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

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.145 by jsr166, Mon Nov 19 01:04:24 2012 UTC vs.
Revision 1.189 by jsr166, Sat Sep 12 19:16:45 2015 UTC

#	Line 37 | Line 37 | import java.util.concurrent.TimeUnit;
37		* ForkJoinPool}s may also be appropriate for use with event-style
38		* tasks that are never joined.
39		*
40	<	* <p>A static {@link #commonPool} is available and appropriate for
40	>	* <p>A static {@link #commonPool()} is available and appropriate for
41		* most applications. The common pool is used by any ForkJoinTask that
42		* is not explicitly submitted to a specified pool. Using the common
43		* pool normally reduces resource usage (its threads are slowly
#	Line 51 | Line 51 | import java.util.concurrent.TimeUnit;
51		* dynamically adding, suspending, or resuming internal worker
52		* threads, even if some tasks are stalled waiting to join
53		* others. However, no such adjustments are guaranteed in the face of
54	<	* blocked IO or other unmanaged synchronization. The nested {@link
54	>	* blocked I/O or other unmanaged synchronization. The nested {@link
55		* ManagedBlocker} interface enables extension of the kinds of
56		* synchronization accommodated.
57		*
#	Line 99 | Line 99 | import java.util.concurrent.TimeUnit;
99		*
100		* <p>The common pool is by default constructed with default
101		* parameters, but these may be controlled by setting three {@link
102	<	* System#getProperty properties} with prefix {@code
102	>	* System#getProperty system properties} with prefix {@code
103		* java.util.concurrent.ForkJoinPool.common}: {@code parallelism} --
104		* an integer greater than zero, {@code threadFactory} -- the class
105		* name of a {@link ForkJoinWorkerThreadFactory}, and {@code
#	Line 239 | Line 239 | public class ForkJoinPool extends Abstra
239		* enable shutdown.  When used as a lock, it is normally only very
240		* briefly held, so is nearly always available after at most a
241		* brief spin, but we use a monitor-based backup strategy to
242	<	* blocking when needed.
242	>	* block when needed.
243		*
244		* Recording WorkQueues.  WorkQueues are recorded in the
245		* "workQueues" array that is created upon first use and expanded
#	Line 248 | Line 248 | public class ForkJoinPool extends Abstra
248		* by a lock but the array is otherwise concurrently readable, and
249		* accessed directly.  To simplify index-based operations, the
250		* array size is always a power of two, and all readers must
251	<	* tolerate null slots. Worker queues are at odd indices Shared
251	>	* tolerate null slots. Worker queues are at odd indices. Shared
252		* (submission) queues are at even indices, up to a maximum of 64
253		* slots, to limit growth even if array needs to expand to add
254		* more workers. Grouping them together in this way simplifies and
#	Line 316 | Line 316 | public class ForkJoinPool extends Abstra
316		* execute. However, many other threads may notice the same task
317		* and each signal to wake up a thread that might take it. So in
318		* general, pools will be over-signalled.  When a submission is
319	<	* added or another worker adds a task to a queue that is
320	<	* apparently empty, they signal waiting workers (or trigger
319	>	* added or another worker adds a task to a queue that has fewer
320	>	* than two tasks, they signal waiting workers (or trigger
321		* creation of new ones if fewer than the given parallelism level
322	<	* -- see signalWork).  These primary signals are buttressed by
323	<	* signals whenever other threads scan for work or do not have a
324	<	* task to process. On most platforms, signalling (unpark)
325	<	* overhead time is noticeably long, and the time between
326	<	* signalling a thread and it actually making progress can be very
327	<	* noticeably long, so it is worth offloading these delays from
328	<	* critical paths as much as possible.
322	>	* -- signalWork), and may leave a hint to the unparked worker to
323	>	* help signal others upon wakeup).  These primary signals are
324	>	* buttressed by others (see method helpSignal) whenever other
325	>	* threads scan for work or do not have a task to process.  On
326	>	* most platforms, signalling (unpark) overhead time is noticeably
327	>	* long, and the time between signalling a thread and it actually
328	>	* making progress can be very noticeably long, so it is worth
329	>	* offloading these delays from critical paths as much as
330	>	* possible.
331		*
332		* Trimming workers. To release resources after periods of lack of
333		* use, a worker starting to wait when the pool is quiescent will
#	Line 393 | Line 395 | public class ForkJoinPool extends Abstra
395		* steals, rather than use per-task bookkeeping.  This sometimes
396		* requires a linear scan of workQueues array to locate stealers,
397		* but often doesn't because stealers leave hints (that may become
398	<	* stale/wrong) of where to locate them.  A stealHint is only a
399	<	* hint because a worker might have had multiple steals and the
400	<	* hint records only one of them (usually the most current).
401	<	* Hinting isolates cost to when it is needed, rather than adding
402	<	* to per-task overhead.  (2) It is "shallow", ignoring nesting
403	<	* and potentially cyclic mutual steals.  (3) It is intentionally
398	>	* stale/wrong) of where to locate them.  It is only a hint
399	>	* because a worker might have had multiple steals and the hint
400	>	* records only one of them (usually the most current).  Hinting
401	>	* isolates cost to when it is needed, rather than adding to
402	>	* per-task overhead.  (2) It is "shallow", ignoring nesting and
403	>	* potentially cyclic mutual steals.  (3) It is intentionally
404		* racy: field currentJoin is updated only while actively joining,
405		* which means that we miss links in the chain during long-lived
406		* tasks, GC stalls etc (which is OK since blocking in such cases
#	Line 438 | Line 440 | public class ForkJoinPool extends Abstra
440		* Common Pool
441		* ===========
442		*
443	<	* The static commonPool always exists after static
443	>	* The static common Pool always exists after static
444		* initialization.  Since it (or any other created pool) need
445		* never be used, we minimize initial construction overhead and
446		* footprint to the setup of about a dozen fields, with no nested
#	Line 525 | Line 527 | public class ForkJoinPool extends Abstra
527		* Default ForkJoinWorkerThreadFactory implementation; creates a
528		* new ForkJoinWorkerThread.
529		*/
530	<	static class DefaultForkJoinWorkerThreadFactory
530	>	static final class DefaultForkJoinWorkerThreadFactory
531		implements ForkJoinWorkerThreadFactory {
532	<	public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
532	>	public final ForkJoinWorkerThread newThread(ForkJoinPool pool) {
533		return new ForkJoinWorkerThread(pool);
534		}
535		}
536
537		/**
538	+	* Per-thread records for threads that submit to pools. Currently
539	+	* holds only pseudo-random seed / index that is used to choose
540	+	* submission queues in method externalPush. In the future, this may
541	+	* also incorporate a means to implement different task rejection
542	+	* and resubmission policies.
543	+	*
544	+	* Seeds for submitters and workers/workQueues work in basically
545	+	* the same way but are initialized and updated using slightly
546	+	* different mechanics. Both are initialized using the same
547	+	* approach as in class ThreadLocal, where successive values are
548	+	* unlikely to collide with previous values. Seeds are then
549	+	* randomly modified upon collisions using xorshifts, which
550	+	* requires a non-zero seed.
551	+	*/
552	+	static final class Submitter {
553	+	int seed;
554	+	Submitter(int s) { seed = s; }
555	+	}
556	+
557	+	/**
558		* Class for artificial tasks that are used to replace the target
559		* of local joins if they are removed from an interior queue slot
560		* in WorkQueue.tryRemoveAndExec. We don't need the proxy to
#	Line 598 | Line 620 | public class ForkJoinPool extends Abstra
620		* trades off slightly slower average field access for the sake of
621		* avoiding really bad worst-case access. (Until better JVM
622		* support is in place, this padding is dependent on transient
623	<	* properties of JVM field layout rules.)  We also take care in
623	>	* properties of JVM field layout rules.) We also take care in
624		* allocating, sizing and resizing the array. Non-shared queue
625		* arrays are initialized by workers before use. Others are
626		* allocated on first use.
#	Line 624 | Line 646 | public class ForkJoinPool extends Abstra
646		*/
647		static final int MAXIMUM_QUEUE_CAPACITY = 1 << 26; // 64M
648
649	+	// Heuristic padding to ameliorate unfortunate memory placements
650	+	volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
651	+
652		int seed;                  // for random scanning; initialize nonzero
653		volatile int eventCount;   // encoded inactivation count; < 0 if inactive
654		int nextWait;              // encoded record of next event waiter
655	<	final int mode;            // lifo, fifo, or shared
631	<	int nsteals;               // cumulative number of steals
655	>	int hint;                  // steal or signal hint (index)
656		int poolIndex;             // index of this queue in pool (or 0)
657	<	int stealHint;             // index of most recent known stealer
657	>	final int mode;            // 0: lifo, > 0: fifo, < 0: shared
658	>	int nsteals;               // number of steals
659		volatile int qlock;        // 1: locked, -1: terminate; else 0
660		volatile int base;         // index of next slot for poll
661		int top;                   // index of next slot for push
#	Line 640 | Line 665 | public class ForkJoinPool extends Abstra
665		volatile Thread parker;    // == owner during call to park; else null
666		volatile ForkJoinTask<?> currentJoin;  // task being joined in awaitJoin
667		ForkJoinTask<?> currentSteal; // current non-local task being executed
643	–	// Heuristic padding to ameliorate unfortunate memory placements
644	–	Object p00, p01, p02, p03, p04, p05, p06, p07;
645	–	Object p08, p09, p0a, p0b, p0c, p0d, p0e;
668
669	<	WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode) {
670	<	this.mode = mode;
669	>	volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17;
670	>	volatile Object pad18, pad19, pad1a, pad1b, pad1c, pad1d;
671	>
672	>	WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode,
673	>	int seed) {
674		this.pool = pool;
675		this.owner = owner;
676	+	this.mode = mode;
677	+	this.seed = seed;
678		// Place indices in the center of array (that is not yet allocated)
679		base = top = INITIAL_QUEUE_CAPACITY >>> 1;
680		}
681
682		/**
683	<	* Pushes a task. Call only by owner in unshared queues.
657	<	* Cases needing resizing or rejection are relayed to fullPush
658	<	* (that also handles shared queues).
659	<	*
660	<	* @param task the task. Caller must ensure non-null.
661	<	* @throw RejectedExecutionException if array cannot be resized
683	>	* Returns the approximate number of tasks in the queue.
684		*/
685	<	final void push(ForkJoinTask<?> task) {
686	<	ForkJoinPool p; ForkJoinTask<?>[] a;
687	<	int s = top, n;
688	<	if ((a = array) != null && a.length > (n = s + 1 - base)) {
689	<	U.putOrderedObject
690	<	(a, (((a.length - 1) & s) << ASHIFT) + ABASE, task);
691	<	top = s + 1;
692	<	if (n <= 1 && (p = pool) != null)
693	<	p.signalWork(this, 1);
694	<	}
695	<	else
696	<	fullPush(task, true);
685	>	final int queueSize() {
686	>	int n = base - top;       // non-owner callers must read base first
687	>	return (n >= 0) ? 0 : -n; // ignore transient negative
688	>	}
689	>
690	>	/**
691	>	* Provides a more accurate estimate of whether this queue has
692	>	* any tasks than does queueSize, by checking whether a
693	>	* near-empty queue has at least one unclaimed task.
694	>	*/
695	>	final boolean isEmpty() {
696	>	ForkJoinTask<?>[] a; int m, s;
697	>	int n = base - (s = top);
698	>	return (n >= 0 ||
699	>	(n == -1 &&
700	>	((a = array) == null ||
701	>	(m = a.length - 1) < 0 ||
702	>	U.getObject
703	>	(a, (long)((m & (s - 1)) << ASHIFT) + ABASE) == null)));
704		}
705
706		/**
707	<	* Pushes a task if lock is free and array is either big
708	<	* enough or can be resized to be big enough. Note: a
680	<	* specialization of a common fast path of this method is in
681	<	* ForkJoinPool.externalPush. When called from a FJWT queue,
682	<	* this can fail only if the pool has been shut down or
683	<	* an out of memory error.
707	>	* Pushes a task. Call only by owner in unshared queues.  (The
708	>	* shared-queue version is embedded in method externalPush.)
709		*
710		* @param task the task. Caller must ensure non-null.
711	<	* @param owned if true, throw RJE on failure
711	>	* @throws RejectedExecutionException if array cannot be resized
712		*/
713	<	final boolean fullPush(ForkJoinTask<?> task, boolean owned) {
714	<	ForkJoinPool p; ForkJoinTask<?>[] a;
715	<	if (owned) {
716	<	if (qlock < 0) // must be shutting down
717	<	throw new RejectedExecutionException();
718	<	}
719	<	else if (!U.compareAndSwapInt(this, QLOCK, 0, 1))
720	<	return false;
721	<	try {
697	<	int s = top, oldLen, len;
698	<	if ((a = array) == null)
699	<	a = array = new ForkJoinTask<?>[len=INITIAL_QUEUE_CAPACITY];
700	<	else if ((oldLen = a.length) > s + 1 - base)
701	<	len = oldLen;
702	<	else if ((len = oldLen << 1) > MAXIMUM_QUEUE_CAPACITY)
703	<	throw new RejectedExecutionException("Capacity exceeded");
704	<	else {
705	<	int oldMask, b;
706	<	ForkJoinTask<?>[] oldA = a;
707	<	a = array = new ForkJoinTask<?>[len];
708	<	if ((oldMask = oldLen - 1) >= 0 && s - (b = base) > 0) {
709	<	int mask = len - 1;
710	<	do {
711	<	ForkJoinTask<?> x;
712	<	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
713	<	int j    = ((b &    mask) << ASHIFT) + ABASE;
714	<	x = (ForkJoinTask<?>)
715	<	U.getObjectVolatile(oldA, oldj);
716	<	if (x != null &&
717	<	U.compareAndSwapObject(oldA, oldj, x, null))
718	<	U.putObjectVolatile(a, j, x);
719	<	} while (++b != s);
720	<	}
713	>	final void push(ForkJoinTask<?> task) {
714	>	ForkJoinTask<?>[] a; ForkJoinPool p;
715	>	int s = top, m, n;
716	>	if ((a = array) != null) {    // ignore if queue removed
717	>	int j = (((m = a.length - 1) & s) << ASHIFT) + ABASE;
718	>	U.putOrderedObject(a, j, task);
719	>	if ((n = (top = s + 1) - base) <= 2) {
720	>	if ((p = pool) != null)
721	>	p.signalWork(this);
722		}
723	<	U.putOrderedObject
724	<	(a, (((len - 1) & s) << ASHIFT) + ABASE, task);
724	<	top = s + 1;
725	<	} finally {
726	<	if (!owned)
727	<	qlock = 0;
723	>	else if (n >= m)
724	>	growArray();
725		}
726	<	if ((p = pool) != null)
727	<	p.signalWork(this, 1);
728	<	return true;
726	>	}
727	>
728	>	/**
729	>	* Initializes or doubles the capacity of array. Call either
730	>	* by owner or with lock held -- it is OK for base, but not
731	>	* top, to move while resizings are in progress.
732	>	*/
733	>	final ForkJoinTask<?>[] growArray() {
734	>	ForkJoinTask<?>[] oldA = array;
735	>	int size = oldA != null ? oldA.length << 1 : INITIAL_QUEUE_CAPACITY;
736	>	if (size > MAXIMUM_QUEUE_CAPACITY)
737	>	throw new RejectedExecutionException("Queue capacity exceeded");
738	>	int oldMask, t, b;
739	>	ForkJoinTask<?>[] a = array = new ForkJoinTask<?>[size];
740	>	if (oldA != null && (oldMask = oldA.length - 1) >= 0 &&
741	>	(t = top) - (b = base) > 0) {
742	>	int mask = size - 1;
743	>	do {
744	>	ForkJoinTask<?> x;
745	>	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
746	>	int j    = ((b &    mask) << ASHIFT) + ABASE;
747	>	x = (ForkJoinTask<?>)U.getObjectVolatile(oldA, oldj);
748	>	if (x != null &&
749	>	U.compareAndSwapObject(oldA, oldj, x, null))
750	>	U.putObjectVolatile(a, j, x);
751	>	} while (++b != t);
752	>	}
753	>	return a;
754		}
755
756		/**
#	Line 852 | Line 874 | public class ForkJoinPool extends Abstra
874		return seed = r ^= r << 5;
875		}
876
855	–	/**
856	–	* Provides a more accurate estimate of size than (top - base)
857	–	* by ordering reads and checking whether a near-empty queue
858	–	* has at least one unclaimed task.
859	–	*/
860	–	final int queueSize() {
861	–	ForkJoinTask<?>[] a; int k, s, n;
862	–	return ((n = base - (s = top)) < 0 &&
863	–	(n != -1 ||
864	–	((a = array) != null && (k = a.length) > 0 &&
865	–	U.getObject
866	–	(a, (long)((((k - 1) & (s - 1)) << ASHIFT) + ABASE)) != null))) ?
867	–	-n : 0;
868	–	}
869	–
877		// Specialized execution methods
878
879		/**
#	Line 900 | Line 907 | public class ForkJoinPool extends Abstra
907		* or any other cancelled task. Returns (true) on any CAS
908		* or consistency check failure so caller can retry.
909		*
910	<	* @return false if no progress can be made, else true;
910	>	* @return false if no progress can be made, else true
911		*/
912		final boolean tryRemoveAndExec(ForkJoinTask<?> task) {
913		boolean stat = true, removed = false, empty = true;
#	Line 945 | Line 952 | public class ForkJoinPool extends Abstra
952
953		/**
954		* Polls for and executes the given task or any other task in
955	<	* its CountedCompleter computation
955	>	* its CountedCompleter computation.
956		*/
957		final boolean pollAndExecCC(ForkJoinTask<?> root) {
958		ForkJoinTask<?>[] a; int b; Object o;
#	Line 980 | Line 987 | public class ForkJoinPool extends Abstra
987		if (t != null) {
988		(currentSteal = t).doExec();
989		currentSteal = null;
990	<	if (++nsteals < 0) {     // spill on overflow
991	<	ForkJoinPool p;
985	<	if ((p = pool) != null)
986	<	p.collectStealCount(this);
987	<	}
988	<	if (top != base) {       // process remaining local tasks
990	>	++nsteals;
991	>	if (base - top < 0) {       // process remaining local tasks
992		if (mode == 0)
993		popAndExecAll();
994		else
#	Line 1017 | Line 1020 | public class ForkJoinPool extends Abstra
1020		s != Thread.State.TIMED_WAITING);
1021		}
1022
1020	–	/**
1021	–	* If this owned and is not already interrupted, try to
1022	–	* interrupt and/or unpark, ignoring exceptions.
1023	–	*/
1024	–	final void interruptOwner() {
1025	–	Thread wt, p;
1026	–	if ((wt = owner) != null && !wt.isInterrupted()) {
1027	–	try {
1028	–	wt.interrupt();
1029	–	} catch (SecurityException ignore) {
1030	–	}
1031	–	}
1032	–	if ((p = parker) != null)
1033	–	U.unpark(p);
1034	–	}
1035	–
1023		// Unsafe mechanics
1024		private static final sun.misc.Unsafe U;
1025		private static final long QLOCK;
1026		private static final int ABASE;
1027		private static final int ASHIFT;
1028		static {
1042	–	int s;
1029		try {
1030		U = getUnsafe();
1031		Class<?> k = WorkQueue.class;
#	Line 1047 | Line 1033 | public class ForkJoinPool extends Abstra
1033		QLOCK = U.objectFieldOffset
1034		(k.getDeclaredField("qlock"));
1035		ABASE = U.arrayBaseOffset(ak);
1036	<	s = U.arrayIndexScale(ak);
1036	>	int scale = U.arrayIndexScale(ak);
1037	>	if ((scale & (scale - 1)) != 0)
1038	>	throw new Error("data type scale not a power of two");
1039	>	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
1040		} catch (Exception e) {
1041		throw new Error(e);
1042		}
1054	–	if ((s & (s-1)) != 0)
1055	–	throw new Error("data type scale not a power of two");
1056	–	ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
1043		}
1044		}
1045
1060	–	/**
1061	–	* Per-thread records for threads that submit to pools. Currently
1062	–	* holds only pseudo-random seed / index that is used to choose
1063	–	* submission queues in method externalPush. In the future, this may
1064	–	* also incorporate a means to implement different task rejection
1065	–	* and resubmission policies.
1066	–	*
1067	–	* Seeds for submitters and workers/workQueues work in basically
1068	–	* the same way but are initialized and updated using slightly
1069	–	* different mechanics. Both are initialized using the same
1070	–	* approach as in class ThreadLocal, where successive values are
1071	–	* unlikely to collide with previous values. Seeds are then
1072	–	* randomly modified upon collisions using xorshifts, which
1073	–	* requires a non-zero seed.
1074	–	*/
1075	–	static final class Submitter {
1076	–	int seed;
1077	–	Submitter(int s) { seed = s; }
1078	–	}
1079	–
1080	–	/** Property prefix for constructing common pool */
1081	–	private static final String propPrefix =
1082	–	"java.util.concurrent.ForkJoinPool.common.";
1083	–
1046		// static fields (initialized in static initializer below)
1047
1048		/**
#	Line 1091 | Line 1053 | public class ForkJoinPool extends Abstra
1053		defaultForkJoinWorkerThreadFactory;
1054
1055		/**
1056	<	* Common (static) pool. Non-null for public use unless a static
1057	<	* construction exception, but internal usages null-check on use
1058	<	* to paranoically avoid potential initialization circularities
1059	<	* as well as to simplify generated code.
1056	>	* Per-thread submission bookkeeping. Shared across all pools
1057	>	* to reduce ThreadLocal pollution and because random motion
1058	>	* to avoid contention in one pool is likely to hold for others.
1059	>	* Lazily initialized on first submission (but null-checked
1060	>	* in other contexts to avoid unnecessary initialization).
1061		*/
1062	<	static final ForkJoinPool commonPool;
1062	>	static final ThreadLocal<Submitter> submitters;
1063
1064		/**
1065		* Permission required for callers of methods that may start or
#	Line 1105 | Line 1068 | public class ForkJoinPool extends Abstra
1068		private static final RuntimePermission modifyThreadPermission;
1069
1070		/**
1071	<	* Per-thread submission bookkeeping. Shared across all pools
1072	<	* to reduce ThreadLocal pollution and because random motion
1073	<	* to avoid contention in one pool is likely to hold for others.
1074	<	* Lazily initialized on first submission (but null-checked
1112	<	* in other contexts to avoid unnecessary initialization).
1071	>	* Common (static) pool. Non-null for public use unless a static
1072	>	* construction exception, but internal usages null-check on use
1073	>	* to paranoically avoid potential initialization circularities
1074	>	* as well as to simplify generated code.
1075		*/
1076	<	static final ThreadLocal<Submitter> submitters;
1076	>	static final ForkJoinPool common;
1077
1078		/**
1079	<	* Common pool parallelism. Must equal commonPool.parallelism.
1079	>	* Common pool parallelism. Must equal common.parallelism.
1080		*/
1081	<	static final int commonPoolParallelism;
1081	>	static final int commonParallelism;
1082
1083		/**
1084		* Sequence number for creating workerNamePrefix.
#	Line 1124 | Line 1086 | public class ForkJoinPool extends Abstra
1086		private static int poolNumberSequence;
1087
1088		/**
1089	<	* Return the next sequence number. We don't expect this to
1090	<	* ever contend so use simple builtin sync.
1089	>	* Returns the next sequence number. We don't expect this to
1090	>	* ever contend, so use simple builtin sync.
1091		*/
1092		private static final synchronized int nextPoolId() {
1093		return ++poolNumberSequence;
#	Line 1149 | Line 1111 | public class ForkJoinPool extends Abstra
1111		private static final long FAST_IDLE_TIMEOUT =  200L * 1000L * 1000L;
1112
1113		/**
1114	+	* Tolerance for idle timeouts, to cope with timer undershoots
1115	+	*/
1116	+	private static final long TIMEOUT_SLOP = 2000000L;
1117	+
1118	+	/**
1119		* The maximum stolen->joining link depth allowed in method
1120		* tryHelpStealer.  Must be a power of two.  Depths for legitimate
1121		* chains are unbounded, but we use a fixed constant to avoid
#	Line 1164 | Line 1131 | public class ForkJoinPool extends Abstra
1131		*/
1132		private static final int SEED_INCREMENT = 0x61c88647;
1133
1134	<	/**
1134	>	/*
1135		* Bits and masks for control variables
1136		*
1137		* Field ctl is a long packed with:
#	Line 1248 | Line 1215 | public class ForkJoinPool extends Abstra
1215		static final int FIFO_QUEUE          =  1;
1216		static final int SHARED_QUEUE        = -1;
1217
1218	+	// bounds for #steps in scan loop -- must be power 2 minus 1
1219	+	private static final int MIN_SCAN    = 0x1ff;   // cover estimation slop
1220	+	private static final int MAX_SCAN    = 0x1ffff; // 4 * max workers
1221	+
1222		// Instance fields
1223
1224		/*
1225	<	* Field layout order in this class tends to matter more than one
1226	<	* would like. Runtime layout order is only loosely related to
1225	>	* Field layout of this class tends to matter more than one would
1226	>	* like. Runtime layout order is only loosely related to
1227		* declaration order and may differ across JVMs, but the following
1228		* empirically works OK on current JVMs.
1229		*/
1230	+
1231	+	// Heuristic padding to ameliorate unfortunate memory placements
1232	+	volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
1233	+
1234		volatile long stealCount;                  // collects worker counts
1235		volatile long ctl;                         // main pool control
1261	–	final int parallelism;                     // parallelism level
1262	–	final int localMode;                       // per-worker scheduling mode
1263	–	volatile int indexSeed;                    // worker/submitter index seed
1236		volatile int plock;                        // shutdown status and seqLock
1237	+	volatile int indexSeed;                    // worker/submitter index seed
1238	+	final int config;                          // mode and parallelism level
1239		WorkQueue[] workQueues;                    // main registry
1240	<	final ForkJoinWorkerThreadFactory factory; // factory for new workers
1240	>	final ForkJoinWorkerThreadFactory factory;
1241		final Thread.UncaughtExceptionHandler ueh; // per-worker UEH
1242		final String workerNamePrefix;             // to create worker name string
1243
1244	<	/*
1244	>	volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17;
1245	>	volatile Object pad18, pad19, pad1a, pad1b;
1246	>
1247	>	/**
1248		* Acquires the plock lock to protect worker array and related
1249		* updates. This method is called only if an initial CAS on plock
1250	<	* fails. This acts as a spinLock for normal cases, but falls back
1250	>	* fails. This acts as a spinlock for normal cases, but falls back
1251		* to builtin monitor to block when (rarely) needed. This would be
1252		* a terrible idea for a highly contended lock, but works fine as
1253	<	* a more conservative alternative to a pure spinlock.  See
1277	<	* internal ConcurrentHashMap documentation for further
1278	<	* explanation of nearly the same construction.
1253	>	* a more conservative alternative to a pure spinlock.
1254		*/
1255		private int acquirePlock() {
1256		int spins = PL_SPINS, r = 0, ps, nps;
#	Line 1283 | Line 1258 | public class ForkJoinPool extends Abstra
1258		if (((ps = plock) & PL_LOCK) == 0 &&
1259		U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK))
1260		return nps;
1261	<	else if (r == 0)
1262	<	r = ThreadLocalRandom.current().nextInt(); // randomize spins
1261	>	else if (r == 0) { // randomize spins if possible
1262	>	Thread t = Thread.currentThread(); WorkQueue w; Submitter z;
1263	>	if ((t instanceof ForkJoinWorkerThread) &&
1264	>	(w = ((ForkJoinWorkerThread)t).workQueue) != null)
1265	>	r = w.seed;
1266	>	else if ((z = submitters.get()) != null)
1267	>	r = z.seed;
1268	>	else
1269	>	r = 1;
1270	>	}
1271		else if (spins >= 0) {
1272		r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
1273		if (r >= 0)
#	Line 1318 | Line 1301 | public class ForkJoinPool extends Abstra
1301		synchronized (this) { notifyAll(); }
1302		}
1303
1304	+	/**
1305	+	* Tries to create and start one worker if fewer than target
1306	+	* parallelism level exist. Adjusts counts etc on failure.
1307	+	*/
1308	+	private void tryAddWorker() {
1309	+	long c; int u;
1310	+	while ((u = (int)((c = ctl) >>> 32)) < 0 &&
1311	+	(u & SHORT_SIGN) != 0 && (int)c == 0) {
1312	+	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
1313	+	((u + UAC_UNIT) & UAC_MASK)) << 32;
1314	+	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1315	+	ForkJoinWorkerThreadFactory fac;
1316	+	Throwable ex = null;
1317	+	ForkJoinWorkerThread wt = null;
1318	+	try {
1319	+	if ((fac = factory) != null &&
1320	+	(wt = fac.newThread(this)) != null) {
1321	+	wt.start();
1322	+	break;
1323	+	}
1324	+	} catch (Throwable e) {
1325	+	ex = e;
1326	+	}
1327	+	deregisterWorker(wt, ex);
1328	+	break;
1329	+	}
1330	+	}
1331	+	}
1332	+
1333		//  Registering and deregistering workers
1334
1335		/**
1336	<	* Callback from ForkJoinWorkerThread constructor to establish its
1337	<	* poolIndex and record its WorkQueue. To avoid scanning bias due
1338	<	* to packing entries in front of the workQueues array, we treat
1339	<	* the array as a simple power-of-two hash table using per-thread
1340	<	* seed as hash, expanding as needed.
1341	<	*
1342	<	* @param w the worker's queue
1343	<	*/
1344	<	final void registerWorker(WorkQueue w) {
1345	<	int s, ps; // generate a rarely colliding candidate index seed
1346	<	do {} while (!U.compareAndSwapInt(this, INDEXSEED,
1347	<	s = indexSeed, s += SEED_INCREMENT) ||
1336	>	* Callback from ForkJoinWorkerThread to establish and record its
1337	>	* WorkQueue. To avoid scanning bias due to packing entries in
1338	>	* front of the workQueues array, we treat the array as a simple
1339	>	* power-of-two hash table using per-thread seed as hash,
1340	>	* expanding as needed.
1341	>	*
1342	>	* @param wt the worker thread
1343	>	* @return the worker's queue
1344	>	*/
1345	>	final WorkQueue registerWorker(ForkJoinWorkerThread wt) {
1346	>	Thread.UncaughtExceptionHandler handler; WorkQueue[] ws; int s, ps;
1347	>	wt.setDaemon(true);
1348	>	if ((handler = ueh) != null)
1349	>	wt.setUncaughtExceptionHandler(handler);
1350	>	do {} while (!U.compareAndSwapInt(this, INDEXSEED, s = indexSeed,
1351	>	s += SEED_INCREMENT) ||
1352		s == 0); // skip 0
1353	+	WorkQueue w = new WorkQueue(this, wt, config >>> 16, s);
1354		if (((ps = plock) & PL_LOCK) != 0 ||
1355		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1356		ps = acquirePlock();
1357		int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1358		try {
1359	<	WorkQueue[] ws;
1343	<	if (w != null && (ws = workQueues) != null) {
1344	<	w.seed = s;
1359	>	if ((ws = workQueues) != null) {    // skip if shutting down
1360		int n = ws.length, m = n - 1;
1361	<	int r = (s << 1) | 1;               // use odd-numbered indices
1362	<	if (ws[r &= m] != null) {           // collision
1363	<	int probes = 0;                 // step by approx half size
1361	>	int r = (s << 1) | 1;           // use odd-numbered indices
1362	>	if (ws[r &= m] != null) {       // collision
1363	>	int probes = 0;             // step by approx half size
1364		int step = (n <= 4) ? 2 : ((n >>> 1) & EVENMASK) + 2;
1365		while (ws[r = (r + step) & m] != null) {
1366		if (++probes >= n) {
#	Line 1355 | Line 1370 | public class ForkJoinPool extends Abstra
1370		}
1371		}
1372		}
1373	<	w.eventCount = w.poolIndex = r;     // establish before recording
1373	>	w.eventCount = w.poolIndex = r; // volatile write orders
1374		ws[r] = w;
1375		}
1376		} finally {
1377		if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1378		releasePlock(nps);
1379		}
1380	+	wt.setName(workerNamePrefix.concat(Integer.toString(w.poolIndex)));
1381	+	return w;
1382		}
1383
1384		/**
#	Line 1377 | Line 1394 | public class ForkJoinPool extends Abstra
1394		WorkQueue w = null;
1395		if (wt != null && (w = wt.workQueue) != null) {
1396		int ps;
1380	–	collectStealCount(w);
1397		w.qlock = -1;                // ensure set
1398	+	long ns = w.nsteals, sc;     // collect steal count
1399	+	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1400	+	sc = stealCount, sc + ns));
1401		if (((ps = plock) & PL_LOCK) != 0 ||
1402		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1403		ps = acquirePlock();
#	Line 1394 | Line 1413 | public class ForkJoinPool extends Abstra
1413		}
1414		}
1415
1416	<	long c;                             // adjust ctl counts
1416	>	long c;                          // adjust ctl counts
1417		do {} while (!U.compareAndSwapLong
1418		(this, CTL, c = ctl, (((c - AC_UNIT) & AC_MASK) |
1419		((c - TC_UNIT) & TC_MASK) |
1420		(c & ~(AC_MASK|TC_MASK)))));
1421
1422	<	if (!tryTerminate(false, false) && w != null) {
1423	<	w.cancelAll();                  // cancel remaining tasks
1424	<	if (w.array != null)            // suppress signal if never ran
1425	<	signalWork(null, 1);        // wake up or create replacement
1426	<	if (ex == null)                 // help clean refs on way out
1427	<	ForkJoinTask.helpExpungeStaleExceptions();
1422	>	if (!tryTerminate(false, false) && w != null && w.array != null) {
1423	>	w.cancelAll();               // cancel remaining tasks
1424	>	WorkQueue[] ws; WorkQueue v; Thread p; int u, i, e;
1425	>	while ((u = (int)((c = ctl) >>> 32)) < 0 && (e = (int)c) >= 0) {
1426	>	if (e > 0) {             // activate or create replacement
1427	>	if ((ws = workQueues) == null ||
1428	>	(i = e & SMASK) >= ws.length ||
1429	>	(v = ws[i]) == null)
1430	>	break;
1431	>	long nc = (((long)(v.nextWait & E_MASK)) |
1432	>	((long)(u + UAC_UNIT) << 32));
1433	>	if (v.eventCount != (e | INT_SIGN))
1434	>	break;
1435	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1436	>	v.eventCount = (e + E_SEQ) & E_MASK;
1437	>	if ((p = v.parker) != null)
1438	>	U.unpark(p);
1439	>	break;
1440	>	}
1441	>	}
1442	>	else {
1443	>	if ((short)u < 0)
1444	>	tryAddWorker();
1445	>	break;
1446	>	}
1447	>	}
1448		}
1449	<
1450	<	if (ex != null)                     // rethrow
1449	>	if (ex == null)                     // help clean refs on way out
1450	>	ForkJoinTask.helpExpungeStaleExceptions();
1451	>	else                                // rethrow
1452		ForkJoinTask.rethrow(ex);
1453		}
1454
1415	–	/**
1416	–	* Collect worker steal count into total. Called on termination
1417	–	* and upon int overflow of local count. (There is a possible race
1418	–	* in the latter case vs any caller of getStealCount, which can
1419	–	* make its results less accurate than usual.)
1420	–	*/
1421	–	final void collectStealCount(WorkQueue w) {
1422	–	if (w != null) {
1423	–	long sc;
1424	–	int ns = w.nsteals;
1425	–	w.nsteals = 0; // handle overflow
1426	–	long steals = (ns >= 0) ? ns : 1L + (long)(Integer.MAX_VALUE);
1427	–	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1428	–	sc = stealCount, sc + steals));
1429	–	}
1430	–	}
1431	–
1455		// Submissions
1456
1457		/**
#	Line 1445 | Line 1468 | public class ForkJoinPool extends Abstra
1468		(ws = workQueues) != null && (m = (ws.length - 1)) >= 0 &&
1469		(q = ws[m & z.seed & SQMASK]) != null &&
1470		U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock
1471	<	int s = q.top, n;
1472	<	if ((a = q.array) != null && a.length > (n = s + 1 - q.base)) {
1473	<	U.putObject(a, (long)(((a.length - 1) & s) << ASHIFT) + ABASE,
1474	<	task);
1471	>	int b = q.base, s = q.top, n, an;
1472	>	if ((a = q.array) != null && (an = a.length) > (n = s + 1 - b)) {
1473	>	int j = (((an - 1) & s) << ASHIFT) + ABASE;
1474	>	U.putOrderedObject(a, j, task);
1475		q.top = s + 1;                     // push on to deque
1476		q.qlock = 0;
1477	<	if (n <= 1)
1478	<	signalWork(q, 1);
1477	>	if (n <= 2)
1478	>	signalWork(q);
1479		return;
1480		}
1481		q.qlock = 0;
#	Line 1463 | Line 1486 | public class ForkJoinPool extends Abstra
1486		/**
1487		* Full version of externalPush. This method is called, among
1488		* other times, upon the first submission of the first task to the
1489	<	* pool, so must perform secondary initialization: creating
1467	<	* workQueue array and setting plock to a valid value. It also
1489	>	* pool, so must perform secondary initialization.  It also
1490		* detects first submission by an external thread by looking up
1491		* its ThreadLocal, and creates a new shared queue if the one at
1492	<	* index if empty or contended. The lock bodies must be
1492	>	* index if empty or contended. The plock lock body must be
1493		* exception-free (so no try/finally) so we optimistically
1494	<	* allocate new queues/arrays outside the locks and throw them
1495	<	* away if (very rarely) not needed. Note that the plock seq value
1496	<	* can eventually wrap around zero, but if so harmlessly fails to
1497	<	* reinitialize.
1494	>	* allocate new queues outside the lock and throw them away if
1495	>	* (very rarely) not needed.
1496	>	*
1497	>	* Secondary initialization occurs when plock is zero, to create
1498	>	* workQueue array and set plock to a valid value.  This lock body
1499	>	* must also be exception-free. Because the plock seq value can
1500	>	* eventually wrap around zero, this method harmlessly fails to
1501	>	* reinitialize if workQueues exists, while still advancing plock.
1502		*/
1503		private void fullExternalPush(ForkJoinTask<?> task) {
1504	<	for (Submitter z = null;;) {
1505	<	WorkQueue[] ws; WorkQueue q; int ps, m, r, s;
1506	<	if ((ps = plock) < 0)
1504	>	int r = 0; // random index seed
1505	>	for (Submitter z = submitters.get();;) {
1506	>	WorkQueue[] ws; WorkQueue q; int ps, m, k;
1507	>	if (z == null) {
1508	>	if (U.compareAndSwapInt(this, INDEXSEED, r = indexSeed,
1509	>	r += SEED_INCREMENT) && r != 0)
1510	>	submitters.set(z = new Submitter(r));
1511	>	}
1512	>	else if (r == 0) {                  // move to a different index
1513	>	r = z.seed;
1514	>	r ^= r << 13;                   // same xorshift as WorkQueues
1515	>	r ^= r >>> 17;
1516	>	z.seed = r ^ (r << 5);
1517	>	}
1518	>	else if ((ps = plock) < 0)
1519		throw new RejectedExecutionException();
1520	<	else if ((ws = workQueues) == null || (m = ws.length - 1) < 0) {
1521	<	int n = parallelism - 1; n |= n >>> 1; n |= n >>> 2;
1522	<	n |= n >>> 4; n |= n >>> 8; n |= n >>> 16;
1523	<	WorkQueue[] nws = new WorkQueue[(n + 1) << 1]; // power of two
1524	<	if ((ps & PL_LOCK) != 0 ||
1520	>	else if (ps == 0 || (ws = workQueues) == null ||
1521	>	(m = ws.length - 1) < 0) { // initialize workQueues
1522	>	int p = config & SMASK;         // find power of two table size
1523	>	int n = (p > 1) ? p - 1 : 1;    // ensure at least 2 slots
1524	>	n |= n >>> 1;
1525	>	n |= n >>> 2;
1526	>	n |= n >>> 4;
1527	>	n |= n >>> 8;
1528	>	n |= n >>> 16;
1529	>	n = (n + 1) << 1;
1530	>	WorkQueue[] nws = ((ws = workQueues) == null || ws.length == 0 ?
1531	>	new WorkQueue[n] : null);
1532	>	if (((ps = plock) & PL_LOCK) != 0 ||
1533		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1534		ps = acquirePlock();
1535	<	if ((ws = workQueues) == null)
1535	>	if (((ws = workQueues) == null || ws.length == 0) && nws != null)
1536		workQueues = nws;
1537		int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1538		if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1539		releasePlock(nps);
1540		}
1541	<	else if (z == null && (z = submitters.get()) == null) {
1542	<	if (U.compareAndSwapInt(this, INDEXSEED,
1543	<	s = indexSeed, s += SEED_INCREMENT) &&
1544	<	s != 0) // skip 0
1545	<	submitters.set(z = new Submitter(s));
1541	>	else if ((q = ws[k = r & m & SQMASK]) != null) {
1542	>	if (q.qlock == 0 && U.compareAndSwapInt(q, QLOCK, 0, 1)) {
1543	>	ForkJoinTask<?>[] a = q.array;
1544	>	int s = q.top;
1545	>	boolean submitted = false;
1546	>	try {                      // locked version of push
1547	>	if ((a != null && a.length > s + 1 - q.base) ||
1548	>	(a = q.growArray()) != null) {   // must presize
1549	>	int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
1550	>	U.putOrderedObject(a, j, task);
1551	>	q.top = s + 1;
1552	>	submitted = true;
1553	>	}
1554	>	} finally {
1555	>	q.qlock = 0;  // unlock
1556	>	}
1557	>	if (submitted) {
1558	>	signalWork(q);
1559	>	return;
1560	>	}
1561	>	}
1562	>	r = 0; // move on failure
1563		}
1564	<	else {
1565	<	int k = (r = z.seed) & m & SQMASK;
1566	<	if ((q = ws[k]) == null && (ps & PL_LOCK) == 0) {
1567	<	(q = new WorkQueue(this, null, SHARED_QUEUE)).poolIndex = k;
1568	<	if (((ps = plock) & PL_LOCK) != 0 ||
1569	<	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1570	<	ps = acquirePlock();
1571	<	WorkQueue w = null;
1572	<	if ((ws = workQueues) != null && k < ws.length &&
1573	<	(w = ws[k]) == null)
1511	<	ws[k] = q;
1512	<	else
1513	<	q = w;
1514	<	int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1515	<	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1516	<	releasePlock(nps);
1517	<	}
1518	<	if (q != null && q.qlock == 0 && q.fullPush(task, false))
1519	<	return;
1520	<	r ^= r << 13;                // same xorshift as WorkQueues
1521	<	r ^= r >>> 17;
1522	<	z.seed = r ^= r << 5;        // move to a different index
1564	>	else if (((ps = plock) & PL_LOCK) == 0) { // create new queue
1565	>	q = new WorkQueue(this, null, SHARED_QUEUE, r);
1566	>	if (((ps = plock) & PL_LOCK) != 0 ||
1567	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1568	>	ps = acquirePlock();
1569	>	if ((ws = workQueues) != null && k < ws.length && ws[k] == null)
1570	>	ws[k] = q;
1571	>	int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1572	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1573	>	releasePlock(nps);
1574		}
1575	+	else
1576	+	r = 0; // try elsewhere while lock held
1577		}
1578		}
1579
#	Line 1535 | Line 1588 | public class ForkJoinPool extends Abstra
1588		}
1589
1590		/**
1591	<	* Tries to create (at most one) or activate (possibly several)
1539	<	* workers if too few are active. On contention failure, continues
1540	<	* until at least one worker is signalled or the given queue is
1541	<	* empty or all workers are active.
1591	>	* Tries to create or activate a worker if too few are active.
1592		*
1593	<	* @param q if non-null, the queue holding tasks to be signalled
1544	<	* @param signals the target number of signals.
1593	>	* @param q the (non-null) queue holding tasks to be signalled
1594		*/
1595	<	final void signalWork(WorkQueue q, int signals) {
1596	<	long c; int e, u, i; WorkQueue[] ws; WorkQueue w; Thread p;
1595	>	final void signalWork(WorkQueue q) {
1596	>	int hint = q.poolIndex;
1597	>	long c; int e, u, i, n; WorkQueue[] ws; WorkQueue w; Thread p;
1598		while ((u = (int)((c = ctl) >>> 32)) < 0) {
1599		if ((e = (int)c) > 0) {
1600		if ((ws = workQueues) != null && ws.length > (i = e & SMASK) &&
#	Line 1552 | Line 1602 | public class ForkJoinPool extends Abstra
1602		long nc = (((long)(w.nextWait & E_MASK)) |
1603		((long)(u + UAC_UNIT) << 32));
1604		if (U.compareAndSwapLong(this, CTL, c, nc)) {
1605	+	w.hint = hint;
1606		w.eventCount = (e + E_SEQ) & E_MASK;
1607		if ((p = w.parker) != null)
1608		U.unpark(p);
1609	<	if (--signals <= 0)
1559	<	break;
1609	>	break;
1610		}
1611	<	else
1562	<	signals = 1;
1563	<	if ((q != null && q.queueSize() == 0))
1611	>	if (q.top - q.base <= 0)
1612		break;
1613		}
1614		else
1615		break;
1616		}
1617	<	else if (e == 0 && (u & SHORT_SIGN) != 0) {
1618	<	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
1619	<	((u + UAC_UNIT) & UAC_MASK)) << 32;
1572	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1573	<	ForkJoinWorkerThread wt = null;
1574	<	Throwable ex = null;
1575	<	boolean started = false;
1576	<	try {
1577	<	ForkJoinWorkerThreadFactory fac;
1578	<	if ((fac = factory) != null &&
1579	<	(wt = fac.newThread(this)) != null) {
1580	<	wt.start();
1581	<	started = true;
1582	<	}
1583	<	} catch (Throwable rex) {
1584	<	ex = rex;
1585	<	}
1586	<	if (!started)
1587	<	deregisterWorker(wt, ex); // adjust counts on failure
1588	<	break;
1589	<	}
1590	<	}
1591	<	else
1617	>	else {
1618	>	if ((short)u < 0)
1619	>	tryAddWorker();
1620		break;
1621	+	}
1622		}
1623		}
1624
#	Line 1599 | Line 1628 | public class ForkJoinPool extends Abstra
1628		* Top-level runloop for workers, called by ForkJoinWorkerThread.run.
1629		*/
1630		final void runWorker(WorkQueue w) {
1631	<	// initialize queue array in this thread
1603	<	w.array = new ForkJoinTask<?>[WorkQueue.INITIAL_QUEUE_CAPACITY];
1631	>	w.growArray(); // allocate queue
1632		do { w.runTask(scan(w)); } while (w.qlock >= 0);
1633		}
1634
#	Line 1612 | Line 1640 | public class ForkJoinPool extends Abstra
1640		* contention, or state changes that indicate possible success on
1641		* re-invocation.
1642		*
1643	<	* The scan searches for tasks across a random permutation of
1644	<	* queues (starting at a random index and stepping by a random
1645	<	* relative prime, checking each at least once).  The scan
1646	<	* terminates upon either finding a non-empty queue, or completing
1647	<	* the sweep. If the worker is not inactivated, it takes and
1648	<	* returns a task from this queue. Otherwise, if not activated, it
1649	<	* signals workers (that may include itself) and returns so caller
1650	<	* can retry. Also returns for trtry if the worker array may have
1651	<	* changed during an empty scan.  On failure to find a task, we
1652	<	* take one of the following actions, after which the caller will
1653	<	* retry calling this method unless terminated.
1643	>	* The scan searches for tasks across queues (starting at a random
1644	>	* index, and relying on registerWorker to irregularly scatter
1645	>	* them within array to avoid bias), checking each at least twice.
1646	>	* The scan terminates upon either finding a non-empty queue, or
1647	>	* completing the sweep. If the worker is not inactivated, it
1648	>	* takes and returns a task from this queue. Otherwise, if not
1649	>	* activated, it signals workers (that may include itself) and
1650	>	* returns so caller can retry. Also returns for true if the
1651	>	* worker array may have changed during an empty scan.  On failure
1652	>	* to find a task, we take one of the following actions, after
1653	>	* which the caller will retry calling this method unless
1654	>	* terminated.
1655		*
1656		* * If pool is terminating, terminate the worker.
1657		*
1658		* * If not already enqueued, try to inactivate and enqueue the
1659		* worker on wait queue. Or, if inactivating has caused the pool
1660	<	* to be quiescent, relay to idleAwaitWork to check for
1661	<	* termination and possibly shrink pool.
1660	>	* to be quiescent, relay to idleAwaitWork to possibly shrink
1661	>	* pool.
1662		*
1663		* * If already enqueued and none of the above apply, possibly
1664	<	* (with 1/2 probability) park awaiting signal, else lingering to
1665	<	* help scan and signal.
1664	>	* park awaiting signal, else lingering to help scan and signal.
1665	>	*
1666	>	* * If a non-empty queue discovered or left as a hint,
1667	>	* help wake up other workers before return.
1668		*
1669		* @param w the worker (via its WorkQueue)
1670		* @return a task or null if none found
1671		*/
1672		private final ForkJoinTask<?> scan(WorkQueue w) {
1673	<	WorkQueue[] ws; WorkQueue q;           // first update random seed
1674	<	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1675	<	int ps = plock, m;                     // volatile read order matters
1676	<	if ((ws = workQueues) != null && (m = ws.length - 1) > 0) {
1677	<	int ec = w.eventCount;             // ec is negative if inactive
1678	<	int step = (r >>> 16) | 1;         // relatively prime
1679	<	for (int j = (m + 1) << 2;  ; --j, r += step) {
1680	<	ForkJoinTask<?> t; ForkJoinTask<?>[] a; int b, n;
1681	<	if ((q = ws[r & m]) != null && (b = q.base) - q.top < 0 &&
1682	<	(a = q.array) != null) {   // probably nonempty
1673	>	WorkQueue[] ws; int m;
1674	>	int ps = plock;                          // read plock before ws
1675	>	if (w != null && (ws = workQueues) != null && (m = ws.length - 1) >= 0) {
1676	>	int ec = w.eventCount;               // ec is negative if inactive
1677	>	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1678	>	w.hint = -1;                         // update seed and clear hint
1679	>	int j = ((m + m + 1) | MIN_SCAN) & MAX_SCAN;
1680	>	do {
1681	>	WorkQueue q; ForkJoinTask<?>[] a; int b;
1682	>	if ((q = ws[(r + j) & m]) != null && (b = q.base) - q.top < 0 &&
1683	>	(a = q.array) != null) {     // probably nonempty
1684		int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1685	<	t = (ForkJoinTask<?>)U.getObjectVolatile(a, i);
1685	>	ForkJoinTask<?> t = (ForkJoinTask<?>)
1686	>	U.getObjectVolatile(a, i);
1687		if (q.base == b && ec >= 0 && t != null &&
1688		U.compareAndSwapObject(a, i, t, null)) {
1689	<	if ((n = q.top - (q.base = b + 1)) > 0)
1690	<	signalWork(q, n);
1691	<	return t;              // taken
1692	<	}
1693	<	if (j < m || (ec < 0 && (ec = w.eventCount) < 0)) {
1694	<	if ((n = q.queueSize() - 1) > 0)
1695	<	signalWork(q, n);
1696	<	break;                 // let caller retry after signal
1697	<	}
1698	<	}
1699	<	else if (j < 0) {              // end of scan
1700	<	long c = ctl; int e;
1701	<	if (plock != ps)           // incomplete sweep
1702	<	break;
1703	<	if ((e = (int)c) < 0)      // pool is terminating
1704	<	w.qlock = -1;
1705	<	else if (ec >= 0) {        // try to enqueue/inactivate
1706	<	long nc = ((long)ec |
1707	<	((c - AC_UNIT) & (AC_MASK|TC_MASK)));
1708	<	w.nextWait = e;
1709	<	w.eventCount = ec | INT_SIGN; // mark as inactive
1710	<	if (ctl != c ||
1711	<	!U.compareAndSwapLong(this, CTL, c, nc))
1712	<	w.eventCount = ec; // unmark on CAS failure
1713	<	else if ((int)(c >> AC_SHIFT) == 1 - parallelism)
1714	<	idleAwaitWork(w, nc, c);  // quiescent
1689	>	if ((q.base = b + 1) - q.top < 0)
1690	>	signalWork(q);
1691	>	return t;                // taken
1692	>	}
1693	>	else if ((ec < 0 || j < m) && (int)(ctl >> AC_SHIFT) <= 0) {
1694	>	w.hint = (r + j) & m;    // help signal below
1695	>	break;                   // cannot take
1696	>	}
1697	>	}
1698	>	} while (--j >= 0);
1699	>
1700	>	int h, e, ns; long c, sc; WorkQueue q;
1701	>	if ((ns = w.nsteals) != 0) {
1702	>	if (U.compareAndSwapLong(this, STEALCOUNT,
1703	>	sc = stealCount, sc + ns))
1704	>	w.nsteals = 0;               // collect steals and rescan
1705	>	}
1706	>	else if (plock != ps)                // consistency check
1707	>	;                                // skip
1708	>	else if ((e = (int)(c = ctl)) < 0)
1709	>	w.qlock = -1;                    // pool is terminating
1710	>	else {
1711	>	if ((h = w.hint) < 0) {
1712	>	if (ec >= 0) {               // try to enqueue/inactivate
1713	>	long nc = (((long)ec |
1714	>	((c - AC_UNIT) & (AC_MASK|TC_MASK))));
1715	>	w.nextWait = e;          // link and mark inactive
1716	>	w.eventCount = ec | INT_SIGN;
1717	>	if (ctl != c || !U.compareAndSwapLong(this, CTL, c, nc))
1718	>	w.eventCount = ec;   // unmark on CAS failure
1719	>	else if ((int)(c >> AC_SHIFT) == 1 - (config & SMASK))
1720	>	idleAwaitWork(w, nc, c);
1721		}
1722	<	else if (w.seed >= 0 && w.eventCount < 0) {
1722	>	else if (w.eventCount < 0 && ctl == c) {
1723		Thread wt = Thread.currentThread();
1724	<	Thread.interrupted();  // clear status
1724	>	Thread.interrupted();    // clear status
1725		U.putObject(wt, PARKBLOCKER, this);
1726	<	w.parker = wt;         // emulate LockSupport.park
1727	<	if (w.eventCount < 0)  // recheck
1728	<	U.park(false, 0L);
1726	>	w.parker = wt;           // emulate LockSupport.park
1727	>	if (w.eventCount < 0)    // recheck
1728	>	U.park(false, 0L);   // block
1729		w.parker = null;
1730		U.putObject(wt, PARKBLOCKER, null);
1731		}
1732	<	break;
1732	>	}
1733	>	if ((h >= 0 || (h = w.hint) >= 0) &&
1734	>	(ws = workQueues) != null && h < ws.length &&
1735	>	(q = ws[h]) != null) {      // signal others before retry
1736	>	WorkQueue v; Thread p; int u, i, s;
1737	>	for (int n = (config & SMASK) - 1;;) {
1738	>	int idleCount = (w.eventCount < 0) ? 0 : -1;
1739	>	if (((s = idleCount - q.base + q.top) <= n &&
1740	>	(n = s) <= 0) ||
1741	>	(u = (int)((c = ctl) >>> 32)) >= 0 ||
1742	>	(e = (int)c) <= 0 || m < (i = e & SMASK) ||
1743	>	(v = ws[i]) == null)
1744	>	break;
1745	>	long nc = (((long)(v.nextWait & E_MASK)) |
1746	>	((long)(u + UAC_UNIT) << 32));
1747	>	if (v.eventCount != (e | INT_SIGN) ||
1748	>	!U.compareAndSwapLong(this, CTL, c, nc))
1749	>	break;
1750	>	v.hint = h;
1751	>	v.eventCount = (e + E_SEQ) & E_MASK;
1752	>	if ((p = v.parker) != null)
1753	>	U.unpark(p);
1754	>	if (--n <= 0)
1755	>	break;
1756	>	}
1757		}
1758		}
1759		}
#	Line 1710 | Line 1773 | public class ForkJoinPool extends Abstra
1773		* @param prevCtl the ctl value to restore if thread is terminated
1774		*/
1775		private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) {
1776	<	if (w.eventCount < 0 &&
1777	<	(this == commonPool || !tryTerminate(false, false)) &&
1778	<	(int)prevCtl != 0) {
1776	>	if (w != null && w.eventCount < 0 &&
1777	>	!tryTerminate(false, false) && (int)prevCtl != 0 &&
1778	>	ctl == currentCtl) {
1779		int dc = -(short)(currentCtl >>> TC_SHIFT);
1780		long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT;
1781	<	long deadline = System.nanoTime() + parkTime - 100000L; // 1ms slop
1781	>	long deadline = System.nanoTime() + parkTime - TIMEOUT_SLOP;
1782		Thread wt = Thread.currentThread();
1783		while (ctl == currentCtl) {
1784		Thread.interrupted();  // timed variant of version in scan()
#	Line 1730 | Line 1793 | public class ForkJoinPool extends Abstra
1793		if (deadline - System.nanoTime() <= 0L &&
1794		U.compareAndSwapLong(this, CTL, currentCtl, prevCtl)) {
1795		w.eventCount = (w.eventCount + E_SEQ) | E_MASK;
1796	+	w.hint = -1;
1797		w.qlock = -1;   // shrink
1798		break;
1799		}
#	Line 1738 | Line 1802 | public class ForkJoinPool extends Abstra
1802		}
1803
1804		/**
1805	<	* Scans through queues looking for work while joining a task;
1806	<	* if any are present, signals.
1805	>	* Scans through queues looking for work while joining a task; if
1806	>	* any present, signals. May return early if more signalling is
1807	>	* detectably unneeded.
1808		*
1809	<	* @param task to return early if done
1809	>	* @param task return early if done
1810		* @param origin an index to start scan
1811		*/
1812	<	final int helpSignal(ForkJoinTask<?> task, int origin) {
1813	<	WorkQueue[] ws; WorkQueue q; int m, n, s;
1814	<	if (task != null && (ws = workQueues) != null &&
1815	<	(m = ws.length - 1) >= 0) {
1816	<	for (int i = 0; i <= m; ++i) {
1817	<	if ((s = task.status) < 0)
1818	<	return s;
1819	<	if ((q = ws[(i + origin) & m]) != null &&
1820	<	(n = q.queueSize()) > 0) {
1821	<	signalWork(q, n);
1822	<	if ((int)(ctl >> AC_SHIFT) >= 0)
1812	>	private void helpSignal(ForkJoinTask<?> task, int origin) {
1813	>	WorkQueue[] ws; WorkQueue w; Thread p; long c; int m, u, e, i, s;
1814	>	if (task != null && task.status >= 0 &&
1815	>	(u = (int)(ctl >>> 32)) < 0 && (u >> UAC_SHIFT) < 0 &&
1816	>	(ws = workQueues) != null && (m = ws.length - 1) >= 0) {
1817	>	outer: for (int k = origin, j = m; j >= 0; --j) {
1818	>	WorkQueue q = ws[k++ & m];
1819	>	for (int n = m;;) { // limit to at most m signals
1820	>	if (task.status < 0)
1821	>	break outer;
1822	>	if (q == null ||
1823	>	((s = -q.base + q.top) <= n && (n = s) <= 0))
1824		break;
1825	+	if ((u = (int)((c = ctl) >>> 32)) >= 0 ||
1826	+	(e = (int)c) <= 0 || m < (i = e & SMASK) ||
1827	+	(w = ws[i]) == null)
1828	+	break outer;
1829	+	long nc = (((long)(w.nextWait & E_MASK)) |
1830	+	((long)(u + UAC_UNIT) << 32));
1831	+	if (w.eventCount != (e | INT_SIGN))
1832	+	break outer;
1833	+	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1834	+	w.eventCount = (e + E_SEQ) & E_MASK;
1835	+	if ((p = w.parker) != null)
1836	+	U.unpark(p);
1837	+	if (--n <= 0)
1838	+	break;
1839	+	}
1840		}
1841		}
1842		}
1762	–	return 0;
1843		}
1844
1845		/**
#	Line 1793 | Line 1873 | public class ForkJoinPool extends Abstra
1873		}
1874		if ((ws = workQueues) == null || (m = ws.length - 1) <= 0)
1875		break restart;              // shutting down
1876	<	if ((v = ws[h = (j.stealHint | 1) & m]) == null ||
1876	>	if ((v = ws[h = (j.hint | 1) & m]) == null ||
1877		v.currentSteal != subtask) {
1878		for (int origin = h;;) {    // find stealer
1879		if (((h = (h + 2) & m) & 15) == 1 &&
#	Line 1801 | Line 1881 | public class ForkJoinPool extends Abstra
1881		continue restart;   // occasional staleness check
1882		if ((v = ws[h]) != null &&
1883		v.currentSteal == subtask) {
1884	<	j.stealHint = h;    // save hint
1884	>	j.hint = h;        // save hint
1885		break;
1886		}
1887		if (h == origin)
#	Line 1855 | Line 1935 | public class ForkJoinPool extends Abstra
1935		* @param task the task to join
1936		* @param mode if shared, exit upon completing any task
1937		* if all workers are active
1858	–	*
1938		*/
1939		private int helpComplete(ForkJoinTask<?> task, int mode) {
1940	<	WorkQueue[] ws; WorkQueue q; int m, n, s;
1940	>	WorkQueue[] ws; WorkQueue q; int m, n, s, u;
1941		if (task != null && (ws = workQueues) != null &&
1942		(m = ws.length - 1) >= 0) {
1943		for (int j = 1, origin = j;;) {
#	Line 1866 | Line 1945 | public class ForkJoinPool extends Abstra
1945		return s;
1946		if ((q = ws[j & m]) != null && q.pollAndExecCC(task)) {
1947		origin = j;
1948	<	if (mode == SHARED_QUEUE && (int)(ctl >> AC_SHIFT) >= 0)
1948	>	if (mode == SHARED_QUEUE &&
1949	>	((u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0))
1950		break;
1951		}
1952		else if ((j = (j + 2) & m) == origin)
#	Line 1884 | Line 1964 | public class ForkJoinPool extends Abstra
1964		* may become starved.
1965		*/
1966		final boolean tryCompensate() {
1967	<	int pc = parallelism, e, u, i, tc; long c;
1967	>	int pc = config & SMASK, e, i, tc; long c;
1968		WorkQueue[] ws; WorkQueue w; Thread p;
1969	<	if ((e = (int)(c = ctl)) >= 0 && (ws = workQueues) != null) {
1969	>	if ((ws = workQueues) != null && (e = (int)(c = ctl)) >= 0) {
1970		if (e != 0 && (i = e & SMASK) < ws.length &&
1971		(w = ws[i]) != null && w.eventCount == (e | INT_SIGN)) {
1972		long nc = ((long)(w.nextWait & E_MASK) |
#	Line 1898 | Line 1978 | public class ForkJoinPool extends Abstra
1978		return true;   // replace with idle worker
1979		}
1980		}
1981	<	else if ((short)((u = (int)(c >>> 32)) >>> UTC_SHIFT) >= 0 &&
1982	<	(u >> UAC_SHIFT) + pc > 1) {
1981	>	else if ((tc = (short)(c >>> TC_SHIFT)) >= 0 &&
1982	>	(int)(c >> AC_SHIFT) + pc > 1) {
1983		long nc = ((c - AC_UNIT) & AC_MASK) | (c & ~AC_MASK);
1984		if (U.compareAndSwapLong(this, CTL, c, nc))
1985	<	return true;    // no compensation
1985	>	return true;   // no compensation
1986		}
1987	<	else if ((tc = u + pc) < MAX_CAP) {
1987	>	else if (tc + pc < MAX_CAP) {
1988		long nc = ((c + TC_UNIT) & TC_MASK) | (c & ~TC_MASK);
1989		if (U.compareAndSwapLong(this, CTL, c, nc)) {
1990	+	ForkJoinWorkerThreadFactory fac;
1991		Throwable ex = null;
1992		ForkJoinWorkerThread wt = null;
1993		try {
1913	–	ForkJoinWorkerThreadFactory fac;
1994		if ((fac = factory) != null &&
1995		(wt = fac.newThread(this)) != null) {
1996		wt.start();
#	Line 1919 | Line 1999 | public class ForkJoinPool extends Abstra
1999		} catch (Throwable rex) {
2000		ex = rex;
2001		}
2002	<	deregisterWorker(wt, ex); // adjust counts etc
2002	>	deregisterWorker(wt, ex); // clean up and return false
2003		}
2004		}
2005		}
#	Line 1938 | Line 2018 | public class ForkJoinPool extends Abstra
2018		if (joiner != null && task != null && (s = task.status) >= 0) {
2019		ForkJoinTask<?> prevJoin = joiner.currentJoin;
2020		joiner.currentJoin = task;
2021	<	do {} while ((s = task.status) >= 0 &&
1942	<	joiner.queueSize() > 0 &&
2021	>	do {} while ((s = task.status) >= 0 && !joiner.isEmpty() &&
2022		joiner.tryRemoveAndExec(task)); // process local tasks
2023	<	if (s >= 0 && (s = task.status) >= 0 &&
2024	<	(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
2025	<	(task instanceof CountedCompleter))
2026	<	s = helpComplete(task, LIFO_QUEUE);
2023	>	if (s >= 0 && (s = task.status) >= 0) {
2024	>	helpSignal(task, joiner.poolIndex);
2025	>	if ((s = task.status) >= 0 &&
2026	>	(task instanceof CountedCompleter))
2027	>	s = helpComplete(task, LIFO_QUEUE);
2028	>	}
2029		while (s >= 0 && (s = task.status) >= 0) {
2030	<	if ((joiner.queueSize() > 0 ||           // try helping
2030	>	if ((!joiner.isEmpty() ||           // try helping
2031		(s = tryHelpStealer(joiner, task)) == 0) &&
2032	<	(s = task.status) >= 0 && tryCompensate()) {
2033	<	if (task.trySetSignal() && (s = task.status) >= 0) {
2034	<	synchronized (task) {
2035	<	if (task.status >= 0) {
2036	<	try {                // see ForkJoinTask
2037	<	task.wait();     //  for explanation
2038	<	} catch (InterruptedException ie) {
2032	>	(s = task.status) >= 0) {
2033	>	helpSignal(task, joiner.poolIndex);
2034	>	if ((s = task.status) >= 0 && tryCompensate()) {
2035	>	if (task.trySetSignal() && (s = task.status) >= 0) {
2036	>	synchronized (task) {
2037	>	if (task.status >= 0) {
2038	>	try {                // see ForkJoinTask
2039	>	task.wait();     //  for explanation
2040	>	} catch (InterruptedException ie) {
2041	>	}
2042		}
2043	+	else
2044	+	task.notifyAll();
2045		}
1960	–	else
1961	–	task.notifyAll();
2046		}
2047	+	long c;                          // re-activate
2048	+	do {} while (!U.compareAndSwapLong
2049	+	(this, CTL, c = ctl, c + AC_UNIT));
2050		}
1964	–	long c;                          // re-activate
1965	–	do {} while (!U.compareAndSwapLong
1966	–	(this, CTL, c = ctl, c + AC_UNIT));
2051		}
2052		}
2053		joiner.currentJoin = prevJoin;
#	Line 1984 | Line 2068 | public class ForkJoinPool extends Abstra
2068		if (joiner != null && task != null && (s = task.status) >= 0) {
2069		ForkJoinTask<?> prevJoin = joiner.currentJoin;
2070		joiner.currentJoin = task;
2071	<	do {} while ((s = task.status) >= 0 &&
1988	<	joiner.queueSize() > 0 &&
2071	>	do {} while ((s = task.status) >= 0 && !joiner.isEmpty() &&
2072		joiner.tryRemoveAndExec(task));
2073	<	if (s >= 0 && (s = task.status) >= 0 &&
2074	<	(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
2075	<	(task instanceof CountedCompleter))
2076	<	s = helpComplete(task, LIFO_QUEUE);
2077	<	if (s >= 0 && joiner.queueSize() == 0) {
2073	>	if (s >= 0 && (s = task.status) >= 0) {
2074	>	helpSignal(task, joiner.poolIndex);
2075	>	if ((s = task.status) >= 0 &&
2076	>	(task instanceof CountedCompleter))
2077	>	s = helpComplete(task, LIFO_QUEUE);
2078	>	}
2079	>	if (s >= 0 && joiner.isEmpty()) {
2080		do {} while (task.status >= 0 &&
2081		tryHelpStealer(joiner, task) > 0);
2082		}
#	Line 2001 | Line 2086 | public class ForkJoinPool extends Abstra
2086
2087		/**
2088		* Returns a (probably) non-empty steal queue, if one is found
2089	<	* during a random, then cyclic scan, else null.  This method must
2090	<	* be retried by caller if, by the time it tries to use the queue,
2006	<	* it is empty.
2089	>	* during a scan, else null.  This method must be retried by
2090	>	* caller if, by the time it tries to use the queue, it is empty.
2091		* @param r a (random) seed for scanning
2092		*/
2093		private WorkQueue findNonEmptyStealQueue(int r) {
2094	<	int step = (r >>> 16) | 1;
2095	<	for (WorkQueue[] ws;;) {
2096	<	int ps = plock, m;
2097	<	if ((ws = workQueues) == null || (m = ws.length - 1) < 1)
2098	<	return null;
2099	<	for (int j = (m + 1) << 2; ; r += step) {
2100	<	WorkQueue q = ws[((r << 1) | 1) & m];
2017	<	if (q != null && q.queueSize() > 0)
2018	<	return q;
2019	<	else if (--j < 0) {
2020	<	if (plock == ps)
2021	<	return null;
2022	<	break;
2094	>	for (;;) {
2095	>	int ps = plock, m; WorkQueue[] ws; WorkQueue q;
2096	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
2097	>	for (int j = (m + 1) << 2; j >= 0; --j) {
2098	>	if ((q = ws[(((r + j) << 1) | 1) & m]) != null &&
2099	>	q.base - q.top < 0)
2100	>	return q;
2101		}
2102		}
2103	+	if (plock == ps)
2104	+	return null;
2105		}
2106		}
2107
#	Line 2033 | Line 2113 | public class ForkJoinPool extends Abstra
2113		*/
2114		final void helpQuiescePool(WorkQueue w) {
2115		for (boolean active = true;;) {
2116	<	ForkJoinTask<?> localTask; // exhaust local queue
2117	<	while ((localTask = w.nextLocalTask()) != null)
2118	<	localTask.doExec();
2119	<	// Similar to loop in scan(), but ignoring submissions
2120	<	WorkQueue q = findNonEmptyStealQueue(w.nextSeed());
2121	<	if (q != null) {
2122	<	ForkJoinTask<?> t; int b;
2116	>	long c; WorkQueue q; ForkJoinTask<?> t; int b;
2117	>	while ((t = w.nextLocalTask()) != null) {
2118	>	if (w.base - w.top < 0)
2119	>	signalWork(w);
2120	>	t.doExec();
2121	>	}
2122	>	if ((q = findNonEmptyStealQueue(w.nextSeed())) != null) {
2123		if (!active) {      // re-establish active count
2044	–	long c;
2124		active = true;
2125		do {} while (!U.compareAndSwapLong
2126		(this, CTL, c = ctl, c + AC_UNIT));
2127		}
2128	<	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2128	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) {
2129	>	if (q.base - q.top < 0)
2130	>	signalWork(q);
2131		w.runSubtask(t);
2132	+	}
2133		}
2134	<	else {
2135	<	long c;
2136	<	if (active) {       // decrement active count without queuing
2134	>	else if (active) {      // decrement active count without queuing
2135	>	long nc = (c = ctl) - AC_UNIT;
2136	>	if ((int)(nc >> AC_SHIFT) + (config & SMASK) == 0)
2137	>	return;         // bypass decrement-then-increment
2138	>	if (U.compareAndSwapLong(this, CTL, c, nc))
2139		active = false;
2056	–	do {} while (!U.compareAndSwapLong
2057	–	(this, CTL, c = ctl, c -= AC_UNIT));
2058	–	}
2059	–	else
2060	–	c = ctl;        // re-increment on exit
2061	–	if ((int)(c >> AC_SHIFT) + parallelism == 0) {
2062	–	do {} while (!U.compareAndSwapLong
2063	–	(this, CTL, c = ctl, c + AC_UNIT));
2064	–	break;
2065	–	}
2140		}
2141	+	else if ((int)((c = ctl) >> AC_SHIFT) + (config & SMASK) == 0 &&
2142	+	U.compareAndSwapLong(this, CTL, c, c + AC_UNIT))
2143	+	return;
2144		}
2145		}
2146
#	Line 2079 | Line 2156 | public class ForkJoinPool extends Abstra
2156		return t;
2157		if ((q = findNonEmptyStealQueue(w.nextSeed())) == null)
2158		return null;
2159	<	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2159	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) {
2160	>	if (q.base - q.top < 0)
2161	>	signalWork(q);
2162		return t;
2163	+	}
2164		}
2165		}
2166
#	Line 2109 | Line 2189 | public class ForkJoinPool extends Abstra
2189		* producing extra tasks amortizes the uncertainty of progress and
2190		* diffusion assumptions.
2191		*
2192	<	* So, users will want to use values larger, but not much larger
2192	>	* So, users will want to use values larger (but not much larger)
2193		* than 1 to both smooth over transient shortages and hedge
2194		* against uneven progress; as traded off against the cost of
2195		* extra task overhead. We leave the user to pick a threshold
#	Line 2133 | Line 2213 | public class ForkJoinPool extends Abstra
2213		static int getSurplusQueuedTaskCount() {
2214		Thread t; ForkJoinWorkerThread wt; ForkJoinPool pool; WorkQueue q;
2215		if (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)) {
2216	<	int b = (q = (wt = (ForkJoinWorkerThread)t).workQueue).base;
2217	<	int p = (pool = wt.pool).parallelism;
2216	>	int p = (pool = (wt = (ForkJoinWorkerThread)t).pool).config & SMASK;
2217	>	int n = (q = wt.workQueue).top - q.base;
2218		int a = (int)(pool.ctl >> AC_SHIFT) + p;
2219	<	return q.top - b - (a > (p >>>= 1) ? 0 :
2220	<	a > (p >>>= 1) ? 1 :
2221	<	a > (p >>>= 1) ? 2 :
2222	<	a > (p >>>= 1) ? 4 :
2223	<	8);
2219	>	return n - (a > (p >>>= 1) ? 0 :
2220	>	a > (p >>>= 1) ? 1 :
2221	>	a > (p >>>= 1) ? 2 :
2222	>	a > (p >>>= 1) ? 4 :
2223	>	8);
2224		}
2225		return 0;
2226		}
#	Line 2162 | Line 2242 | public class ForkJoinPool extends Abstra
2242		* @return true if now terminating or terminated
2243		*/
2244		private boolean tryTerminate(boolean now, boolean enable) {
2245	<	if (this == commonPool)                     // cannot shut down
2245	>	int ps;
2246	>	if (this == common)                    // cannot shut down
2247		return false;
2248	+	if ((ps = plock) >= 0) {                   // enable by setting plock
2249	+	if (!enable)
2250	+	return false;
2251	+	if ((ps & PL_LOCK) != 0 ||
2252	+	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
2253	+	ps = acquirePlock();
2254	+	int nps = ((ps + PL_LOCK) & ~SHUTDOWN) | SHUTDOWN;
2255	+	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
2256	+	releasePlock(nps);
2257	+	}
2258		for (long c;;) {
2259	<	if (((c = ctl) & STOP_BIT) != 0) {      // already terminating
2260	<	if ((short)(c >>> TC_SHIFT) == -parallelism) {
2259	>	if (((c = ctl) & STOP_BIT) != 0) {     // already terminating
2260	>	if ((short)(c >>> TC_SHIFT) == -(config & SMASK)) {
2261		synchronized (this) {
2262	<	notifyAll();                // signal when 0 workers
2262	>	notifyAll();               // signal when 0 workers
2263		}
2264		}
2265		return true;
2266		}
2267	<	if (plock >= 0) {                       // not yet enabled
2268	<	int ps;
2269	<	if (!enable)
2267	>	if (!now) {                            // check if idle & no tasks
2268	>	WorkQueue[] ws; WorkQueue w;
2269	>	if ((int)(c >> AC_SHIFT) != -(config & SMASK))
2270		return false;
2271	<	if (((ps = plock) & PL_LOCK) != 0 ||
2272	<	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
2273	<	ps = acquirePlock();
2274	<	int nps = SHUTDOWN;
2275	<	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
2276	<	releasePlock(nps);
2277	<	}
2278	<	if (!now) {                             // check if idle & no tasks
2279	<	if ((int)(c >> AC_SHIFT) != -parallelism ||
2280	<	hasQueuedSubmissions())
2190	<	return false;
2191	<	// Check for unqueued inactive workers. One pass suffices.
2192	<	WorkQueue[] ws = workQueues; WorkQueue w;
2193	<	if (ws != null) {
2194	<	for (int i = 1; i < ws.length; i += 2) {
2195	<	if ((w = ws[i]) != null && w.eventCount >= 0)
2196	<	return false;
2271	>	if ((ws = workQueues) != null) {
2272	>	for (int i = 0; i < ws.length; ++i) {
2273	>	if ((w = ws[i]) != null) {
2274	>	if (!w.isEmpty()) {    // signal unprocessed tasks
2275	>	signalWork(w);
2276	>	return false;
2277	>	}
2278	>	if ((i & 1) != 0 && w.eventCount >= 0)
2279	>	return false;      // unqueued inactive worker
2280	>	}
2281		}
2282		}
2283		}
2284		if (U.compareAndSwapLong(this, CTL, c, c | STOP_BIT)) {
2285		for (int pass = 0; pass < 3; ++pass) {
2286	<	WorkQueue[] ws = workQueues;
2287	<	if (ws != null) {
2204	<	WorkQueue w;
2286	>	WorkQueue[] ws; WorkQueue w; Thread wt;
2287	>	if ((ws = workQueues) != null) {
2288		int n = ws.length;
2289		for (int i = 0; i < n; ++i) {
2290		if ((w = ws[i]) != null) {
2291		w.qlock = -1;
2292		if (pass > 0) {
2293		w.cancelAll();
2294	<	if (pass > 1)
2295	<	w.interruptOwner();
2294	>	if (pass > 1 && (wt = w.owner) != null) {
2295	>	if (!wt.isInterrupted()) {
2296	>	try {
2297	>	wt.interrupt();
2298	>	} catch (Throwable ignore) {
2299	>	}
2300	>	}
2301	>	U.unpark(wt);
2302	>	}
2303		}
2304		}
2305		}
2306		// Wake up workers parked on event queue
2307		int i, e; long cc; Thread p;
2308		while ((e = (int)(cc = ctl) & E_MASK) != 0 &&
2309	<	(i = e & SMASK) < n &&
2309	>	(i = e & SMASK) < n && i >= 0 &&
2310		(w = ws[i]) != null) {
2311		long nc = ((long)(w.nextWait & E_MASK) |
2312		((cc + AC_UNIT) & AC_MASK) |
#	Line 2244 | Line 2334 | public class ForkJoinPool extends Abstra
2334		static WorkQueue commonSubmitterQueue() {
2335		ForkJoinPool p; WorkQueue[] ws; int m; Submitter z;
2336		return ((z = submitters.get()) != null &&
2337	<	(p = commonPool) != null &&
2337	>	(p = common) != null &&
2338		(ws = p.workQueues) != null &&
2339		(m = ws.length - 1) >= 0) ?
2340		ws[m & z.seed & SQMASK] : null;
#	Line 2255 | Line 2345 | public class ForkJoinPool extends Abstra
2345		*/
2346		static boolean tryExternalUnpush(ForkJoinTask<?> t) {
2347		ForkJoinPool p; WorkQueue[] ws; WorkQueue q; Submitter z;
2348	<	ForkJoinTask<?>[] a;  int m, s; long j;
2349	<	if ((z = submitters.get()) != null &&
2350	<	(p = commonPool) != null &&
2348	>	ForkJoinTask<?>[] a;  int m, s;
2349	>	if (t != null &&
2350	>	(z = submitters.get()) != null &&
2351	>	(p = common) != null &&
2352		(ws = p.workQueues) != null &&
2353		(m = ws.length - 1) >= 0 &&
2354		(q = ws[m & z.seed & SQMASK]) != null &&
2355		(s = q.top) != q.base &&
2356	<	(a = q.array) != null &&
2357	<	U.getObjectVolatile
2358	<	(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
2359	<	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2360	<	if (q.array == a && q.top == s && // recheck
2361	<	U.compareAndSwapObject(a, j, t, null)) {
2362	<	q.top = s - 1;
2356	>	(a = q.array) != null) {
2357	>	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
2358	>	if (U.getObject(a, j) == t &&
2359	>	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2360	>	if (q.array == a && q.top == s && // recheck
2361	>	U.compareAndSwapObject(a, j, t, null)) {
2362	>	q.top = s - 1;
2363	>	q.qlock = 0;
2364	>	return true;
2365	>	}
2366		q.qlock = 0;
2273	–	return true;
2367		}
2275	–	q.qlock = 0;
2368		}
2369		return false;
2370		}
#	Line 2287 | Line 2379 | public class ForkJoinPool extends Abstra
2379		if (q != null && (a = q.array) != null && (m = (a.length - 1)) >= 0 &&
2380		root != null && root.status >= 0) {
2381		for (;;) {
2382	<	int s; Object o; CountedCompleter<?> task = null;
2382	>	int s, u; Object o; CountedCompleter<?> task = null;
2383		if ((s = q.top) - q.base > 0) {
2384		long j = ((m & (s - 1)) << ASHIFT) + ABASE;
2385		if ((o = U.getObject(a, j)) != null &&
#	Line 2310 | Line 2402 | public class ForkJoinPool extends Abstra
2402		}
2403		if (task != null)
2404		task.doExec();
2405	<	if (root.status < 0 || (int)(ctl >> AC_SHIFT) >= 0)
2405	>	if (root.status < 0 ||
2406	>	(u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0)
2407		break;
2408		if (task == null) {
2409	<	if (helpSignal(root, q.poolIndex) >= 0)
2409	>	helpSignal(root, q.poolIndex);
2410	>	if (root.status >= 0)
2411		helpComplete(root, SHARED_QUEUE);
2412		break;
2413		}
#	Line 2328 | Line 2422 | public class ForkJoinPool extends Abstra
2422		static void externalHelpJoin(ForkJoinTask<?> t) {
2423		// Some hard-to-avoid overlap with tryExternalUnpush
2424		ForkJoinPool p; WorkQueue[] ws; WorkQueue q, w; Submitter z;
2425	<	ForkJoinTask<?>[] a;  int m, s, n; long j;
2426	<	if (t != null && t.status >= 0 &&
2425	>	ForkJoinTask<?>[] a;  int m, s, n;
2426	>	if (t != null &&
2427		(z = submitters.get()) != null &&
2428	<	(p = commonPool) != null &&
2428	>	(p = common) != null &&
2429		(ws = p.workQueues) != null &&
2430		(m = ws.length - 1) >= 0 &&
2431		(q = ws[m & z.seed & SQMASK]) != null &&
2432		(a = q.array) != null) {
2433	<	if ((s = q.top) != q.base &&
2434	<	U.getObjectVolatile
2435	<	(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
2436	<	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2437	<	if (q.array == a && q.top == s &&
2438	<	U.compareAndSwapObject(a, j, t, null)) {
2439	<	q.top = s - 1;
2440	<	q.qlock = 0;
2441	<	t.doExec();
2433	>	int am = a.length - 1;
2434	>	if ((s = q.top) != q.base) {
2435	>	long j = ((am & (s - 1)) << ASHIFT) + ABASE;
2436	>	if (U.getObject(a, j) == t &&
2437	>	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2438	>	if (q.array == a && q.top == s &&
2439	>	U.compareAndSwapObject(a, j, t, null)) {
2440	>	q.top = s - 1;
2441	>	q.qlock = 0;
2442	>	t.doExec();
2443	>	}
2444	>	else
2445	>	q.qlock = 0;
2446		}
2349	–	else
2350	–	q.qlock = 0;
2447		}
2448		if (t.status >= 0) {
2449		if (t instanceof CountedCompleter)
#	Line 2358 | Line 2454 | public class ForkJoinPool extends Abstra
2454		}
2455		}
2456
2361	–	/**
2362	–	* Restricted version of helpQuiescePool for external callers
2363	–	*/
2364	–	static void externalHelpQuiescePool() {
2365	–	ForkJoinPool p; ForkJoinTask<?> t; WorkQueue q; int b;
2366	–	int r = ThreadLocalRandom.current().nextInt();
2367	–	if ((p = commonPool) != null &&
2368	–	(q = p.findNonEmptyStealQueue(r)) != null &&
2369	–	(b = q.base) - q.top < 0 &&
2370	–	(t = q.pollAt(b)) != null)
2371	–	t.doExec();
2372	–	}
2373	–
2457		// Exported methods
2458
2459		// Constructors
#	Line 2387 | Line 2470 | public class ForkJoinPool extends Abstra
2470		*         java.lang.RuntimePermission}{@code ("modifyThread")}
2471		*/
2472		public ForkJoinPool() {
2473	<	this(Runtime.getRuntime().availableProcessors(),
2473	>	this(Math.min(MAX_CAP, Runtime.getRuntime().availableProcessors()),
2474		defaultForkJoinWorkerThreadFactory, null, false);
2475		}
2476
#	Line 2442 | Line 2525 | public class ForkJoinPool extends Abstra
2525		throw new NullPointerException();
2526		if (parallelism <= 0 || parallelism > MAX_CAP)
2527		throw new IllegalArgumentException();
2445	–	this.parallelism = parallelism;
2528		this.factory = factory;
2529		this.ueh = handler;
2530	<	this.localMode = asyncMode ? FIFO_QUEUE : LIFO_QUEUE;
2530	>	this.config = parallelism | (asyncMode ? (FIFO_QUEUE << 16) : 0);
2531		long np = (long)(-parallelism); // offset ctl counts
2532		this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
2533		int pn = nextPoolId();
#	Line 2462 | Line 2544 | public class ForkJoinPool extends Abstra
2544		ForkJoinPool(int parallelism, long ctl,
2545		ForkJoinWorkerThreadFactory factory,
2546		Thread.UncaughtExceptionHandler handler) {
2547	<	this.parallelism = parallelism;
2547	>	this.config = parallelism;
2548		this.ctl = ctl;
2549		this.factory = factory;
2550		this.ueh = handler;
2469	–	this.localMode = LIFO_QUEUE;
2551		this.workerNamePrefix = "ForkJoinPool.commonPool-worker-";
2552		}
2553
2554		/**
2555	<	* Returns the common pool instance.
2555	>	* Returns the common pool instance. This pool is statically
2556	>	* constructed; its run state is unaffected by attempts to {@link
2557	>	* #shutdown} or {@link #shutdownNow}. However this pool and any
2558	>	* ongoing processing are automatically terminated upon program
2559	>	* {@link System#exit}.  Any program that relies on asynchronous
2560	>	* task processing to complete before program termination should
2561	>	* invoke {@code commonPool().}{@link #awaitQuiescence}, before
2562	>	* exit.
2563		*
2564		* @return the common pool instance
2565	+	* @since 1.8
2566		*/
2567		public static ForkJoinPool commonPool() {
2568	<	return commonPool; // cannot be null (if so, a static init error)
2568	>	// assert common != null : "static init error";
2569	>	return common;
2570		}
2571
2572		// Execution methods
#	Line 2599 | Line 2689 | public class ForkJoinPool extends Abstra
2689		// In previous versions of this class, this method constructed
2690		// a task to run ForkJoinTask.invokeAll, but now external
2691		// invocation of multiple tasks is at least as efficient.
2692	<	List<ForkJoinTask<T>> fs = new ArrayList<ForkJoinTask<T>>(tasks.size());
2603	<	// Workaround needed because method wasn't declared with
2604	<	// wildcards in return type but should have been.
2605	<	@SuppressWarnings({"unchecked", "rawtypes"})
2606	<	List<Future<T>> futures = (List<Future<T>>) (List) fs;
2692	>	ArrayList<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
2693
2694		boolean done = false;
2695		try {
2696		for (Callable<T> t : tasks) {
2697		ForkJoinTask<T> f = new ForkJoinTask.AdaptedCallable<T>(t);
2698	+	futures.add(f);
2699		externalPush(f);
2613	–	fs.add(f);
2700		}
2701	<	for (ForkJoinTask<T> f : fs)
2702	<	f.quietlyJoin();
2701	>	for (int i = 0, size = futures.size(); i < size; i++)
2702	>	((ForkJoinTask<?>)futures.get(i)).quietlyJoin();
2703		done = true;
2704		return futures;
2705		} finally {
2706		if (!done)
2707	<	for (ForkJoinTask<T> f : fs)
2708	<	f.cancel(false);
2707	>	for (int i = 0, size = futures.size(); i < size; i++)
2708	>	futures.get(i).cancel(false);
2709		}
2710		}
2711
#	Line 2648 | Line 2734 | public class ForkJoinPool extends Abstra
2734		* @return the targeted parallelism level of this pool
2735		*/
2736		public int getParallelism() {
2737	<	return parallelism;
2737	>	return config & SMASK;
2738		}
2739
2740		/**
2741		* Returns the targeted parallelism level of the common pool.
2742		*
2743		* @return the targeted parallelism level of the common pool
2744	+	* @since 1.8
2745		*/
2746		public static int getCommonPoolParallelism() {
2747	<	return commonPoolParallelism;
2747	>	return commonParallelism;
2748		}
2749
2750		/**
#	Line 2669 | Line 2756 | public class ForkJoinPool extends Abstra
2756		* @return the number of worker threads
2757		*/
2758		public int getPoolSize() {
2759	<	return parallelism + (short)(ctl >>> TC_SHIFT);
2759	>	return (config & SMASK) + (short)(ctl >>> TC_SHIFT);
2760		}
2761
2762		/**
#	Line 2679 | Line 2766 | public class ForkJoinPool extends Abstra
2766		* @return {@code true} if this pool uses async mode
2767		*/
2768		public boolean getAsyncMode() {
2769	<	return localMode != 0;
2769	>	return (config >>> 16) == FIFO_QUEUE;
2770		}
2771
2772		/**
#	Line 2710 | Line 2797 | public class ForkJoinPool extends Abstra
2797		* @return the number of active threads
2798		*/
2799		public int getActiveThreadCount() {
2800	<	int r = parallelism + (int)(ctl >> AC_SHIFT);
2800	>	int r = (config & SMASK) + (int)(ctl >> AC_SHIFT);
2801		return (r <= 0) ? 0 : r; // suppress momentarily negative values
2802		}
2803
#	Line 2726 | Line 2813 | public class ForkJoinPool extends Abstra
2813		* @return {@code true} if all threads are currently idle
2814		*/
2815		public boolean isQuiescent() {
2816	<	return (int)(ctl >> AC_SHIFT) + parallelism == 0;
2816	>	return (int)(ctl >> AC_SHIFT) + (config & SMASK) == 0;
2817		}
2818
2819		/**
#	Line 2803 | Line 2890 | public class ForkJoinPool extends Abstra
2890		WorkQueue[] ws; WorkQueue w;
2891		if ((ws = workQueues) != null) {
2892		for (int i = 0; i < ws.length; i += 2) {
2893	<	if ((w = ws[i]) != null && w.queueSize() != 0)
2893	>	if ((w = ws[i]) != null && !w.isEmpty())
2894		return true;
2895		}
2896		}
#	Line 2889 | Line 2976 | public class ForkJoinPool extends Abstra
2976		}
2977		}
2978		}
2979	<	int pc = parallelism;
2979	>	int pc = (config & SMASK);
2980		int tc = pc + (short)(c >>> TC_SHIFT);
2981		int ac = pc + (int)(c >> AC_SHIFT);
2982		if (ac < 0) // ignore transient negative
#	Line 2915 | Line 3002 | public class ForkJoinPool extends Abstra
3002		* Possibly initiates an orderly shutdown in which previously
3003		* submitted tasks are executed, but no new tasks will be
3004		* accepted. Invocation has no effect on execution state if this
3005	<	* is the {@link #commonPool}, and no additional effect if
3005	>	* is the {@link #commonPool()}, and no additional effect if
3006		* already shut down.  Tasks that are in the process of being
3007		* submitted concurrently during the course of this method may or
3008		* may not be rejected.
#	Line 2933 | Line 3020 | public class ForkJoinPool extends Abstra
3020		/**
3021		* Possibly attempts to cancel and/or stop all tasks, and reject
3022		* all subsequently submitted tasks.  Invocation has no effect on
3023	<	* execution state if this is the {@link #commonPool}, and no
3023	>	* execution state if this is the {@link #commonPool()}, and no
3024		* additional effect if already shut down. Otherwise, tasks that
3025		* are in the process of being submitted or executed concurrently
3026		* during the course of this method may or may not be
#	Line 2962 | Line 3049 | public class ForkJoinPool extends Abstra
3049		public boolean isTerminated() {
3050		long c = ctl;
3051		return ((c & STOP_BIT) != 0L &&
3052	<	(short)(c >>> TC_SHIFT) == -parallelism);
3052	>	(short)(c >>> TC_SHIFT) == -(config & SMASK));
3053		}
3054
3055		/**
#	Line 2970 | Line 3057 | public class ForkJoinPool extends Abstra
3057		* commenced but not yet completed.  This method may be useful for
3058		* debugging. A return of {@code true} reported a sufficient
3059		* period after shutdown may indicate that submitted tasks have
3060	<	* ignored or suppressed interruption, or are waiting for IO,
3060	>	* ignored or suppressed interruption, or are waiting for I/O,
3061		* causing this executor not to properly terminate. (See the
3062		* advisory notes for class {@link ForkJoinTask} stating that
3063		* tasks should not normally entail blocking operations.  But if
#	Line 2981 | Line 3068 | public class ForkJoinPool extends Abstra
3068		public boolean isTerminating() {
3069		long c = ctl;
3070		return ((c & STOP_BIT) != 0L &&
3071	<	(short)(c >>> TC_SHIFT) != -parallelism);
3071	>	(short)(c >>> TC_SHIFT) != -(config & SMASK));
3072		}
3073
3074		/**
#	Line 2996 | Line 3083 | public class ForkJoinPool extends Abstra
3083		/**
3084		* Blocks until all tasks have completed execution after a
3085		* shutdown request, or the timeout occurs, or the current thread
3086	<	* is interrupted, whichever happens first. Note that the {@link
3087	<	* #commonPool()} never terminates until program shutdown so
3088	<	* this method will always time out.
3086	>	* is interrupted, whichever happens first. Because the {@link
3087	>	* #commonPool()} never terminates until program shutdown, when
3088	>	* applied to the common pool, this method is equivalent to {@link
3089	>	* #awaitQuiescence} but always returns {@code false}.
3090		*
3091		* @param timeout the maximum time to wait
3092		* @param unit the time unit of the timeout argument
#	Line 3008 | Line 3096 | public class ForkJoinPool extends Abstra
3096		*/
3097		public boolean awaitTermination(long timeout, TimeUnit unit)
3098		throws InterruptedException {
3099	+	if (Thread.interrupted())
3100	+	throw new InterruptedException();
3101	+	if (this == common) {
3102	+	awaitQuiescence(timeout, unit);
3103	+	return false;
3104	+	}
3105		long nanos = unit.toNanos(timeout);
3106		if (isTerminated())
3107		return true;
#	Line 3027 | Line 3121 | public class ForkJoinPool extends Abstra
3121		}
3122
3123		/**
3124	+	* If called by a ForkJoinTask operating in this pool, equivalent
3125	+	* in effect to {@link ForkJoinTask#helpQuiesce}. Otherwise,
3126	+	* waits and/or attempts to assist performing tasks until this
3127	+	* pool {@link #isQuiescent} or the indicated timeout elapses.
3128	+	*
3129	+	* @param timeout the maximum time to wait
3130	+	* @param unit the time unit of the timeout argument
3131	+	* @return {@code true} if quiescent; {@code false} if the
3132	+	* timeout elapsed.
3133	+	*/
3134	+	public boolean awaitQuiescence(long timeout, TimeUnit unit) {
3135	+	long nanos = unit.toNanos(timeout);
3136	+	ForkJoinWorkerThread wt;
3137	+	Thread thread = Thread.currentThread();
3138	+	if ((thread instanceof ForkJoinWorkerThread) &&
3139	+	(wt = (ForkJoinWorkerThread)thread).pool == this) {
3140	+	helpQuiescePool(wt.workQueue);
3141	+	return true;
3142	+	}
3143	+	long startTime = System.nanoTime();
3144	+	WorkQueue[] ws;
3145	+	int r = 0, m;
3146	+	boolean found = true;
3147	+	while (!isQuiescent() && (ws = workQueues) != null &&
3148	+	(m = ws.length - 1) >= 0) {
3149	+	if (!found) {
3150	+	if ((System.nanoTime() - startTime) > nanos)
3151	+	return false;
3152	+	Thread.yield(); // cannot block
3153	+	}
3154	+	found = false;
3155	+	for (int j = (m + 1) << 2; j >= 0; --j) {
3156	+	ForkJoinTask<?> t; WorkQueue q; int b;
3157	+	if ((q = ws[r++ & m]) != null && (b = q.base) - q.top < 0) {
3158	+	found = true;
3159	+	if ((t = q.pollAt(b)) != null) {
3160	+	if (q.base - q.top < 0)
3161	+	signalWork(q);
3162	+	t.doExec();
3163	+	}
3164	+	break;
3165	+	}
3166	+	}
3167	+	}
3168	+	return true;
3169	+	}
3170	+
3171	+	/**
3172	+	* Waits and/or attempts to assist performing tasks indefinitely
3173	+	* until the {@link #commonPool()} {@link #isQuiescent}.
3174	+	*/
3175	+	static void quiesceCommonPool() {
3176	+	common.awaitQuiescence(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
3177	+	}
3178	+
3179	+	/**
3180		* Interface for extending managed parallelism for tasks running
3181		* in {@link ForkJoinPool}s.
3182		*
#	Line 3125 | Line 3275 | public class ForkJoinPool extends Abstra
3275		if (t instanceof ForkJoinWorkerThread) {
3276		ForkJoinPool p = ((ForkJoinWorkerThread)t).pool;
3277		while (!blocker.isReleasable()) { // variant of helpSignal
3278	<	WorkQueue[] ws; WorkQueue q; int m, n;
3278	>	WorkQueue[] ws; WorkQueue q; int m, u;
3279		if ((ws = p.workQueues) != null && (m = ws.length - 1) >= 0) {
3280		for (int i = 0; i <= m; ++i) {
3281		if (blocker.isReleasable())
3282		return;
3283	<	if ((q = ws[i]) != null && (n = q.queueSize()) > 0) {
3284	<	p.signalWork(q, n);
3285	<	if ((int)(p.ctl >> AC_SHIFT) >= 0)
3283	>	if ((q = ws[i]) != null && q.base - q.top < 0) {
3284	>	p.signalWork(q);
3285	>	if ((u = (int)(p.ctl >>> 32)) >= 0 ||
3286	>	(u >> UAC_SHIFT) >= 0)
3287		break;
3288		}
3289		}
#	Line 3178 | Line 3329 | public class ForkJoinPool extends Abstra
3329		private static final long QLOCK;
3330
3331		static {
3332	<	// Establish common pool parameters
3182	<	// TBD: limit or report ignored exceptions?
3183	<
3184	<	int par = 0;
3185	<	ForkJoinWorkerThreadFactory fac = null;
3186	<	Thread.UncaughtExceptionHandler handler = null;
3187	<	try {
3188	<	String pp = System.getProperty(propPrefix + "parallelism");
3189	<	String hp = System.getProperty(propPrefix + "exceptionHandler");
3190	<	String fp = System.getProperty(propPrefix + "threadFactory");
3191	<	if (fp != null)
3192	<	fac = ((ForkJoinWorkerThreadFactory)ClassLoader.
3193	<	getSystemClassLoader().loadClass(fp).newInstance());
3194	<	if (hp != null)
3195	<	handler = ((Thread.UncaughtExceptionHandler)ClassLoader.
3196	<	getSystemClassLoader().loadClass(hp).newInstance());
3197	<	if (pp != null)
3198	<	par = Integer.parseInt(pp);
3199	<	} catch (Exception ignore) {
3200	<	}
3201	<
3202	<	int s; // initialize field offsets for CAS etc
3332	>	// initialize field offsets for CAS etc
3333		try {
3334		U = getUnsafe();
3335		Class<?> k = ForkJoinPool.class;
#	Line 3219 | Line 3349 | public class ForkJoinPool extends Abstra
3349		(wk.getDeclaredField("qlock"));
3350		Class<?> ak = ForkJoinTask[].class;
3351		ABASE = U.arrayBaseOffset(ak);
3352	<	s = U.arrayIndexScale(ak);
3353	<	ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
3352	>	int scale = U.arrayIndexScale(ak);
3353	>	if ((scale & (scale - 1)) != 0)
3354	>	throw new Error("data type scale not a power of two");
3355	>	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
3356		} catch (Exception e) {
3357		throw new Error(e);
3358		}
3359	<	if ((s & (s-1)) != 0)
3360	<	throw new Error("data type scale not a power of two");
3359	>
3360	>	submitters = new ThreadLocal<Submitter>();
3361	>	ForkJoinWorkerThreadFactory fac = defaultForkJoinWorkerThreadFactory =
3362	>	new DefaultForkJoinWorkerThreadFactory();
3363	>	modifyThreadPermission = new RuntimePermission("modifyThread");
3364
3365		/*
3366	<	* For extra caution, computations to set up pool state are
3367	<	* here; the constructor just assigns these values to fields.
3366	>	* Establish common pool parameters.  For extra caution,
3367	>	* computations to set up common pool state are here; the
3368	>	* constructor just assigns these values to fields.
3369		*/
3370	<	ForkJoinWorkerThreadFactory defaultFac =
3371	<	defaultForkJoinWorkerThreadFactory =
3372	<	new DefaultForkJoinWorkerThreadFactory();
3373	<	if (fac == null)
3374	<	fac = defaultFac;
3370	>
3371	>	int par = 0;
3372	>	Thread.UncaughtExceptionHandler handler = null;
3373	>	try {  // TBD: limit or report ignored exceptions?
3374	>	String pp = System.getProperty
3375	>	("java.util.concurrent.ForkJoinPool.common.parallelism");
3376	>	String hp = System.getProperty
3377	>	("java.util.concurrent.ForkJoinPool.common.exceptionHandler");
3378	>	String fp = System.getProperty
3379	>	("java.util.concurrent.ForkJoinPool.common.threadFactory");
3380	>	if (fp != null)
3381	>	fac = ((ForkJoinWorkerThreadFactory)ClassLoader.
3382	>	getSystemClassLoader().loadClass(fp).newInstance());
3383	>	if (hp != null)
3384	>	handler = ((Thread.UncaughtExceptionHandler)ClassLoader.
3385	>	getSystemClassLoader().loadClass(hp).newInstance());
3386	>	if (pp != null)
3387	>	par = Integer.parseInt(pp);
3388	>	} catch (Exception ignore) {
3389	>	}
3390	>
3391		if (par <= 0)
3392		par = Runtime.getRuntime().availableProcessors();
3393		if (par > MAX_CAP)
3394		par = MAX_CAP;
3395	+	commonParallelism = par;
3396		long np = (long)(-par); // precompute initial ctl value
3397		long ct = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
3398
3399	<	commonPoolParallelism = par;
3247	<	commonPool = new ForkJoinPool(par, ct, fac, handler);
3248	<	modifyThreadPermission = new RuntimePermission("modifyThread");
3249	<	submitters = new ThreadLocal<Submitter>();
3399	>	common = new ForkJoinPool(par, ct, fac, handler);
3400		}
3401
3402		/**
#	Line 3259 | Line 3409 | public class ForkJoinPool extends Abstra
3409		private static sun.misc.Unsafe getUnsafe() {
3410		try {
3411		return sun.misc.Unsafe.getUnsafe();
3412	<	} catch (SecurityException se) {
3413	<	try {
3414	<	return java.security.AccessController.doPrivileged
3415	<	(new java.security
3416	<	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
3417	<	public sun.misc.Unsafe run() throws Exception {
3418	<	java.lang.reflect.Field f = sun.misc
3419	<	.Unsafe.class.getDeclaredField("theUnsafe");
3420	<	f.setAccessible(true);
3421	<	return (sun.misc.Unsafe) f.get(null);
3422	<	}});
3423	<	} catch (java.security.PrivilegedActionException e) {
3424	<	throw new RuntimeException("Could not initialize intrinsics",
3425	<	e.getCause());
3426	<	}
3412	>	} catch (SecurityException tryReflectionInstead) {}
3413	>	try {
3414	>	return java.security.AccessController.doPrivileged
3415	>	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
3416	>	public sun.misc.Unsafe run() throws Exception {
3417	>	Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
3418	>	for (java.lang.reflect.Field f : k.getDeclaredFields()) {
3419	>	f.setAccessible(true);
3420	>	Object x = f.get(null);
3421	>	if (k.isInstance(x))
3422	>	return k.cast(x);
3423	>	}
3424	>	throw new NoSuchFieldError("the Unsafe");
3425	>	}});
3426	>	} catch (java.security.PrivilegedActionException e) {
3427	>	throw new RuntimeException("Could not initialize intrinsics",
3428	>	e.getCause());
3429		}
3430		}
3279	–
3431		}

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