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root/jsr166/jsr166/src/jsr166e/ForkJoinPool.java

Comparing jsr166/src/jsr166e/ForkJoinPool.java (file contents):
Revision 1.9 by dl, Tue Oct 30 14:23:03 2012 UTC vs.
Revision 1.15 by jsr166, Sun Nov 18 06:31:13 2012 UTC

#	Line 11 | Line 11 | import java.util.Arrays;
11		import java.util.Collection;
12		import java.util.Collections;
13		import java.util.List;
14	–	import java.util.Random;
14		import java.util.concurrent.AbstractExecutorService;
15		import java.util.concurrent.Callable;
16		import java.util.concurrent.ExecutorService;
#	Line 20 | Line 19 | import java.util.concurrent.RejectedExec
19		import java.util.concurrent.RunnableFuture;
20		import java.util.concurrent.ThreadLocalRandom;
21		import java.util.concurrent.TimeUnit;
23	–	import java.util.concurrent.atomic.AtomicInteger;
24	–	import java.util.concurrent.atomic.AtomicLong;
25	–	import java.util.concurrent.locks.AbstractQueuedSynchronizer;
26	–	import java.util.concurrent.locks.Condition;
22
23		/**
24		* An {@link ExecutorService} for running {@link ForkJoinTask}s.
#	Line 48 | Line 43 | import java.util.concurrent.locks.Condit
43		* is not explicitly submitted to a specified pool. Using the common
44		* pool normally reduces resource usage (its threads are slowly
45		* reclaimed during periods of non-use, and reinstated upon subsequent
46	<	* use).  The common pool is by default constructed with default
52	<	* parameters, but these may be controlled by setting any or all of
53	<	* the three properties {@code
54	<	* java.util.concurrent.ForkJoinPool.common.{parallelism,
55	<	* threadFactory, exceptionHandler}}.
46	>	* use).
47		*
48		* <p>For applications that require separate or custom pools, a {@code
49		* ForkJoinPool} may be constructed with a given target parallelism
#	Line 107 | Line 98 | import java.util.concurrent.locks.Condit
98		*  </tr>
99		* </table>
100		*
101	+	* <p>The common pool is by default constructed with default
102	+	* parameters, but these may be controlled by setting three {@link
103	+	* System#getProperty properties} with prefix {@code
104	+	* java.util.concurrent.ForkJoinPool.common}: {@code parallelism} --
105	+	* an integer greater than zero, {@code threadFactory} -- the class
106	+	* name of a {@link ForkJoinWorkerThreadFactory}, and {@code
107	+	* exceptionHandler} -- the class name of a {@link
108	+	* java.lang.Thread.UncaughtExceptionHandler
109	+	* Thread.UncaughtExceptionHandler}. Upon any error in establishing
110	+	* these settings, default parameters are used.
111	+	*
112		* <p><b>Implementation notes</b>: This implementation restricts the
113		* maximum number of running threads to 32767. Attempts to create
114		* pools with greater than the maximum number result in
#	Line 193 | Line 195 | public class ForkJoinPool extends Abstra
195		* WorkQueues are also used in a similar way for tasks submitted
196		* to the pool. We cannot mix these tasks in the same queues used
197		* for work-stealing (this would contaminate lifo/fifo
198	<	* processing). Instead, we loosely associate submission queues
198	>	* processing). Instead, we randomly associate submission queues
199		* with submitting threads, using a form of hashing.  The
200		* ThreadLocal Submitter class contains a value initially used as
201		* a hash code for choosing existing queues, but may be randomly
202		* repositioned upon contention with other submitters.  In
203	<	* essence, submitters act like workers except that they never
204	<	* take tasks, and they are multiplexed on to a finite number of
205	<	* shared work queues. However, classes are set up so that future
206	<	* extensions could allow submitters to optionally help perform
207	<	* tasks as well. Insertion of tasks in shared mode requires a
208	<	* lock (mainly to protect in the case of resizing) but we use
209	<	* only a simple spinlock (using bits in field runState), because
210	<	* submitters encountering a busy queue move on to try or create
211	<	* other queues -- they block only when creating and registering
212	<	* new queues.
203	>	* essence, submitters act like workers except that they are
204	>	* restricted to executing local tasks that they submitted (or in
205	>	* the case of CountedCompleters, others with the same root task).
206	>	* However, because most shared/external queue operations are more
207	>	* expensive than internal, and because, at steady state, external
208	>	* submitters will compete for CPU with workers, ForkJoinTask.join
209	>	* and related methods disable them from repeatedly helping to
210	>	* process tasks if all workers are active.  Insertion of tasks in
211	>	* shared mode requires a lock (mainly to protect in the case of
212	>	* resizing) but we use only a simple spinlock (using bits in
213	>	* field qlock), because submitters encountering a busy queue move
214	>	* on to try or create other queues -- they block only when
215	>	* creating and registering new queues.
216		*
217		* Management
218		* ==========
#	Line 229 | Line 234 | public class ForkJoinPool extends Abstra
234		* and their negations (used for thresholding) to fit into 16bit
235		* fields.
236		*
237	<	* Field "runState" contains 32 bits needed to register and
238	<	* deregister WorkQueues, as well as to enable shutdown. It is
239	<	* only modified under a lock (normally briefly held, but
240	<	* occasionally protecting allocations and resizings) but even
241	<	* when locked remains available to check consistency.
237	>	* Field "plock" is a form of sequence lock with a saturating
238	>	* shutdown bit (similarly for per-queue "qlocks"), mainly
239	>	* protecting updates to the workQueues array, as well as to
240	>	* enable shutdown.  When used as a lock, it is normally only very
241	>	* briefly held, so is nearly always available after at most a
242	>	* brief spin, but we use a monitor-based backup strategy to
243	>	* blocking when needed.
244		*
245		* Recording WorkQueues.  WorkQueues are recorded in the
246		* "workQueues" array that is created upon first use and expanded
#	Line 242 | Line 249 | public class ForkJoinPool extends Abstra
249		* by a lock but the array is otherwise concurrently readable, and
250		* accessed directly.  To simplify index-based operations, the
251		* array size is always a power of two, and all readers must
252	<	* tolerate null slots. Shared (submission) queues are at even
253	<	* indices, worker queues at odd indices. Grouping them together
254	<	* in this way simplifies and speeds up task scanning.
252	>	* tolerate null slots. Worker queues are at odd indices Shared
253	>	* (submission) queues are at even indices, up to a maximum of 64
254	>	* slots, to limit growth even if array needs to expand to add
255	>	* more workers. Grouping them together in this way simplifies and
256	>	* speeds up task scanning.
257		*
258		* All worker thread creation is on-demand, triggered by task
259		* submissions, replacement of terminated workers, and/or
#	Line 305 | Line 314 | public class ForkJoinPool extends Abstra
314		*
315		* Signalling.  We create or wake up workers only when there
316		* appears to be at least one task they might be able to find and
317	<	* execute.  When a submission is added or another worker adds a
318	<	* task to a queue that previously had fewer than two tasks, they
319	<	* signal waiting workers (or trigger creation of new ones if
320	<	* fewer than the given parallelism level -- see signalWork).
321	<	* These primary signals are buttressed by signals during rescans;
322	<	* together these cover the signals needed in cases when more
323	<	* tasks are pushed but untaken, and improve performance compared
324	<	* to having one thread wake up all workers.
317	>	* execute. However, many other threads may notice the same task
318	>	* and each signal to wake up a thread that might take it. So in
319	>	* general, pools will be over-signalled.  When a submission is
320	>	* added or another worker adds a task to a queue that is
321	>	* apparently empty, they signal waiting workers (or trigger
322	>	* creation of new ones if fewer than the given parallelism level
323	>	* -- see signalWork).  These primary signals are buttressed by
324	>	* signals whenever other threads scan for work or do not have a
325	>	* task to process. On most platforms, signalling (unpark)
326	>	* overhead time is noticeably long, and the time between
327	>	* signalling a thread and it actually making progress can be very
328	>	* noticeably long, so it is worth offloading these delays from
329	>	* critical paths as much as possible.
330		*
331		* Trimming workers. To release resources after periods of lack of
332		* use, a worker starting to wait when the pool is quiescent will
#	Line 323 | Line 337 | public class ForkJoinPool extends Abstra
337		* periods of non-use.
338		*
339		* Shutdown and Termination. A call to shutdownNow atomically sets
340	<	* a runState bit and then (non-atomically) sets each worker's
341	<	* runState status, cancels all unprocessed tasks, and wakes up
340	>	* a plock bit and then (non-atomically) sets each worker's
341	>	* qlock status, cancels all unprocessed tasks, and wakes up
342		* all waiting workers.  Detecting whether termination should
343		* commence after a non-abrupt shutdown() call requires more work
344		* and bookkeeping. We need consensus about quiescence (i.e., that
#	Line 352 | Line 366 | public class ForkJoinPool extends Abstra
366		*      method tryCompensate() may create or re-activate a spare
367		*      thread to compensate for blocked joiners until they unblock.
368		*
369	<	* A third form (implemented in tryRemoveAndExec and
370	<	* tryPollForAndExec) amounts to helping a hypothetical
371	<	* compensator: If we can readily tell that a possible action of a
372	<	* compensator is to steal and execute the task being joined, the
373	<	* joining thread can do so directly, without the need for a
374	<	* compensation thread (although at the expense of larger run-time
375	<	* stacks, but the tradeoff is typically worthwhile).
369	>	* A third form (implemented in tryRemoveAndExec) amounts to
370	>	* helping a hypothetical compensator: If we can readily tell that
371	>	* a possible action of a compensator is to steal and execute the
372	>	* task being joined, the joining thread can do so directly,
373	>	* without the need for a compensation thread (although at the
374	>	* expense of larger run-time stacks, but the tradeoff is
375	>	* typically worthwhile).
376		*
377		* The ManagedBlocker extension API can't use helping so relies
378		* only on compensation in method awaitBlocker.
#	Line 393 | Line 407 | public class ForkJoinPool extends Abstra
407		* to find work (see MAX_HELP) and fall back to suspending the
408		* worker and if necessary replacing it with another.
409		*
410	+	* Helping actions for CountedCompleters are much simpler: Method
411	+	* helpComplete can take and execute any task with the same root
412	+	* as the task being waited on. However, this still entails some
413	+	* traversal of completer chains, so is less efficient than using
414	+	* CountedCompleters without explicit joins.
415	+	*
416		* It is impossible to keep exactly the target parallelism number
417		* of threads running at any given time.  Determining the
418		* existence of conservatively safe helping targets, the
#	Line 414 | Line 434 | public class ForkJoinPool extends Abstra
434		* intractable) game with an opponent that may choose the worst
435		* (for us) active thread to stall at any time.  We take several
436		* precautions to bound losses (and thus bound gains), mainly in
437	<	* methods tryCompensate and awaitJoin: (1) We only try
438	<	* compensation after attempting enough helping steps (measured
439	<	* via counting and timing) that we have already consumed the
440	<	* estimated cost of creating and activating a new thread.  (2) We
441	<	* allow up to 50% of threads to be blocked before initially
442	<	* adding any others, and unless completely saturated, check that
443	<	* some work is available for a new worker before adding. Also, we
444	<	* create up to only 50% more threads until entering a mode that
445	<	* only adds a thread if all others are possibly blocked.  All
446	<	* together, this means that we might be half as fast to react,
447	<	* and create half as many threads as possible in the ideal case,
448	<	* but present vastly fewer anomalies in all other cases compared
449	<	* to both more aggressive and more conservative alternatives.
450	<	*
451	<	* Style notes: There is a lot of representation-level coupling
452	<	* among classes ForkJoinPool, ForkJoinWorkerThread, and
453	<	* ForkJoinTask.  The fields of WorkQueue maintain data structures
454	<	* managed by ForkJoinPool, so are directly accessed.  There is
455	<	* little point trying to reduce this, since any associated future
456	<	* changes in representations will need to be accompanied by
457	<	* algorithmic changes anyway. Several methods intrinsically
458	<	* sprawl because they must accumulate sets of consistent reads of
459	<	* volatiles held in local variables.  Methods signalWork() and
460	<	* scan() are the main bottlenecks, so are especially heavily
437	>	* methods tryCompensate and awaitJoin.
438	>	*
439	>	* Common Pool
440	>	* ===========
441	>	*
442	>	* The static commonPool always exists after static
443	>	* initialization.  Since it (or any other created pool) need
444	>	* never be used, we minimize initial construction overhead and
445	>	* footprint to the setup of about a dozen fields, with no nested
446	>	* allocation. Most bootstrapping occurs within method
447	>	* fullExternalPush during the first submission to the pool.
448	>	*
449	>	* When external threads submit to the common pool, they can
450	>	* perform some subtask processing (see externalHelpJoin and
451	>	* related methods).  We do not need to record whether these
452	>	* submissions are to the common pool -- if not, externalHelpJoin
453	>	* returns quickly (at the most helping to signal some common pool
454	>	* workers). These submitters would otherwise be blocked waiting
455	>	* for completion, so the extra effort (with liberally sprinkled
456	>	* task status checks) in inapplicable cases amounts to an odd
457	>	* form of limited spin-wait before blocking in ForkJoinTask.join.
458	>	*
459	>	* Style notes
460	>	* ===========
461	>	*
462	>	* There is a lot of representation-level coupling among classes
463	>	* ForkJoinPool, ForkJoinWorkerThread, and ForkJoinTask.  The
464	>	* fields of WorkQueue maintain data structures managed by
465	>	* ForkJoinPool, so are directly accessed.  There is little point
466	>	* trying to reduce this, since any associated future changes in
467	>	* representations will need to be accompanied by algorithmic
468	>	* changes anyway. Several methods intrinsically sprawl because
469	>	* they must accumulate sets of consistent reads of volatiles held
470	>	* in local variables.  Methods signalWork() and scan() are the
471	>	* main bottlenecks, so are especially heavily
472		* micro-optimized/mangled.  There are lots of inline assignments
473		* (of form "while ((local = field) != 0)") which are usually the
474		* simplest way to ensure the required read orderings (which are
#	Line 445 | Line 476 | public class ForkJoinPool extends Abstra
476		* declarations of these locals at the heads of methods or blocks.
477		* There are several occurrences of the unusual "do {} while
478		* (!cas...)"  which is the simplest way to force an update of a
479	<	* CAS'ed variable. There are also other coding oddities that help
479	>	* CAS'ed variable. There are also other coding oddities (including
480	>	* several unnecessary-looking hoisted null checks) that help
481		* some methods perform reasonably even when interpreted (not
482		* compiled).
483		*
#	Line 508 | Line 540 | public class ForkJoinPool extends Abstra
540		* actually do anything beyond having a unique identity.
541		*/
542		static final class EmptyTask extends ForkJoinTask<Void> {
543	+	private static final long serialVersionUID = -7721805057305804111L;
544		EmptyTask() { status = ForkJoinTask.NORMAL; } // force done
545		public final Void getRawResult() { return null; }
546		public final void setRawResult(Void x) {}
#	Line 528 | Line 561 | public class ForkJoinPool extends Abstra
561		*
562		* Field "top" is the index (mod array.length) of the next queue
563		* slot to push to or pop from. It is written only by owner thread
564	<	* for push, or under lock for trySharedPush, and accessed by
565	<	* other threads only after reading (volatile) base.  Both top and
566	<	* base are allowed to wrap around on overflow, but (top - base)
567	<	* (or more commonly -(base - top) to force volatile read of base
568	<	* before top) still estimates size.
564	>	* for push, or under lock for external/shared push, and accessed
565	>	* by other threads only after reading (volatile) base.  Both top
566	>	* and base are allowed to wrap around on overflow, but (top -
567	>	* base) (or more commonly -(base - top) to force volatile read of
568	>	* base before top) still estimates size. The lock ("qlock") is
569	>	* forced to -1 on termination, causing all further lock attempts
570	>	* to fail. (Note: we don't need CAS for termination state because
571	>	* upon pool shutdown, all shared-queues will stop being used
572	>	* anyway.)  Nearly all lock bodies are set up so that exceptions
573	>	* within lock bodies are "impossible" (modulo JVM errors that
574	>	* would cause failure anyway.)
575		*
576		* The array slots are read and written using the emulation of
577		* volatiles/atomics provided by Unsafe. Insertions must in
578		* general use putOrderedObject as a form of releasing store to
579		* ensure that all writes to the task object are ordered before
580	<	* its publication in the queue. (Although we can avoid one case
581	<	* of this when locked in trySharedPush.) All removals entail a
582	<	* CAS to null.  The array is always a power of two. To ensure
583	<	* safety of Unsafe array operations, all accesses perform
545	<	* explicit null checks and implicit bounds checks via
546	<	* power-of-two masking.
580	>	* its publication in the queue.  All removals entail a CAS to
581	>	* null.  The array is always a power of two. To ensure safety of
582	>	* Unsafe array operations, all accesses perform explicit null
583	>	* checks and implicit bounds checks via power-of-two masking.
584		*
585		* In addition to basic queuing support, this class contains
586		* fields described elsewhere to control execution. It turns out
587	<	* to work better memory-layout-wise to include them in this
588	<	* class rather than a separate class.
587	>	* to work better memory-layout-wise to include them in this class
588	>	* rather than a separate class.
589		*
590		* Performance on most platforms is very sensitive to placement of
591		* instances of both WorkQueues and their arrays -- we absolutely
#	Line 564 | Line 601 | public class ForkJoinPool extends Abstra
601		* support is in place, this padding is dependent on transient
602		* properties of JVM field layout rules.)  We also take care in
603		* allocating, sizing and resizing the array. Non-shared queue
604	<	* arrays are initialized (via method growArray) by workers before
605	<	* use. Others are allocated on first use.
604	>	* arrays are initialized by workers before use. Others are
605	>	* allocated on first use.
606		*/
607		static final class WorkQueue {
608		/**
#	Line 588 | Line 625 | public class ForkJoinPool extends Abstra
625		*/
626		static final int MAXIMUM_QUEUE_CAPACITY = 1 << 26; // 64M
627
591	–	volatile long totalSteals; // cumulative number of steals
628		int seed;                  // for random scanning; initialize nonzero
629		volatile int eventCount;   // encoded inactivation count; < 0 if inactive
630		int nextWait;              // encoded record of next event waiter
595	–	int rescans;               // remaining scans until block
596	–	int nsteals;               // top-level task executions since last idle
631		final int mode;            // lifo, fifo, or shared
632	+	int nsteals;               // cumulative number of steals
633		int poolIndex;             // index of this queue in pool (or 0)
634		int stealHint;             // index of most recent known stealer
635	<	volatile int runState;     // 1: locked, -1: terminate; else 0
635	>	volatile int qlock;        // 1: locked, -1: terminate; else 0
636		volatile int base;         // index of next slot for poll
637		int top;                   // index of next slot for push
638		ForkJoinTask<?>[] array;   // the elements (initially unallocated)
#	Line 619 | Line 654 | public class ForkJoinPool extends Abstra
654		}
655
656		/**
622	–	* Returns the approximate number of tasks in the queue.
623	–	*/
624	–	final int queueSize() {
625	–	int n = base - top;       // non-owner callers must read base first
626	–	return (n >= 0) ? 0 : -n; // ignore transient negative
627	–	}
628	–
629	–	/**
630	–	* Provides a more accurate estimate of whether this queue has
631	–	* any tasks than does queueSize, by checking whether a
632	–	* near-empty queue has at least one unclaimed task.
633	–	*/
634	–	final boolean isEmpty() {
635	–	ForkJoinTask<?>[] a; int m, s;
636	–	int n = base - (s = top);
637	–	return (n >= 0 ||
638	–	(n == -1 &&
639	–	((a = array) == null ||
640	–	(m = a.length - 1) < 0 ||
641	–	U.getObjectVolatile
642	–	(a, ((m & (s - 1)) << ASHIFT) + ABASE) == null)));
643	–	}
644	–
645	–	/**
657		* Pushes a task. Call only by owner in unshared queues.
658	+	* Cases needing resizing or rejection are relayed to fullPush
659	+	* (that also handles shared queues).
660		*
661		* @param task the task. Caller must ensure non-null.
662		* @throw RejectedExecutionException if array cannot be resized
663		*/
664		final void push(ForkJoinTask<?> task) {
665	<	ForkJoinTask<?>[] a; ForkJoinPool p;
666	<	int s = top, m, n;
667	<	if ((a = array) != null) {    // ignore if queue removed
665	>	ForkJoinPool p; ForkJoinTask<?>[] a;
666	>	int s = top, n;
667	>	if ((a = array) != null && a.length > (n = s + 1 - base)) {
668		U.putOrderedObject
669	<	(a, (((m = a.length - 1) & s) << ASHIFT) + ABASE, task);
670	<	if ((n = (top = s + 1) - base) <= 2) {
671	<	if ((p = pool) != null)
672	<	p.signalWork();
660	<	}
661	<	else if (n >= m)
662	<	growArray(true);
669	>	(a, (((a.length - 1) & s) << ASHIFT) + ABASE, task);
670	>	top = s + 1;
671	>	if (n <= 1 && (p = pool) != null)
672	>	p.signalWork(this, 1);
673		}
674	+	else
675	+	fullPush(task, true);
676		}
677
678		/**
679		* Pushes a task if lock is free and array is either big
680	<	* enough or can be resized to be big enough.
680	>	* enough or can be resized to be big enough. Note: a
681	>	* specialization of a common fast path of this method is in
682	>	* ForkJoinPool.externalPush. When called from a FJWT queue,
683	>	* this can fail only if the pool has been shut down or
684	>	* an out of memory error.
685		*
686		* @param task the task. Caller must ensure non-null.
687	<	* @return true if submitted
687	>	* @param owned if true, throw RJE on failure
688		*/
689	<	final boolean trySharedPush(ForkJoinTask<?> task) {
690	<	boolean submitted = false;
691	<	if (runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
692	<	ForkJoinTask<?>[] a = array;
693	<	int s = top;
694	<	try {
695	<	if ((a != null && a.length > s + 1 - base) ||
696	<	(a = growArray(false)) != null) { // must presize
697	<	int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
698	<	U.putObject(a, (long)j, task);    // don't need "ordered"
699	<	top = s + 1;
700	<	submitted = true;
689	>	final boolean fullPush(ForkJoinTask<?> task, boolean owned) {
690	>	ForkJoinPool p; ForkJoinTask<?>[] a;
691	>	if (owned) {
692	>	if (qlock < 0) // must be shutting down
693	>	throw new RejectedExecutionException();
694	>	}
695	>	else if (!U.compareAndSwapInt(this, QLOCK, 0, 1))
696	>	return false;
697	>	try {
698	>	int s = top, oldLen, len;
699	>	if ((a = array) == null)
700	>	a = array = new ForkJoinTask<?>[len=INITIAL_QUEUE_CAPACITY];
701	>	else if ((oldLen = a.length) > s + 1 - base)
702	>	len = oldLen;
703	>	else if ((len = oldLen << 1) > MAXIMUM_QUEUE_CAPACITY)
704	>	throw new RejectedExecutionException("Capacity exceeded");
705	>	else {
706	>	int oldMask, b;
707	>	ForkJoinTask<?>[] oldA = a;
708	>	a = array = new ForkJoinTask<?>[len];
709	>	if ((oldMask = oldLen - 1) >= 0 && s - (b = base) > 0) {
710	>	int mask = len - 1;
711	>	do {
712	>	ForkJoinTask<?> x;
713	>	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
714	>	int j    = ((b &    mask) << ASHIFT) + ABASE;
715	>	x = (ForkJoinTask<?>)
716	>	U.getObjectVolatile(oldA, oldj);
717	>	if (x != null &&
718	>	U.compareAndSwapObject(oldA, oldj, x, null))
719	>	U.putObjectVolatile(a, j, x);
720	>	} while (++b != s);
721		}
686	–	} finally {
687	–	runState = 0;                         // unlock
722		}
723	+	U.putOrderedObject
724	+	(a, (((len - 1) & s) << ASHIFT) + ABASE, task);
725	+	top = s + 1;
726	+	} finally {
727	+	if (!owned)
728	+	qlock = 0;
729		}
730	<	return submitted;
730	>	if ((p = pool) != null)
731	>	p.signalWork(this, 1);
732	>	return true;
733		}
734
735		/**
#	Line 710 | Line 752 | public class ForkJoinPool extends Abstra
752		return null;
753		}
754
713	–	final ForkJoinTask<?> sharedPop() {
714	–	ForkJoinTask<?> task = null;
715	–	if (runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
716	–	try {
717	–	ForkJoinTask<?>[] a; int m;
718	–	if ((a = array) != null && (m = a.length - 1) >= 0) {
719	–	for (int s; (s = top - 1) - base >= 0;) {
720	–	long j = ((m & s) << ASHIFT) + ABASE;
721	–	ForkJoinTask<?> t =
722	–	(ForkJoinTask<?>)U.getObject(a, j);
723	–	if (t == null)
724	–	break;
725	–	if (U.compareAndSwapObject(a, j, t, null)) {
726	–	top = s;
727	–	task = t;
728	–	break;
729	–	}
730	–	}
731	–	}
732	–	} finally {
733	–	runState = 0;
734	–	}
735	–	}
736	–	return task;
737	–	}
738	–
739	–	/**
740	–	* Version of pop that takes top element only if it
741	–	* its root is the given CountedCompleter.
742	–	*/
743	–	final ForkJoinTask<?> popCC(CountedCompleter<?> root) {
744	–	ForkJoinTask<?>[] a; int m;
745	–	if (root != null && (a = array) != null && (m = a.length - 1) >= 0) {
746	–	for (int s; (s = top - 1) - base >= 0;) {
747	–	long j = ((m & s) << ASHIFT) + ABASE;
748	–	ForkJoinTask<?> t =
749	–	(ForkJoinTask<?>)U.getObject(a, j);
750	–	if (t == null || !(t instanceof CountedCompleter) ||
751	–	((CountedCompleter<?>)t).getRoot() != root)
752	–	break;
753	–	if (U.compareAndSwapObject(a, j, t, null)) {
754	–	top = s;
755	–	return t;
756	–	}
757	–	if (root.status < 0)
758	–	break;
759	–	}
760	–	}
761	–	return null;
762	–	}
763	–
764	–	/**
765	–	* Shared version of popCC
766	–	*/
767	–	final ForkJoinTask<?> sharedPopCC(CountedCompleter<?> root) {
768	–	ForkJoinTask<?> task = null;
769	–	if (root != null &&
770	–	runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
771	–	try {
772	–	ForkJoinTask<?>[] a; int m;
773	–	if ((a = array) != null && (m = a.length - 1) >= 0) {
774	–	for (int s; (s = top - 1) - base >= 0;) {
775	–	long j = ((m & s) << ASHIFT) + ABASE;
776	–	ForkJoinTask<?> t =
777	–	(ForkJoinTask<?>)U.getObject(a, j);
778	–	if (t == null || !(t instanceof CountedCompleter) ||
779	–	((CountedCompleter<?>)t).getRoot() != root)
780	–	break;
781	–	if (U.compareAndSwapObject(a, j, t, null)) {
782	–	top = s;
783	–	task = t;
784	–	break;
785	–	}
786	–	if (root.status < 0)
787	–	break;
788	–	}
789	–	}
790	–	} finally {
791	–	runState = 0;
792	–	}
793	–	}
794	–	return task;
795	–	}
796	–
755		/**
756		* Takes a task in FIFO order if b is base of queue and a task
757		* can be claimed without contention. Specialized versions
#	Line 831 | Line 789 | public class ForkJoinPool extends Abstra
789		else if (base == b) {
790		if (b + 1 == top)
791		break;
792	<	Thread.yield(); // wait for lagging update
792	>	Thread.yield(); // wait for lagging update (very rare)
793		}
794		}
795		return null;
#	Line 858 | Line 816 | public class ForkJoinPool extends Abstra
816
817		/**
818		* Pops the given task only if it is at the current top.
819	+	* (A shared version is available only via FJP.tryExternalUnpush)
820		*/
821		final boolean tryUnpush(ForkJoinTask<?> t) {
822		ForkJoinTask<?>[] a; int s;
#	Line 871 | Line 830 | public class ForkJoinPool extends Abstra
830		}
831
832		/**
874	–	* Version of tryUnpush for shared queues; called by non-FJ
875	–	* submitters after prechecking that task probably exists.
876	–	*/
877	–	final boolean trySharedUnpush(ForkJoinTask<?> t) {
878	–	boolean success = false;
879	–	if (runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
880	–	try {
881	–	ForkJoinTask<?>[] a; int s;
882	–	if ((a = array) != null && (s = top) != base &&
883	–	U.compareAndSwapObject
884	–	(a, (((a.length - 1) & --s) << ASHIFT) + ABASE, t, null)) {
885	–	top = s;
886	–	success = true;
887	–	}
888	–	} finally {
889	–	runState = 0;                         // unlock
890	–	}
891	–	}
892	–	return success;
893	–	}
894	–
895	–	/**
896	–	* Polls the given task only if it is at the current base.
897	–	*/
898	–	final boolean pollFor(ForkJoinTask<?> task) {
899	–	ForkJoinTask<?>[] a; int b;
900	–	if ((b = base) - top < 0 && (a = array) != null) {
901	–	int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
902	–	if (U.getObjectVolatile(a, j) == task && base == b &&
903	–	U.compareAndSwapObject(a, j, task, null)) {
904	–	base = b + 1;
905	–	return true;
906	–	}
907	–	}
908	–	return false;
909	–	}
910	–
911	–	/**
912	–	* Initializes or doubles the capacity of array. Call either
913	–	* by owner or with lock held -- it is OK for base, but not
914	–	* top, to move while resizings are in progress.
915	–	*
916	–	* @param rejectOnFailure if true, throw exception if capacity
917	–	* exceeded (relayed ultimately to user); else return null.
918	–	*/
919	–	final ForkJoinTask<?>[] growArray(boolean rejectOnFailure) {
920	–	ForkJoinTask<?>[] oldA = array;
921	–	int size = oldA != null ? oldA.length << 1 : INITIAL_QUEUE_CAPACITY;
922	–	if (size <= MAXIMUM_QUEUE_CAPACITY) {
923	–	int oldMask, t, b;
924	–	ForkJoinTask<?>[] a = array = new ForkJoinTask<?>[size];
925	–	if (oldA != null && (oldMask = oldA.length - 1) >= 0 &&
926	–	(t = top) - (b = base) > 0) {
927	–	int mask = size - 1;
928	–	do {
929	–	ForkJoinTask<?> x;
930	–	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
931	–	int j    = ((b &    mask) << ASHIFT) + ABASE;
932	–	x = (ForkJoinTask<?>)U.getObjectVolatile(oldA, oldj);
933	–	if (x != null &&
934	–	U.compareAndSwapObject(oldA, oldj, x, null))
935	–	U.putObjectVolatile(a, j, x);
936	–	} while (++b != t);
937	–	}
938	–	return a;
939	–	}
940	–	else if (!rejectOnFailure)
941	–	return null;
942	–	else
943	–	throw new RejectedExecutionException("Queue capacity exceeded");
944	–	}
945	–
946	–	/**
833		* Removes and cancels all known tasks, ignoring any exceptions.
834		*/
835		final void cancelAll() {
#	Line 967 | Line 853 | public class ForkJoinPool extends Abstra
853		return seed = r ^= r << 5;
854		}
855
856	<	// Execution methods
856	>	/**
857	>	* Provides a more accurate estimate of size than (top - base)
858	>	* by ordering reads and checking whether a near-empty queue
859	>	* has at least one unclaimed task.
860	>	*/
861	>	final int queueSize() {
862	>	ForkJoinTask<?>[] a; int k, s, n;
863	>	return ((n = base - (s = top)) < 0 &&
864	>	(n != -1 ||
865	>	((a = array) != null && (k = a.length) > 0 &&
866	>	U.getObject
867	>	(a, (long)((((k - 1) & (s - 1)) << ASHIFT) + ABASE)) != null))) ?
868	>	-n : 0;
869	>	}
870	>
871	>	// Specialized execution methods
872
873		/**
874		* Pops and runs tasks until empty.
#	Line 996 | Line 897 | public class ForkJoinPool extends Abstra
897		}
898
899		/**
900	<	* If present, removes from queue and executes the given task, or
901	<	* any other cancelled task. Returns (true) immediately on any CAS
900	>	* If present, removes from queue and executes the given task,
901	>	* or any other cancelled task. Returns (true) on any CAS
902		* or consistency check failure so caller can retry.
903		*
904	<	* @return 0 if no progress can be made, else positive
1004	<	* (this unusual convention simplifies use with tryHelpStealer.)
904	>	* @return false if no progress can be made, else true;
905		*/
906	<	final int tryRemoveAndExec(ForkJoinTask<?> task) {
907	<	int stat = 1;
1008	<	boolean removed = false, empty = true;
906	>	final boolean tryRemoveAndExec(ForkJoinTask<?> task) {
907	>	boolean stat = true, removed = false, empty = true;
908		ForkJoinTask<?>[] a; int m, s, b, n;
909		if ((a = array) != null && (m = a.length - 1) >= 0 &&
910		(n = (s = top) - (b = base)) > 0) {
#	Line 1035 | Line 934 | public class ForkJoinPool extends Abstra
934		}
935		if (--n == 0) {
936		if (!empty && base == b)
937	<	stat = 0;
937	>	stat = false;
938		break;
939		}
940		}
#	Line 1046 | Line 945 | public class ForkJoinPool extends Abstra
945		}
946
947		/**
948	+	* Polls for and executes the given task or any other task in
949	+	* its CountedCompleter computation
950	+	*/
951	+	final boolean pollAndExecCC(ForkJoinTask<?> root) {
952	+	ForkJoinTask<?>[] a; int b; Object o;
953	+	outer: while ((b = base) - top < 0 && (a = array) != null) {
954	+	long j = (((a.length - 1) & b) << ASHIFT) + ABASE;
955	+	if ((o = U.getObject(a, j)) == null ||
956	+	!(o instanceof CountedCompleter))
957	+	break;
958	+	for (CountedCompleter<?> t = (CountedCompleter<?>)o, r = t;;) {
959	+	if (r == root) {
960	+	if (base == b &&
961	+	U.compareAndSwapObject(a, j, t, null)) {
962	+	base = b + 1;
963	+	t.doExec();
964	+	return true;
965	+	}
966	+	else
967	+	break; // restart
968	+	}
969	+	if ((r = r.completer) == null)
970	+	break outer; // not part of root computation
971	+	}
972	+	}
973	+	return false;
974	+	}
975	+
976	+	/**
977		* Executes a top-level task and any local tasks remaining
978		* after execution.
979		*/
980		final void runTask(ForkJoinTask<?> t) {
981		if (t != null) {
982	<	currentSteal = t;
983	<	t.doExec();
982	>	(currentSteal = t).doExec();
983	>	currentSteal = null;
984	>	if (++nsteals < 0) {     // spill on overflow
985	>	ForkJoinPool p;
986	>	if ((p = pool) != null)
987	>	p.collectStealCount(this);
988	>	}
989		if (top != base) {       // process remaining local tasks
990		if (mode == 0)
991		popAndExecAll();
992		else
993		pollAndExecAll();
994		}
1062	–	++nsteals;
1063	–	currentSteal = null;
995		}
996		}
997
#	Line 1070 | Line 1001 | public class ForkJoinPool extends Abstra
1001		final void runSubtask(ForkJoinTask<?> t) {
1002		if (t != null) {
1003		ForkJoinTask<?> ps = currentSteal;
1004	<	currentSteal = t;
1074	<	t.doExec();
1004	>	(currentSteal = t).doExec();
1005		currentSteal = ps;
1006		}
1007		}
#	Line 1106 | Line 1036 | public class ForkJoinPool extends Abstra
1036
1037		// Unsafe mechanics
1038		private static final sun.misc.Unsafe U;
1039	<	private static final long RUNSTATE;
1039	>	private static final long QLOCK;
1040		private static final int ABASE;
1041		private static final int ASHIFT;
1042		static {
#	Line 1115 | Line 1045 | public class ForkJoinPool extends Abstra
1045		U = getUnsafe();
1046		Class<?> k = WorkQueue.class;
1047		Class<?> ak = ForkJoinTask[].class;
1048	<	RUNSTATE = U.objectFieldOffset
1049	<	(k.getDeclaredField("runState"));
1048	>	QLOCK = U.objectFieldOffset
1049	>	(k.getDeclaredField("qlock"));
1050		ABASE = U.arrayBaseOffset(ak);
1051		s = U.arrayIndexScale(ak);
1052		} catch (Exception e) {
#	Line 1131 | Line 1061 | public class ForkJoinPool extends Abstra
1061		/**
1062		* Per-thread records for threads that submit to pools. Currently
1063		* holds only pseudo-random seed / index that is used to choose
1064	<	* submission queues in method doSubmit. In the future, this may
1064	>	* submission queues in method externalPush. In the future, this may
1065		* also incorporate a means to implement different task rejection
1066		* and resubmission policies.
1067		*
#	Line 1139 | Line 1069 | public class ForkJoinPool extends Abstra
1069		* the same way but are initialized and updated using slightly
1070		* different mechanics. Both are initialized using the same
1071		* approach as in class ThreadLocal, where successive values are
1072	<	* unlikely to collide with previous values. This is done during
1073	<	* registration for workers, but requires a separate AtomicInteger
1074	<	* for submitters. Seeds are then randomly modified upon
1145	<	* collisions using xorshifts, which requires a non-zero seed.
1072	>	* unlikely to collide with previous values. Seeds are then
1073	>	* randomly modified upon collisions using xorshifts, which
1074	>	* requires a non-zero seed.
1075		*/
1076		static final class Submitter {
1077		int seed;
1078	<	Submitter() {
1150	<	int s = nextSubmitterSeed.getAndAdd(SEED_INCREMENT);
1151	<	seed = (s == 0) ? 1 : s; // ensure non-zero
1152	<	}
1078	>	Submitter(int s) { seed = s; }
1079		}
1080
1081	<	/** ThreadLocal class for Submitters */
1082	<	static final class ThreadSubmitter extends ThreadLocal<Submitter> {
1083	<	public Submitter initialValue() { return new Submitter(); }
1158	<	}
1081	>	/** Property prefix for constructing common pool */
1082	>	private static final String propPrefix =
1083	>	"java.util.concurrent.ForkJoinPool.common.";
1084
1085		// static fields (initialized in static initializer below)
1086
#	Line 1166 | Line 1091 | public class ForkJoinPool extends Abstra
1091		public static final ForkJoinWorkerThreadFactory
1092		defaultForkJoinWorkerThreadFactory;
1093
1169	–
1170	–	/** Property prefix for constructing common pool */
1171	–	private static final String propPrefix =
1172	–	"java.util.concurrent.ForkJoinPool.common.";
1173	–
1094		/**
1095		* Common (static) pool. Non-null for public use unless a static
1096	<	* construction exception, but internal usages must null-check on
1097	<	* use.
1096	>	* construction exception, but internal usages null-check on use
1097	>	* to paranoically avoid potential initialization circularities
1098	>	* as well as to simplify generated code.
1099		*/
1100		static final ForkJoinPool commonPool;
1101
1102		/**
1103	<	* Common pool parallelism. Must equal commonPool.parallelism.
1103	>	* Permission required for callers of methods that may start or
1104	>	* kill threads.
1105		*/
1106	<	static final int commonPoolParallelism;
1106	>	private static final RuntimePermission modifyThreadPermission;
1107
1108		/**
1109	<	* Generator for assigning sequence numbers as pool names.
1109	>	* Per-thread submission bookkeeping. Shared across all pools
1110	>	* to reduce ThreadLocal pollution and because random motion
1111	>	* to avoid contention in one pool is likely to hold for others.
1112	>	* Lazily initialized on first submission (but null-checked
1113	>	* in other contexts to avoid unnecessary initialization).
1114		*/
1115	<	private static final AtomicInteger poolNumberGenerator;
1115	>	static final ThreadLocal<Submitter> submitters;
1116
1117		/**
1118	<	* Generator for initial hashes/seeds for submitters. Accessed by
1193	<	* Submitter class constructor.
1118	>	* Common pool parallelism. Must equal commonPool.parallelism.
1119		*/
1120	<	static final AtomicInteger nextSubmitterSeed;
1120	>	static final int commonPoolParallelism;
1121
1122		/**
1123	<	* Permission required for callers of methods that may start or
1199	<	* kill threads.
1123	>	* Sequence number for creating workerNamePrefix.
1124		*/
1125	<	private static final RuntimePermission modifyThreadPermission;
1125	>	private static int poolNumberSequence;
1126
1127		/**
1128	<	* Per-thread submission bookkeeping. Shared across all pools
1129	<	* to reduce ThreadLocal pollution and because random motion
1206	<	* to avoid contention in one pool is likely to hold for others.
1128	>	* Return the next sequence number. We don't expect this to
1129	>	* ever contend so use simple builtin sync.
1130		*/
1131	<	private static final ThreadSubmitter submitters;
1131	>	private static final synchronized int nextPoolId() {
1132	>	return ++poolNumberSequence;
1133	>	}
1134
1135		// static constants
1136
1137		/**
1138	<	* Initial timeout value (in nanoseconds) for the thread triggering
1139	<	* quiescence to park waiting for new work. On timeout, the thread
1140	<	* will instead try to shrink the number of workers.
1138	>	* Initial timeout value (in nanoseconds) for the thread
1139	>	* triggering quiescence to park waiting for new work. On timeout,
1140	>	* the thread will instead try to shrink the number of
1141	>	* workers. The value should be large enough to avoid overly
1142	>	* aggressive shrinkage during most transient stalls (long GCs
1143	>	* etc).
1144		*/
1145	<	private static final long IDLE_TIMEOUT      = 1000L * 1000L * 1000L; // 1sec
1145	>	private static final long IDLE_TIMEOUT      = 2000L * 1000L * 1000L; // 2sec
1146
1147		/**
1148		* Timeout value when there are more threads than parallelism level
1149		*/
1150	<	private static final long FAST_IDLE_TIMEOUT =  100L * 1000L * 1000L;
1150	>	private static final long FAST_IDLE_TIMEOUT =  200L * 1000L * 1000L;
1151
1152		/**
1153		* The maximum stolen->joining link depth allowed in method
1154	<	* tryHelpStealer.  Must be a power of two. This value also
1227	<	* controls the maximum number of times to try to help join a task
1228	<	* without any apparent progress or change in pool state before
1229	<	* giving up and blocking (see awaitJoin).  Depths for legitimate
1154	>	* tryHelpStealer.  Must be a power of two.  Depths for legitimate
1155		* chains are unbounded, but we use a fixed constant to avoid
1156		* (otherwise unchecked) cycles and to bound staleness of
1157		* traversal parameters at the expense of sometimes blocking when
#	Line 1235 | Line 1160 | public class ForkJoinPool extends Abstra
1160		private static final int MAX_HELP = 64;
1161
1162		/**
1238	–	* Secondary time-based bound (in nanosecs) for helping attempts
1239	–	* before trying compensated blocking in awaitJoin. Used in
1240	–	* conjunction with MAX_HELP to reduce variance due to different
1241	–	* polling rates associated with different helping options. The
1242	–	* value should roughly approximate the time required to create
1243	–	* and/or activate a worker thread.
1244	–	*/
1245	–	private static final long COMPENSATION_DELAY = 1L << 18; // ~0.25 millisec
1246	–
1247	–	/**
1163		* Increment for seed generators. See class ThreadLocal for
1164		* explanation.
1165		*/
#	Line 1278 | Line 1193 | public class ForkJoinPool extends Abstra
1193		* scan for them to avoid queuing races. Note however that
1194		* eventCount updates lag releases so usage requires care.
1195		*
1196	<	* Field runState is an int packed with:
1196	>	* Field plock is an int packed with:
1197		* SHUTDOWN: true if shutdown is enabled (1 bit)
1198	<	* SEQ:  a sequence number updated upon (de)registering workers (30 bits)
1199	<	* INIT: set true after workQueues array construction (1 bit)
1198	>	* SEQ:  a sequence lock, with PL_LOCK bit set if locked (30 bits)
1199	>	* SIGNAL: set when threads may be waiting on the lock (1 bit)
1200		*
1201		* The sequence number enables simple consistency checks:
1202		* Staleness of read-only operations on the workQueues array can
1203	<	* be checked by comparing runState before vs after the reads.
1203	>	* be checked by comparing plock before vs after the reads.
1204		*/
1205
1206		// bit positions/shifts for fields
#	Line 1297 | Line 1212 | public class ForkJoinPool extends Abstra
1212		// bounds
1213		private static final int  SMASK      = 0xffff;  // short bits
1214		private static final int  MAX_CAP    = 0x7fff;  // max #workers - 1
1215	<	private static final int  SQMASK     = 0xfffe;  // even short bits
1215	>	private static final int  EVENMASK   = 0xfffe;  // even short bits
1216	>	private static final int  SQMASK     = 0x007e;  // max 64 (even) slots
1217		private static final int  SHORT_SIGN = 1 << 15;
1218		private static final int  INT_SIGN   = 1 << 31;
1219
#	Line 1322 | Line 1238 | public class ForkJoinPool extends Abstra
1238		private static final int E_MASK      = 0x7fffffff; // no STOP_BIT
1239		private static final int E_SEQ       = 1 << EC_SHIFT;
1240
1241	<	// runState bits
1241	>	// plock bits
1242		private static final int SHUTDOWN    = 1 << 31;
1243	+	private static final int PL_LOCK     = 2;
1244	+	private static final int PL_SIGNAL   = 1;
1245	+	private static final int PL_SPINS    = 1 << 8;
1246
1247		// access mode for WorkQueue
1248		static final int LIFO_QUEUE          =  0;
#	Line 1338 | Line 1257 | public class ForkJoinPool extends Abstra
1257		* declaration order and may differ across JVMs, but the following
1258		* empirically works OK on current JVMs.
1259		*/
1341	–
1260		volatile long stealCount;                  // collects worker counts
1261		volatile long ctl;                         // main pool control
1262		final int parallelism;                     // parallelism level
1263		final int localMode;                       // per-worker scheduling mode
1264	<	volatile int nextWorkerNumber;             // to create worker name string
1265	<	final int submitMask;                      // submit queue index bound
1348	<	int nextSeed;                              // for initializing worker seeds
1349	<	volatile int mainLock;                     // spinlock for array updates
1350	<	volatile int runState;                     // shutdown status and seq
1264	>	volatile int indexSeed;                    // worker/submitter index seed
1265	>	volatile int plock;                        // shutdown status and seqLock
1266		WorkQueue[] workQueues;                    // main registry
1267		final ForkJoinWorkerThreadFactory factory; // factory for new workers
1268		final Thread.UncaughtExceptionHandler ueh; // per-worker UEH
1269		final String workerNamePrefix;             // to create worker name string
1270
1271		/*
1272	<	* Mechanics for main lock protecting worker array updates.  Uses
1273	<	* the same strategy as ConcurrentHashMap bins -- a spinLock for
1274	<	* normal cases, but falling back to builtin lock when (rarely)
1275	<	* needed.  See internal ConcurrentHashMap documentation for
1276	<	* explanation.
1277	<	*/
1278	<
1279	<	static final int LOCK_WAITING = 2; // bit to indicate need for signal
1280	<	static final int MAX_LOCK_SPINS = 1 << 8;
1281	<
1282	<	private void tryAwaitMainLock() {
1283	<	int spins = MAX_LOCK_SPINS, r = 0, h;
1284	<	while (((h = mainLock) & 1) != 0) {
1285	<	if (r == 0)
1272	>	* Acquires the plock lock to protect worker array and related
1273	>	* updates. This method is called only if an initial CAS on plock
1274	>	* fails. This acts as a spinLock for normal cases, but falls back
1275	>	* to builtin monitor to block when (rarely) needed. This would be
1276	>	* a terrible idea for a highly contended lock, but works fine as
1277	>	* a more conservative alternative to a pure spinlock.  See
1278	>	* internal ConcurrentHashMap documentation for further
1279	>	* explanation of nearly the same construction.
1280	>	*/
1281	>	private int acquirePlock() {
1282	>	int spins = PL_SPINS, r = 0, ps, nps;
1283	>	for (;;) {
1284	>	if (((ps = plock) & PL_LOCK) == 0 &&
1285	>	U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK))
1286	>	return nps;
1287	>	else if (r == 0)
1288		r = ThreadLocalRandom.current().nextInt(); // randomize spins
1289		else if (spins >= 0) {
1290		r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
1291		if (r >= 0)
1292		--spins;
1293		}
1294	<	else if (U.compareAndSwapInt(this, MAINLOCK, h, h | LOCK_WAITING)) {
1294	>	else if (U.compareAndSwapInt(this, PLOCK, ps, ps | PL_SIGNAL)) {
1295		synchronized (this) {
1296	<	if ((mainLock & LOCK_WAITING) != 0) {
1296	>	if ((plock & PL_SIGNAL) != 0) {
1297		try {
1298		wait();
1299		} catch (InterruptedException ie) {
1300	<	Thread.currentThread().interrupt();
1300	>	try {
1301	>	Thread.currentThread().interrupt();
1302	>	} catch (SecurityException ignore) {
1303	>	}
1304		}
1305		}
1306		else
1307	<	notifyAll(); // possibly won race vs signaller
1307	>	notifyAll();
1308		}
1389	–	break;
1309		}
1310		}
1311		}
1312
1394	–	//  Creating, registering, and deregistering workers
1395	–
1313		/**
1314	<	* Tries to create and start a worker
1314	>	* Unlocks and signals any thread waiting for plock. Called only
1315	>	* when CAS of seq value for unlock fails.
1316		*/
1317	<	private void addWorker() {
1318	<	Throwable ex = null;
1319	<	ForkJoinWorkerThread wt = null;
1402	<	try {
1403	<	if ((wt = factory.newThread(this)) != null) {
1404	<	wt.start();
1405	<	return;
1406	<	}
1407	<	} catch (Throwable e) {
1408	<	ex = e;
1409	<	}
1410	<	deregisterWorker(wt, ex); // adjust counts etc on failure
1317	>	private void releasePlock(int ps) {
1318	>	plock = ps;
1319	>	synchronized (this) { notifyAll(); }
1320		}
1321
1322	<	/**
1414	<	* Callback from ForkJoinWorkerThread constructor to assign a
1415	<	* public name. This must be separate from registerWorker because
1416	<	* it is called during the "super" constructor call in
1417	<	* ForkJoinWorkerThread.
1418	<	*/
1419	<	final String nextWorkerName() {
1420	<	int n;
1421	<	do {} while(!U.compareAndSwapInt(this, NEXTWORKERNUMBER,
1422	<	n = nextWorkerNumber, ++n));
1423	<	return workerNamePrefix.concat(Integer.toString(n));
1424	<	}
1322	>	//  Registering and deregistering workers
1323
1324		/**
1325		* Callback from ForkJoinWorkerThread constructor to establish its
#	Line 1433 | Line 1331 | public class ForkJoinPool extends Abstra
1331		* @param w the worker's queue
1332		*/
1333		final void registerWorker(WorkQueue w) {
1334	<	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1335	<	tryAwaitMainLock();
1334	>	int s, ps; // generate a rarely colliding candidate index seed
1335	>	do {} while (!U.compareAndSwapInt(this, INDEXSEED,
1336	>	s = indexSeed, s += SEED_INCREMENT) ||
1337	>	s == 0); // skip 0
1338	>	if (((ps = plock) & PL_LOCK) != 0 ||
1339	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1340	>	ps = acquirePlock();
1341	>	int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1342		try {
1343		WorkQueue[] ws;
1344	<	if ((ws = workQueues) == null)
1345	<	ws = workQueues = new WorkQueue[submitMask + 1];
1346	<	if (w != null) {
1443	<	int rs, n =  ws.length, m = n - 1;
1444	<	int s = nextSeed += SEED_INCREMENT; // rarely-colliding sequence
1445	<	w.seed = (s == 0) ? 1 : s;          // ensure non-zero seed
1344	>	if (w != null && (ws = workQueues) != null) {
1345	>	w.seed = s;
1346	>	int n = ws.length, m = n - 1;
1347		int r = (s << 1) | 1;               // use odd-numbered indices
1348		if (ws[r &= m] != null) {           // collision
1349		int probes = 0;                 // step by approx half size
1350	<	int step = (n <= 4) ? 2 : ((n >>> 1) & SQMASK) + 2;
1350	>	int step = (n <= 4) ? 2 : ((n >>> 1) & EVENMASK) + 2;
1351		while (ws[r = (r + step) & m] != null) {
1352		if (++probes >= n) {
1353		workQueues = ws = Arrays.copyOf(ws, n <<= 1);
#	Line 1456 | Line 1357 | public class ForkJoinPool extends Abstra
1357		}
1358		}
1359		w.eventCount = w.poolIndex = r;     // establish before recording
1360	<	ws[r] = w;                          // also update seq
1460	<	runState = ((rs = runState) & SHUTDOWN) | ((rs + 2) & ~SHUTDOWN);
1360	>	ws[r] = w;
1361		}
1362		} finally {
1363	<	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1364	<	mainLock = 0;
1465	<	synchronized (this) { notifyAll(); };
1466	<	}
1363	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1364	>	releasePlock(nps);
1365		}
1468	–
1366		}
1367
1368		/**
1369		* Final callback from terminating worker, as well as upon failure
1370	<	* to construct or start a worker in addWorker.  Removes record of
1371	<	* worker from array, and adjusts counts. If pool is shutting
1372	<	* down, tries to complete termination.
1370	>	* to construct or start a worker.  Removes record of worker from
1371	>	* array, and adjusts counts. If pool is shutting down, tries to
1372	>	* complete termination.
1373		*
1374	<	* @param wt the worker thread or null if addWorker failed
1374	>	* @param wt the worker thread or null if construction failed
1375		* @param ex the exception causing failure, or null if none
1376		*/
1377		final void deregisterWorker(ForkJoinWorkerThread wt, Throwable ex) {
1378		WorkQueue w = null;
1379		if (wt != null && (w = wt.workQueue) != null) {
1380	<	w.runState = -1;                // ensure runState is set
1381	<	long steals = w.totalSteals + w.nsteals, sc;
1382	<	do {} while(!U.compareAndSwapLong(this, STEALCOUNT,
1383	<	sc = stealCount, sc + steals));
1384	<	int idx = w.poolIndex;
1385	<	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1386	<	tryAwaitMainLock();
1380	>	int ps;
1381	>	collectStealCount(w);
1382	>	w.qlock = -1;                // ensure set
1383	>	if (((ps = plock) & PL_LOCK) != 0 ||
1384	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1385	>	ps = acquirePlock();
1386	>	int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1387		try {
1388	+	int idx = w.poolIndex;
1389		WorkQueue[] ws = workQueues;
1390		if (ws != null && idx >= 0 && idx < ws.length && ws[idx] == w)
1391		ws[idx] = null;
1392		} finally {
1393	<	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1394	<	mainLock = 0;
1497	<	synchronized (this) { notifyAll(); };
1498	<	}
1393	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1394	>	releasePlock(nps);
1395		}
1396		}
1397
#	Line 1508 | Line 1404 | public class ForkJoinPool extends Abstra
1404		if (!tryTerminate(false, false) && w != null) {
1405		w.cancelAll();                  // cancel remaining tasks
1406		if (w.array != null)            // suppress signal if never ran
1407	<	signalWork();               // wake up or create replacement
1407	>	signalWork(null, 1);        // wake up or create replacement
1408		if (ex == null)                 // help clean refs on way out
1409		ForkJoinTask.helpExpungeStaleExceptions();
1410		}
1411
1412		if (ex != null)                     // rethrow
1413	<	U.throwException(ex);
1413	>	ForkJoinTask.rethrow(ex);
1414	>	}
1415	>
1416	>	/**
1417	>	* Collect worker steal count into total. Called on termination
1418	>	* and upon int overflow of local count. (There is a possible race
1419	>	* in the latter case vs any caller of getStealCount, which can
1420	>	* make its results less accurate than usual.)
1421	>	*/
1422	>	final void collectStealCount(WorkQueue w) {
1423	>	if (w != null) {
1424	>	long sc;
1425	>	int ns = w.nsteals;
1426	>	w.nsteals = 0; // handle overflow
1427	>	long steals = (ns >= 0) ? ns : 1L + (long)(Integer.MAX_VALUE);
1428	>	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1429	>	sc = stealCount, sc + steals));
1430	>	}
1431		}
1432
1433		// Submissions
#	Line 1522 | Line 1435 | public class ForkJoinPool extends Abstra
1435		/**
1436		* Unless shutting down, adds the given task to a submission queue
1437		* at submitter's current queue index (modulo submission
1438	<	* range). If no queue exists at the index, one is created.  If
1439	<	* the queue is busy, another index is randomly chosen. The
1527	<	* submitMask bounds the effective number of queues to the
1528	<	* (nearest power of two for) parallelism level.
1438	>	* range). Only the most common path is directly handled in this
1439	>	* method. All others are relayed to fullExternalPush.
1440		*
1441		* @param task the task. Caller must ensure non-null.
1442		*/
1443	<	private void doSubmit(ForkJoinTask<?> task) {
1444	<	Submitter s = submitters.get();
1445	<	for (int r = s.seed, m = submitMask;;) {
1446	<	WorkQueue[] ws; WorkQueue q;
1447	<	int k = r & m & SQMASK;          // use only even indices
1448	<	if (runState < 0)
1449	<	throw new RejectedExecutionException(); // shutting down
1450	<	else if ((ws = workQueues) == null || ws.length <= k) {
1451	<	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1452	<	tryAwaitMainLock();
1453	<	try {
1454	<	if (workQueues == null)
1455	<	workQueues = new WorkQueue[submitMask + 1];
1456	<	} finally {
1546	<	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1547	<	mainLock = 0;
1548	<	synchronized (this) { notifyAll(); };
1549	<	}
1550	<	}
1551	<	}
1552	<	else if ((q = ws[k]) == null) {  // create new queue
1553	<	WorkQueue nq = new WorkQueue(this, null, SHARED_QUEUE);
1554	<	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
1555	<	tryAwaitMainLock();
1556	<	try {
1557	<	int rs = runState;       // to update seq
1558	<	if (ws == workQueues && ws[k] == null) {
1559	<	ws[k] = nq;
1560	<	runState = ((rs & SHUTDOWN) | ((rs + 2) & ~SHUTDOWN));
1561	<	}
1562	<	} finally {
1563	<	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
1564	<	mainLock = 0;
1565	<	synchronized (this) { notifyAll(); };
1566	<	}
1567	<	}
1568	<	}
1569	<	else if (q.trySharedPush(task)) {
1570	<	signalWork();
1443	>	final void externalPush(ForkJoinTask<?> task) {
1444	>	WorkQueue[] ws; WorkQueue q; Submitter z; int m; ForkJoinTask<?>[] a;
1445	>	if ((z = submitters.get()) != null && plock > 0 &&
1446	>	(ws = workQueues) != null && (m = (ws.length - 1)) >= 0 &&
1447	>	(q = ws[m & z.seed & SQMASK]) != null &&
1448	>	U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock
1449	>	int s = q.top, n;
1450	>	if ((a = q.array) != null && a.length > (n = s + 1 - q.base)) {
1451	>	U.putObject(a, (long)(((a.length - 1) & s) << ASHIFT) + ABASE,
1452	>	task);
1453	>	q.top = s + 1;                     // push on to deque
1454	>	q.qlock = 0;
1455	>	if (n <= 1)
1456	>	signalWork(q, 1);
1457		return;
1458		}
1459	<	else if (m > 1) {                // move to a different index
1574	<	r ^= r << 13;                // same xorshift as WorkQueues
1575	<	r ^= r >>> 17;
1576	<	s.seed = r ^= r << 5;
1577	<	}
1578	<	else
1579	<	Thread.yield();              // yield if no alternatives
1459	>	q.qlock = 0;
1460		}
1461	+	fullExternalPush(task);
1462		}
1463
1464		/**
1465	<	* Submits the given (non-null) task to the common pool, if possible.
1466	<	*/
1467	<	static void submitToCommonPool(ForkJoinTask<?> task) {
1468	<	ForkJoinPool p;
1469	<	if ((p = commonPool) == null)
1470	<	throw new RejectedExecutionException("Common Pool Unavailable");
1471	<	p.doSubmit(task);
1472	<	}
1473	<
1474	<	/**
1475	<	* Returns true if caller is (or may be) submitter to the common
1476	<	* pool, and not all workers are active, and there appear to be
1477	<	* tasks in the associated submission queue.
1478	<	*/
1479	<	static boolean canHelpCommonPool() {
1480	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
1481	<	int k = submitters.get().seed & SQMASK;
1482	<	return ((p = commonPool) != null &&
1483	<	(int)(p.ctl >> AC_SHIFT) < 0 &&
1484	<	(ws = p.workQueues) != null &&
1485	<	ws.length > (k &= p.submitMask) &&
1486	<	(q = ws[k]) != null &&
1487	<	q.top - q.base > 0);
1488	<	}
1489	<
1490	<	/**
1491	<	* Returns true if the given task was submitted to common pool
1492	<	* and has not yet commenced execution, and is available for
1493	<	* removal according to execution policies; if so removing the
1494	<	* submission from the pool.
1495	<	*
1496	<	* @param task the task
1497	<	* @return true if successful
1498	<	*/
1499	<	static boolean tryUnsubmitFromCommonPool(ForkJoinTask<?> task) {
1500	<	// Peek, looking for task and eligibility before
1501	<	// using trySharedUnpush to actually take it under lock
1502	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
1503	<	ForkJoinTask<?>[] a; int s;
1504	<	int k = submitters.get().seed & SQMASK;
1505	<	return ((p = commonPool) != null &&
1506	<	(int)(p.ctl >> AC_SHIFT) < 0 &&
1507	<	(ws = p.workQueues) != null &&
1508	<	ws.length > (k &= p.submitMask) &&
1509	<	(q = ws[k]) != null &&
1510	<	(a = q.array) != null &&
1511	<	(s = q.top - 1) - q.base >= 0 &&
1512	<	s >= 0 && s < a.length &&
1513	<	a[s] == task &&
1514	<	q.trySharedUnpush(task));
1515	<	}
1516	<
1517	<	/**
1518	<	* Tries to pop a task from common pool with given root
1519	<	*/
1520	<	static ForkJoinTask<?> popCCFromCommonPool(CountedCompleter<?> root) {
1521	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
1522	<	ForkJoinTask<?> t;
1523	<	int k = submitters.get().seed & SQMASK;
1524	<	if (root != null &&
1525	<	(p = commonPool) != null &&
1645	<	(int)(p.ctl >> AC_SHIFT) < 0 &&
1646	<	(ws = p.workQueues) != null &&
1647	<	ws.length > (k &= p.submitMask) &&
1648	<	(q = ws[k]) != null && q.top - q.base > 0 &&
1649	<	root.status < 0 &&
1650	<	(t = q.sharedPopCC(root)) != null)
1651	<	return t;
1652	<	return null;
1465	>	* Full version of externalPush. This method is called, among
1466	>	* other times, upon the first submission of the first task to the
1467	>	* pool, so must perform secondary initialization: creating
1468	>	* workQueue array and setting plock to a valid value. It also
1469	>	* detects first submission by an external thread by looking up
1470	>	* its ThreadLocal, and creates a new shared queue if the one at
1471	>	* index if empty or contended. The lock bodies must be
1472	>	* exception-free (so no try/finally) so we optimistically
1473	>	* allocate new queues/arrays outside the locks and throw them
1474	>	* away if (very rarely) not needed. Note that the plock seq value
1475	>	* can eventually wrap around zero, but if so harmlessly fails to
1476	>	* reinitialize.
1477	>	*/
1478	>	private void fullExternalPush(ForkJoinTask<?> task) {
1479	>	for (Submitter z = null;;) {
1480	>	WorkQueue[] ws; WorkQueue q; int ps, m, r, s;
1481	>	if ((ps = plock) < 0)
1482	>	throw new RejectedExecutionException();
1483	>	else if ((ws = workQueues) == null || (m = ws.length - 1) < 0) {
1484	>	int n = parallelism - 1; n |= n >>> 1; n |= n >>> 2;
1485	>	n |= n >>> 4; n |= n >>> 8; n |= n >>> 16;
1486	>	WorkQueue[] nws = new WorkQueue[(n + 1) << 1]; // power of two
1487	>	if ((ps & PL_LOCK) != 0 ||
1488	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1489	>	ps = acquirePlock();
1490	>	if ((ws = workQueues) == null)
1491	>	workQueues = nws;
1492	>	int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1493	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1494	>	releasePlock(nps);
1495	>	}
1496	>	else if (z == null && (z = submitters.get()) == null) {
1497	>	if (U.compareAndSwapInt(this, INDEXSEED,
1498	>	s = indexSeed, s += SEED_INCREMENT) &&
1499	>	s != 0) // skip 0
1500	>	submitters.set(z = new Submitter(s));
1501	>	}
1502	>	else {
1503	>	int k = (r = z.seed) & m & SQMASK;
1504	>	if ((q = ws[k]) == null && (ps & PL_LOCK) == 0) {
1505	>	(q = new WorkQueue(this, null, SHARED_QUEUE)).poolIndex = k;
1506	>	if (((ps = plock) & PL_LOCK) != 0 ||
1507	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1508	>	ps = acquirePlock();
1509	>	WorkQueue w = null;
1510	>	if ((ws = workQueues) != null && k < ws.length &&
1511	>	(w = ws[k]) == null)
1512	>	ws[k] = q;
1513	>	else
1514	>	q = w;
1515	>	int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1516	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1517	>	releasePlock(nps);
1518	>	}
1519	>	if (q != null && q.qlock == 0 && q.fullPush(task, false))
1520	>	return;
1521	>	r ^= r << 13;                // same xorshift as WorkQueues
1522	>	r ^= r >>> 17;
1523	>	z.seed = r ^= r << 5;        // move to a different index
1524	>	}
1525	>	}
1526		}
1527
1655	–
1528		// Maintaining ctl counts
1529
1530		/**
#	Line 1664 | Line 1536 | public class ForkJoinPool extends Abstra
1536		}
1537
1538		/**
1539	<	* Tries to create one or activate one or more workers if too few are active.
1540	<	*/
1541	<	final void signalWork() {
1542	<	long c; int u;
1543	<	while ((u = (int)((c = ctl) >>> 32)) < 0) {     // too few active
1544	<	WorkQueue[] ws = workQueues; int e, i; WorkQueue w; Thread p;
1545	<	if ((e = (int)c) > 0) {                     // at least one waiting
1546	<	if (ws != null && (i = e & SMASK) < ws.length &&
1539	>	* Tries to create (at most one) or activate (possibly several)
1540	>	* workers if too few are active. On contention failure, continues
1541	>	* until at least one worker is signalled or the given queue is
1542	>	* empty or all workers are active.
1543	>	*
1544	>	* @param q if non-null, the queue holding tasks to be signalled
1545	>	* @param signals the target number of signals.
1546	>	*/
1547	>	final void signalWork(WorkQueue q, int signals) {
1548	>	long c; int e, u, i; WorkQueue[] ws; WorkQueue w; Thread p;
1549	>	while ((u = (int)((c = ctl) >>> 32)) < 0) {
1550	>	if ((e = (int)c) > 0) {
1551	>	if ((ws = workQueues) != null && ws.length > (i = e & SMASK) &&
1552		(w = ws[i]) != null && w.eventCount == (e | INT_SIGN)) {
1553		long nc = (((long)(w.nextWait & E_MASK)) |
1554		((long)(u + UAC_UNIT) << 32));
1555		if (U.compareAndSwapLong(this, CTL, c, nc)) {
1556		w.eventCount = (e + E_SEQ) & E_MASK;
1557		if ((p = w.parker) != null)
1558	<	U.unpark(p);                // activate and release
1559	<	break;
1558	>	U.unpark(p);
1559	>	if (--signals <= 0)
1560	>	break;
1561		}
1562	+	else
1563	+	signals = 1;
1564	+	if ((q != null && q.queueSize() == 0))
1565	+	break;
1566		}
1567		else
1568		break;
1569		}
1570	<	else if (e == 0 && (u & SHORT_SIGN) != 0) { // too few total
1570	>	else if (e == 0 && (u & SHORT_SIGN) != 0) {
1571		long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
1572		((u + UAC_UNIT) & UAC_MASK)) << 32;
1573		if (U.compareAndSwapLong(this, CTL, c, nc)) {
1574	<	addWorker();
1574	>	ForkJoinWorkerThread wt = null;
1575	>	Throwable ex = null;
1576	>	boolean started = false;
1577	>	try {
1578	>	ForkJoinWorkerThreadFactory fac;
1579	>	if ((fac = factory) != null &&
1580	>	(wt = fac.newThread(this)) != null) {
1581	>	wt.start();
1582	>	started = true;
1583	>	}
1584	>	} catch (Throwable rex) {
1585	>	ex = rex;
1586	>	}
1587	>	if (!started)
1588	>	deregisterWorker(wt, ex); // adjust counts on failure
1589		break;
1590		}
1591		}
#	Line 1704 | Line 1600 | public class ForkJoinPool extends Abstra
1600		* Top-level runloop for workers, called by ForkJoinWorkerThread.run.
1601		*/
1602		final void runWorker(WorkQueue w) {
1603	<	w.growArray(false);         // initialize queue array in this thread
1604	<	do { w.runTask(scan(w)); } while (w.runState >= 0);
1603	>	// initialize queue array in this thread
1604	>	w.array = new ForkJoinTask<?>[WorkQueue.INITIAL_QUEUE_CAPACITY];
1605	>	do { w.runTask(scan(w)); } while (w.qlock >= 0);
1606		}
1607
1608		/**
#	Line 1721 | Line 1618 | public class ForkJoinPool extends Abstra
1618		* relative prime, checking each at least once).  The scan
1619		* terminates upon either finding a non-empty queue, or completing
1620		* the sweep. If the worker is not inactivated, it takes and
1621	<	* returns a task from this queue.  On failure to find a task, we
1621	>	* returns a task from this queue. Otherwise, if not activated, it
1622	>	* signals workers (that may include itself) and returns so caller
1623	>	* can retry. Also returns for trtry if the worker array may have
1624	>	* changed during an empty scan.  On failure to find a task, we
1625		* take one of the following actions, after which the caller will
1626		* retry calling this method unless terminated.
1627		*
1628		* * If pool is terminating, terminate the worker.
1629		*
1730	–	* * If not a complete sweep, try to release a waiting worker.  If
1731	–	* the scan terminated because the worker is inactivated, then the
1732	–	* released worker will often be the calling worker, and it can
1733	–	* succeed obtaining a task on the next call. Or maybe it is
1734	–	* another worker, but with same net effect. Releasing in other
1735	–	* cases as well ensures that we have enough workers running.
1736	–	*
1630		* * If not already enqueued, try to inactivate and enqueue the
1631		* worker on wait queue. Or, if inactivating has caused the pool
1632		* to be quiescent, relay to idleAwaitWork to check for
1633		* termination and possibly shrink pool.
1634		*
1635	<	* * If already inactive, and the caller has run a task since the
1636	<	* last empty scan, return (to allow rescan) unless others are
1637	<	* also inactivated.  Field WorkQueue.rescans counts down on each
1745	<	* scan to ensure eventual inactivation and blocking.
1746	<	*
1747	<	* * If already enqueued and none of the above apply, park
1748	<	* awaiting signal,
1635	>	* * If already enqueued and none of the above apply, possibly
1636	>	* (with 1/2 probability) park awaiting signal, else lingering to
1637	>	* help scan and signal.
1638		*
1639		* @param w the worker (via its WorkQueue)
1640		* @return a task or null if none found
1641		*/
1642		private final ForkJoinTask<?> scan(WorkQueue w) {
1643	<	WorkQueue[] ws;                       // first update random seed
1643	>	WorkQueue[] ws; WorkQueue q;           // first update random seed
1644		int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1645	<	int rs = runState, m;                 // volatile read order matters
1645	>	int ps = plock, m;                     // volatile read order matters
1646		if ((ws = workQueues) != null && (m = ws.length - 1) > 0) {
1647	<	int ec = w.eventCount;            // ec is negative if inactive
1648	<	int step = (r >>> 16) | 1;        // relative prime
1649	<	for (int j = (m + 1) << 2; ; r += step) {
1650	<	WorkQueue q; ForkJoinTask<?> t; ForkJoinTask<?>[] a; int b;
1647	>	int ec = w.eventCount;             // ec is negative if inactive
1648	>	int step = (r >>> 16) | 1;         // relatively prime
1649	>	for (int j = (m + 1) << 2;  ; --j, r += step) {
1650	>	ForkJoinTask<?> t; ForkJoinTask<?>[] a; int b, n;
1651		if ((q = ws[r & m]) != null && (b = q.base) - q.top < 0 &&
1652	<	(a = q.array) != null) {  // probably nonempty
1652	>	(a = q.array) != null) {   // probably nonempty
1653		int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1654		t = (ForkJoinTask<?>)U.getObjectVolatile(a, i);
1655		if (q.base == b && ec >= 0 && t != null &&
1656		U.compareAndSwapObject(a, i, t, null)) {
1657	<	if (q.top - (q.base = b + 1) > 0)
1658	<	signalWork();    // help pushes signal
1659	<	return t;
1660	<	}
1661	<	else if (ec < 0 || j <= m) {
1662	<	rs = 0;               // mark scan as imcomplete
1663	<	break;                // caller can retry after release
1657	>	if ((n = q.top - (q.base = b + 1)) > 0)
1658	>	signalWork(q, n);
1659	>	return t;              // taken
1660	>	}
1661	>	if (j < m || (ec < 0 && (ec = w.eventCount) < 0)) {
1662	>	if ((n = q.queueSize() - 1) > 0)
1663	>	signalWork(q, n);
1664	>	break;                 // let caller retry after signal
1665		}
1666		}
1667	<	if (--j < 0)
1668	<	break;
1669	<	}
1670	<
1671	<	long c = ctl; int e = (int)c, a = (int)(c >> AC_SHIFT), nr, ns;
1672	<	if (e < 0)                        // decode ctl on empty scan
1673	<	w.runState = -1;              // pool is terminating
1674	<	else if (rs == 0 || rs != runState) { // incomplete scan
1675	<	WorkQueue v; Thread p;        // try to release a waiter
1676	<	if (e > 0 && a < 0 && w.eventCount == ec &&
1677	<	(v = ws[e & m]) != null && v.eventCount == (e | INT_SIGN)) {
1678	<	long nc = ((long)(v.nextWait & E_MASK) |
1679	<	((c + AC_UNIT) & (AC_MASK|TC_MASK)));
1680	<	if (ctl == c && U.compareAndSwapLong(this, CTL, c, nc)) {
1681	<	v.eventCount = (e + E_SEQ) & E_MASK;
1682	<	if ((p = v.parker) != null)
1683	<	U.unpark(p);
1667	>	else if (j < 0) {              // end of scan
1668	>	long c = ctl; int e;
1669	>	if (plock != ps)           // incomplete sweep
1670	>	break;
1671	>	if ((e = (int)c) < 0)      // pool is terminating
1672	>	w.qlock = -1;
1673	>	else if (ec >= 0) {        // try to enqueue/inactivate
1674	>	long nc = ((long)ec |
1675	>	((c - AC_UNIT) & (AC_MASK|TC_MASK)));
1676	>	w.nextWait = e;
1677	>	w.eventCount = ec | INT_SIGN; // mark as inactive
1678	>	if (ctl != c ||
1679	>	!U.compareAndSwapLong(this, CTL, c, nc))
1680	>	w.eventCount = ec; // unmark on CAS failure
1681	>	else if ((int)(c >> AC_SHIFT) == 1 - parallelism)
1682	>	idleAwaitWork(w, nc, c);  // quiescent
1683	>	}
1684	>	else if (w.seed >= 0 && w.eventCount < 0) {
1685	>	Thread wt = Thread.currentThread();
1686	>	Thread.interrupted();  // clear status
1687	>	U.putObject(wt, PARKBLOCKER, this);
1688	>	w.parker = wt;         // emulate LockSupport.park
1689	>	if (w.eventCount < 0)  // recheck
1690	>	U.park(false, 0L);
1691	>	w.parker = null;
1692	>	U.putObject(wt, PARKBLOCKER, null);
1693		}
1694	<	}
1796	<	}
1797	<	else if (ec >= 0) {               // try to enqueue/inactivate
1798	<	long nc = (long)ec | ((c - AC_UNIT) & (AC_MASK|TC_MASK));
1799	<	w.nextWait = e;
1800	<	w.eventCount = ec | INT_SIGN; // mark as inactive
1801	<	if (ctl != c || !U.compareAndSwapLong(this, CTL, c, nc))
1802	<	w.eventCount = ec;        // unmark on CAS failure
1803	<	else {
1804	<	if ((ns = w.nsteals) != 0) {
1805	<	w.nsteals = 0;        // set rescans if ran task
1806	<	w.rescans = (a > 0) ? 0 : a + parallelism;
1807	<	w.totalSteals += ns;
1808	<	}
1809	<	if (a == 1 - parallelism) // quiescent
1810	<	idleAwaitWork(w, nc, c);
1811	<	}
1812	<	}
1813	<	else if (w.eventCount < 0) {      // already queued
1814	<	int ac = a + parallelism;
1815	<	if ((nr = w.rescans) > 0)     // continue rescanning
1816	<	w.rescans = (ac < nr) ? ac : nr - 1;
1817	<	else if (((w.seed >>> 16) & ac) == 0) { // randomize park
1818	<	Thread.interrupted();     // clear status
1819	<	Thread wt = Thread.currentThread();
1820	<	U.putObject(wt, PARKBLOCKER, this);
1821	<	w.parker = wt;            // emulate LockSupport.park
1822	<	if (w.eventCount < 0)     // recheck
1823	<	U.park(false, 0L);
1824	<	w.parker = null;
1825	<	U.putObject(wt, PARKBLOCKER, null);
1694	>	break;
1695		}
1696		}
1697		}
#	Line 1842 | Line 1711 | public class ForkJoinPool extends Abstra
1711		* @param prevCtl the ctl value to restore if thread is terminated
1712		*/
1713		private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) {
1714	<	if (w.eventCount < 0 && !tryTerminate(false, false) &&
1715	<	(int)prevCtl != 0 && !hasQueuedSubmissions() && ctl == currentCtl) {
1714	>	if (w.eventCount < 0 &&
1715	>	(this == commonPool || !tryTerminate(false, false)) &&
1716	>	(int)prevCtl != 0) {
1717		int dc = -(short)(currentCtl >>> TC_SHIFT);
1718		long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT;
1719		long deadline = System.nanoTime() + parkTime - 100000L; // 1ms slop
#	Line 1861 | Line 1731 | public class ForkJoinPool extends Abstra
1731		if (deadline - System.nanoTime() <= 0L &&
1732		U.compareAndSwapLong(this, CTL, currentCtl, prevCtl)) {
1733		w.eventCount = (w.eventCount + E_SEQ) | E_MASK;
1734	<	w.runState = -1;   // shrink
1734	>	w.qlock = -1;   // shrink
1735		break;
1736		}
1737		}
#	Line 1869 | Line 1739 | public class ForkJoinPool extends Abstra
1739		}
1740
1741		/**
1742	+	* Scans through queues looking for work while joining a task;
1743	+	* if any are present, signals.
1744	+	*
1745	+	* @param task to return early if done
1746	+	* @param origin an index to start scan
1747	+	*/
1748	+	final int helpSignal(ForkJoinTask<?> task, int origin) {
1749	+	WorkQueue[] ws; WorkQueue q; int m, n, s;
1750	+	if (task != null && (ws = workQueues) != null &&
1751	+	(m = ws.length - 1) >= 0) {
1752	+	for (int i = 0; i <= m; ++i) {
1753	+	if ((s = task.status) < 0)
1754	+	return s;
1755	+	if ((q = ws[(i + origin) & m]) != null &&
1756	+	(n = q.queueSize()) > 0) {
1757	+	signalWork(q, n);
1758	+	if ((int)(ctl >> AC_SHIFT) >= 0)
1759	+	break;
1760	+	}
1761	+	}
1762	+	}
1763	+	return 0;
1764	+	}
1765	+
1766	+	/**
1767		* Tries to locate and execute tasks for a stealer of the given
1768		* task, or in turn one of its stealers, Traces currentSteal ->
1769		* currentJoin links looking for a thread working on a descendant
#	Line 1955 | Line 1850 | public class ForkJoinPool extends Abstra
1850		}
1851
1852		/**
1853	<	* If task is at base of some steal queue, steals and executes it.
1853	>	* Analog of tryHelpStealer for CountedCompleters. Tries to steal
1854	>	* and run tasks within the target's computation
1855	>	*
1856	>	* @param task the task to join
1857	>	* @param mode if shared, exit upon completing any task
1858	>	* if all workers are active
1859		*
1960	–	* @param joiner the joining worker
1961	–	* @param task the task
1860		*/
1861	<	private void tryPollForAndExec(WorkQueue joiner, ForkJoinTask<?> task) {
1862	<	WorkQueue[] ws;
1863	<	if ((ws = workQueues) != null) {
1864	<	for (int j = 1; j < ws.length && task.status >= 0; j += 2) {
1865	<	WorkQueue q = ws[j];
1866	<	if (q != null && q.pollFor(task)) {
1867	<	joiner.runSubtask(task);
1868	<	break;
1861	>	private int helpComplete(ForkJoinTask<?> task, int mode) {
1862	>	WorkQueue[] ws; WorkQueue q; int m, n, s;
1863	>	if (task != null && (ws = workQueues) != null &&
1864	>	(m = ws.length - 1) >= 0) {
1865	>	for (int j = 1, origin = j;;) {
1866	>	if ((s = task.status) < 0)
1867	>	return s;
1868	>	if ((q = ws[j & m]) != null && q.pollAndExecCC(task)) {
1869	>	origin = j;
1870	>	if (mode == SHARED_QUEUE && (int)(ctl >> AC_SHIFT) >= 0)
1871	>	break;
1872		}
1873	+	else if ((j = (j + 2) & m) == origin)
1874	+	break;
1875		}
1876		}
1877	+	return 0;
1878		}
1879
1880		/**
1881		* Tries to decrement active count (sometimes implicitly) and
1882		* possibly release or create a compensating worker in preparation
1883		* for blocking. Fails on contention or termination. Otherwise,
1884	<	* adds a new thread if no idle workers are available and either
1885	<	* pool would become completely starved or: (at least half
1982	<	* starved, and fewer than 50% spares exist, and there is at least
1983	<	* one task apparently available). Even though the availability
1984	<	* check requires a full scan, it is worthwhile in reducing false
1985	<	* alarms.
1986	<	*
1987	<	* @param task if non-null, a task being waited for
1988	<	* @param blocker if non-null, a blocker being waited for
1989	<	* @return true if the caller can block, else should recheck and retry
1884	>	* adds a new thread if no idle workers are available and pool
1885	>	* may become starved.
1886		*/
1887	<	final boolean tryCompensate(ForkJoinTask<?> task, ManagedBlocker blocker) {
1888	<	int pc = parallelism, e;
1889	<	long c = ctl;
1890	<	WorkQueue[] ws = workQueues;
1891	<	if ((e = (int)c) >= 0 && ws != null) {
1892	<	int u, a, ac, hc;
1893	<	int tc = (short)((u = (int)(c >>> 32)) >>> UTC_SHIFT) + pc;
1894	<	boolean replace = false;
1895	<	if ((a = u >> UAC_SHIFT) <= 0) {
1896	<	if ((ac = a + pc) <= 1)
1897	<	replace = true;
1898	<	else if ((e > 0 || (task != null &&
1899	<	ac <= (hc = pc >>> 1) && tc < pc + hc))) {
2004	<	WorkQueue w;
2005	<	for (int j = 0; j < ws.length; ++j) {
2006	<	if ((w = ws[j]) != null && !w.isEmpty()) {
2007	<	replace = true;
2008	<	break;   // in compensation range and tasks available
2009	<	}
2010	<	}
1887	>	final boolean tryCompensate() {
1888	>	int pc = parallelism, e, u, i, tc; long c;
1889	>	WorkQueue[] ws; WorkQueue w; Thread p;
1890	>	if ((e = (int)(c = ctl)) >= 0 && (ws = workQueues) != null) {
1891	>	if (e != 0 && (i = e & SMASK) < ws.length &&
1892	>	(w = ws[i]) != null && w.eventCount == (e | INT_SIGN)) {
1893	>	long nc = ((long)(w.nextWait & E_MASK) |
1894	>	(c & (AC_MASK|TC_MASK)));
1895	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1896	>	w.eventCount = (e + E_SEQ) & E_MASK;
1897	>	if ((p = w.parker) != null)
1898	>	U.unpark(p);
1899	>	return true;   // replace with idle worker
1900		}
1901		}
1902	<	if ((task == null || task.status >= 0) && // recheck need to block
1903	<	(blocker == null || !blocker.isReleasable()) && ctl == c) {
1904	<	if (!replace) {          // no compensation
1905	<	long nc = ((c - AC_UNIT) & AC_MASK) | (c & ~AC_MASK);
1906	<	if (U.compareAndSwapLong(this, CTL, c, nc))
1907	<	return true;
1908	<	}
1909	<	else if (e != 0) {       // release an idle worker
1910	<	WorkQueue w; Thread p; int i;
1911	<	if ((i = e & SMASK) < ws.length && (w = ws[i]) != null) {
1912	<	long nc = ((long)(w.nextWait & E_MASK) |
1913	<	(c & (AC_MASK|TC_MASK)));
1914	<	if (w.eventCount == (e | INT_SIGN) &&
1915	<	U.compareAndSwapLong(this, CTL, c, nc)) {
1916	<	w.eventCount = (e + E_SEQ) & E_MASK;
1917	<	if ((p = w.parker) != null)
2029	<	U.unpark(p);
1902	>	else if ((short)((u = (int)(c >>> 32)) >>> UTC_SHIFT) >= 0 &&
1903	>	(u >> UAC_SHIFT) + pc > 1) {
1904	>	long nc = ((c - AC_UNIT) & AC_MASK) | (c & ~AC_MASK);
1905	>	if (U.compareAndSwapLong(this, CTL, c, nc))
1906	>	return true;    // no compensation
1907	>	}
1908	>	else if ((tc = u + pc) < MAX_CAP) {
1909	>	long nc = ((c + TC_UNIT) & TC_MASK) | (c & ~TC_MASK);
1910	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1911	>	Throwable ex = null;
1912	>	ForkJoinWorkerThread wt = null;
1913	>	try {
1914	>	ForkJoinWorkerThreadFactory fac;
1915	>	if ((fac = factory) != null &&
1916	>	(wt = fac.newThread(this)) != null) {
1917	>	wt.start();
1918		return true;
1919		}
1920	+	} catch (Throwable rex) {
1921	+	ex = rex;
1922		}
1923	<	}
2034	<	else if (tc < MAX_CAP) { // create replacement
2035	<	long nc = ((c + TC_UNIT) & TC_MASK) | (c & ~TC_MASK);
2036	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
2037	<	addWorker();
2038	<	return true;
2039	<	}
1923	>	deregisterWorker(wt, ex); // adjust counts etc
1924		}
1925		}
1926		}
#	Line 2051 | Line 1935 | public class ForkJoinPool extends Abstra
1935		* @return task status on exit
1936		*/
1937		final int awaitJoin(WorkQueue joiner, ForkJoinTask<?> task) {
1938	<	int s;
1939	<	if ((s = task.status) >= 0) {
1938	>	int s = 0;
1939	>	if (joiner != null && task != null && (s = task.status) >= 0) {
1940		ForkJoinTask<?> prevJoin = joiner.currentJoin;
1941		joiner.currentJoin = task;
1942	<	long startTime = 0L;
1943	<	for (int k = 0;;) {
1944	<	if ((s = (joiner.isEmpty() ?           // try to help
1945	<	tryHelpStealer(joiner, task) :
1946	<	joiner.tryRemoveAndExec(task))) == 0 &&
1947	<	(s = task.status) >= 0) {
1948	<	if (k == 0) {
1949	<	startTime = System.nanoTime();
1950	<	tryPollForAndExec(joiner, task); // check uncommon case
1951	<	}
1952	<	else if ((k & (MAX_HELP - 1)) == 0 &&
1953	<	System.nanoTime() - startTime >=
1954	<	COMPENSATION_DELAY &&
1955	<	tryCompensate(task, null)) {
1956	<	if (task.trySetSignal()) {
1957	<	synchronized (task) {
1958	<	if (task.status >= 0) {
2075	<	try {                // see ForkJoinTask
2076	<	task.wait();     //  for explanation
2077	<	} catch (InterruptedException ie) {
2078	<	}
1942	>	do {} while ((s = task.status) >= 0 &&
1943	>	joiner.queueSize() > 0 &&
1944	>	joiner.tryRemoveAndExec(task)); // process local tasks
1945	>	if (s >= 0 && (s = task.status) >= 0 &&
1946	>	(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
1947	>	(task instanceof CountedCompleter))
1948	>	s = helpComplete(task, LIFO_QUEUE);
1949	>	while (s >= 0 && (s = task.status) >= 0) {
1950	>	if ((joiner.queueSize() > 0 ||           // try helping
1951	>	(s = tryHelpStealer(joiner, task)) == 0) &&
1952	>	(s = task.status) >= 0 && tryCompensate()) {
1953	>	if (task.trySetSignal() && (s = task.status) >= 0) {
1954	>	synchronized (task) {
1955	>	if (task.status >= 0) {
1956	>	try {                // see ForkJoinTask
1957	>	task.wait();     //  for explanation
1958	>	} catch (InterruptedException ie) {
1959		}
2080	–	else
2081	–	task.notifyAll();
1960		}
1961	+	else
1962	+	task.notifyAll();
1963		}
2084	–	long c;                          // re-activate
2085	–	do {} while (!U.compareAndSwapLong
2086	–	(this, CTL, c = ctl, c + AC_UNIT));
1964		}
1965	+	long c;                          // re-activate
1966	+	do {} while (!U.compareAndSwapLong
1967	+	(this, CTL, c = ctl, c + AC_UNIT));
1968		}
2089	–	if (s < 0 || (s = task.status) < 0) {
2090	–	joiner.currentJoin = prevJoin;
2091	–	break;
2092	–	}
2093	–	else if ((k++ & (MAX_HELP - 1)) == MAX_HELP >>> 1)
2094	–	Thread.yield();                     // for politeness
1969		}
1970	+	joiner.currentJoin = prevJoin;
1971		}
1972		return s;
1973		}
#	Line 2104 | Line 1979 | public class ForkJoinPool extends Abstra
1979		*
1980		* @param joiner the joining worker
1981		* @param task the task
2107	–	* @return task status on exit
1982		*/
1983	<	final int helpJoinOnce(WorkQueue joiner, ForkJoinTask<?> task) {
1983	>	final void helpJoinOnce(WorkQueue joiner, ForkJoinTask<?> task) {
1984		int s;
1985	<	while ((s = task.status) >= 0 &&
1986	<	(joiner.isEmpty() ?
1987	<	tryHelpStealer(joiner, task) :
1988	<	joiner.tryRemoveAndExec(task)) != 0)
1989	<	;
1990	<	return s;
1985	>	if (joiner != null && task != null && (s = task.status) >= 0) {
1986	>	ForkJoinTask<?> prevJoin = joiner.currentJoin;
1987	>	joiner.currentJoin = task;
1988	>	do {} while ((s = task.status) >= 0 &&
1989	>	joiner.queueSize() > 0 &&
1990	>	joiner.tryRemoveAndExec(task));
1991	>	if (s >= 0 && (s = task.status) >= 0 &&
1992	>	(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
1993	>	(task instanceof CountedCompleter))
1994	>	s = helpComplete(task, LIFO_QUEUE);
1995	>	if (s >= 0 && joiner.queueSize() == 0) {
1996	>	do {} while (task.status >= 0 &&
1997	>	tryHelpStealer(joiner, task) > 0);
1998	>	}
1999	>	joiner.currentJoin = prevJoin;
2000	>	}
2001		}
2002
2003		/**
#	Line 2121 | Line 2005 | public class ForkJoinPool extends Abstra
2005		* during a random, then cyclic scan, else null.  This method must
2006		* be retried by caller if, by the time it tries to use the queue,
2007		* it is empty.
2008	+	* @param r a (random) seed for scanning
2009		*/
2010	<	private WorkQueue findNonEmptyStealQueue(WorkQueue w) {
2126	<	// Similar to loop in scan(), but ignoring submissions
2127	<	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
2010	>	private WorkQueue findNonEmptyStealQueue(int r) {
2011		int step = (r >>> 16) | 1;
2012		for (WorkQueue[] ws;;) {
2013	<	int rs = runState, m;
2013	>	int ps = plock, m;
2014		if ((ws = workQueues) == null || (m = ws.length - 1) < 1)
2015		return null;
2016		for (int j = (m + 1) << 2; ; r += step) {
2017		WorkQueue q = ws[((r << 1) | 1) & m];
2018	<	if (q != null && !q.isEmpty())
2018	>	if (q != null && q.queueSize() > 0)
2019		return q;
2020		else if (--j < 0) {
2021	<	if (runState == rs)
2021	>	if (plock == ps)
2022		return null;
2023		break;
2024		}
#	Line 2154 | Line 2037 | public class ForkJoinPool extends Abstra
2037		ForkJoinTask<?> localTask; // exhaust local queue
2038		while ((localTask = w.nextLocalTask()) != null)
2039		localTask.doExec();
2040	<	WorkQueue q = findNonEmptyStealQueue(w);
2040	>	// Similar to loop in scan(), but ignoring submissions
2041	>	WorkQueue q = findNonEmptyStealQueue(w.nextSeed());
2042		if (q != null) {
2043		ForkJoinTask<?> t; int b;
2044		if (!active) {      // re-establish active count
#	Line 2185 | Line 2069 | public class ForkJoinPool extends Abstra
2069		}
2070
2071		/**
2188	–	* Restricted version of helpQuiescePool for non-FJ callers
2189	–	*/
2190	–	static void externalHelpQuiescePool() {
2191	–	ForkJoinPool p; WorkQueue[] ws; WorkQueue q, sq;
2192	–	ForkJoinTask<?>[] a; int b;
2193	–	ForkJoinTask<?> t = null;
2194	–	int k = submitters.get().seed & SQMASK;
2195	–	if ((p = commonPool) != null &&
2196	–	(int)(p.ctl >> AC_SHIFT) < 0 &&
2197	–	(ws = p.workQueues) != null &&
2198	–	ws.length > (k &= p.submitMask) &&
2199	–	(q = ws[k]) != null) {
2200	–	while (q.top - q.base > 0) {
2201	–	if ((t = q.sharedPop()) != null)
2202	–	break;
2203	–	}
2204	–	if (t == null && (sq = p.findNonEmptyStealQueue(q)) != null &&
2205	–	(b = sq.base) - sq.top < 0)
2206	–	t = sq.pollAt(b);
2207	–	if (t != null)
2208	–	t.doExec();
2209	–	}
2210	–	}
2211	–
2212	–	/**
2072		* Gets and removes a local or stolen task for the given worker.
2073		*
2074		* @return a task, if available
#	Line 2219 | Line 2078 | public class ForkJoinPool extends Abstra
2078		WorkQueue q; int b;
2079		if ((t = w.nextLocalTask()) != null)
2080		return t;
2081	<	if ((q = findNonEmptyStealQueue(w)) == null)
2081	>	if ((q = findNonEmptyStealQueue(w.nextSeed())) == null)
2082		return null;
2083		if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2084		return t;
#	Line 2227 | Line 2086 | public class ForkJoinPool extends Abstra
2086		}
2087
2088		/**
2089	<	* Returns the approximate (non-atomic) number of idle threads per
2090	<	* active thread to offset steal queue size for method
2091	<	* ForkJoinTask.getSurplusQueuedTaskCount().
2092	<	*/
2093	<	final int idlePerActive() {
2094	<	// Approximate at powers of two for small values, saturate past 4
2095	<	int p = parallelism;
2096	<	int a = p + (int)(ctl >> AC_SHIFT);
2097	<	return (a > (p >>>= 1) ? 0 :
2098	<	a > (p >>>= 1) ? 1 :
2099	<	a > (p >>>= 1) ? 2 :
2100	<	a > (p >>>= 1) ? 4 :
2101	<	8);
2102	<	}
2103	<
2104	<	/**
2105	<	* Returns approximate submission queue length for the given caller
2106	<	*/
2107	<	static int getEstimatedSubmitterQueueLength() {
2108	<	ForkJoinPool p; WorkQueue[] ws; WorkQueue q;
2109	<	int k = submitters.get().seed & SQMASK;
2110	<	return ((p = commonPool) != null &&
2111	<	p.runState >= 0 &&
2112	<	(ws = p.workQueues) != null &&
2113	<	ws.length > (k &= p.submitMask) &&
2114	<	(q = ws[k]) != null) ?
2115	<	q.queueSize() : 0;
2089	>	* Returns a cheap heuristic guide for task partitioning when
2090	>	* programmers, frameworks, tools, or languages have little or no
2091	>	* idea about task granularity.  In essence by offering this
2092	>	* method, we ask users only about tradeoffs in overhead vs
2093	>	* expected throughput and its variance, rather than how finely to
2094	>	* partition tasks.
2095	>	*
2096	>	* In a steady state strict (tree-structured) computation, each
2097	>	* thread makes available for stealing enough tasks for other
2098	>	* threads to remain active. Inductively, if all threads play by
2099	>	* the same rules, each thread should make available only a
2100	>	* constant number of tasks.
2101	>	*
2102	>	* The minimum useful constant is just 1. But using a value of 1
2103	>	* would require immediate replenishment upon each steal to
2104	>	* maintain enough tasks, which is infeasible.  Further,
2105	>	* partitionings/granularities of offered tasks should minimize
2106	>	* steal rates, which in general means that threads nearer the top
2107	>	* of computation tree should generate more than those nearer the
2108	>	* bottom. In perfect steady state, each thread is at
2109	>	* approximately the same level of computation tree. However,
2110	>	* producing extra tasks amortizes the uncertainty of progress and
2111	>	* diffusion assumptions.
2112	>	*
2113	>	* So, users will want to use values larger, but not much larger
2114	>	* than 1 to both smooth over transient shortages and hedge
2115	>	* against uneven progress; as traded off against the cost of
2116	>	* extra task overhead. We leave the user to pick a threshold
2117	>	* value to compare with the results of this call to guide
2118	>	* decisions, but recommend values such as 3.
2119	>	*
2120	>	* When all threads are active, it is on average OK to estimate
2121	>	* surplus strictly locally. In steady-state, if one thread is
2122	>	* maintaining say 2 surplus tasks, then so are others. So we can
2123	>	* just use estimated queue length.  However, this strategy alone
2124	>	* leads to serious mis-estimates in some non-steady-state
2125	>	* conditions (ramp-up, ramp-down, other stalls). We can detect
2126	>	* many of these by further considering the number of "idle"
2127	>	* threads, that are known to have zero queued tasks, so
2128	>	* compensate by a factor of (#idle/#active) threads.
2129	>	*
2130	>	* Note: The approximation of #busy workers as #active workers is
2131	>	* not very good under current signalling scheme, and should be
2132	>	* improved.
2133	>	*/
2134	>	static int getSurplusQueuedTaskCount() {
2135	>	Thread t; ForkJoinWorkerThread wt; ForkJoinPool pool; WorkQueue q;
2136	>	if (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)) {
2137	>	int b = (q = (wt = (ForkJoinWorkerThread)t).workQueue).base;
2138	>	int p = (pool = wt.pool).parallelism;
2139	>	int a = (int)(pool.ctl >> AC_SHIFT) + p;
2140	>	return q.top - b - (a > (p >>>= 1) ? 0 :
2141	>	a > (p >>>= 1) ? 1 :
2142	>	a > (p >>>= 1) ? 2 :
2143	>	a > (p >>>= 1) ? 4 :
2144	>	8);
2145	>	}
2146	>	return 0;
2147		}
2148
2149		//  Termination
#	Line 2273 | Line 2163 | public class ForkJoinPool extends Abstra
2163		* @return true if now terminating or terminated
2164		*/
2165		private boolean tryTerminate(boolean now, boolean enable) {
2166	+	if (this == commonPool)                     // cannot shut down
2167	+	return false;
2168		for (long c;;) {
2169		if (((c = ctl) & STOP_BIT) != 0) {      // already terminating
2170		if ((short)(c >>> TC_SHIFT) == -parallelism) {
2171	<	synchronized(this) {
2171	>	synchronized (this) {
2172		notifyAll();                // signal when 0 workers
2173		}
2174		}
2175		return true;
2176		}
2177	<	if (runState >= 0) {                    // not yet enabled
2177	>	if (plock >= 0) {                       // not yet enabled
2178	>	int ps;
2179		if (!enable)
2180		return false;
2181	<	while (!U.compareAndSwapInt(this, MAINLOCK, 0, 1))
2182	<	tryAwaitMainLock();
2183	<	try {
2184	<	runState |= SHUTDOWN;
2185	<	} finally {
2186	<	if (!U.compareAndSwapInt(this, MAINLOCK, 1, 0)) {
2294	<	mainLock = 0;
2295	<	synchronized (this) { notifyAll(); };
2296	<	}
2297	<	}
2181	>	if (((ps = plock) & PL_LOCK) != 0 ||
2182	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
2183	>	ps = acquirePlock();
2184	>	int nps = SHUTDOWN;
2185	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
2186	>	releasePlock(nps);
2187		}
2188		if (!now) {                             // check if idle & no tasks
2189		if ((int)(c >> AC_SHIFT) != -parallelism ||
#	Line 2317 | Line 2206 | public class ForkJoinPool extends Abstra
2206		int n = ws.length;
2207		for (int i = 0; i < n; ++i) {
2208		if ((w = ws[i]) != null) {
2209	<	w.runState = -1;
2209	>	w.qlock = -1;
2210		if (pass > 0) {
2211		w.cancelAll();
2212		if (pass > 1)
#	Line 2336 | Line 2225 | public class ForkJoinPool extends Abstra
2225		if (w.eventCount == (e | INT_SIGN) &&
2226		U.compareAndSwapLong(this, CTL, cc, nc)) {
2227		w.eventCount = (e + E_SEQ) & E_MASK;
2228	<	w.runState = -1;
2228	>	w.qlock = -1;
2229		if ((p = w.parker) != null)
2230		U.unpark(p);
2231		}
#	Line 2347 | Line 2236 | public class ForkJoinPool extends Abstra
2236		}
2237		}
2238
2239	+	// external operations on common pool
2240	+
2241	+	/**
2242	+	* Returns common pool queue for a thread that has submitted at
2243	+	* least one task.
2244	+	*/
2245	+	static WorkQueue commonSubmitterQueue() {
2246	+	ForkJoinPool p; WorkQueue[] ws; int m; Submitter z;
2247	+	return ((z = submitters.get()) != null &&
2248	+	(p = commonPool) != null &&
2249	+	(ws = p.workQueues) != null &&
2250	+	(m = ws.length - 1) >= 0) ?
2251	+	ws[m & z.seed & SQMASK] : null;
2252	+	}
2253	+
2254	+	/**
2255	+	* Tries to pop the given task from submitter's queue in common pool.
2256	+	*/
2257	+	static boolean tryExternalUnpush(ForkJoinTask<?> t) {
2258	+	ForkJoinPool p; WorkQueue[] ws; WorkQueue q; Submitter z;
2259	+	ForkJoinTask<?>[] a;  int m, s; long j;
2260	+	if ((z = submitters.get()) != null &&
2261	+	(p = commonPool) != null &&
2262	+	(ws = p.workQueues) != null &&
2263	+	(m = ws.length - 1) >= 0 &&
2264	+	(q = ws[m & z.seed & SQMASK]) != null &&
2265	+	(s = q.top) != q.base &&
2266	+	(a = q.array) != null &&
2267	+	U.getObjectVolatile
2268	+	(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
2269	+	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2270	+	if (q.array == a && q.top == s && // recheck
2271	+	U.compareAndSwapObject(a, j, t, null)) {
2272	+	q.top = s - 1;
2273	+	q.qlock = 0;
2274	+	return true;
2275	+	}
2276	+	q.qlock = 0;
2277	+	}
2278	+	return false;
2279	+	}
2280	+
2281	+	/**
2282	+	* Tries to pop and run local tasks within the same computation
2283	+	* as the given root. On failure, tries to help complete from
2284	+	* other queues via helpComplete.
2285	+	*/
2286	+	private void externalHelpComplete(WorkQueue q, ForkJoinTask<?> root) {
2287	+	ForkJoinTask<?>[] a; int m;
2288	+	if (q != null && (a = q.array) != null && (m = (a.length - 1)) >= 0 &&
2289	+	root != null && root.status >= 0) {
2290	+	for (;;) {
2291	+	int s; Object o; CountedCompleter<?> task = null;
2292	+	if ((s = q.top) - q.base > 0) {
2293	+	long j = ((m & (s - 1)) << ASHIFT) + ABASE;
2294	+	if ((o = U.getObject(a, j)) != null &&
2295	+	(o instanceof CountedCompleter)) {
2296	+	CountedCompleter<?> t = (CountedCompleter<?>)o, r = t;
2297	+	do {
2298	+	if (r == root) {
2299	+	if (U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2300	+	if (q.array == a && q.top == s &&
2301	+	U.compareAndSwapObject(a, j, t, null)) {
2302	+	q.top = s - 1;
2303	+	task = t;
2304	+	}
2305	+	q.qlock = 0;
2306	+	}
2307	+	break;
2308	+	}
2309	+	} while ((r = r.completer) != null);
2310	+	}
2311	+	}
2312	+	if (task != null)
2313	+	task.doExec();
2314	+	if (root.status < 0 || (int)(ctl >> AC_SHIFT) >= 0)
2315	+	break;
2316	+	if (task == null) {
2317	+	if (helpSignal(root, q.poolIndex) >= 0)
2318	+	helpComplete(root, SHARED_QUEUE);
2319	+	break;
2320	+	}
2321	+	}
2322	+	}
2323	+	}
2324	+
2325	+	/**
2326	+	* Tries to help execute or signal availability of the given task
2327	+	* from submitter's queue in common pool.
2328	+	*/
2329	+	static void externalHelpJoin(ForkJoinTask<?> t) {
2330	+	// Some hard-to-avoid overlap with tryExternalUnpush
2331	+	ForkJoinPool p; WorkQueue[] ws; WorkQueue q, w; Submitter z;
2332	+	ForkJoinTask<?>[] a;  int m, s, n; long j;
2333	+	if (t != null && t.status >= 0 &&
2334	+	(z = submitters.get()) != null &&
2335	+	(p = commonPool) != null &&
2336	+	(ws = p.workQueues) != null &&
2337	+	(m = ws.length - 1) >= 0 &&
2338	+	(q = ws[m & z.seed & SQMASK]) != null &&
2339	+	(a = q.array) != null) {
2340	+	if ((s = q.top) != q.base &&
2341	+	U.getObjectVolatile
2342	+	(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
2343	+	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2344	+	if (q.array == a && q.top == s &&
2345	+	U.compareAndSwapObject(a, j, t, null)) {
2346	+	q.top = s - 1;
2347	+	q.qlock = 0;
2348	+	t.doExec();
2349	+	}
2350	+	else
2351	+	q.qlock = 0;
2352	+	}
2353	+	if (t.status >= 0) {
2354	+	if (t instanceof CountedCompleter)
2355	+	p.externalHelpComplete(q, t);
2356	+	else
2357	+	p.helpSignal(t, q.poolIndex);
2358	+	}
2359	+	}
2360	+	}
2361	+
2362	+	/**
2363	+	* Restricted version of helpQuiescePool for external callers
2364	+	*/
2365	+	static void externalHelpQuiescePool() {
2366	+	ForkJoinPool p; ForkJoinTask<?> t; WorkQueue q; int b;
2367	+	int r = ThreadLocalRandom.current().nextInt();
2368	+	if ((p = commonPool) != null &&
2369	+	(q = p.findNonEmptyStealQueue(r)) != null &&
2370	+	(b = q.base) - q.top < 0 &&
2371	+	(t = q.pollAt(b)) != null)
2372	+	t.doExec();
2373	+	}
2374	+
2375		// Exported methods
2376
2377		// Constructors
#	Line 2424 | Line 2449 | public class ForkJoinPool extends Abstra
2449		this.localMode = asyncMode ? FIFO_QUEUE : LIFO_QUEUE;
2450		long np = (long)(-parallelism); // offset ctl counts
2451		this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
2452	<	// Use nearest power 2 for workQueues size. See Hackers Delight sec 3.2.
2428	<	int n = parallelism - 1;
2429	<	n |= n >>> 1; n |= n >>> 2; n |= n >>> 4; n |= n >>> 8; n |= n >>> 16;
2430	<	this.submitMask = ((n + 1) << 1) - 1;
2431	<	int pn = poolNumberGenerator.incrementAndGet();
2452	>	int pn = nextPoolId();
2453		StringBuilder sb = new StringBuilder("ForkJoinPool-");
2454		sb.append(Integer.toString(pn));
2455		sb.append("-worker-");
2456		this.workerNamePrefix = sb.toString();
2436	–	this.runState = 1;              // set init flag
2457		}
2458
2459		/**
2460		* Constructor for common pool, suitable only for static initialization.
2461		* Basically the same as above, but uses smallest possible initial footprint.
2462		*/
2463	<	ForkJoinPool(int parallelism, int submitMask,
2463	>	ForkJoinPool(int parallelism, long ctl,
2464		ForkJoinWorkerThreadFactory factory,
2465		Thread.UncaughtExceptionHandler handler) {
2466	+	this.parallelism = parallelism;
2467	+	this.ctl = ctl;
2468		this.factory = factory;
2469		this.ueh = handler;
2448	–	this.submitMask = submitMask;
2449	–	this.parallelism = parallelism;
2450	–	long np = (long)(-parallelism);
2451	–	this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
2470		this.localMode = LIFO_QUEUE;
2471		this.workerNamePrefix = "ForkJoinPool.commonPool-worker-";
2454	–	this.runState = 1;
2472		}
2473
2474		/**
#	Line 2460 | Line 2477 | public class ForkJoinPool extends Abstra
2477		* @return the common pool instance
2478		*/
2479		public static ForkJoinPool commonPool() {
2480	<	ForkJoinPool p;
2464	<	if ((p = commonPool) == null)
2465	<	throw new Error("Common Pool Unavailable");
2466	<	return p;
2480	>	return commonPool; // cannot be null (if so, a static init error)
2481		}
2482
2483		// Execution methods
#	Line 2487 | Line 2501 | public class ForkJoinPool extends Abstra
2501		public <T> T invoke(ForkJoinTask<T> task) {
2502		if (task == null)
2503		throw new NullPointerException();
2504	<	doSubmit(task);
2504	>	externalPush(task);
2505		return task.join();
2506		}
2507
#	Line 2502 | Line 2516 | public class ForkJoinPool extends Abstra
2516		public void execute(ForkJoinTask<?> task) {
2517		if (task == null)
2518		throw new NullPointerException();
2519	<	doSubmit(task);
2519	>	externalPush(task);
2520		}
2521
2522		// AbstractExecutorService methods
#	Line 2520 | Line 2534 | public class ForkJoinPool extends Abstra
2534		job = (ForkJoinTask<?>) task;
2535		else
2536		job = new ForkJoinTask.AdaptedRunnableAction(task);
2537	<	doSubmit(job);
2537	>	externalPush(job);
2538		}
2539
2540		/**
#	Line 2535 | Line 2549 | public class ForkJoinPool extends Abstra
2549		public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) {
2550		if (task == null)
2551		throw new NullPointerException();
2552	<	doSubmit(task);
2552	>	externalPush(task);
2553		return task;
2554		}
2555
#	Line 2546 | Line 2560 | public class ForkJoinPool extends Abstra
2560		*/
2561		public <T> ForkJoinTask<T> submit(Callable<T> task) {
2562		ForkJoinTask<T> job = new ForkJoinTask.AdaptedCallable<T>(task);
2563	<	doSubmit(job);
2563	>	externalPush(job);
2564		return job;
2565		}
2566
#	Line 2557 | Line 2571 | public class ForkJoinPool extends Abstra
2571		*/
2572		public <T> ForkJoinTask<T> submit(Runnable task, T result) {
2573		ForkJoinTask<T> job = new ForkJoinTask.AdaptedRunnable<T>(task, result);
2574	<	doSubmit(job);
2574	>	externalPush(job);
2575		return job;
2576		}
2577
#	Line 2574 | Line 2588 | public class ForkJoinPool extends Abstra
2588		job = (ForkJoinTask<?>) task;
2589		else
2590		job = new ForkJoinTask.AdaptedRunnableAction(task);
2591	<	doSubmit(job);
2591	>	externalPush(job);
2592		return job;
2593		}
2594
#	Line 2596 | Line 2610 | public class ForkJoinPool extends Abstra
2610		try {
2611		for (Callable<T> t : tasks) {
2612		ForkJoinTask<T> f = new ForkJoinTask.AdaptedCallable<T>(t);
2613	<	doSubmit(f);
2613	>	externalPush(f);
2614		fs.add(f);
2615		}
2616		for (ForkJoinTask<T> f : fs)
#	Line 2733 | Line 2747 | public class ForkJoinPool extends Abstra
2747		if ((ws = workQueues) != null) {
2748		for (int i = 1; i < ws.length; i += 2) {
2749		if ((w = ws[i]) != null)
2750	<	count += w.totalSteals;
2750	>	count += w.nsteals;
2751		}
2752		}
2753		return count;
#	Line 2790 | Line 2804 | public class ForkJoinPool extends Abstra
2804		WorkQueue[] ws; WorkQueue w;
2805		if ((ws = workQueues) != null) {
2806		for (int i = 0; i < ws.length; i += 2) {
2807	<	if ((w = ws[i]) != null && !w.isEmpty())
2807	>	if ((w = ws[i]) != null && w.queueSize() != 0)
2808		return true;
2809		}
2810		}
#	Line 2869 | Line 2883 | public class ForkJoinPool extends Abstra
2883		qs += size;
2884		else {
2885		qt += size;
2886	<	st += w.totalSteals;
2886	>	st += w.nsteals;
2887		if (w.isApparentlyUnblocked())
2888		++rc;
2889		}
#	Line 2885 | Line 2899 | public class ForkJoinPool extends Abstra
2899		if ((c & STOP_BIT) != 0)
2900		level = (tc == 0) ? "Terminated" : "Terminating";
2901		else
2902	<	level = runState < 0 ? "Shutting down" : "Running";
2902	>	level = plock < 0 ? "Shutting down" : "Running";
2903		return super.toString() +
2904		"[" + level +
2905		", parallelism = " + pc +
#	Line 2914 | Line 2928 | public class ForkJoinPool extends Abstra
2928		*/
2929		public void shutdown() {
2930		checkPermission();
2931	<	if (this != commonPool)
2918	<	tryTerminate(false, true);
2931	>	tryTerminate(false, true);
2932		}
2933
2934		/**
#	Line 2938 | Line 2951 | public class ForkJoinPool extends Abstra
2951		*/
2952		public List<Runnable> shutdownNow() {
2953		checkPermission();
2954	<	if (this != commonPool)
2942	<	tryTerminate(true, true);
2954	>	tryTerminate(true, true);
2955		return Collections.emptyList();
2956		}
2957
#	Line 2979 | Line 2991 | public class ForkJoinPool extends Abstra
2991		* @return {@code true} if this pool has been shut down
2992		*/
2993		public boolean isShutdown() {
2994	<	return runState < 0;
2994	>	return plock < 0;
2995		}
2996
2997		/**
2998	<	* Blocks until all tasks have completed execution after a shutdown
2999	<	* request, or the timeout occurs, or the current thread is
3000	<	* interrupted, whichever happens first.
2998	>	* Blocks until all tasks have completed execution after a
2999	>	* shutdown request, or the timeout occurs, or the current thread
3000	>	* is interrupted, whichever happens first. Note that the {@link
3001	>	* #commonPool()} never terminates until program shutdown so
3002	>	* this method will always time out.
3003		*
3004		* @param timeout the maximum time to wait
3005		* @param unit the time unit of the timeout argument
#	Line 3000 | Line 3014 | public class ForkJoinPool extends Abstra
3014		return true;
3015		long startTime = System.nanoTime();
3016		boolean terminated = false;
3017	<	synchronized(this) {
3017	>	synchronized (this) {
3018		for (long waitTime = nanos, millis = 0L;;) {
3019		if (terminated = isTerminated() ||
3020		waitTime <= 0L ||
#	Line 3109 | Line 3123 | public class ForkJoinPool extends Abstra
3123		public static void managedBlock(ManagedBlocker blocker)
3124		throws InterruptedException {
3125		Thread t = Thread.currentThread();
3126	<	ForkJoinPool p = ((t instanceof ForkJoinWorkerThread) ?
3127	<	((ForkJoinWorkerThread)t).pool : null);
3128	<	while (!blocker.isReleasable()) {
3129	<	if (p == null || p.tryCompensate(null, blocker)) {
3130	<	try {
3131	<	do {} while (!blocker.isReleasable() && !blocker.block());
3132	<	} finally {
3133	<	if (p != null)
3126	>	if (t instanceof ForkJoinWorkerThread) {
3127	>	ForkJoinPool p = ((ForkJoinWorkerThread)t).pool;
3128	>	while (!blocker.isReleasable()) { // variant of helpSignal
3129	>	WorkQueue[] ws; WorkQueue q; int m, n;
3130	>	if ((ws = p.workQueues) != null && (m = ws.length - 1) >= 0) {
3131	>	for (int i = 0; i <= m; ++i) {
3132	>	if (blocker.isReleasable())
3133	>	return;
3134	>	if ((q = ws[i]) != null && (n = q.queueSize()) > 0) {
3135	>	p.signalWork(q, n);
3136	>	if ((int)(p.ctl >> AC_SHIFT) >= 0)
3137	>	break;
3138	>	}
3139	>	}
3140	>	}
3141	>	if (p.tryCompensate()) {
3142	>	try {
3143	>	do {} while (!blocker.isReleasable() &&
3144	>	!blocker.block());
3145	>	} finally {
3146		p.incrementActiveCount();
3147	+	}
3148	+	break;
3149		}
3122	–	break;
3150		}
3151		}
3152	+	else {
3153	+	do {} while (!blocker.isReleasable() &&
3154	+	!blocker.block());
3155	+	}
3156		}
3157
3158		// AbstractExecutorService overrides.  These rely on undocumented
#	Line 3142 | Line 3173 | public class ForkJoinPool extends Abstra
3173		private static final long PARKBLOCKER;
3174		private static final int ABASE;
3175		private static final int ASHIFT;
3145	–	private static final long NEXTWORKERNUMBER;
3176		private static final long STEALCOUNT;
3177	<	private static final long MAINLOCK;
3177	>	private static final long PLOCK;
3178	>	private static final long INDEXSEED;
3179	>	private static final long QLOCK;
3180
3181		static {
3182	<	poolNumberGenerator = new AtomicInteger();
3183	<	nextSubmitterSeed = new AtomicInteger(0x55555555);
3184	<	modifyThreadPermission = new RuntimePermission("modifyThread");
3185	<	defaultForkJoinWorkerThreadFactory =
3186	<	new DefaultForkJoinWorkerThreadFactory();
3187	<	submitters = new ThreadSubmitter();
3188	<	int s;
3182	>	// Establish common pool parameters
3183	>	// TBD: limit or report ignored exceptions?
3184	>
3185	>	int par = 0;
3186	>	ForkJoinWorkerThreadFactory fac = null;
3187	>	Thread.UncaughtExceptionHandler handler = null;
3188	>	try {
3189	>	String pp = System.getProperty(propPrefix + "parallelism");
3190	>	String hp = System.getProperty(propPrefix + "exceptionHandler");
3191	>	String fp = System.getProperty(propPrefix + "threadFactory");
3192	>	if (fp != null)
3193	>	fac = ((ForkJoinWorkerThreadFactory)ClassLoader.
3194	>	getSystemClassLoader().loadClass(fp).newInstance());
3195	>	if (hp != null)
3196	>	handler = ((Thread.UncaughtExceptionHandler)ClassLoader.
3197	>	getSystemClassLoader().loadClass(hp).newInstance());
3198	>	if (pp != null)
3199	>	par = Integer.parseInt(pp);
3200	>	} catch (Exception ignore) {
3201	>	}
3202	>
3203	>	int s; // initialize field offsets for CAS etc
3204		try {
3205		U = getUnsafe();
3206		Class<?> k = ForkJoinPool.class;
3160	–	Class<?> ak = ForkJoinTask[].class;
3207		CTL = U.objectFieldOffset
3208		(k.getDeclaredField("ctl"));
3163	–	NEXTWORKERNUMBER = U.objectFieldOffset
3164	–	(k.getDeclaredField("nextWorkerNumber"));
3209		STEALCOUNT = U.objectFieldOffset
3210		(k.getDeclaredField("stealCount"));
3211	<	MAINLOCK = U.objectFieldOffset
3212	<	(k.getDeclaredField("mainLock"));
3211	>	PLOCK = U.objectFieldOffset
3212	>	(k.getDeclaredField("plock"));
3213	>	INDEXSEED = U.objectFieldOffset
3214	>	(k.getDeclaredField("indexSeed"));
3215		Class<?> tk = Thread.class;
3216		PARKBLOCKER = U.objectFieldOffset
3217		(tk.getDeclaredField("parkBlocker"));
3218	+	Class<?> wk = WorkQueue.class;
3219	+	QLOCK = U.objectFieldOffset
3220	+	(wk.getDeclaredField("qlock"));
3221	+	Class<?> ak = ForkJoinTask[].class;
3222		ABASE = U.arrayBaseOffset(ak);
3223		s = U.arrayIndexScale(ak);
3224		ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
#	Line 3177 | Line 3227 | public class ForkJoinPool extends Abstra
3227		}
3228		if ((s & (s-1)) != 0)
3229		throw new Error("data type scale not a power of two");
3230	<	try { // Establish common pool
3231	<	String pp = System.getProperty(propPrefix + "parallelism");
3232	<	String fp = System.getProperty(propPrefix + "threadFactory");
3233	<	String up = System.getProperty(propPrefix + "exceptionHandler");
3234	<	ForkJoinWorkerThreadFactory fac = (fp == null) ?
3235	<	defaultForkJoinWorkerThreadFactory :
3236	<	((ForkJoinWorkerThreadFactory)ClassLoader.
3237	<	getSystemClassLoader().loadClass(fp).newInstance());
3238	<	Thread.UncaughtExceptionHandler ueh = (up == null)? null :
3239	<	((Thread.UncaughtExceptionHandler)ClassLoader.
3240	<	getSystemClassLoader().loadClass(up).newInstance());
3241	<	int par;
3242	<	if ((pp == null || (par = Integer.parseInt(pp)) <= 0))
3243	<	par = Runtime.getRuntime().availableProcessors();
3244	<	if (par > MAX_CAP)
3245	<	par = MAX_CAP;
3246	<	commonPoolParallelism = par;
3247	<	int n = par - 1; // precompute submit mask
3248	<	n |= n >>> 1; n |= n >>> 2; n |= n >>> 4;
3249	<	n |= n >>> 8; n |= n >>> 16;
3250	<	int mask = ((n + 1) << 1) - 1;
3201	<	commonPool = new ForkJoinPool(par, mask, fac, ueh);
3202	<	} catch (Exception e) {
3203	<	throw new Error(e);
3204	<	}
3230	>
3231	>	/*
3232	>	* For extra caution, computations to set up pool state are
3233	>	* here; the constructor just assigns these values to fields.
3234	>	*/
3235	>	ForkJoinWorkerThreadFactory defaultFac =
3236	>	defaultForkJoinWorkerThreadFactory =
3237	>	new DefaultForkJoinWorkerThreadFactory();
3238	>	if (fac == null)
3239	>	fac = defaultFac;
3240	>	if (par <= 0)
3241	>	par = Runtime.getRuntime().availableProcessors();
3242	>	if (par > MAX_CAP)
3243	>	par = MAX_CAP;
3244	>	long np = (long)(-par); // precompute initial ctl value
3245	>	long ct = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
3246	>
3247	>	commonPoolParallelism = par;
3248	>	commonPool = new ForkJoinPool(par, ct, fac, handler);
3249	>	modifyThreadPermission = new RuntimePermission("modifyThread");
3250	>	submitters = new ThreadLocal<Submitter>();
3251		}
3252
3253		/**

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