanceof CountedCompleter))
944	<	break;
945	<	for (CountedCompleter<?> t = (CountedCompleter<?>)o, r = t;;) {
946	<	if (r == root) {
947	<	if (base == b &&
948	<	U.compareAndSwapObject(a, j, t, null)) {
949	<	base = b + 1;
950	<	t.doExec();
942	>	if ((o = U.getObjectVolatile(a, j)) == null)
943	>	return true; // retry
944	>	if (o instanceof CountedCompleter) {
945	>	for (t = (CountedCompleter<?>)o, r = t;;) {
946	>	if (r == root) {
947	>	if (base == b &&
948	>	U.compareAndSwapObject(a, j, t, null)) {
949	>	U.putOrderedInt(this, QBASE, b + 1);
950	>	t.doExec();
951	>	}
952		return true;
953		}
954	<	else
955	<	break; // restart
954	>	else if ((r = r.completer) == null)
955	>	break; // not part of root computation
956		}
975	–	if ((r = r.completer) == null)
976	–	break outer; // not part of root computation
957		}
958		}
959		return false;
960		}
961
962		/**
963	<	* Executes a top-level task and any local tasks remaining
964	<	* after execution.
963	>	* Tries to pop and execute the given task or any other task
964	>	* in its CountedCompleter computation.
965		*/
966	<	final void runTask(ForkJoinTask<?> t) {
967	<	if (t != null) {
968	<	(currentSteal = t).doExec();
969	<	currentSteal = null;
970	<	++nsteals;
971	<	if (base - top < 0) {       // process remaining local tasks
972	<	if (mode == 0)
973	<	popAndExecAll();
974	<	else
975	<	pollAndExecAll();
966	>	final boolean externalPopAndExecCC(CountedCompleter<?> root) {
967	>	ForkJoinTask<?>[] a; int s; Object o; CountedCompleter<?> t, r;
968	>	if (base - (s = top) < 0 && (a = array) != null) {
969	>	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
970	>	if ((o = U.getObject(a, j)) instanceof CountedCompleter) {
971	>	for (t = (CountedCompleter<?>)o, r = t;;) {
972	>	if (r == root) {
973	>	if (U.compareAndSwapInt(this, QLOCK, 0, 1)) {
974	>	if (top == s && array == a &&
975	>	U.compareAndSwapObject(a, j, t, null)) {
976	>	top = s - 1;
977	>	qlock = 0;
978	>	t.doExec();
979	>	}
980	>	else
981	>	qlock = 0;
982	>	}
983	>	return true;
984	>	}
985	>	else if ((r = r.completer) == null)
986	>	break;
987	>	}
988		}
989		}
990	+	return false;
991		}
992
993		/**
994	<	* Executes a non-top-level (stolen) task.
994	>	* Internal version
995		*/
996	<	final void runSubtask(ForkJoinTask<?> t) {
997	<	if (t != null) {
998	<	ForkJoinTask<?> ps = currentSteal;
999	<	(currentSteal = t).doExec();
1000	<	currentSteal = ps;
996	>	final boolean internalPopAndExecCC(CountedCompleter<?> root) {
997	>	ForkJoinTask<?>[] a; int s; Object o; CountedCompleter<?> t, r;
998	>	if (base - (s = top) < 0 && (a = array) != null) {
999	>	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
1000	>	if ((o = U.getObject(a, j)) instanceof CountedCompleter) {
1001	>	for (t = (CountedCompleter<?>)o, r = t;;) {
1002	>	if (r == root) {
1003	>	if (U.compareAndSwapObject(a, j, t, null)) {
1004	>	top = s - 1;
1005	>	t.doExec();
1006	>	}
1007	>	return true;
1008	>	}
1009	>	else if ((r = r.completer) == null)
1010	>	break;
1011	>	}
1012	>	}
1013		}
1014	+	return false;
1015		}
1016
1017		/**
#	Line 1022 | Line 1028 | public class ForkJoinPool extends Abstra
1028
1029		// Unsafe mechanics
1030		private static final sun.misc.Unsafe U;
1031	+	private static final long QBASE;
1032		private static final long QLOCK;
1033		private static final int ABASE;
1034		private static final int ASHIFT;
#	Line 1030 | Line 1037 | public class ForkJoinPool extends Abstra
1037		U = getUnsafe();
1038		Class<?> k = WorkQueue.class;
1039		Class<?> ak = ForkJoinTask[].class;
1040	+	QBASE = U.objectFieldOffset
1041	+	(k.getDeclaredField("base"));
1042		QLOCK = U.objectFieldOffset
1043		(k.getDeclaredField("qlock"));
1044		ABASE = U.arrayBaseOffset(ak);
#	Line 1046 | Line 1055 | public class ForkJoinPool extends Abstra
1055		// static fields (initialized in static initializer below)
1056
1057		/**
1049	–	* Creates a new ForkJoinWorkerThread. This factory is used unless
1050	–	* overridden in ForkJoinPool constructors.
1051	–	*/
1052	–	public static final ForkJoinWorkerThreadFactory
1053	–	defaultForkJoinWorkerThreadFactory;
1054	–
1055	–	/**
1058		* Per-thread submission bookkeeping. Shared across all pools
1059		* to reduce ThreadLocal pollution and because random motion
1060		* to avoid contention in one pool is likely to hold for others.
#	Line 1062 | Line 1064 | public class ForkJoinPool extends Abstra
1064		static final ThreadLocal<Submitter> submitters;
1065
1066		/**
1067	+	* Creates a new ForkJoinWorkerThread. This factory is used unless
1068	+	* overridden in ForkJoinPool constructors.
1069	+	*/
1070	+	public static final ForkJoinWorkerThreadFactory
1071	+	defaultForkJoinWorkerThreadFactory;
1072	+
1073	+	/**
1074		* Permission required for callers of methods that may start or
1075		* kill threads.
1076		*/
#	Line 1076 | Line 1085 | public class ForkJoinPool extends Abstra
1085		static final ForkJoinPool common;
1086
1087		/**
1088	<	* Common pool parallelism. Must equal common.parallelism.
1088	>	* Common pool parallelism. To allow simpler use and management
1089	>	* when common pool threads are disabled, we allow the underlying
1090	>	* common.parallelism field to be zero, but in that case still report
1091	>	* parallelism as 1 to reflect resulting caller-runs mechanics.
1092		*/
1093		static final int commonParallelism;
1094
#	Line 1215 | Line 1227 | public class ForkJoinPool extends Abstra
1227		static final int FIFO_QUEUE          =  1;
1228		static final int SHARED_QUEUE        = -1;
1229
1218	–	// bounds for #steps in scan loop -- must be power 2 minus 1
1219	–	private static final int MIN_SCAN    = 0x1ff;   // cover estimation slop
1220	–	private static final int MAX_SCAN    = 0x1ffff; // 4 * max workers
1221	–
1222	–	// Instance fields
1223	–
1224	–	/*
1225	–	* Field layout of this class tends to matter more than one would
1226	–	* like. Runtime layout order is only loosely related to
1227	–	* declaration order and may differ across JVMs, but the following
1228	–	* empirically works OK on current JVMs.
1229	–	*/
1230	–
1230		// Heuristic padding to ameliorate unfortunate memory placements
1231		volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
1232
1233	+	// Instance fields
1234		volatile long stealCount;                  // collects worker counts
1235		volatile long ctl;                         // main pool control
1236		volatile int plock;                        // shutdown status and seqLock
1237		volatile int indexSeed;                    // worker/submitter index seed
1238	<	final int config;                          // mode and parallelism level
1238	>	final short parallelism;                   // parallelism level
1239	>	final short mode;                          // LIFO/FIFO
1240		WorkQueue[] workQueues;                    // main registry
1241		final ForkJoinWorkerThreadFactory factory;
1242	<	final Thread.UncaughtExceptionHandler ueh; // per-worker UEH
1242	>	final UncaughtExceptionHandler ueh;        // per-worker UEH
1243		final String workerNamePrefix;             // to create worker name string
1244
1245		volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17;
#	Line 1253 | Line 1254 | public class ForkJoinPool extends Abstra
1254		* a more conservative alternative to a pure spinlock.
1255		*/
1256		private int acquirePlock() {
1257	<	int spins = PL_SPINS, r = 0, ps, nps;
1257	>	int spins = PL_SPINS, ps, nps;
1258		for (;;) {
1259		if (((ps = plock) & PL_LOCK) == 0 &&
1260		U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK))
1261		return nps;
1261	–	else if (r == 0) { // randomize spins if possible
1262	–	Thread t = Thread.currentThread(); WorkQueue w; Submitter z;
1263	–	if ((t instanceof ForkJoinWorkerThread) &&
1264	–	(w = ((ForkJoinWorkerThread)t).workQueue) != null)
1265	–	r = w.seed;
1266	–	else if ((z = submitters.get()) != null)
1267	–	r = z.seed;
1268	–	else
1269	–	r = 1;
1270	–	}
1262		else if (spins >= 0) {
1263	<	r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
1273	<	if (r >= 0)
1263	>	if (ThreadLocalRandom.current().nextInt() >= 0)
1264		--spins;
1265		}
1266		else if (U.compareAndSwapInt(this, PLOCK, ps, ps | PL_SIGNAL)) {
#	Line 1306 | Line 1296 | public class ForkJoinPool extends Abstra
1296		* parallelism level exist. Adjusts counts etc on failure.
1297		*/
1298		private void tryAddWorker() {
1299	<	long c; int u;
1299	>	long c; int u, e;
1300		while ((u = (int)((c = ctl) >>> 32)) < 0 &&
1301	<	(u & SHORT_SIGN) != 0 && (int)c == 0) {
1302	<	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
1303	<	((u + UAC_UNIT) & UAC_MASK)) << 32;
1301	>	(u & SHORT_SIGN) != 0 && (e = (int)c) >= 0) {
1302	>	long nc = ((long)(((u + UTC_UNIT) & UTC_MASK) |
1303	>	((u + UAC_UNIT) & UAC_MASK)) << 32) | (long)e;
1304		if (U.compareAndSwapLong(this, CTL, c, nc)) {
1305		ForkJoinWorkerThreadFactory fac;
1306		Throwable ex = null;
#	Line 1321 | Line 1311 | public class ForkJoinPool extends Abstra
1311		wt.start();
1312		break;
1313		}
1314	<	} catch (Throwable e) {
1315	<	ex = e;
1314	>	} catch (Throwable rex) {
1315	>	ex = rex;
1316		}
1317		deregisterWorker(wt, ex);
1318		break;
#	Line 1343 | Line 1333 | public class ForkJoinPool extends Abstra
1333		* @return the worker's queue
1334		*/
1335		final WorkQueue registerWorker(ForkJoinWorkerThread wt) {
1336	<	Thread.UncaughtExceptionHandler handler; WorkQueue[] ws; int s, ps;
1336	>	UncaughtExceptionHandler handler; WorkQueue[] ws; int s, ps;
1337		wt.setDaemon(true);
1338		if ((handler = ueh) != null)
1339		wt.setUncaughtExceptionHandler(handler);
1340		do {} while (!U.compareAndSwapInt(this, INDEXSEED, s = indexSeed,
1341		s += SEED_INCREMENT) ||
1342		s == 0); // skip 0
1343	<	WorkQueue w = new WorkQueue(this, wt, config >>> 16, s);
1343	>	WorkQueue w = new WorkQueue(this, wt, mode, s);
1344		if (((ps = plock) & PL_LOCK) != 0 ||
1345		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1346		ps = acquirePlock();
#	Line 1370 | Line 1360 | public class ForkJoinPool extends Abstra
1360		}
1361		}
1362		}
1363	<	w.eventCount = w.poolIndex = r; // volatile write orders
1363	>	w.poolIndex = (short)r;
1364	>	w.eventCount = r; // volatile write orders
1365		ws[r] = w;
1366		}
1367		} finally {
1368		if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1369		releasePlock(nps);
1370		}
1371	<	wt.setName(workerNamePrefix.concat(Integer.toString(w.poolIndex)));
1371	>	wt.setName(workerNamePrefix.concat(Integer.toString(w.poolIndex >>> 1)));
1372		return w;
1373		}
1374
#	Line 1387 | Line 1378 | public class ForkJoinPool extends Abstra
1378		* array, and adjusts counts. If pool is shutting down, tries to
1379		* complete termination.
1380		*
1381	<	* @param wt the worker thread or null if construction failed
1381	>	* @param wt the worker thread, or null if construction failed
1382		* @param ex the exception causing failure, or null if none
1383		*/
1384		final void deregisterWorker(ForkJoinWorkerThread wt, Throwable ex) {
1385		WorkQueue w = null;
1386		if (wt != null && (w = wt.workQueue) != null) {
1387	<	int ps;
1387	>	int ps; long sc;
1388		w.qlock = -1;                // ensure set
1389	<	long ns = w.nsteals, sc;     // collect steal count
1390	<	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1400	<	sc = stealCount, sc + ns));
1389	>	do {} while(!U.compareAndSwapLong(this, STEALCOUNT, sc = stealCount,
1390	>	sc + w.nsteals));
1391		if (((ps = plock) & PL_LOCK) != 0 ||
1392		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1393		ps = acquirePlock();
#	Line 1455 | Line 1445 | public class ForkJoinPool extends Abstra
1445		// Submissions
1446
1447		/**
1448	+	* Per-thread records for threads that submit to pools. Currently
1449	+	* holds only pseudo-random seed / index that is used to choose
1450	+	* submission queues in method externalPush. In the future, this may
1451	+	* also incorporate a means to implement different task rejection
1452	+	* and resubmission policies.
1453	+	*
1454	+	* Seeds for submitters and workers/workQueues work in basically
1455	+	* the same way but are initialized and updated using slightly
1456	+	* different mechanics. Both are initialized using the same
1457	+	* approach as in class ThreadLocal, where successive values are
1458	+	* unlikely to collide with previous values. Seeds are then
1459	+	* randomly modified upon collisions using xorshifts, which
1460	+	* requires a non-zero seed.
1461	+	*/
1462	+	static final class Submitter {
1463	+	int seed;
1464	+	Submitter(int s) { seed = s; }
1465	+	}
1466	+
1467	+	/**
1468		* Unless shutting down, adds the given task to a submission queue
1469		* at submitter's current queue index (modulo submission
1470		* range). Only the most common path is directly handled in this
#	Line 1463 | Line 1473 | public class ForkJoinPool extends Abstra
1473		* @param task the task. Caller must ensure non-null.
1474		*/
1475		final void externalPush(ForkJoinTask<?> task) {
1476	<	WorkQueue[] ws; WorkQueue q; Submitter z; int m; ForkJoinTask<?>[] a;
1477	<	if ((z = submitters.get()) != null && plock > 0 &&
1478	<	(ws = workQueues) != null && (m = (ws.length - 1)) >= 0 &&
1479	<	(q = ws[m & z.seed & SQMASK]) != null &&
1476	>	Submitter z = submitters.get();
1477	>	WorkQueue q; int r, m, s, n, am; ForkJoinTask<?>[] a;
1478	>	int ps = plock;
1479	>	WorkQueue[] ws = workQueues;
1480	>	if (z != null && ps > 0 && ws != null && (m = (ws.length - 1)) >= 0 &&
1481	>	(q = ws[m & (r = z.seed) & SQMASK]) != null && r != 0 &&
1482		U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock
1483	<	int b = q.base, s = q.top, n, an;
1484	<	if ((a = q.array) != null && (an = a.length) > (n = s + 1 - b)) {
1485	<	int j = (((an - 1) & s) << ASHIFT) + ABASE;
1483	>	if ((a = q.array) != null &&
1484	>	(am = a.length - 1) > (n = (s = q.top) - q.base)) {
1485	>	int j = ((am & s) << ASHIFT) + ABASE;
1486		U.putOrderedObject(a, j, task);
1487		q.top = s + 1;                     // push on to deque
1488		q.qlock = 0;
1489	<	if (n <= 2)
1490	<	signalWork(q);
1489	>	if (n <= 1)
1490	>	signalWork(ws, q);
1491		return;
1492		}
1493		q.qlock = 0;
#	Line 1513 | Line 1525 | public class ForkJoinPool extends Abstra
1525		r = z.seed;
1526		r ^= r << 13;                   // same xorshift as WorkQueues
1527		r ^= r >>> 17;
1528	<	z.seed = r ^ (r << 5);
1528	>	z.seed = r ^= (r << 5);
1529		}
1530	<	else if ((ps = plock) < 0)
1530	>	if ((ps = plock) < 0)
1531		throw new RejectedExecutionException();
1532		else if (ps == 0 || (ws = workQueues) == null ||
1533		(m = ws.length - 1) < 0) { // initialize workQueues
1534	<	int p = config & SMASK;         // find power of two table size
1534	>	int p = parallelism;            // find power of two table size
1535		int n = (p > 1) ? p - 1 : 1;    // ensure at least 2 slots
1536		n |= n >>> 1; n |= n >>> 2;  n |= n >>> 4;
1537		n |= n >>> 8; n |= n >>> 16; n = (n + 1) << 1;
#	Line 1551 | Line 1563 | public class ForkJoinPool extends Abstra
1563		q.qlock = 0;  // unlock
1564		}
1565		if (submitted) {
1566	<	signalWork(q);
1566	>	signalWork(ws, q);
1567		return;
1568		}
1569		}
#	Line 1559 | Line 1571 | public class ForkJoinPool extends Abstra
1571		}
1572		else if (((ps = plock) & PL_LOCK) == 0) { // create new queue
1573		q = new WorkQueue(this, null, SHARED_QUEUE, r);
1574	+	q.poolIndex = (short)k;
1575		if (((ps = plock) & PL_LOCK) != 0 ||
1576		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1577		ps = acquirePlock();
#	Line 1569 | Line 1582 | public class ForkJoinPool extends Abstra
1582		releasePlock(nps);
1583		}
1584		else
1585	<	r = 0; // try elsewhere while lock held
1585	>	r = 0;
1586		}
1587		}
1588
#	Line 1580 | Line 1593 | public class ForkJoinPool extends Abstra
1593		*/
1594		final void incrementActiveCount() {
1595		long c;
1596	<	do {} while (!U.compareAndSwapLong(this, CTL, c = ctl, c + AC_UNIT));
1596	>	do {} while (!U.compareAndSwapLong
1597	>	(this, CTL, c = ctl, ((c & ~AC_MASK) |
1598	>	((c & AC_MASK) + AC_UNIT))));
1599		}
1600
1601		/**
1602		* Tries to create or activate a worker if too few are active.
1603		*
1604	<	* @param q the (non-null) queue holding tasks to be signalled
1604	>	* @param ws the worker array to use to find signallees
1605	>	* @param q if non-null, the queue holding tasks to be processed
1606		*/
1607	<	final void signalWork(WorkQueue q) {
1608	<	int hint = q.poolIndex;
1609	<	long c; int e, u, i, n; WorkQueue[] ws; WorkQueue w; Thread p;
1610	<	while ((u = (int)((c = ctl) >>> 32)) < 0) {
1611	<	if ((e = (int)c) > 0) {
1612	<	if ((ws = workQueues) != null && ws.length > (i = e & SMASK) &&
1597	<	(w = ws[i]) != null && w.eventCount == (e | INT_SIGN)) {
1598	<	long nc = (((long)(w.nextWait & E_MASK)) |
1599	<	((long)(u + UAC_UNIT) << 32));
1600	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1601	<	w.hint = hint;
1602	<	w.eventCount = (e + E_SEQ) & E_MASK;
1603	<	if ((p = w.parker) != null)
1604	<	U.unpark(p);
1605	<	break;
1606	<	}
1607	<	if (q.top - q.base <= 0)
1608	<	break;
1609	<	}
1610	<	else
1611	<	break;
1612	<	}
1613	<	else {
1607	>	final void signalWork(WorkQueue[] ws, WorkQueue q) {
1608	>	for (;;) {
1609	>	long c; int e, u, i; WorkQueue w; Thread p;
1610	>	if ((u = (int)((c = ctl) >>> 32)) >= 0)
1611	>	break;
1612	>	if ((e = (int)c) <= 0) {
1613		if ((short)u < 0)
1614		tryAddWorker();
1615		break;
1616		}
1617	+	if (ws == null || ws.length <= (i = e & SMASK) ||
1618	+	(w = ws[i]) == null)
1619	+	break;
1620	+	long nc = (((long)(w.nextWait & E_MASK)) |
1621	+	((long)(u + UAC_UNIT)) << 32);
1622	+	int ne = (e + E_SEQ) & E_MASK;
1623	+	if (w.eventCount == (e | INT_SIGN) &&
1624	+	U.compareAndSwapLong(this, CTL, c, nc)) {
1625	+	w.eventCount = ne;
1626	+	if ((p = w.parker) != null)
1627	+	U.unpark(p);
1628	+	break;
1629	+	}
1630	+	if (q != null && q.base >= q.top)
1631	+	break;
1632		}
1633		}
1634
#	Line 1625 | Line 1639 | public class ForkJoinPool extends Abstra
1639		*/
1640		final void runWorker(WorkQueue w) {
1641		w.growArray(); // allocate queue
1642	<	do { w.runTask(scan(w)); } while (w.qlock >= 0);
1642	>	for (int r = w.hint; scan(w, r) == 0; ) {
1643	>	r ^= r << 13; r ^= r >>> 17; r ^= r << 5; // xorshift
1644	>	}
1645		}
1646
1647		/**
1648	<	* Scans for and, if found, returns one task, else possibly
1648	>	* Scans for and, if found, runs one task, else possibly
1649		* inactivates the worker. This method operates on single reads of
1650		* volatile state and is designed to be re-invoked continuously,
1651		* in part because it returns upon detecting inconsistencies,
1652		* contention, or state changes that indicate possible success on
1653		* re-invocation.
1654		*
1655	<	* The scan searches for tasks across queues (starting at a random
1656	<	* index, and relying on registerWorker to irregularly scatter
1657	<	* them within array to avoid bias), checking each at least twice.
1658	<	* The scan terminates upon either finding a non-empty queue, or
1659	<	* completing the sweep. If the worker is not inactivated, it
1660	<	* takes and returns a task from this queue. Otherwise, if not
1661	<	* activated, it signals workers (that may include itself) and
1662	<	* returns so caller can retry. Also returns for true if the
1663	<	* worker array may have changed during an empty scan.  On failure
1648	<	* to find a task, we take one of the following actions, after
1649	<	* which the caller will retry calling this method unless
1650	<	* terminated.
1651	<	*
1652	<	* * If pool is terminating, terminate the worker.
1653	<	*
1654	<	* * If not already enqueued, try to inactivate and enqueue the
1655	<	* worker on wait queue. Or, if inactivating has caused the pool
1656	<	* to be quiescent, relay to idleAwaitWork to possibly shrink
1657	<	* pool.
1658	<	*
1659	<	* * If already enqueued and none of the above apply, possibly
1660	<	* park awaiting signal, else lingering to help scan and signal.
1661	<	*
1662	<	* * If a non-empty queue discovered or left as a hint,
1663	<	* help wake up other workers before return.
1655	>	* The scan searches for tasks across queues starting at a random
1656	>	* index, checking each at least twice.  The scan terminates upon
1657	>	* either finding a non-empty queue, or completing the sweep. If
1658	>	* the worker is not inactivated, it takes and runs a task from
1659	>	* this queue. Otherwise, if not activated, it tries to activate
1660	>	* itself or some other worker by signalling. On failure to find a
1661	>	* task, returns (for retry) if pool state may have changed during
1662	>	* an empty scan, or tries to inactivate if active, else possibly
1663	>	* blocks or terminates via method awaitWork.
1664		*
1665		* @param w the worker (via its WorkQueue)
1666	<	* @return a task or null if none found
1666	>	* @param r a random seed
1667	>	* @return worker qlock status if would have waited, else 0
1668		*/
1669	<	private final ForkJoinTask<?> scan(WorkQueue w) {
1669	>	private final int scan(WorkQueue w, int r) {
1670		WorkQueue[] ws; int m;
1671	<	int ps = plock;                          // read plock before ws
1672	<	if (w != null && (ws = workQueues) != null && (m = ws.length - 1) >= 0) {
1673	<	int ec = w.eventCount;               // ec is negative if inactive
1674	<	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1675	<	w.hint = -1;                         // update seed and clear hint
1676	<	int j = ((m + m + 1) | MIN_SCAN) & MAX_SCAN;
1677	<	do {
1678	<	WorkQueue q; ForkJoinTask<?>[] a; int b;
1679	<	if ((q = ws[(r + j) & m]) != null && (b = q.base) - q.top < 0 &&
1680	<	(a = q.array) != null) {     // probably nonempty
1681	<	int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1682	<	ForkJoinTask<?> t = (ForkJoinTask<?>)
1683	<	U.getObjectVolatile(a, i);
1684	<	if (q.base == b && ec >= 0 && t != null &&
1685	<	U.compareAndSwapObject(a, i, t, null)) {
1686	<	if ((q.base = b + 1) - q.top < 0)
1687	<	signalWork(q);
1688	<	return t;                // taken
1689	<	}
1690	<	else if ((ec < 0 || j < m) && (int)(ctl >> AC_SHIFT) <= 0) {
1691	<	w.hint = (r + j) & m;    // help signal below
1692	<	break;                   // cannot take
1693	<	}
1694	<	}
1695	<	} while (--j >= 0);
1696	<
1697	<	int h, e, ns; long c, sc; WorkQueue q;
1697	<	if ((ns = w.nsteals) != 0) {
1698	<	if (U.compareAndSwapLong(this, STEALCOUNT,
1699	<	sc = stealCount, sc + ns))
1700	<	w.nsteals = 0;               // collect steals and rescan
1701	<	}
1702	<	else if (plock != ps)                // consistency check
1703	<	;                                // skip
1704	<	else if ((e = (int)(c = ctl)) < 0)
1705	<	w.qlock = -1;                    // pool is terminating
1706	<	else {
1707	<	if ((h = w.hint) < 0) {
1708	<	if (ec >= 0) {               // try to enqueue/inactivate
1709	<	long nc = (((long)ec |
1710	<	((c - AC_UNIT) & (AC_MASK|TC_MASK))));
1711	<	w.nextWait = e;          // link and mark inactive
1671	>	long c = ctl;                            // for consistency check
1672	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0 && w != null) {
1673	>	for (int j = m + m + 1, ec = w.eventCount;;) {
1674	>	WorkQueue q; int b, e; ForkJoinTask<?>[] a; ForkJoinTask<?> t;
1675	>	if ((q = ws[(r - j) & m]) != null &&
1676	>	(b = q.base) - q.top < 0 && (a = q.array) != null) {
1677	>	long i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1678	>	if ((t = ((ForkJoinTask<?>)
1679	>	U.getObjectVolatile(a, i))) != null) {
1680	>	if (ec < 0)
1681	>	helpRelease(c, ws, w, q, b);
1682	>	else if (q.base == b &&
1683	>	U.compareAndSwapObject(a, i, t, null)) {
1684	>	U.putOrderedInt(q, QBASE, b + 1);
1685	>	if ((b + 1) - q.top < 0)
1686	>	signalWork(ws, q);
1687	>	w.runTask(t);
1688	>	}
1689	>	}
1690	>	break;
1691	>	}
1692	>	else if (--j < 0) {
1693	>	if ((ec | (e = (int)c)) < 0) // inactive or terminating
1694	>	return awaitWork(w, c, ec);
1695	>	else if (ctl == c) {         // try to inactivate and enqueue
1696	>	long nc = (long)ec | ((c - AC_UNIT) & (AC_MASK|TC_MASK));
1697	>	w.nextWait = e;
1698		w.eventCount = ec | INT_SIGN;
1699	<	if (ctl != c || !U.compareAndSwapLong(this, CTL, c, nc))
1700	<	w.eventCount = ec;   // unmark on CAS failure
1715	<	else if ((int)(c >> AC_SHIFT) == 1 - (config & SMASK))
1716	<	idleAwaitWork(w, nc, c);
1717	<	}
1718	<	else if (w.eventCount < 0 && ctl == c) {
1719	<	Thread wt = Thread.currentThread();
1720	<	Thread.interrupted();    // clear status
1721	<	U.putObject(wt, PARKBLOCKER, this);
1722	<	w.parker = wt;           // emulate LockSupport.park
1723	<	if (w.eventCount < 0)    // recheck
1724	<	U.park(false, 0L);   // block
1725	<	w.parker = null;
1726	<	U.putObject(wt, PARKBLOCKER, null);
1727	<	}
1728	<	}
1729	<	if ((h >= 0 || (h = w.hint) >= 0) &&
1730	<	(ws = workQueues) != null && h < ws.length &&
1731	<	(q = ws[h]) != null) {      // signal others before retry
1732	<	WorkQueue v; Thread p; int u, i, s;
1733	<	for (int n = (config & SMASK) - 1;;) {
1734	<	int idleCount = (w.eventCount < 0) ? 0 : -1;
1735	<	if (((s = idleCount - q.base + q.top) <= n &&
1736	<	(n = s) <= 0) ||
1737	<	(u = (int)((c = ctl) >>> 32)) >= 0 ||
1738	<	(e = (int)c) <= 0 || m < (i = e & SMASK) ||
1739	<	(v = ws[i]) == null)
1740	<	break;
1741	<	long nc = (((long)(v.nextWait & E_MASK)) |
1742	<	((long)(u + UAC_UNIT) << 32));
1743	<	if (v.eventCount != (e | INT_SIGN) ||
1744	<	!U.compareAndSwapLong(this, CTL, c, nc))
1745	<	break;
1746	<	v.hint = h;
1747	<	v.eventCount = (e + E_SEQ) & E_MASK;
1748	<	if ((p = v.parker) != null)
1749	<	U.unpark(p);
1750	<	if (--n <= 0)
1751	<	break;
1699	>	if (!U.compareAndSwapLong(this, CTL, c, nc))
1700	>	w.eventCount = ec;   // back out
1701		}
1702	+	break;
1703		}
1704		}
1705		}
1706	<	return null;
1706	>	return 0;
1707		}
1708
1709		/**
1710	<	* If inactivating worker w has caused the pool to become
1711	<	* quiescent, checks for pool termination, and, so long as this is
1712	<	* not the only worker, waits for event for up to a given
1713	<	* duration.  On timeout, if ctl has not changed, terminates the
1714	<	* worker, which will in turn wake up another worker to possibly
1715	<	* repeat this process.
1710	>	* A continuation of scan(), possibly blocking or terminating
1711	>	* worker w. Returns without blocking if pool state has apparently
1712	>	* changed since last invocation.  Also, if inactivating w has
1713	>	* caused the pool to become quiescent, checks for pool
1714	>	* termination, and, so long as this is not the only worker, waits
1715	>	* for event for up to a given duration.  On timeout, if ctl has
1716	>	* not changed, terminates the worker, which will in turn wake up
1717	>	* another worker to possibly repeat this process.
1718		*
1719		* @param w the calling worker
1720	<	* @param currentCtl the ctl value triggering possible quiescence
1721	<	* @param prevCtl the ctl value to restore if thread is terminated
1720	>	* @param c the ctl value on entry to scan
1721	>	* @param ec the worker's eventCount on entry to scan
1722		*/
1723	<	private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) {
1724	<	if (w != null && w.eventCount < 0 &&
1725	<	!tryTerminate(false, false) && (int)prevCtl != 0 &&
1726	<	ctl == currentCtl) {
1727	<	int dc = -(short)(currentCtl >>> TC_SHIFT);
1728	<	long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT;
1729	<	long deadline = System.nanoTime() + parkTime - TIMEOUT_SLOP;
1730	<	Thread wt = Thread.currentThread();
1731	<	while (ctl == currentCtl) {
1732	<	Thread.interrupted();  // timed variant of version in scan()
1733	<	U.putObject(wt, PARKBLOCKER, this);
1734	<	w.parker = wt;
1735	<	if (ctl == currentCtl)
1736	<	U.park(false, parkTime);
1737	<	w.parker = null;
1738	<	U.putObject(wt, PARKBLOCKER, null);
1739	<	if (ctl != currentCtl)
1740	<	break;
1741	<	if (deadline - System.nanoTime() <= 0L &&
1742	<	U.compareAndSwapLong(this, CTL, currentCtl, prevCtl)) {
1743	<	w.eventCount = (w.eventCount + E_SEQ) | E_MASK;
1744	<	w.hint = -1;
1745	<	w.qlock = -1;   // shrink
1746	<	break;
1723	>	private final int awaitWork(WorkQueue w, long c, int ec) {
1724	>	int stat, ns; long parkTime, deadline;
1725	>	if ((stat = w.qlock) >= 0 && w.eventCount == ec && ctl == c &&
1726	>	!Thread.interrupted()) {
1727	>	int e = (int)c;
1728	>	int u = (int)(c >>> 32);
1729	>	int d = (u >> UAC_SHIFT) + parallelism; // active count
1730	>
1731	>	if (e < 0 || (d <= 0 && tryTerminate(false, false)))
1732	>	stat = w.qlock = -1;          // pool is terminating
1733	>	else if ((ns = w.nsteals) != 0) { // collect steals and retry
1734	>	long sc;
1735	>	w.nsteals = 0;
1736	>	do {} while(!U.compareAndSwapLong(this, STEALCOUNT,
1737	>	sc = stealCount, sc + ns));
1738	>	}
1739	>	else {
1740	>	long pc = ((d > 0 || ec != (e | INT_SIGN)) ? 0L :
1741	>	((long)(w.nextWait & E_MASK)) | // ctl to restore
1742	>	((long)(u + UAC_UNIT)) << 32);
1743	>	if (pc != 0L) {               // timed wait if last waiter
1744	>	int dc = -(short)(c >>> TC_SHIFT);
1745	>	parkTime = (dc < 0 ? FAST_IDLE_TIMEOUT:
1746	>	(dc + 1) * IDLE_TIMEOUT);
1747	>	deadline = System.nanoTime() + parkTime - TIMEOUT_SLOP;
1748	>	}
1749	>	else
1750	>	parkTime = deadline = 0L;
1751	>	if (w.eventCount == ec && ctl == c) {
1752	>	Thread wt = Thread.currentThread();
1753	>	U.putObject(wt, PARKBLOCKER, this);
1754	>	w.parker = wt;            // emulate LockSupport.park
1755	>	if (w.eventCount == ec && ctl == c)
1756	>	U.park(false, parkTime);  // must recheck before park
1757	>	w.parker = null;
1758	>	U.putObject(wt, PARKBLOCKER, null);
1759	>	if (parkTime != 0L && ctl == c &&
1760	>	deadline - System.nanoTime() <= 0L &&
1761	>	U.compareAndSwapLong(this, CTL, c, pc))
1762	>	stat = w.qlock = -1;  // shrink pool
1763		}
1764		}
1765		}
1766	+	return stat;
1767		}
1768
1769		/**
1770	<	* Scans through queues looking for work while joining a task; if
1771	<	* any present, signals. May return early if more signalling is
1772	<	* detectably unneeded.
1773	<	*
1774	<	* @param task return early if done
1775	<	* @param origin an index to start scan
1776	<	*/
1777	<	private void helpSignal(ForkJoinTask<?> task, int origin) {
1778	<	WorkQueue[] ws; WorkQueue w; Thread p; long c; int m, u, e, i, s;
1779	<	if (task != null && task.status >= 0 &&
1780	<	(u = (int)(ctl >>> 32)) < 0 && (u >> UAC_SHIFT) < 0 &&
1781	<	(ws = workQueues) != null && (m = ws.length - 1) >= 0) {
1782	<	outer: for (int k = origin, j = m; j >= 0; --j) {
1783	<	WorkQueue q = ws[k++ & m];
1784	<	for (int n = m;;) { // limit to at most m signals
1785	<	if (task.status < 0)
1786	<	break outer;
1787	<	if (q == null ||
1788	<	((s = -q.base + q.top) <= n && (n = s) <= 0))
1789	<	break;
1821	<	if ((u = (int)((c = ctl) >>> 32)) >= 0 ||
1822	<	(e = (int)c) <= 0 || m < (i = e & SMASK) ||
1823	<	(w = ws[i]) == null)
1824	<	break outer;
1825	<	long nc = (((long)(w.nextWait & E_MASK)) |
1826	<	((long)(u + UAC_UNIT) << 32));
1827	<	if (w.eventCount != (e | INT_SIGN))
1828	<	break outer;
1829	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1830	<	w.eventCount = (e + E_SEQ) & E_MASK;
1831	<	if ((p = w.parker) != null)
1832	<	U.unpark(p);
1833	<	if (--n <= 0)
1834	<	break;
1835	<	}
1836	<	}
1770	>	* Possibly releases (signals) a worker. Called only from scan()
1771	>	* when a worker with apparently inactive status finds a non-empty
1772	>	* queue. This requires revalidating all of the associated state
1773	>	* from caller.
1774	>	*/
1775	>	private final void helpRelease(long c, WorkQueue[] ws, WorkQueue w,
1776	>	WorkQueue q, int b) {
1777	>	WorkQueue v; int e, i; Thread p;
1778	>	if (w != null && w.eventCount < 0 && (e = (int)c) > 0 &&
1779	>	ws != null && ws.length > (i = e & SMASK) &&
1780	>	(v = ws[i]) != null && ctl == c) {
1781	>	long nc = (((long)(v.nextWait & E_MASK)) |
1782	>	((long)((int)(c >>> 32) + UAC_UNIT)) << 32);
1783	>	int ne = (e + E_SEQ) & E_MASK;
1784	>	if (q != null && q.base == b && w.eventCount < 0 &&
1785	>	v.eventCount == (e | INT_SIGN) &&
1786	>	U.compareAndSwapLong(this, CTL, c, nc)) {
1787	>	v.eventCount = ne;
1788	>	if ((p = v.parker) != null)
1789	>	U.unpark(p);
1790		}
1791		}
1792		}
#	Line 1858 | Line 1811 | public class ForkJoinPool extends Abstra
1811		*/
1812		private int tryHelpStealer(WorkQueue joiner, ForkJoinTask<?> task) {
1813		int stat = 0, steps = 0;                    // bound to avoid cycles
1814	<	if (joiner != null && task != null) {       // hoist null checks
1814	>	if (task != null && joiner != null &&
1815	>	joiner.base - joiner.top >= 0) {        // hoist checks
1816		restart: for (;;) {
1817		ForkJoinTask<?> subtask = task;     // current target
1818		for (WorkQueue j = joiner, v;;) {   // v is stealer of subtask
#	Line 1885 | Line 1839 | public class ForkJoinPool extends Abstra
1839		}
1840		}
1841		for (;;) { // help stealer or descend to its stealer
1842	<	ForkJoinTask[] a;  int b;
1842	>	ForkJoinTask[] a; int b;
1843		if (subtask.status < 0)     // surround probes with
1844		continue restart;       //   consistency checks
1845		if ((b = v.base) - v.top < 0 && (a = v.array) != null) {
#	Line 1896 | Line 1850 | public class ForkJoinPool extends Abstra
1850		v.currentSteal != subtask)
1851		continue restart;   // stale
1852		stat = 1;               // apparent progress
1853	<	if (t != null && v.base == b &&
1854	<	U.compareAndSwapObject(a, i, t, null)) {
1855	<	v.base = b + 1;     // help stealer
1856	<	joiner.runSubtask(t);
1853	>	if (v.base == b) {
1854	>	if (t == null)
1855	>	break restart;
1856	>	if (U.compareAndSwapObject(a, i, t, null)) {
1857	>	U.putOrderedInt(v, QBASE, b + 1);
1858	>	ForkJoinTask<?> ps = joiner.currentSteal;
1859	>	int jt = joiner.top;
1860	>	do {
1861	>	joiner.currentSteal = t;
1862	>	t.doExec(); // clear local tasks too
1863	>	} while (task.status >= 0 &&
1864	>	joiner.top != jt &&
1865	>	(t = joiner.pop()) != null);
1866	>	joiner.currentSteal = ps;
1867	>	break restart;
1868	>	}
1869		}
1904	–	else if (v.base == b && ++steps == MAX_HELP)
1905	–	break restart;      // v apparently stalled
1870		}
1871		else {                      // empty -- try to descend
1872		ForkJoinTask<?> next = v.currentJoin;
#	Line 1929 | Line 1893 | public class ForkJoinPool extends Abstra
1893		* and run tasks within the target's computation.
1894		*
1895		* @param task the task to join
1932	–	* @param mode if shared, exit upon completing any task
1933	–	* if all workers are active
1896		*/
1897	<	private int helpComplete(ForkJoinTask<?> task, int mode) {
1898	<	WorkQueue[] ws; WorkQueue q; int m, n, s, u;
1899	<	if (task != null && (ws = workQueues) != null &&
1900	<	(m = ws.length - 1) >= 0) {
1901	<	for (int j = 1, origin = j;;) {
1897	>	private int helpComplete(WorkQueue joiner, CountedCompleter<?> task) {
1898	>	WorkQueue[] ws; int m;
1899	>	int s = 0;
1900	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0 &&
1901	>	joiner != null && task != null) {
1902	>	int j = joiner.poolIndex;
1903	>	int scans = m + m + 1;
1904	>	long c = 0L;              // for stability check
1905	>	for (int k = scans; ; j += 2) {
1906	>	WorkQueue q;
1907		if ((s = task.status) < 0)
1908	<	return s;
1909	<	if ((q = ws[j & m]) != null && q.pollAndExecCC(task)) {
1910	<	origin = j;
1911	<	if (mode == SHARED_QUEUE &&
1912	<	((u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0))
1908	>	break;
1909	>	else if (joiner.internalPopAndExecCC(task))
1910	>	k = scans;
1911	>	else if ((s = task.status) < 0)
1912	>	break;
1913	>	else if ((q = ws[j & m]) != null && q.pollAndExecCC(task))
1914	>	k = scans;
1915	>	else if (--k < 0) {
1916	>	if (c == (c = ctl))
1917		break;
1918	+	k = scans;
1919		}
1948	–	else if ((j = (j + 2) & m) == origin)
1949	–	break;
1920		}
1921		}
1922	<	return 0;
1922	>	return s;
1923		}
1924
1925		/**
#	Line 1958 | Line 1928 | public class ForkJoinPool extends Abstra
1928		* for blocking. Fails on contention or termination. Otherwise,
1929		* adds a new thread if no idle workers are available and pool
1930		* may become starved.
1931	+	*
1932	+	* @param c the assumed ctl value
1933		*/
1934	<	final boolean tryCompensate() {
1935	<	int pc = config & SMASK, e, i, tc; long c;
1936	<	WorkQueue[] ws; WorkQueue w; Thread p;
1937	<	if ((ws = workQueues) != null && (e = (int)(c = ctl)) >= 0) {
1938	<	if (e != 0 && (i = e & SMASK) < ws.length &&
1939	<	(w = ws[i]) != null && w.eventCount == (e | INT_SIGN)) {
1934	>	final boolean tryCompensate(long c) {
1935	>	WorkQueue[] ws = workQueues;
1936	>	int pc = parallelism, e = (int)c, m, tc;
1937	>	if (ws != null && (m = ws.length - 1) >= 0 && e >= 0 && ctl == c) {
1938	>	WorkQueue w = ws[e & m];
1939	>	if (e != 0 && w != null) {
1940	>	Thread p;
1941		long nc = ((long)(w.nextWait & E_MASK) |
1942		(c & (AC_MASK|TC_MASK)));
1943	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1944	<	w.eventCount = (e + E_SEQ) & E_MASK;
1943	>	int ne = (e + E_SEQ) & E_MASK;
1944	>	if (w.eventCount == (e | INT_SIGN) &&
1945	>	U.compareAndSwapLong(this, CTL, c, nc)) {
1946	>	w.eventCount = ne;
1947		if ((p = w.parker) != null)
1948		U.unpark(p);
1949		return true;   // replace with idle worker
#	Line 2011 | Line 1986 | public class ForkJoinPool extends Abstra
1986		*/
1987		final int awaitJoin(WorkQueue joiner, ForkJoinTask<?> task) {
1988		int s = 0;
1989	<	if (joiner != null && task != null && (s = task.status) >= 0) {
1989	>	if (task != null && (s = task.status) >= 0 && joiner != null) {
1990		ForkJoinTask<?> prevJoin = joiner.currentJoin;
1991		joiner.currentJoin = task;
1992	<	do {} while ((s = task.status) >= 0 && !joiner.isEmpty() &&
1993	<	joiner.tryRemoveAndExec(task)); // process local tasks
1994	<	if (s >= 0 && (s = task.status) >= 0) {
1995	<	helpSignal(task, joiner.poolIndex);
1996	<	if ((s = task.status) >= 0 &&
2022	<	(task instanceof CountedCompleter))
2023	<	s = helpComplete(task, LIFO_QUEUE);
2024	<	}
1992	>	do {} while (joiner.tryRemoveAndExec(task) && // process local tasks
1993	>	(s = task.status) >= 0);
1994	>	if (s >= 0 && (task instanceof CountedCompleter))
1995	>	s = helpComplete(joiner, (CountedCompleter<?>)task);
1996	>	long cc = 0;        // for stability checks
1997		while (s >= 0 && (s = task.status) >= 0) {
1998	<	if ((!joiner.isEmpty() ||           // try helping
2027	<	(s = tryHelpStealer(joiner, task)) == 0) &&
1998	>	if ((s = tryHelpStealer(joiner, task)) == 0 &&
1999		(s = task.status) >= 0) {
2000	<	helpSignal(task, joiner.poolIndex);
2001	<	if ((s = task.status) >= 0 && tryCompensate()) {
2000	>	if (!tryCompensate(cc))
2001	>	cc = ctl;
2002	>	else {
2003		if (task.trySetSignal() && (s = task.status) >= 0) {
2004		synchronized (task) {
2005		if (task.status >= 0) {
#	Line 2040 | Line 2012 | public class ForkJoinPool extends Abstra
2012		task.notifyAll();
2013		}
2014		}
2015	<	long c;                          // re-activate
2015	>	long c; // reactivate
2016		do {} while (!U.compareAndSwapLong
2017	<	(this, CTL, c = ctl, c + AC_UNIT));
2017	>	(this, CTL, c = ctl,
2018	>	((c & ~AC_MASK) |
2019	>	((c & AC_MASK) + AC_UNIT))));
2020		}
2021		}
2022		}
#	Line 2064 | Line 2038 | public class ForkJoinPool extends Abstra
2038		if (joiner != null && task != null && (s = task.status) >= 0) {
2039		ForkJoinTask<?> prevJoin = joiner.currentJoin;
2040		joiner.currentJoin = task;
2041	<	do {} while ((s = task.status) >= 0 && !joiner.isEmpty() &&
2042	<	joiner.tryRemoveAndExec(task));
2043	<	if (s >= 0 && (s = task.status) >= 0) {
2044	<	helpSignal(task, joiner.poolIndex);
2045	<	if ((s = task.status) >= 0 &&
2072	<	(task instanceof CountedCompleter))
2073	<	s = helpComplete(task, LIFO_QUEUE);
2074	<	}
2075	<	if (s >= 0 && joiner.isEmpty()) {
2041	>	do {} while (joiner.tryRemoveAndExec(task) && // process local tasks
2042	>	(s = task.status) >= 0);
2043	>	if (s >= 0) {
2044	>	if (task instanceof CountedCompleter)
2045	>	helpComplete(joiner, (CountedCompleter<?>)task);
2046		do {} while (task.status >= 0 &&
2047		tryHelpStealer(joiner, task) > 0);
2048		}
#	Line 2084 | Line 2054 | public class ForkJoinPool extends Abstra
2054		* Returns a (probably) non-empty steal queue, if one is found
2055		* during a scan, else null.  This method must be retried by
2056		* caller if, by the time it tries to use the queue, it is empty.
2087	–	* @param r a (random) seed for scanning
2057		*/
2058	<	private WorkQueue findNonEmptyStealQueue(int r) {
2058	>	private WorkQueue findNonEmptyStealQueue() {
2059	>	int r = ThreadLocalRandom.current().nextInt();
2060		for (;;) {
2061		int ps = plock, m; WorkQueue[] ws; WorkQueue q;
2062		if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
2063		for (int j = (m + 1) << 2; j >= 0; --j) {
2064	<	if ((q = ws[(((r + j) << 1) | 1) & m]) != null &&
2064	>	if ((q = ws[(((r - j) << 1) | 1) & m]) != null &&
2065		q.base - q.top < 0)
2066		return q;
2067		}
#	Line 2108 | Line 2078 | public class ForkJoinPool extends Abstra
2078		* find tasks either.
2079		*/
2080		final void helpQuiescePool(WorkQueue w) {
2081	+	ForkJoinTask<?> ps = w.currentSteal;
2082		for (boolean active = true;;) {
2083		long c; WorkQueue q; ForkJoinTask<?> t; int b;
2084	<	while ((t = w.nextLocalTask()) != null) {
2114	<	if (w.base - w.top < 0)
2115	<	signalWork(w);
2084	>	while ((t = w.nextLocalTask()) != null)
2085		t.doExec();
2086	<	}
2118	<	if ((q = findNonEmptyStealQueue(w.nextSeed())) != null) {
2086	>	if ((q = findNonEmptyStealQueue()) != null) {
2087		if (!active) {      // re-establish active count
2088		active = true;
2089		do {} while (!U.compareAndSwapLong
2090	<	(this, CTL, c = ctl, c + AC_UNIT));
2090	>	(this, CTL, c = ctl,
2091	>	((c & ~AC_MASK) |
2092	>	((c & AC_MASK) + AC_UNIT))));
2093		}
2094		if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) {
2095	<	if (q.base - q.top < 0)
2096	<	signalWork(q);
2127	<	w.runSubtask(t);
2095	>	(w.currentSteal = t).doExec();
2096	>	w.currentSteal = ps;
2097		}
2098		}
2099		else if (active) {       // decrement active count without queuing
2100	<	long nc = (c = ctl) - AC_UNIT;
2101	<	if ((int)(nc >> AC_SHIFT) + (config & SMASK) == 0)
2102	<	return;          // bypass decrement-then-increment
2100	>	long nc = ((c = ctl) & ~AC_MASK) | ((c & AC_MASK) - AC_UNIT);
2101	>	if ((int)(nc >> AC_SHIFT) + parallelism == 0)
2102	>	break;          // bypass decrement-then-increment
2103		if (U.compareAndSwapLong(this, CTL, c, nc))
2104		active = false;
2105		}
2106	<	else if ((int)((c = ctl) >> AC_SHIFT) + (config & SMASK) == 0 &&
2107	<	U.compareAndSwapLong(this, CTL, c, c + AC_UNIT))
2108	<	return;
2106	>	else if ((int)((c = ctl) >> AC_SHIFT) + parallelism <= 0 &&
2107	>	U.compareAndSwapLong
2108	>	(this, CTL, c, ((c & ~AC_MASK) |
2109	>	((c & AC_MASK) + AC_UNIT))))
2110	>	break;
2111		}
2112		}
2113
#	Line 2150 | Line 2121 | public class ForkJoinPool extends Abstra
2121		WorkQueue q; int b;
2122		if ((t = w.nextLocalTask()) != null)
2123		return t;
2124	<	if ((q = findNonEmptyStealQueue(w.nextSeed())) == null)
2124	>	if ((q = findNonEmptyStealQueue()) == null)
2125		return null;
2126	<	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) {
2156	<	if (q.base - q.top < 0)
2157	<	signalWork(q);
2126	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2127		return t;
2159	–	}
2128		}
2129		}
2130
#	Line 2209 | Line 2177 | public class ForkJoinPool extends Abstra
2177		static int getSurplusQueuedTaskCount() {
2178		Thread t; ForkJoinWorkerThread wt; ForkJoinPool pool; WorkQueue q;
2179		if (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)) {
2180	<	int p = (pool = (wt = (ForkJoinWorkerThread)t).pool).config & SMASK;
2180	>	int p = (pool = (wt = (ForkJoinWorkerThread)t).pool).parallelism;
2181		int n = (q = wt.workQueue).top - q.base;
2182		int a = (int)(pool.ctl >> AC_SHIFT) + p;
2183		return n - (a > (p >>>= 1) ? 0 :
#	Line 2239 | Line 2207 | public class ForkJoinPool extends Abstra
2207		*/
2208		private boolean tryTerminate(boolean now, boolean enable) {
2209		int ps;
2210	<	if (this == common)                    // cannot shut down
2210	>	if (this == common)                        // cannot shut down
2211		return false;
2212		if ((ps = plock) >= 0) {                   // enable by setting plock
2213		if (!enable)
#	Line 2253 | Line 2221 | public class ForkJoinPool extends Abstra
2221		}
2222		for (long c;;) {
2223		if (((c = ctl) & STOP_BIT) != 0) {     // already terminating
2224	<	if ((short)(c >>> TC_SHIFT) == -(config & SMASK)) {
2224	>	if ((short)(c >>> TC_SHIFT) + parallelism <= 0) {
2225		synchronized (this) {
2226		notifyAll();               // signal when 0 workers
2227		}
#	Line 2262 | Line 2230 | public class ForkJoinPool extends Abstra
2230		}
2231		if (!now) {                            // check if idle & no tasks
2232		WorkQueue[] ws; WorkQueue w;
2233	<	if ((int)(c >> AC_SHIFT) != -(config & SMASK))
2233	>	if ((int)(c >> AC_SHIFT) + parallelism > 0)
2234		return false;
2235		if ((ws = workQueues) != null) {
2236		for (int i = 0; i < ws.length; ++i) {
2237	<	if ((w = ws[i]) != null) {
2238	<	if (!w.isEmpty()) {    // signal unprocessed tasks
2239	<	signalWork(w);
2240	<	return false;
2241	<	}
2274	<	if ((i & 1) != 0 && w.eventCount >= 0)
2275	<	return false;      // unqueued inactive worker
2237	>	if ((w = ws[i]) != null &&
2238	>	(!w.isEmpty() ||
2239	>	((i & 1) != 0 && w.eventCount >= 0))) {
2240	>	signalWork(ws, w);
2241	>	return false;
2242		}
2243		}
2244		}
#	Line 2328 | Line 2294 | public class ForkJoinPool extends Abstra
2294		* least one task.
2295		*/
2296		static WorkQueue commonSubmitterQueue() {
2297	<	ForkJoinPool p; WorkQueue[] ws; int m; Submitter z;
2297	>	Submitter z; ForkJoinPool p; WorkQueue[] ws; int m, r;
2298		return ((z = submitters.get()) != null &&
2299		(p = common) != null &&
2300		(ws = p.workQueues) != null &&
#	Line 2339 | Line 2305 | public class ForkJoinPool extends Abstra
2305		/**
2306		* Tries to pop the given task from submitter's queue in common pool.
2307		*/
2308	<	static boolean tryExternalUnpush(ForkJoinTask<?> t) {
2309	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q; Submitter z;
2310	<	ForkJoinTask<?>[] a;  int m, s;
2311	<	if (t != null &&
2312	<	(z = submitters.get()) != null &&
2313	<	(p = common) != null &&
2314	<	(ws = p.workQueues) != null &&
2315	<	(m = ws.length - 1) >= 0 &&
2316	<	(q = ws[m & z.seed & SQMASK]) != null &&
2351	<	(s = q.top) != q.base &&
2352	<	(a = q.array) != null) {
2308	>	final boolean tryExternalUnpush(ForkJoinTask<?> task) {
2309	>	WorkQueue joiner; ForkJoinTask<?>[] a; int m, s;
2310	>	Submitter z = submitters.get();
2311	>	WorkQueue[] ws = workQueues;
2312	>	boolean popped = false;
2313	>	if (z != null && ws != null && (m = ws.length - 1) >= 0 &&
2314	>	(joiner = ws[z.seed & m & SQMASK]) != null &&
2315	>	joiner.base != (s = joiner.top) &&
2316	>	(a = joiner.array) != null) {
2317		long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
2318	<	if (U.getObject(a, j) == t &&
2319	<	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2320	<	if (q.array == a && q.top == s && // recheck
2321	<	U.compareAndSwapObject(a, j, t, null)) {
2322	<	q.top = s - 1;
2323	<	q.qlock = 0;
2360	<	return true;
2318	>	if (U.getObject(a, j) == task &&
2319	>	U.compareAndSwapInt(joiner, QLOCK, 0, 1)) {
2320	>	if (joiner.top == s && joiner.array == a &&
2321	>	U.compareAndSwapObject(a, j, task, null)) {
2322	>	joiner.top = s - 1;
2323	>	popped = true;
2324		}
2325	<	q.qlock = 0;
2325	>	joiner.qlock = 0;
2326		}
2327		}
2328	<	return false;
2328	>	return popped;
2329		}
2330
2331	<	/**
2332	<	* Tries to pop and run local tasks within the same computation
2333	<	* as the given root. On failure, tries to help complete from
2334	<	* other queues via helpComplete.
2335	<	*/
2336	<	private void externalHelpComplete(WorkQueue q, ForkJoinTask<?> root) {
2337	<	ForkJoinTask<?>[] a; int m;
2338	<	if (q != null && (a = q.array) != null && (m = (a.length - 1)) >= 0 &&
2339	<	root != null && root.status >= 0) {
2340	<	for (;;) {
2341	<	int s, u; Object o; CountedCompleter<?> task = null;
2342	<	if ((s = q.top) - q.base > 0) {
2343	<	long j = ((m & (s - 1)) << ASHIFT) + ABASE;
2381	<	if ((o = U.getObject(a, j)) != null &&
2382	<	(o instanceof CountedCompleter)) {
2383	<	CountedCompleter<?> t = (CountedCompleter<?>)o, r = t;
2384	<	do {
2385	<	if (r == root) {
2386	<	if (U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2387	<	if (q.array == a && q.top == s &&
2388	<	U.compareAndSwapObject(a, j, t, null)) {
2389	<	q.top = s - 1;
2390	<	task = t;
2391	<	}
2392	<	q.qlock = 0;
2393	<	}
2394	<	break;
2395	<	}
2396	<	} while ((r = r.completer) != null);
2397	<	}
2398	<	}
2399	<	if (task != null)
2400	<	task.doExec();
2401	<	if (root.status < 0 ||
2402	<	(u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0)
2331	>	final int externalHelpComplete(CountedCompleter<?> task) {
2332	>	WorkQueue joiner; int m, j;
2333	>	Submitter z = submitters.get();
2334	>	WorkQueue[] ws = workQueues;
2335	>	int s = 0;
2336	>	if (z != null && ws != null && (m = ws.length - 1) >= 0 &&
2337	>	(joiner = ws[(j = z.seed) & m & SQMASK]) != null && task != null) {
2338	>	int scans = m + m + 1;
2339	>	long c = 0L;             // for stability check
2340	>	j |= 1;                  // poll odd queues
2341	>	for (int k = scans; ; j += 2) {
2342	>	WorkQueue q;
2343	>	if ((s = task.status) < 0)
2344		break;
2345	<	if (task == null) {
2346	<	helpSignal(root, q.poolIndex);
2347	<	if (root.status >= 0)
2407	<	helpComplete(root, SHARED_QUEUE);
2345	>	else if (joiner.externalPopAndExecCC(task))
2346	>	k = scans;
2347	>	else if ((s = task.status) < 0)
2348		break;
2349	+	else if ((q = ws[j & m]) != null && q.pollAndExecCC(task))
2350	+	k = scans;
2351	+	else if (--k < 0) {
2352	+	if (c == (c = ctl))
2353	+	break;
2354	+	k = scans;
2355		}
2356		}
2357		}
2358	<	}
2413	<
2414	<	/**
2415	<	* Tries to help execute or signal availability of the given task
2416	<	* from submitter's queue in common pool.
2417	<	*/
2418	<	static void externalHelpJoin(ForkJoinTask<?> t) {
2419	<	// Some hard-to-avoid overlap with tryExternalUnpush
2420	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q, w; Submitter z;
2421	<	ForkJoinTask<?>[] a;  int m, s, n;
2422	<	if (t != null &&
2423	<	(z = submitters.get()) != null &&
2424	<	(p = common) != null &&
2425	<	(ws = p.workQueues) != null &&
2426	<	(m = ws.length - 1) >= 0 &&
2427	<	(q = ws[m & z.seed & SQMASK]) != null &&
2428	<	(a = q.array) != null) {
2429	<	int am = a.length - 1;
2430	<	if ((s = q.top) != q.base) {
2431	<	long j = ((am & (s - 1)) << ASHIFT) + ABASE;
2432	<	if (U.getObject(a, j) == t &&
2433	<	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2434	<	if (q.array == a && q.top == s &&
2435	<	U.compareAndSwapObject(a, j, t, null)) {
2436	<	q.top = s - 1;
2437	<	q.qlock = 0;
2438	<	t.doExec();
2439	<	}
2440	<	else
2441	<	q.qlock = 0;
2442	<	}
2443	<	}
2444	<	if (t.status >= 0) {
2445	<	if (t instanceof CountedCompleter)
2446	<	p.externalHelpComplete(q, t);
2447	<	else
2448	<	p.helpSignal(t, q.poolIndex);
2449	<	}
2450	<	}
2358	>	return s;
2359		}
2360
2361		// Exported methods
#	Line 2514 | Line 2422 | public class ForkJoinPool extends Abstra
2422		*/
2423		public ForkJoinPool(int parallelism,
2424		ForkJoinWorkerThreadFactory factory,
2425	<	Thread.UncaughtExceptionHandler handler,
2425	>	UncaughtExceptionHandler handler,
2426		boolean asyncMode) {
2427	+	this(checkParallelism(parallelism),
2428	+	checkFactory(factory),
2429	+	handler,
2430	+	(asyncMode ? FIFO_QUEUE : LIFO_QUEUE),
2431	+	"ForkJoinPool-" + nextPoolId() + "-worker-");
2432		checkPermission();
2433	<	if (factory == null)
2434	<	throw new NullPointerException();
2433	>	}
2434	>
2435	>	private static int checkParallelism(int parallelism) {
2436		if (parallelism <= 0 || parallelism > MAX_CAP)
2437		throw new IllegalArgumentException();
2438	<	this.factory = factory;
2439	<	this.ueh = handler;
2440	<	this.config = parallelism | (asyncMode ? (FIFO_QUEUE << 16) : 0);
2441	<	long np = (long)(-parallelism); // offset ctl counts
2442	<	this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
2443	<	int pn = nextPoolId();
2444	<	StringBuilder sb = new StringBuilder("ForkJoinPool-");
2445	<	sb.append(Integer.toString(pn));
2532	<	sb.append("-worker-");
2533	<	this.workerNamePrefix = sb.toString();
2438	>	return parallelism;
2439	>	}
2440	>
2441	>	private static ForkJoinWorkerThreadFactory checkFactory
2442	>	(ForkJoinWorkerThreadFactory factory) {
2443	>	if (factory == null)
2444	>	throw new NullPointerException();
2445	>	return factory;
2446		}
2447
2448		/**
2449	<	* Constructor for common pool, suitable only for static initialization.
2450	<	* Basically the same as above, but uses smallest possible initial footprint.
2451	<	*/
2452	<	ForkJoinPool(int parallelism, long ctl,
2453	<	ForkJoinWorkerThreadFactory factory,
2454	<	Thread.UncaughtExceptionHandler handler) {
2455	<	this.config = parallelism;
2456	<	this.ctl = ctl;
2449	>	* Creates a {@code ForkJoinPool} with the given parameters, without
2450	>	* any security checks or parameter validation.  Invoked directly by
2451	>	* makeCommonPool.
2452	>	*/
2453	>	private ForkJoinPool(int parallelism,
2454	>	ForkJoinWorkerThreadFactory factory,
2455	>	UncaughtExceptionHandler handler,
2456	>	int mode,
2457	>	String workerNamePrefix) {
2458	>	this.workerNamePrefix = workerNamePrefix;
2459		this.factory = factory;
2460		this.ueh = handler;
2461	<	this.workerNamePrefix = "ForkJoinPool.commonPool-worker-";
2461	>	this.mode = (short)mode;
2462	>	this.parallelism = (short)parallelism;
2463	>	long np = (long)(-parallelism); // offset ctl counts
2464	>	this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
2465		}
2466
2467		/**
#	Line 2554 | Line 2471 | public class ForkJoinPool extends Abstra
2471		* ongoing processing are automatically terminated upon program
2472		* {@link System#exit}.  Any program that relies on asynchronous
2473		* task processing to complete before program termination should
2474	<	* invoke {@code commonPool().}{@link #awaitQuiescence}, before
2475	<	* exit.
2474	>	* invoke {@code commonPool().}{@link #awaitQuiescence awaitQuiescence},
2475	>	* before exit.
2476		*
2477		* @return the common pool instance
2478		* @since 1.8
#	Line 2618 | Line 2535 | public class ForkJoinPool extends Abstra
2535		if (task instanceof ForkJoinTask<?>) // avoid re-wrap
2536		job = (ForkJoinTask<?>) task;
2537		else
2538	<	job = new ForkJoinTask.AdaptedRunnableAction(task);
2538	>	job = new ForkJoinTask.RunnableExecuteAction(task);
2539		externalPush(job);
2540		}
2541
#	Line 2720 | Line 2637 | public class ForkJoinPool extends Abstra
2637		*
2638		* @return the handler, or {@code null} if none
2639		*/
2640	<	public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
2640	>	public UncaughtExceptionHandler getUncaughtExceptionHandler() {
2641		return ueh;
2642		}
2643
#	Line 2730 | Line 2647 | public class ForkJoinPool extends Abstra
2647		* @return the targeted parallelism level of this pool
2648		*/
2649		public int getParallelism() {
2650	<	return config & SMASK;
2650	>	int par;
2651	>	return ((par = parallelism) > 0) ? par : 1;
2652		}
2653
2654		/**
#	Line 2752 | Line 2670 | public class ForkJoinPool extends Abstra
2670		* @return the number of worker threads
2671		*/
2672		public int getPoolSize() {
2673	<	return (config & SMASK) + (short)(ctl >>> TC_SHIFT);
2673	>	return parallelism + (short)(ctl >>> TC_SHIFT);
2674		}
2675
2676		/**
#	Line 2762 | Line 2680 | public class ForkJoinPool extends Abstra
2680		* @return {@code true} if this pool uses async mode
2681		*/
2682		public boolean getAsyncMode() {
2683	<	return (config >>> 16) == FIFO_QUEUE;
2683	>	return mode == FIFO_QUEUE;
2684		}
2685
2686		/**
#	Line 2793 | Line 2711 | public class ForkJoinPool extends Abstra
2711		* @return the number of active threads
2712		*/
2713		public int getActiveThreadCount() {
2714	<	int r = (config & SMASK) + (int)(ctl >> AC_SHIFT);
2714	>	int r = parallelism + (int)(ctl >> AC_SHIFT);
2715		return (r <= 0) ? 0 : r; // suppress momentarily negative values
2716		}
2717
#	Line 2809 | Line 2727 | public class ForkJoinPool extends Abstra
2727		* @return {@code true} if all threads are currently idle
2728		*/
2729		public boolean isQuiescent() {
2730	<	return (int)(ctl >> AC_SHIFT) + (config & SMASK) == 0;
2730	>	return parallelism + (int)(ctl >> AC_SHIFT) <= 0;
2731		}
2732
2733		/**
#	Line 2972 | Line 2890 | public class ForkJoinPool extends Abstra
2890		}
2891		}
2892		}
2893	<	int pc = (config & SMASK);
2893	>	int pc = parallelism;
2894		int tc = pc + (short)(c >>> TC_SHIFT);
2895		int ac = pc + (int)(c >> AC_SHIFT);
2896		if (ac < 0) // ignore transient negative
#	Line 3045 | Line 2963 | public class ForkJoinPool extends Abstra
2963		public boolean isTerminated() {
2964		long c = ctl;
2965		return ((c & STOP_BIT) != 0L &&
2966	<	(short)(c >>> TC_SHIFT) == -(config & SMASK));
2966	>	(short)(c >>> TC_SHIFT) + parallelism <= 0);
2967		}
2968
2969		/**
#	Line 3064 | Line 2982 | public class ForkJoinPool extends Abstra
2982		public boolean isTerminating() {
2983		long c = ctl;
2984		return ((c & STOP_BIT) != 0L &&
2985	<	(short)(c >>> TC_SHIFT) != -(config & SMASK));
2985	>	(short)(c >>> TC_SHIFT) + parallelism > 0);
2986		}
2987
2988		/**
#	Line 3082 | Line 3000 | public class ForkJoinPool extends Abstra
3000		* is interrupted, whichever happens first. Because the {@link
3001		* #commonPool()} never terminates until program shutdown, when
3002		* applied to the common pool, this method is equivalent to {@link
3003	<	* #awaitQuiescence} but always returns {@code false}.
3003	>	* #awaitQuiescence(long, TimeUnit)} but always returns {@code false}.
3004		*
3005		* @param timeout the maximum time to wait
3006		* @param unit the time unit of the timeout argument
#	Line 3101 | Line 3019 | public class ForkJoinPool extends Abstra
3019		long nanos = unit.toNanos(timeout);
3020		if (isTerminated())
3021		return true;
3022	<	long startTime = System.nanoTime();
3023	<	boolean terminated = false;
3022	>	if (nanos <= 0L)
3023	>	return false;
3024	>	long deadline = System.nanoTime() + nanos;
3025		synchronized (this) {
3026	<	for (long waitTime = nanos, millis = 0L;;) {
3027	<	if (terminated = isTerminated() ||
3028	<	waitTime <= 0L ||
3029	<	(millis = unit.toMillis(waitTime)) <= 0L)
3030	<	break;
3031	<	wait(millis);
3032	<	waitTime = nanos - (System.nanoTime() - startTime);
3026	>	for (;;) {
3027	>	if (isTerminated())
3028	>	return true;
3029	>	if (nanos <= 0L)
3030	>	return false;
3031	>	long millis = TimeUnit.NANOSECONDS.toMillis(nanos);
3032	>	wait(millis > 0L ? millis : 1L);
3033	>	nanos = deadline - System.nanoTime();
3034		}
3035		}
3116	–	return terminated;
3036		}
3037
3038		/**
#	Line 3152 | Line 3071 | public class ForkJoinPool extends Abstra
3071		ForkJoinTask<?> t; WorkQueue q; int b;
3072		if ((q = ws[r++ & m]) != null && (b = q.base) - q.top < 0) {
3073		found = true;
3074	<	if ((t = q.pollAt(b)) != null) {
3156	<	if (q.base - q.top < 0)
3157	<	signalWork(q);
3074	>	if ((t = q.pollAt(b)) != null)
3075		t.doExec();
3159	–	}
3076		break;
3077		}
3078		}
#	Line 3181 | Line 3097 | public class ForkJoinPool extends Abstra
3097		* not necessary. Method {@code block} blocks the current thread
3098		* if necessary (perhaps internally invoking {@code isReleasable}
3099		* before actually blocking). These actions are performed by any
3100	<	* thread invoking {@link ForkJoinPool#managedBlock}.  The
3101	<	* unusual methods in this API accommodate synchronizers that may,
3102	<	* but don't usually, block for long periods. Similarly, they
3100	>	* thread invoking {@link ForkJoinPool#managedBlock(ManagedBlocker)}.
3101	>	* The unusual methods in this API accommodate synchronizers that
3102	>	* may, but don't usually, block for long periods. Similarly, they
3103		* allow more efficient internal handling of cases in which
3104		* additional workers may be, but usually are not, needed to
3105		* ensure sufficient parallelism.  Toward this end,
#	Line 3241 | Line 3157 | public class ForkJoinPool extends Abstra
3157
3158		/**
3159		* Returns {@code true} if blocking is unnecessary.
3160	+	* @return {@code true} if blocking is unnecessary
3161		*/
3162		boolean isReleasable();
3163		}
#	Line 3270 | Line 3187 | public class ForkJoinPool extends Abstra
3187		Thread t = Thread.currentThread();
3188		if (t instanceof ForkJoinWorkerThread) {
3189		ForkJoinPool p = ((ForkJoinWorkerThread)t).pool;
3190	<	while (!blocker.isReleasable()) { // variant of helpSignal
3191	<	WorkQueue[] ws; WorkQueue q; int m, u;
3275	<	if ((ws = p.workQueues) != null && (m = ws.length - 1) >= 0) {
3276	<	for (int i = 0; i <= m; ++i) {
3277	<	if (blocker.isReleasable())
3278	<	return;
3279	<	if ((q = ws[i]) != null && q.base - q.top < 0) {
3280	<	p.signalWork(q);
3281	<	if ((u = (int)(p.ctl >>> 32)) >= 0 ||
3282	<	(u >> UAC_SHIFT) >= 0)
3283	<	break;
3284	<	}
3285	<	}
3286	<	}
3287	<	if (p.tryCompensate()) {
3190	>	while (!blocker.isReleasable()) {
3191	>	if (p.tryCompensate(p.ctl)) {
3192		try {
3193		do {} while (!blocker.isReleasable() &&
3194		!blocker.block());
#	Line 3322 | Line 3226 | public class ForkJoinPool extends Abstra
3226		private static final long STEALCOUNT;
3227		private static final long PLOCK;
3228		private static final long INDEXSEED;
3229	+	private static final long QBASE;
3230		private static final long QLOCK;
3231
3232		static {
#	Line 3341 | Line 3246 | public class ForkJoinPool extends Abstra
3246		PARKBLOCKER = U.objectFieldOffset
3247		(tk.getDeclaredField("parkBlocker"));
3248		Class<?> wk = WorkQueue.class;
3249	+	QBASE = U.objectFieldOffset
3250	+	(wk.getDeclaredField("base"));
3251		QLOCK = U.objectFieldOffset
3252		(wk.getDeclaredField("qlock"));
3253		Class<?> ak = ForkJoinTask[].class;
#	Line 3354 | Line 3261 | public class ForkJoinPool extends Abstra
3261		}
3262
3263		submitters = new ThreadLocal<Submitter>();
3264	<	ForkJoinWorkerThreadFactory fac = defaultForkJoinWorkerThreadFactory =
3264	>	defaultForkJoinWorkerThreadFactory =
3265		new DefaultForkJoinWorkerThreadFactory();
3266		modifyThreadPermission = new RuntimePermission("modifyThread");
3267
3268	<	/*
3269	<	* Establish common pool parameters.  For extra caution,
3270	<	* computations to set up common pool state are here; the
3271	<	* constructor just assigns these values to fields.
3272	<	*/
3268	>	common = java.security.AccessController.doPrivileged
3269	>	(new java.security.PrivilegedAction<ForkJoinPool>() {
3270	>	public ForkJoinPool run() { return makeCommonPool(); }});
3271	>	int par = common.parallelism; // report 1 even if threads disabled
3272	>	commonParallelism = par > 0 ? par : 1;
3273	>	}
3274
3275	<	int par = 0;
3276	<	Thread.UncaughtExceptionHandler handler = null;
3277	<	try {  // TBD: limit or report ignored exceptions?
3275	>	/**
3276	>	* Creates and returns the common pool, respecting user settings
3277	>	* specified via system properties.
3278	>	*/
3279	>	private static ForkJoinPool makeCommonPool() {
3280	>	int parallelism = -1;
3281	>	ForkJoinWorkerThreadFactory factory
3282	>	= defaultForkJoinWorkerThreadFactory;
3283	>	UncaughtExceptionHandler handler = null;
3284	>	try {  // ignore exceptions in accesing/parsing properties
3285		String pp = System.getProperty
3286		("java.util.concurrent.ForkJoinPool.common.parallelism");
3372	–	String hp = System.getProperty
3373	–	("java.util.concurrent.ForkJoinPool.common.exceptionHandler");
3287		String fp = System.getProperty
3288		("java.util.concurrent.ForkJoinPool.common.threadFactory");
3289	+	String hp = System.getProperty
3290	+	("java.util.concurrent.ForkJoinPool.common.exceptionHandler");
3291	+	if (pp != null)
3292	+	parallelism = Integer.parseInt(pp);
3293		if (fp != null)
3294	<	fac = ((ForkJoinWorkerThreadFactory)ClassLoader.
3295	<	getSystemClassLoader().loadClass(fp).newInstance());
3294	>	factory = ((ForkJoinWorkerThreadFactory)ClassLoader.
3295	>	getSystemClassLoader().loadClass(fp).newInstance());
3296		if (hp != null)
3297	<	handler = ((Thread.UncaughtExceptionHandler)ClassLoader.
3297	>	handler = ((UncaughtExceptionHandler)ClassLoader.
3298		getSystemClassLoader().loadClass(hp).newInstance());
3382	–	if (pp != null)
3383	–	par = Integer.parseInt(pp);
3299		} catch (Exception ignore) {
3300		}
3301
3302	<	if (par <= 0)
3303	<	par = Runtime.getRuntime().availableProcessors();
3304	<	if (par > MAX_CAP)
3305	<	par = MAX_CAP;
3306	<	commonParallelism = par;
3307	<	long np = (long)(-par); // precompute initial ctl value
3308	<	long ct = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
3394	<
3395	<	common = new ForkJoinPool(par, ct, fac, handler);
3302	>	if (parallelism < 0 && // default 1 less than #cores
3303	>	(parallelism = Runtime.getRuntime().availableProcessors() - 1) < 0)
3304	>	parallelism = 0;
3305	>	if (parallelism > MAX_CAP)
3306	>	parallelism = MAX_CAP;
3307	>	return new ForkJoinPool(parallelism, factory, handler, LIFO_QUEUE,
3308	>	"ForkJoinPool.commonPool-worker-");
3309		}
3310
3311		/**

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