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

Comparing jsr166/src/jsr166e/ForkJoinPool.java (file contents):
Revision 1.14 by jsr166, Wed Nov 14 19:05:03 2012 UTC vs.
Revision 1.34 by dl, Mon Dec 17 16:31:08 2012 UTC

#	Line 17 | Line 17 | import java.util.concurrent.ExecutorServ
17		import java.util.concurrent.Future;
18		import java.util.concurrent.RejectedExecutionException;
19		import java.util.concurrent.RunnableFuture;
20	–	import java.util.concurrent.ThreadLocalRandom;
20		import java.util.concurrent.TimeUnit;
21
22		/**
#	Line 38 | 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 52 | 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 63 | Line 62 | import java.util.concurrent.TimeUnit;
62		* {@link #toString} returns indications of pool state in a
63		* convenient form for informal monitoring.
64		*
65	<	* <p> As is the case with other ExecutorServices, there are three
65	>	* <p>As is the case with other ExecutorServices, there are three
66		* main task execution methods summarized in the following table.
67		* These are designed to be used primarily by clients not already
68		* engaged in fork/join computations in the current pool.  The main
#	Line 100 | 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
106		* exceptionHandler} -- the class name of a {@link
107	+	* java.lang.Thread.UncaughtExceptionHandler
108		* Thread.UncaughtExceptionHandler}. Upon any error in establishing
109		* these settings, default parameters are used.
110		*
#	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 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	>	* @throw 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 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;
#	Line 1057 | Line 1044 | public class ForkJoinPool extends Abstra
1044		}
1045		}
1046
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	–
1047		// static fields (initialized in static initializer below)
1048
1049		/**
#	Line 1091 | Line 1054 | public class ForkJoinPool extends Abstra
1054		defaultForkJoinWorkerThreadFactory;
1055
1056		/**
1057	<	* Common (static) pool. Non-null for public use unless a static
1058	<	* construction exception, but internal usages null-check on use
1059	<	* to paranoically avoid potential initialization circularities
1060	<	* as well as to simplify generated code.
1057	>	* Per-thread submission bookkeeping. Shared across all pools
1058	>	* to reduce ThreadLocal pollution and because random motion
1059	>	* to avoid contention in one pool is likely to hold for others.
1060	>	* Lazily initialized on first submission (but null-checked
1061	>	* in other contexts to avoid unnecessary initialization).
1062		*/
1063	<	static final ForkJoinPool commonPool;
1063	>	static final ThreadLocal<Submitter> submitters;
1064
1065		/**
1066		* Permission required for callers of methods that may start or
#	Line 1105 | Line 1069 | public class ForkJoinPool extends Abstra
1069		private static final RuntimePermission modifyThreadPermission;
1070
1071		/**
1072	<	* Per-thread submission bookkeeping. Shared across all pools
1073	<	* to reduce ThreadLocal pollution and because random motion
1074	<	* to avoid contention in one pool is likely to hold for others.
1075	<	* Lazily initialized on first submission (but null-checked
1112	<	* in other contexts to avoid unnecessary initialization).
1072	>	* Common (static) pool. Non-null for public use unless a static
1073	>	* construction exception, but internal usages null-check on use
1074	>	* to paranoically avoid potential initialization circularities
1075	>	* as well as to simplify generated code.
1076		*/
1077	<	static final ThreadLocal<Submitter> submitters;
1077	>	static final ForkJoinPool commonPool;
1078
1079		/**
1080		* Common pool parallelism. Must equal commonPool.parallelism.
#	Line 1149 | Line 1112 | public class ForkJoinPool extends Abstra
1112		private static final long FAST_IDLE_TIMEOUT =  200L * 1000L * 1000L;
1113
1114		/**
1115	+	* Tolerance for idle timeouts, to cope with timer undershoots
1116	+	*/
1117	+	private static final long TIMEOUT_SLOP = 2000000L;
1118	+
1119	+	/**
1120		* The maximum stolen->joining link depth allowed in method
1121		* tryHelpStealer.  Must be a power of two.  Depths for legitimate
1122		* chains are unbounded, but we use a fixed constant to avoid
#	Line 1248 | Line 1216 | public class ForkJoinPool extends Abstra
1216		static final int FIFO_QUEUE          =  1;
1217		static final int SHARED_QUEUE        = -1;
1218
1219	+	// bounds for #steps in scan loop -- must be power 2 minus 1
1220	+	private static final int MIN_SCAN    = 0x1ff;   // cover estimation slop
1221	+	private static final int MAX_SCAN    = 0x1ffff; // 4 * max workers
1222	+
1223		// Instance fields
1224
1225		/*
1226	<	* Field layout order in this class tends to matter more than one
1227	<	* would like. Runtime layout order is only loosely related to
1226	>	* Field layout of this class tends to matter more than one would
1227	>	* like. Runtime layout order is only loosely related to
1228		* declaration order and may differ across JVMs, but the following
1229		* empirically works OK on current JVMs.
1230		*/
1231	+
1232	+	// Heuristic padding to ameliorate unfortunate memory placements
1233	+	volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
1234	+
1235		volatile long stealCount;                  // collects worker counts
1236		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
1237		volatile int plock;                        // shutdown status and seqLock
1238	+	volatile int indexSeed;                    // worker/submitter index seed
1239	+	final int config;                          // mode and parallelism level
1240		WorkQueue[] workQueues;                    // main registry
1241	<	final ForkJoinWorkerThreadFactory factory; // factory for new workers
1241	>	final ForkJoinWorkerThreadFactory factory;
1242		final Thread.UncaughtExceptionHandler ueh; // per-worker UEH
1243		final String workerNamePrefix;             // to create worker name string
1244
1245	+	volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17;
1246	+	volatile Object pad18, pad19, pad1a, pad1b;
1247	+
1248		/*
1249		* Acquires the plock lock to protect worker array and related
1250		* updates. This method is called only if an initial CAS on plock
1251		* fails. This acts as a spinLock for normal cases, but falls back
1252		* to builtin monitor to block when (rarely) needed. This would be
1253		* a terrible idea for a highly contended lock, but works fine as
1254	<	* a more conservative alternative to a pure spinlock.  See
1277	<	* internal ConcurrentHashMap documentation for further
1278	<	* explanation of nearly the same construction.
1254	>	* a more conservative alternative to a pure spinlock.
1255		*/
1256		private int acquirePlock() {
1257		int spins = PL_SPINS, r = 0, ps, nps;
#	Line 1283 | Line 1259 | public class ForkJoinPool extends Abstra
1259		if (((ps = plock) & PL_LOCK) == 0 &&
1260		U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK))
1261		return nps;
1262	<	else if (r == 0)
1263	<	r = ThreadLocalRandom.current().nextInt(); // randomize spins
1262	>	else if (r == 0) { // randomize spins if possible
1263	>	Thread t = Thread.currentThread(); WorkQueue w; Submitter z;
1264	>	if ((t instanceof ForkJoinWorkerThread) &&
1265	>	(w = ((ForkJoinWorkerThread)t).workQueue) != null)
1266	>	r = w.seed;
1267	>	else if ((z = submitters.get()) != null)
1268	>	r = z.seed;
1269	>	else
1270	>	r = 1;
1271	>	}
1272		else if (spins >= 0) {
1273		r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
1274		if (r >= 0)
#	Line 1318 | Line 1302 | public class ForkJoinPool extends Abstra
1302		synchronized (this) { notifyAll(); }
1303		}
1304
1305	+	/**
1306	+	* Performs secondary initialization, called when plock is zero.
1307	+	* Creates workQueue array and sets plock to a valid value.  The
1308	+	* lock body must be exception-free (so no try/finally) so we
1309	+	* optimistically allocate new array outside the lock and throw
1310	+	* away if (very rarely) not needed. (A similar tactic is used in
1311	+	* fullExternalPush.)  Because the plock seq value can eventually
1312	+	* wrap around zero, this method harmlessly fails to reinitialize
1313	+	* if workQueues exists, while still advancing plock.
1314	+	*
1315	+	* Additionally tries to create the first worker.
1316	+	*/
1317	+	private void initWorkers() {
1318	+	WorkQueue[] ws, nws; int ps;
1319	+	int p = config & SMASK;        // find power of two table size
1320	+	int n = (p > 1) ? p - 1 : 1;   // ensure at least 2 slots
1321	+	n |= n >>> 1; n |= n >>> 2; n |= n >>> 4; n |= n >>> 8; n |= n >>> 16;
1322	+	n = (n + 1) << 1;
1323	+	if ((ws = workQueues) == null || ws.length == 0)
1324	+	nws = new WorkQueue[n];
1325	+	else
1326	+	nws = null;
1327	+	if (((ps = plock) & PL_LOCK) != 0 ||
1328	+	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1329	+	ps = acquirePlock();
1330	+	if (((ws = workQueues) == null || ws.length == 0) && nws != null)
1331	+	workQueues = nws;
1332	+	int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1333	+	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1334	+	releasePlock(nps);
1335	+	tryAddWorker();
1336	+	}
1337	+
1338	+	/**
1339	+	* Tries to create and start one worker if fewer than target
1340	+	* parallelism level exist. Adjusts counts etc on failure.
1341	+	*/
1342	+	private void tryAddWorker() {
1343	+	long c; int u;
1344	+	while ((u = (int)((c = ctl) >>> 32)) < 0 &&
1345	+	(u & SHORT_SIGN) != 0 && (int)c == 0) {
1346	+	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
1347	+	((u + UAC_UNIT) & UAC_MASK)) << 32;
1348	+	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1349	+	ForkJoinWorkerThreadFactory fac;
1350	+	Throwable ex = null;
1351	+	ForkJoinWorkerThread wt = null;
1352	+	try {
1353	+	if ((fac = factory) != null &&
1354	+	(wt = fac.newThread(this)) != null) {
1355	+	wt.start();
1356	+	break;
1357	+	}
1358	+	} catch (Throwable e) {
1359	+	ex = e;
1360	+	}
1361	+	deregisterWorker(wt, ex);
1362	+	break;
1363	+	}
1364	+	}
1365	+	}
1366	+
1367		//  Registering and deregistering workers
1368
1369		/**
1370	<	* Callback from ForkJoinWorkerThread constructor to establish its
1371	<	* poolIndex and record its WorkQueue. To avoid scanning bias due
1372	<	* to packing entries in front of the workQueues array, we treat
1373	<	* the array as a simple power-of-two hash table using per-thread
1374	<	* seed as hash, expanding as needed.
1375	<	*
1376	<	* @param w the worker's queue
1377	<	*/
1378	<	final void registerWorker(WorkQueue w) {
1379	<	int s, ps; // generate a rarely colliding candidate index seed
1380	<	do {} while (!U.compareAndSwapInt(this, INDEXSEED,
1381	<	s = indexSeed, s += SEED_INCREMENT) ||
1370	>	* Callback from ForkJoinWorkerThread to establish and record its
1371	>	* WorkQueue. To avoid scanning bias due to packing entries in
1372	>	* front of the workQueues array, we treat the array as a simple
1373	>	* power-of-two hash table using per-thread seed as hash,
1374	>	* expanding as needed.
1375	>	*
1376	>	* @param wt the worker thread
1377	>	* @return the worker's queue
1378	>	*/
1379	>	final WorkQueue registerWorker(ForkJoinWorkerThread wt) {
1380	>	Thread.UncaughtExceptionHandler handler; WorkQueue[] ws; int s, ps;
1381	>	wt.setDaemon(true);
1382	>	if ((handler = ueh) != null)
1383	>	wt.setUncaughtExceptionHandler(handler);
1384	>	do {} while (!U.compareAndSwapInt(this, INDEXSEED, s = indexSeed,
1385	>	s += SEED_INCREMENT) ||
1386		s == 0); // skip 0
1387	+	WorkQueue w = new WorkQueue(this, wt, config >>> 16, s);
1388		if (((ps = plock) & PL_LOCK) != 0 ||
1389		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1390		ps = acquirePlock();
1391		int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1392		try {
1393	<	WorkQueue[] ws;
1343	<	if (w != null && (ws = workQueues) != null) {
1344	<	w.seed = s;
1393	>	if ((ws = workQueues) != null) {    // skip if shutting down
1394		int n = ws.length, m = n - 1;
1395	<	int r = (s << 1) | 1;               // use odd-numbered indices
1396	<	if (ws[r &= m] != null) {           // collision
1397	<	int probes = 0;                 // step by approx half size
1395	>	int r = (s << 1) | 1;           // use odd-numbered indices
1396	>	if (ws[r &= m] != null) {       // collision
1397	>	int probes = 0;             // step by approx half size
1398		int step = (n <= 4) ? 2 : ((n >>> 1) & EVENMASK) + 2;
1399		while (ws[r = (r + step) & m] != null) {
1400		if (++probes >= n) {
#	Line 1355 | Line 1404 | public class ForkJoinPool extends Abstra
1404		}
1405		}
1406		}
1407	<	w.eventCount = w.poolIndex = r;     // establish before recording
1407	>	w.eventCount = w.poolIndex = r; // volatile write orders
1408		ws[r] = w;
1409		}
1410		} finally {
1411		if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1412		releasePlock(nps);
1413		}
1414	+	wt.setName(workerNamePrefix.concat(Integer.toString(w.poolIndex)));
1415	+	return w;
1416		}
1417
1418		/**
#	Line 1377 | Line 1428 | public class ForkJoinPool extends Abstra
1428		WorkQueue w = null;
1429		if (wt != null && (w = wt.workQueue) != null) {
1430		int ps;
1380	–	collectStealCount(w);
1431		w.qlock = -1;                // ensure set
1432	+	long ns = w.nsteals, sc;     // collect steal count
1433	+	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1434	+	sc = stealCount, sc + ns));
1435		if (((ps = plock) & PL_LOCK) != 0 ||
1436		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1437		ps = acquirePlock();
#	Line 1394 | Line 1447 | public class ForkJoinPool extends Abstra
1447		}
1448		}
1449
1450	<	long c;                             // adjust ctl counts
1450	>	long c;                          // adjust ctl counts
1451		do {} while (!U.compareAndSwapLong
1452		(this, CTL, c = ctl, (((c - AC_UNIT) & AC_MASK) |
1453		((c - TC_UNIT) & TC_MASK) |
1454		(c & ~(AC_MASK|TC_MASK)))));
1455
1456	<	if (!tryTerminate(false, false) && w != null) {
1457	<	w.cancelAll();                  // cancel remaining tasks
1458	<	if (w.array != null)            // suppress signal if never ran
1459	<	signalWork(null, 1);        // wake up or create replacement
1460	<	if (ex == null)                 // help clean refs on way out
1461	<	ForkJoinTask.helpExpungeStaleExceptions();
1456	>	if (!tryTerminate(false, false) && w != null && w.array != null) {
1457	>	w.cancelAll();               // cancel remaining tasks
1458	>	WorkQueue[] ws; WorkQueue v; Thread p; int u, i, e;
1459	>	while ((u = (int)((c = ctl) >>> 32)) < 0 && (e = (int)c) >= 0) {
1460	>	if (e > 0) {             // activate or create replacement
1461	>	if ((ws = workQueues) == null ||
1462	>	(i = e & SMASK) >= ws.length ||
1463	>	(v = ws[i]) != null)
1464	>	break;
1465	>	long nc = (((long)(v.nextWait & E_MASK)) |
1466	>	((long)(u + UAC_UNIT) << 32));
1467	>	if (v.eventCount != (e | INT_SIGN))
1468	>	break;
1469	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1470	>	v.eventCount = (e + E_SEQ) & E_MASK;
1471	>	if ((p = v.parker) != null)
1472	>	U.unpark(p);
1473	>	break;
1474	>	}
1475	>	}
1476	>	else {
1477	>	if ((short)u < 0)
1478	>	tryAddWorker();
1479	>	break;
1480	>	}
1481	>	}
1482		}
1483	<
1484	<	if (ex != null)                     // rethrow
1483	>	if (ex == null)                     // help clean refs on way out
1484	>	ForkJoinTask.helpExpungeStaleExceptions();
1485	>	else                                // rethrow
1486		ForkJoinTask.rethrow(ex);
1487		}
1488
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	–
1489		// Submissions
1490
1491		/**
#	Line 1445 | Line 1502 | public class ForkJoinPool extends Abstra
1502		(ws = workQueues) != null && (m = (ws.length - 1)) >= 0 &&
1503		(q = ws[m & z.seed & SQMASK]) != null &&
1504		U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock
1505	<	int s = q.top, n;
1506	<	if ((a = q.array) != null && a.length > (n = s + 1 - q.base)) {
1507	<	U.putObject(a, (long)(((a.length - 1) & s) << ASHIFT) + ABASE,
1508	<	task);
1505	>	int b = q.base, s = q.top, n, an;
1506	>	if ((a = q.array) != null && (an = a.length) > (n = s + 1 - b)) {
1507	>	int j = (((an - 1) & s) << ASHIFT) + ABASE;
1508	>	U.putOrderedObject(a, j, task);
1509		q.top = s + 1;                     // push on to deque
1510		q.qlock = 0;
1511	<	if (n <= 1)
1512	<	signalWork(q, 1);
1511	>	if (n <= 2)
1512	>	signalWork(q);
1513		return;
1514		}
1515		q.qlock = 0;
#	Line 1463 | Line 1520 | public class ForkJoinPool extends Abstra
1520		/**
1521		* Full version of externalPush. This method is called, among
1522		* other times, upon the first submission of the first task to the
1523	<	* pool, so must perform secondary initialization: creating
1524	<	* workQueue array and setting plock to a valid value. It also
1525	<	* detects first submission by an external thread by looking up
1526	<	* its ThreadLocal, and creates a new shared queue if the one at
1527	<	* index if empty or contended. The lock bodies must be
1528	<	* exception-free (so no try/finally) so we optimistically
1529	<	* allocate new queues/arrays outside the locks and throw them
1473	<	* away if (very rarely) not needed. Note that the plock seq value
1474	<	* can eventually wrap around zero, but if so harmlessly fails to
1475	<	* reinitialize.
1523	>	* pool, so must perform secondary initialization (via
1524	>	* initWorkers). It also detects first submission by an external
1525	>	* thread by looking up its ThreadLocal, and creates a new shared
1526	>	* queue if the one at index if empty or contended. The plock lock
1527	>	* body must be exception-free (so no try/finally) so we
1528	>	* optimistically allocate new queues outside the lock and throw
1529	>	* them away if (very rarely) not needed.
1530		*/
1531		private void fullExternalPush(ForkJoinTask<?> task) {
1532	<	for (Submitter z = null;;) {
1533	<	WorkQueue[] ws; WorkQueue q; int ps, m, r, s;
1534	<	if ((ps = plock) < 0)
1532	>	int r = 0; // random index seed
1533	>	for (Submitter z = submitters.get();;) {
1534	>	WorkQueue[] ws; WorkQueue q; int ps, m, k;
1535	>	if (z == null) {
1536	>	if (U.compareAndSwapInt(this, INDEXSEED, r = indexSeed,
1537	>	r += SEED_INCREMENT) && r != 0)
1538	>	submitters.set(z = new Submitter(r));
1539	>	}
1540	>	else if (r == 0) {               // move to a different index
1541	>	r = z.seed;
1542	>	r ^= r << 13;                // same xorshift as WorkQueues
1543	>	r ^= r >>> 17;
1544	>	z.seed = r ^ (r << 5);
1545	>	}
1546	>	else if ((ps = plock) < 0)
1547		throw new RejectedExecutionException();
1548	<	else if ((ws = workQueues) == null || (m = ws.length - 1) < 0) {
1549	<	int n = parallelism - 1; n |= n >>> 1; n |= n >>> 2;
1550	<	n |= n >>> 4; n |= n >>> 8; n |= n >>> 16;
1551	<	WorkQueue[] nws = new WorkQueue[(n + 1) << 1]; // power of two
1552	<	if ((ps & PL_LOCK) != 0 ||
1548	>	else if (ps == 0 || (ws = workQueues) == null ||
1549	>	(m = ws.length - 1) < 0)
1550	>	initWorkers();
1551	>	else if ((q = ws[k = r & m & SQMASK]) != null) {
1552	>	if (q.qlock == 0 && U.compareAndSwapInt(q, QLOCK, 0, 1)) {
1553	>	ForkJoinTask<?>[] a = q.array;
1554	>	int s = q.top;
1555	>	boolean submitted = false;
1556	>	try {                      // locked version of push
1557	>	if ((a != null && a.length > s + 1 - q.base) ||
1558	>	(a = q.growArray()) != null) {   // must presize
1559	>	int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
1560	>	U.putOrderedObject(a, j, task);
1561	>	q.top = s + 1;
1562	>	submitted = true;
1563	>	}
1564	>	} finally {
1565	>	q.qlock = 0;  // unlock
1566	>	}
1567	>	if (submitted) {
1568	>	signalWork(q);
1569	>	return;
1570	>	}
1571	>	}
1572	>	r = 0; // move on failure
1573	>	}
1574	>	else if (((ps = plock) & PL_LOCK) == 0) { // create new queue
1575	>	q = new WorkQueue(this, null, SHARED_QUEUE, r);
1576	>	if (((ps = plock) & PL_LOCK) != 0 ||
1577		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1578		ps = acquirePlock();
1579	<	if ((ws = workQueues) == null)
1580	<	workQueues = nws;
1579	>	if ((ws = workQueues) != null && k < ws.length && ws[k] == null)
1580	>	ws[k] = q;
1581		int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1582		if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1583		releasePlock(nps);
1584		}
1585	<	else if (z == null && (z = submitters.get()) == null) {
1586	<	if (U.compareAndSwapInt(this, INDEXSEED,
1497	<	s = indexSeed, s += SEED_INCREMENT) &&
1498	<	s != 0) // skip 0
1499	<	submitters.set(z = new Submitter(s));
1500	<	}
1501	<	else {
1502	<	int k = (r = z.seed) & m & SQMASK;
1503	<	if ((q = ws[k]) == null && (ps & PL_LOCK) == 0) {
1504	<	(q = new WorkQueue(this, null, SHARED_QUEUE)).poolIndex = k;
1505	<	if (((ps = plock) & PL_LOCK) != 0 ||
1506	<	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1507	<	ps = acquirePlock();
1508	<	WorkQueue w = null;
1509	<	if ((ws = workQueues) != null && k < ws.length &&
1510	<	(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
1523	<	}
1585	>	else
1586	>	r = 0; // try elsewhere while lock held
1587		}
1588		}
1589
#	Line 1535 | Line 1598 | public class ForkJoinPool extends Abstra
1598		}
1599
1600		/**
1601	<	* 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.
1601	>	* Tries to create or activate a worker if too few are active.
1602		*
1603	<	* @param q if non-null, the queue holding tasks to be signalled
1544	<	* @param signals the target number of signals.
1603	>	* @param q the (non-null) queue holding tasks to be signalled
1604		*/
1605	<	final void signalWork(WorkQueue q, int signals) {
1606	<	long c; int e, u, i; WorkQueue[] ws; WorkQueue w; Thread p;
1605	>	final void signalWork(WorkQueue q) {
1606	>	int hint = q.poolIndex;
1607	>	long c; int e, u, i, n; WorkQueue[] ws; WorkQueue w; Thread p;
1608		while ((u = (int)((c = ctl) >>> 32)) < 0) {
1609		if ((e = (int)c) > 0) {
1610		if ((ws = workQueues) != null && ws.length > (i = e & SMASK) &&
#	Line 1552 | Line 1612 | public class ForkJoinPool extends Abstra
1612		long nc = (((long)(w.nextWait & E_MASK)) |
1613		((long)(u + UAC_UNIT) << 32));
1614		if (U.compareAndSwapLong(this, CTL, c, nc)) {
1615	+	w.hint = hint;
1616		w.eventCount = (e + E_SEQ) & E_MASK;
1617		if ((p = w.parker) != null)
1618		U.unpark(p);
1619	<	if (--signals <= 0)
1559	<	break;
1619	>	break;
1620		}
1621	<	else
1562	<	signals = 1;
1563	<	if ((q != null && q.queueSize() == 0))
1621	>	if (q.top - q.base <= 0)
1622		break;
1623		}
1624		else
1625		break;
1626		}
1627	<	else if (e == 0 && (u & SHORT_SIGN) != 0) {
1628	<	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
1629	<	((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
1627	>	else {
1628	>	if ((short)u < 0)
1629	>	tryAddWorker();
1630		break;
1631	+	}
1632		}
1633		}
1634
#	Line 1599 | Line 1638 | public class ForkJoinPool extends Abstra
1638		* Top-level runloop for workers, called by ForkJoinWorkerThread.run.
1639		*/
1640		final void runWorker(WorkQueue w) {
1641	<	// initialize queue array in this thread
1603	<	w.array = new ForkJoinTask<?>[WorkQueue.INITIAL_QUEUE_CAPACITY];
1641	>	w.growArray(); // allocate queue
1642		do { w.runTask(scan(w)); } while (w.qlock >= 0);
1643		}
1644
#	Line 1612 | Line 1650 | public class ForkJoinPool extends Abstra
1650		* contention, or state changes that indicate possible success on
1651		* re-invocation.
1652		*
1653	<	* The scan searches for tasks across a random permutation of
1654	<	* queues (starting at a random index and stepping by a random
1655	<	* relative prime, checking each at least once).  The scan
1656	<	* terminates upon either finding a non-empty queue, or completing
1657	<	* the sweep. If the worker is not inactivated, it takes and
1658	<	* returns a task from this queue. Otherwise, if not activated, it
1659	<	* signals workers (that may include itself) and returns so caller
1660	<	* can retry. Also returns for trtry if the worker array may have
1661	<	* changed during an empty scan.  On failure to find a task, we
1662	<	* take one of the following actions, after which the caller will
1663	<	* retry calling this method unless terminated.
1653	>	* The scan searches for tasks across queues (starting at a random
1654	>	* index, and relying on registerWorker to irregularly scatter
1655	>	* them within array to avoid bias), checking each at least twice.
1656	>	* The scan terminates upon either finding a non-empty queue, or
1657	>	* completing the sweep. If the worker is not inactivated, it
1658	>	* takes and returns a task from this queue. Otherwise, if not
1659	>	* activated, it signals workers (that may include itself) and
1660	>	* returns so caller can retry. Also returns for true if the
1661	>	* worker array may have changed during an empty scan.  On failure
1662	>	* to find a task, we take one of the following actions, after
1663	>	* which the caller will retry calling this method unless
1664	>	* terminated.
1665		*
1666		* * If pool is terminating, terminate the worker.
1667		*
1668		* * If not already enqueued, try to inactivate and enqueue the
1669		* worker on wait queue. Or, if inactivating has caused the pool
1670	<	* to be quiescent, relay to idleAwaitWork to check for
1671	<	* termination and possibly shrink pool.
1670	>	* to be quiescent, relay to idleAwaitWork to possibly shrink
1671	>	* pool.
1672		*
1673		* * If already enqueued and none of the above apply, possibly
1674	<	* (with 1/2 probability) park awaiting signal, else lingering to
1675	<	* help scan and signal.
1674	>	* park awaiting signal, else lingering to help scan and signal.
1675	>	*
1676	>	* * If a non-empty queue discovered or left as a hint,
1677	>	* help wake up other workers before return
1678		*
1679		* @param w the worker (via its WorkQueue)
1680		* @return a task or null if none found
1681		*/
1682		private final ForkJoinTask<?> scan(WorkQueue w) {
1683	<	WorkQueue[] ws; WorkQueue q;           // first update random seed
1684	<	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1685	<	int ps = plock, m;                     // volatile read order matters
1686	<	if ((ws = workQueues) != null && (m = ws.length - 1) > 0) {
1687	<	int ec = w.eventCount;             // ec is negative if inactive
1688	<	int step = (r >>> 16) | 1;         // relatively prime
1689	<	for (int j = (m + 1) << 2;  ; --j, r += step) {
1690	<	ForkJoinTask<?> t; ForkJoinTask<?>[] a; int b, n;
1691	<	if ((q = ws[r & m]) != null && (b = q.base) - q.top < 0 &&
1692	<	(a = q.array) != null) {   // probably nonempty
1683	>	WorkQueue[] ws; int m;
1684	>	int ps = plock;                          // read plock before ws
1685	>	if (w != null && (ws = workQueues) != null && (m = ws.length - 1) >= 0) {
1686	>	int ec = w.eventCount;               // ec is negative if inactive
1687	>	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1688	>	w.hint = -1;                         // update seed and clear hint
1689	>	int j = ((m + m + 1) | MIN_SCAN) & MAX_SCAN;
1690	>	do {
1691	>	WorkQueue q; ForkJoinTask<?>[] a; int b;
1692	>	if ((q = ws[(r + j) & m]) != null && (b = q.base) - q.top < 0 &&
1693	>	(a = q.array) != null) {     // probably nonempty
1694		int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1695	<	t = (ForkJoinTask<?>)U.getObjectVolatile(a, i);
1695	>	ForkJoinTask<?> t = (ForkJoinTask<?>)
1696	>	U.getObjectVolatile(a, i);
1697		if (q.base == b && ec >= 0 && t != null &&
1698		U.compareAndSwapObject(a, i, t, null)) {
1699	<	if ((n = q.top - (q.base = b + 1)) > 0)
1700	<	signalWork(q, n);
1701	<	return t;              // taken
1702	<	}
1703	<	if (j < m || (ec < 0 && (ec = w.eventCount) < 0)) {
1704	<	if ((n = q.queueSize() - 1) > 0)
1705	<	signalWork(q, n);
1706	<	break;                 // let caller retry after signal
1707	<	}
1708	<	}
1709	<	else if (j < 0) {              // end of scan
1710	<	long c = ctl; int e;
1711	<	if (plock != ps)           // incomplete sweep
1712	<	break;
1713	<	if ((e = (int)c) < 0)      // pool is terminating
1714	<	w.qlock = -1;
1715	<	else if (ec >= 0) {        // try to enqueue/inactivate
1716	<	long nc = ((long)ec |
1717	<	((c - AC_UNIT) & (AC_MASK|TC_MASK)));
1718	<	w.nextWait = e;
1719	<	w.eventCount = ec | INT_SIGN; // mark as inactive
1720	<	if (ctl != c ||
1721	<	!U.compareAndSwapLong(this, CTL, c, nc))
1722	<	w.eventCount = ec; // unmark on CAS failure
1723	<	else if ((int)(c >> AC_SHIFT) == 1 - parallelism)
1724	<	idleAwaitWork(w, nc, c);  // quiescent
1699	>	if ((q.base = b + 1) - q.top < 0)
1700	>	signalWork(q);
1701	>	return t;                // taken
1702	>	}
1703	>	else if ((ec < 0 || j < m) && (int)(ctl >> AC_SHIFT) <= 0) {
1704	>	w.hint = (r + j) & m;    // help signal below
1705	>	break;                   // cannot take
1706	>	}
1707	>	}
1708	>	} while (--j >= 0);
1709	>
1710	>	int h, e, ns; long c, sc; WorkQueue q;
1711	>	if ((ns = w.nsteals) != 0) {
1712	>	if (U.compareAndSwapLong(this, STEALCOUNT,
1713	>	sc = stealCount, sc + ns))
1714	>	w.nsteals = 0;               // collect steals and rescan
1715	>	}
1716	>	else if (plock != ps)                // consistency check
1717	>	;                                // skip
1718	>	else if ((e = (int)(c = ctl)) < 0)
1719	>	w.qlock = -1;                    // pool is terminating
1720	>	else {
1721	>	if ((h = w.hint) < 0) {
1722	>	if (ec >= 0) {               // try to enqueue/inactivate
1723	>	long nc = (((long)ec |
1724	>	((c - AC_UNIT) & (AC_MASK|TC_MASK))));
1725	>	w.nextWait = e;          // link and mark inactive
1726	>	w.eventCount = ec | INT_SIGN;
1727	>	if (ctl != c || !U.compareAndSwapLong(this, CTL, c, nc))
1728	>	w.eventCount = ec;   // unmark on CAS failure
1729	>	else if ((int)(c >> AC_SHIFT) == 1 - (config & SMASK))
1730	>	idleAwaitWork(w, nc, c);
1731		}
1732	<	else if (w.seed >= 0 && w.eventCount < 0) {
1732	>	else if (w.eventCount < 0 && !tryTerminate(false, false) &&
1733	>	ctl == c) {         // block
1734		Thread wt = Thread.currentThread();
1735	<	Thread.interrupted();  // clear status
1735	>	Thread.interrupted();    // clear status
1736		U.putObject(wt, PARKBLOCKER, this);
1737	<	w.parker = wt;         // emulate LockSupport.park
1738	<	if (w.eventCount < 0)  // recheck
1737	>	w.parker = wt;           // emulate LockSupport.park
1738	>	if (w.eventCount < 0)    // recheck
1739		U.park(false, 0L);
1740		w.parker = null;
1741		U.putObject(wt, PARKBLOCKER, null);
1742		}
1743	<	break;
1743	>	}
1744	>	if ((h >= 0 || (h = w.hint) >= 0) &&
1745	>	(ws = workQueues) != null && h < ws.length &&
1746	>	(q = ws[h]) != null) {      // signal others before retry
1747	>	WorkQueue v; Thread p; int u, i, s;
1748	>	for (int n = (config & SMASK) >>> 1;;) {
1749	>	int idleCount = (w.eventCount < 0) ? 0 : -1;
1750	>	if (((s = idleCount - q.base + q.top) <= n &&
1751	>	(n = s) <= 0) ||
1752	>	(u = (int)((c = ctl) >>> 32)) >= 0 ||
1753	>	(e = (int)c) <= 0 || m < (i = e & SMASK) ||
1754	>	(v = ws[i]) == null)
1755	>	break;
1756	>	long nc = (((long)(v.nextWait & E_MASK)) |
1757	>	((long)(u + UAC_UNIT) << 32));
1758	>	if (v.eventCount != (e | INT_SIGN) ||
1759	>	!U.compareAndSwapLong(this, CTL, c, nc))
1760	>	break;
1761	>	v.hint = h;
1762	>	v.eventCount = (e + E_SEQ) & E_MASK;
1763	>	if ((p = v.parker) != null)
1764	>	U.unpark(p);
1765	>	if (--n <= 0)
1766	>	break;
1767	>	}
1768		}
1769		}
1770		}
#	Line 1710 | Line 1784 | public class ForkJoinPool extends Abstra
1784		* @param prevCtl the ctl value to restore if thread is terminated
1785		*/
1786		private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) {
1787	<	if (w.eventCount < 0 &&
1788	<	(this == commonPool || !tryTerminate(false, false)) &&
1715	<	(int)prevCtl != 0) {
1787	>	if (w != null && w.eventCount < 0 &&
1788	>	!tryTerminate(false, false) && (int)prevCtl != 0) {
1789		int dc = -(short)(currentCtl >>> TC_SHIFT);
1790		long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT;
1791	<	long deadline = System.nanoTime() + parkTime - 100000L; // 1ms slop
1791	>	long deadline = System.nanoTime() + parkTime - TIMEOUT_SLOP;
1792		Thread wt = Thread.currentThread();
1793		while (ctl == currentCtl) {
1794		Thread.interrupted();  // timed variant of version in scan()
#	Line 1738 | Line 1811 | public class ForkJoinPool extends Abstra
1811		}
1812
1813		/**
1814	<	* Scans through queues looking for work while joining a task;
1815	<	* if any are present, signals.
1814	>	* Scans through queues looking for work while joining a task; if
1815	>	* any present, signals. May return early if more signalling is
1816	>	* detectably unneeded.
1817		*
1818	<	* @param task to return early if done
1818	>	* @param task return early if done
1819		* @param origin an index to start scan
1820		*/
1821	<	final int helpSignal(ForkJoinTask<?> task, int origin) {
1822	<	WorkQueue[] ws; WorkQueue q; int m, n, s;
1823	<	if (task != null && (ws = workQueues) != null &&
1824	<	(m = ws.length - 1) >= 0) {
1825	<	for (int i = 0; i <= m; ++i) {
1826	<	if ((s = task.status) < 0)
1827	<	return s;
1828	<	if ((q = ws[(i + origin) & m]) != null &&
1829	<	(n = q.queueSize()) > 0) {
1830	<	signalWork(q, n);
1831	<	if ((int)(ctl >> AC_SHIFT) >= 0)
1821	>	private void helpSignal(ForkJoinTask<?> task, int origin) {
1822	>	WorkQueue[] ws; WorkQueue w; Thread p; long c; int m, u, e, i, s;
1823	>	if (task != null && task.status >= 0 &&
1824	>	(u = (int)(ctl >>> 32)) < 0 && (u >> UAC_SHIFT) < 0 &&
1825	>	(ws = workQueues) != null && (m = ws.length - 1) >= 0) {
1826	>	outer: for (int k = origin, j = m; j >= 0; --j) {
1827	>	WorkQueue q = ws[k++ & m];
1828	>	for (int n = m;;) { // limit to at most m signals
1829	>	if (task.status < 0)
1830	>	break outer;
1831	>	if (q == null ||
1832	>	((s = -q.base + q.top) <= n && (n = s) <= 0))
1833		break;
1834	+	if ((u = (int)((c = ctl) >>> 32)) >= 0 ||
1835	+	(e = (int)c) <= 0 || m < (i = e & SMASK) ||
1836	+	(w = ws[i]) == null)
1837	+	break outer;
1838	+	long nc = (((long)(w.nextWait & E_MASK)) |
1839	+	((long)(u + UAC_UNIT) << 32));
1840	+	if (w.eventCount != (e | INT_SIGN))
1841	+	break outer;
1842	+	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1843	+	w.eventCount = (e + E_SEQ) & E_MASK;
1844	+	if ((p = w.parker) != null)
1845	+	U.unpark(p);
1846	+	if (--n <= 0)
1847	+	break;
1848	+	}
1849		}
1850		}
1851		}
1762	–	return 0;
1852		}
1853
1854		/**
#	Line 1793 | Line 1882 | public class ForkJoinPool extends Abstra
1882		}
1883		if ((ws = workQueues) == null || (m = ws.length - 1) <= 0)
1884		break restart;              // shutting down
1885	<	if ((v = ws[h = (j.stealHint | 1) & m]) == null ||
1885	>	if ((v = ws[h = (j.hint | 1) & m]) == null ||
1886		v.currentSteal != subtask) {
1887		for (int origin = h;;) {    // find stealer
1888		if (((h = (h + 2) & m) & 15) == 1 &&
#	Line 1801 | Line 1890 | public class ForkJoinPool extends Abstra
1890		continue restart;   // occasional staleness check
1891		if ((v = ws[h]) != null &&
1892		v.currentSteal == subtask) {
1893	<	j.stealHint = h;    // save hint
1893	>	j.hint = h;        // save hint
1894		break;
1895		}
1896		if (h == origin)
#	Line 1850 | Line 1939 | public class ForkJoinPool extends Abstra
1939
1940		/**
1941		* Analog of tryHelpStealer for CountedCompleters. Tries to steal
1942	<	* and run tasks within the target's computation
1942	>	* and run tasks within the target's computation.
1943		*
1944		* @param task the task to join
1945		* @param mode if shared, exit upon completing any task
#	Line 1858 | Line 1947 | public class ForkJoinPool extends Abstra
1947		*
1948		*/
1949		private int helpComplete(ForkJoinTask<?> task, int mode) {
1950	<	WorkQueue[] ws; WorkQueue q; int m, n, s;
1950	>	WorkQueue[] ws; WorkQueue q; int m, n, s, u;
1951		if (task != null && (ws = workQueues) != null &&
1952		(m = ws.length - 1) >= 0) {
1953		for (int j = 1, origin = j;;) {
#	Line 1866 | Line 1955 | public class ForkJoinPool extends Abstra
1955		return s;
1956		if ((q = ws[j & m]) != null && q.pollAndExecCC(task)) {
1957		origin = j;
1958	<	if (mode == SHARED_QUEUE && (int)(ctl >> AC_SHIFT) >= 0)
1958	>	if (mode == SHARED_QUEUE &&
1959	>	((u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0))
1960		break;
1961		}
1962		else if ((j = (j + 2) & m) == origin)
#	Line 1884 | Line 1974 | public class ForkJoinPool extends Abstra
1974		* may become starved.
1975		*/
1976		final boolean tryCompensate() {
1977	<	int pc = parallelism, e, u, i, tc; long c;
1977	>	int pc = config & SMASK, e, i, tc; long c;
1978		WorkQueue[] ws; WorkQueue w; Thread p;
1979	<	if ((e = (int)(c = ctl)) >= 0 && (ws = workQueues) != null) {
1979	>	if ((ws = workQueues) != null && (e = (int)(c = ctl)) >= 0) {
1980		if (e != 0 && (i = e & SMASK) < ws.length &&
1981		(w = ws[i]) != null && w.eventCount == (e | INT_SIGN)) {
1982		long nc = ((long)(w.nextWait & E_MASK) |
#	Line 1898 | Line 1988 | public class ForkJoinPool extends Abstra
1988		return true;   // replace with idle worker
1989		}
1990		}
1991	<	else if ((short)((u = (int)(c >>> 32)) >>> UTC_SHIFT) >= 0 &&
1992	<	(u >> UAC_SHIFT) + pc > 1) {
1991	>	else if ((tc = (short)(c >>> TC_SHIFT)) >= 0 &&
1992	>	(int)(c >> AC_SHIFT) + pc > 1) {
1993		long nc = ((c - AC_UNIT) & AC_MASK) | (c & ~AC_MASK);
1994		if (U.compareAndSwapLong(this, CTL, c, nc))
1995	<	return true;    // no compensation
1995	>	return true;   // no compensation
1996		}
1997	<	else if ((tc = u + pc) < MAX_CAP) {
1997	>	else if (tc + pc < MAX_CAP) {
1998		long nc = ((c + TC_UNIT) & TC_MASK) | (c & ~TC_MASK);
1999		if (U.compareAndSwapLong(this, CTL, c, nc)) {
2000	+	ForkJoinWorkerThreadFactory fac;
2001		Throwable ex = null;
2002		ForkJoinWorkerThread wt = null;
2003		try {
1913	–	ForkJoinWorkerThreadFactory fac;
2004		if ((fac = factory) != null &&
2005		(wt = fac.newThread(this)) != null) {
2006		wt.start();
#	Line 1919 | Line 2009 | public class ForkJoinPool extends Abstra
2009		} catch (Throwable rex) {
2010		ex = rex;
2011		}
2012	<	deregisterWorker(wt, ex); // adjust counts etc
2012	>	deregisterWorker(wt, ex); // clean up and return false
2013		}
2014		}
2015		}
#	Line 1938 | Line 2028 | public class ForkJoinPool extends Abstra
2028		if (joiner != null && task != null && (s = task.status) >= 0) {
2029		ForkJoinTask<?> prevJoin = joiner.currentJoin;
2030		joiner.currentJoin = task;
2031	<	do {} while ((s = task.status) >= 0 &&
1942	<	joiner.queueSize() > 0 &&
2031	>	do {} while ((s = task.status) >= 0 && !joiner.isEmpty() &&
2032		joiner.tryRemoveAndExec(task)); // process local tasks
2033	<	if (s >= 0 && (s = task.status) >= 0 &&
2034	<	(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
2035	<	(task instanceof CountedCompleter))
2036	<	s = helpComplete(task, LIFO_QUEUE);
2033	>	if (s >= 0 && (s = task.status) >= 0) {
2034	>	helpSignal(task, joiner.poolIndex);
2035	>	if ((s = task.status) >= 0 &&
2036	>	(task instanceof CountedCompleter))
2037	>	s = helpComplete(task, LIFO_QUEUE);
2038	>	}
2039		while (s >= 0 && (s = task.status) >= 0) {
2040	<	if ((joiner.queueSize() > 0 ||           // try helping
2040	>	if ((!joiner.isEmpty() ||           // try helping
2041		(s = tryHelpStealer(joiner, task)) == 0) &&
2042	<	(s = task.status) >= 0 && tryCompensate()) {
2043	<	if (task.trySetSignal() && (s = task.status) >= 0) {
2044	<	synchronized (task) {
2045	<	if (task.status >= 0) {
2046	<	try {                // see ForkJoinTask
2047	<	task.wait();     //  for explanation
2048	<	} catch (InterruptedException ie) {
2042	>	(s = task.status) >= 0) {
2043	>	helpSignal(task, joiner.poolIndex);
2044	>	if ((s = task.status) >= 0 && tryCompensate()) {
2045	>	if (task.trySetSignal() && (s = task.status) >= 0) {
2046	>	synchronized (task) {
2047	>	if (task.status >= 0) {
2048	>	try {                // see ForkJoinTask
2049	>	task.wait();     //  for explanation
2050	>	} catch (InterruptedException ie) {
2051	>	}
2052		}
2053	+	else
2054	+	task.notifyAll();
2055		}
1960	–	else
1961	–	task.notifyAll();
2056		}
2057	+	long c;                          // re-activate
2058	+	do {} while (!U.compareAndSwapLong
2059	+	(this, CTL, c = ctl, c + AC_UNIT));
2060		}
1964	–	long c;                          // re-activate
1965	–	do {} while (!U.compareAndSwapLong
1966	–	(this, CTL, c = ctl, c + AC_UNIT));
2061		}
2062		}
2063		joiner.currentJoin = prevJoin;
#	Line 1984 | Line 2078 | public class ForkJoinPool extends Abstra
2078		if (joiner != null && task != null && (s = task.status) >= 0) {
2079		ForkJoinTask<?> prevJoin = joiner.currentJoin;
2080		joiner.currentJoin = task;
2081	<	do {} while ((s = task.status) >= 0 &&
1988	<	joiner.queueSize() > 0 &&
2081	>	do {} while ((s = task.status) >= 0 && !joiner.isEmpty() &&
2082		joiner.tryRemoveAndExec(task));
2083	<	if (s >= 0 && (s = task.status) >= 0 &&
2084	<	(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
2085	<	(task instanceof CountedCompleter))
2086	<	s = helpComplete(task, LIFO_QUEUE);
2087	<	if (s >= 0 && joiner.queueSize() == 0) {
2083	>	if (s >= 0 && (s = task.status) >= 0) {
2084	>	helpSignal(task, joiner.poolIndex);
2085	>	if ((s = task.status) >= 0 &&
2086	>	(task instanceof CountedCompleter))
2087	>	s = helpComplete(task, LIFO_QUEUE);
2088	>	}
2089	>	if (s >= 0 && joiner.isEmpty()) {
2090		do {} while (task.status >= 0 &&
2091		tryHelpStealer(joiner, task) > 0);
2092		}
#	Line 2007 | Line 2102 | public class ForkJoinPool extends Abstra
2102		* @param r a (random) seed for scanning
2103		*/
2104		private WorkQueue findNonEmptyStealQueue(int r) {
2010	–	int step = (r >>> 16) | 1;
2105		for (WorkQueue[] ws;;) {
2106	<	int ps = plock, m;
2106	>	int ps = plock, m, n;
2107		if ((ws = workQueues) == null || (m = ws.length - 1) < 1)
2108		return null;
2109	<	for (int j = (m + 1) << 2; ; r += step) {
2110	<	WorkQueue q = ws[((r << 1) | 1) & m];
2111	<	if (q != null && q.queueSize() > 0)
2109	>	for (int j = (m + 1) << 2; ;) {
2110	>	WorkQueue q = ws[(((r + j) << 1) | 1) & m];
2111	>	if (q != null && (n = q.base - q.top) < 0) {
2112	>	if (n < -1)
2113	>	signalWork(q);
2114		return q;
2115	+	}
2116		else if (--j < 0) {
2117		if (plock == ps)
2118		return null;
#	Line 2058 | Line 2155 | public class ForkJoinPool extends Abstra
2155		}
2156		else
2157		c = ctl;        // re-increment on exit
2158	<	if ((int)(c >> AC_SHIFT) + parallelism == 0) {
2158	>	if ((int)(c >> AC_SHIFT) + (config & SMASK) == 0) {
2159		do {} while (!U.compareAndSwapLong
2160		(this, CTL, c = ctl, c + AC_UNIT));
2161		break;
#	Line 2133 | Line 2230 | public class ForkJoinPool extends Abstra
2230		static int getSurplusQueuedTaskCount() {
2231		Thread t; ForkJoinWorkerThread wt; ForkJoinPool pool; WorkQueue q;
2232		if (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)) {
2233	<	int b = (q = (wt = (ForkJoinWorkerThread)t).workQueue).base;
2234	<	int p = (pool = wt.pool).parallelism;
2233	>	int p = (pool = (wt = (ForkJoinWorkerThread)t).pool).config & SMASK;
2234	>	int n = (q = wt.workQueue).top - q.base;
2235		int a = (int)(pool.ctl >> AC_SHIFT) + p;
2236	<	return q.top - b - (a > (p >>>= 1) ? 0 :
2237	<	a > (p >>>= 1) ? 1 :
2238	<	a > (p >>>= 1) ? 2 :
2239	<	a > (p >>>= 1) ? 4 :
2240	<	8);
2236	>	return n - (a > (p >>>= 1) ? 0 :
2237	>	a > (p >>>= 1) ? 1 :
2238	>	a > (p >>>= 1) ? 2 :
2239	>	a > (p >>>= 1) ? 4 :
2240	>	8);
2241		}
2242		return 0;
2243		}
#	Line 2166 | Line 2263 | public class ForkJoinPool extends Abstra
2263		return false;
2264		for (long c;;) {
2265		if (((c = ctl) & STOP_BIT) != 0) {      // already terminating
2266	<	if ((short)(c >>> TC_SHIFT) == -parallelism) {
2266	>	if ((short)(c >>> TC_SHIFT) == -(config & SMASK)) {
2267		synchronized (this) {
2268		notifyAll();                // signal when 0 workers
2269		}
#	Line 2180 | Line 2277 | public class ForkJoinPool extends Abstra
2277		if (((ps = plock) & PL_LOCK) != 0 ||
2278		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
2279		ps = acquirePlock();
2280	<	int nps = SHUTDOWN;
2281	<	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
2185	<	releasePlock(nps);
2280	>	if (!U.compareAndSwapInt(this, PLOCK, ps, SHUTDOWN))
2281	>	releasePlock(SHUTDOWN);
2282		}
2283		if (!now) {                             // check if idle & no tasks
2284	<	if ((int)(c >> AC_SHIFT) != -parallelism ||
2284	>	if ((int)(c >> AC_SHIFT) != -(config & SMASK) ||
2285		hasQueuedSubmissions())
2286		return false;
2287		// Check for unqueued inactive workers. One pass suffices.
#	Line 2201 | Line 2297 | public class ForkJoinPool extends Abstra
2297		for (int pass = 0; pass < 3; ++pass) {
2298		WorkQueue[] ws = workQueues;
2299		if (ws != null) {
2300	<	WorkQueue w;
2300	>	WorkQueue w; Thread wt;
2301		int n = ws.length;
2302		for (int i = 0; i < n; ++i) {
2303		if ((w = ws[i]) != null) {
2304		w.qlock = -1;
2305		if (pass > 0) {
2306		w.cancelAll();
2307	<	if (pass > 1)
2308	<	w.interruptOwner();
2307	>	if (pass > 1 && (wt = w.owner) != null) {
2308	>	if (!wt.isInterrupted()) {
2309	>	try {
2310	>	wt.interrupt();
2311	>	} catch (SecurityException ignore) {
2312	>	}
2313	>	}
2314	>	U.unpark(wt);
2315	>	}
2316		}
2317		}
2318		}
#	Line 2255 | Line 2358 | public class ForkJoinPool extends Abstra
2358		*/
2359		static boolean tryExternalUnpush(ForkJoinTask<?> t) {
2360		ForkJoinPool p; WorkQueue[] ws; WorkQueue q; Submitter z;
2361	<	ForkJoinTask<?>[] a;  int m, s; long j;
2362	<	if ((z = submitters.get()) != null &&
2361	>	ForkJoinTask<?>[] a;  int m, s;
2362	>	if (t != null &&
2363	>	(z = submitters.get()) != null &&
2364		(p = commonPool) != null &&
2365		(ws = p.workQueues) != null &&
2366		(m = ws.length - 1) >= 0 &&
2367		(q = ws[m & z.seed & SQMASK]) != null &&
2368		(s = q.top) != q.base &&
2369	<	(a = q.array) != null &&
2370	<	U.getObjectVolatile
2371	<	(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
2372	<	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2373	<	if (q.array == a && q.top == s && // recheck
2374	<	U.compareAndSwapObject(a, j, t, null)) {
2375	<	q.top = s - 1;
2369	>	(a = q.array) != null) {
2370	>	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
2371	>	if (U.getObject(a, j) == t &&
2372	>	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2373	>	if (q.array == a && q.top == s && // recheck
2374	>	U.compareAndSwapObject(a, j, t, null)) {
2375	>	q.top = s - 1;
2376	>	q.qlock = 0;
2377	>	return true;
2378	>	}
2379		q.qlock = 0;
2273	–	return true;
2380		}
2275	–	q.qlock = 0;
2381		}
2382		return false;
2383		}
#	Line 2287 | Line 2392 | public class ForkJoinPool extends Abstra
2392		if (q != null && (a = q.array) != null && (m = (a.length - 1)) >= 0 &&
2393		root != null && root.status >= 0) {
2394		for (;;) {
2395	<	int s; Object o; CountedCompleter<?> task = null;
2395	>	int s, u; Object o; CountedCompleter<?> task = null;
2396		if ((s = q.top) - q.base > 0) {
2397		long j = ((m & (s - 1)) << ASHIFT) + ABASE;
2398		if ((o = U.getObject(a, j)) != null &&
#	Line 2310 | Line 2415 | public class ForkJoinPool extends Abstra
2415		}
2416		if (task != null)
2417		task.doExec();
2418	<	if (root.status < 0 || (int)(ctl >> AC_SHIFT) >= 0)
2418	>	if (root.status < 0 ||
2419	>	(u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0)
2420		break;
2421		if (task == null) {
2422	<	if (helpSignal(root, q.poolIndex) >= 0)
2422	>	helpSignal(root, q.poolIndex);
2423	>	if (root.status >= 0)
2424		helpComplete(root, SHARED_QUEUE);
2425		break;
2426		}
#	Line 2328 | Line 2435 | public class ForkJoinPool extends Abstra
2435		static void externalHelpJoin(ForkJoinTask<?> t) {
2436		// Some hard-to-avoid overlap with tryExternalUnpush
2437		ForkJoinPool p; WorkQueue[] ws; WorkQueue q, w; Submitter z;
2438	<	ForkJoinTask<?>[] a;  int m, s, n; long j;
2439	<	if (t != null && t.status >= 0 &&
2438	>	ForkJoinTask<?>[] a;  int m, s, n;
2439	>	if (t != null &&
2440		(z = submitters.get()) != null &&
2441		(p = commonPool) != null &&
2442		(ws = p.workQueues) != null &&
2443		(m = ws.length - 1) >= 0 &&
2444		(q = ws[m & z.seed & SQMASK]) != null &&
2445		(a = q.array) != null) {
2446	<	if ((s = q.top) != q.base &&
2447	<	U.getObjectVolatile
2448	<	(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
2449	<	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2450	<	if (q.array == a && q.top == s &&
2451	<	U.compareAndSwapObject(a, j, t, null)) {
2452	<	q.top = s - 1;
2453	<	q.qlock = 0;
2454	<	t.doExec();
2446	>	int am = a.length - 1;
2447	>	if ((s = q.top) != q.base) {
2448	>	long j = ((am & (s - 1)) << ASHIFT) + ABASE;
2449	>	if (U.getObject(a, j) == t &&
2450	>	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2451	>	if (q.array == a && q.top == s &&
2452	>	U.compareAndSwapObject(a, j, t, null)) {
2453	>	q.top = s - 1;
2454	>	q.qlock = 0;
2455	>	t.doExec();
2456	>	}
2457	>	else
2458	>	q.qlock = 0;
2459		}
2349	–	else
2350	–	q.qlock = 0;
2460		}
2461		if (t.status >= 0) {
2462		if (t instanceof CountedCompleter)
#	Line 2363 | Line 2472 | public class ForkJoinPool extends Abstra
2472		*/
2473		static void externalHelpQuiescePool() {
2474		ForkJoinPool p; ForkJoinTask<?> t; WorkQueue q; int b;
2366	–	int r = ThreadLocalRandom.current().nextInt();
2475		if ((p = commonPool) != null &&
2476	<	(q = p.findNonEmptyStealQueue(r)) != null &&
2476	>	(q = p.findNonEmptyStealQueue(1)) != null &&
2477		(b = q.base) - q.top < 0 &&
2478		(t = q.pollAt(b)) != null)
2479		t.doExec();
#	Line 2442 | Line 2550 | public class ForkJoinPool extends Abstra
2550		throw new NullPointerException();
2551		if (parallelism <= 0 || parallelism > MAX_CAP)
2552		throw new IllegalArgumentException();
2445	–	this.parallelism = parallelism;
2553		this.factory = factory;
2554		this.ueh = handler;
2555	<	this.localMode = asyncMode ? FIFO_QUEUE : LIFO_QUEUE;
2555	>	this.config = parallelism | (asyncMode ? (FIFO_QUEUE << 16) : 0);
2556		long np = (long)(-parallelism); // offset ctl counts
2557		this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
2558		int pn = nextPoolId();
#	Line 2462 | Line 2569 | public class ForkJoinPool extends Abstra
2569		ForkJoinPool(int parallelism, long ctl,
2570		ForkJoinWorkerThreadFactory factory,
2571		Thread.UncaughtExceptionHandler handler) {
2572	<	this.parallelism = parallelism;
2572	>	this.config = parallelism;
2573		this.ctl = ctl;
2574		this.factory = factory;
2575		this.ueh = handler;
2469	–	this.localMode = LIFO_QUEUE;
2576		this.workerNamePrefix = "ForkJoinPool.commonPool-worker-";
2577		}
2578
2579		/**
2580	<	* Returns the common pool instance.
2580	>	* Returns the common pool instance. This pool is statically
2581	>	* constructed; its run state is unaffected by attempts to
2582	>	* {@link @shutdown} or {@link #shutdownNow}.
2583		*
2584		* @return the common pool instance
2585		*/
2586		public static ForkJoinPool commonPool() {
2587	<	return commonPool; // cannot be null (if so, a static init error)
2587	>	// assert commonPool != null : "static init error";
2588	>	return commonPool;
2589		}
2590
2591		// Execution methods
#	Line 2648 | Line 2757 | public class ForkJoinPool extends Abstra
2757		* @return the targeted parallelism level of this pool
2758		*/
2759		public int getParallelism() {
2760	<	return parallelism;
2760	>	return config & SMASK;
2761		}
2762
2763		/**
#	Line 2669 | Line 2778 | public class ForkJoinPool extends Abstra
2778		* @return the number of worker threads
2779		*/
2780		public int getPoolSize() {
2781	<	return parallelism + (short)(ctl >>> TC_SHIFT);
2781	>	return (config & SMASK) + (short)(ctl >>> TC_SHIFT);
2782		}
2783
2784		/**
#	Line 2679 | Line 2788 | public class ForkJoinPool extends Abstra
2788		* @return {@code true} if this pool uses async mode
2789		*/
2790		public boolean getAsyncMode() {
2791	<	return localMode != 0;
2791	>	return (config >>> 16) == FIFO_QUEUE;
2792		}
2793
2794		/**
#	Line 2710 | Line 2819 | public class ForkJoinPool extends Abstra
2819		* @return the number of active threads
2820		*/
2821		public int getActiveThreadCount() {
2822	<	int r = parallelism + (int)(ctl >> AC_SHIFT);
2822	>	int r = (config & SMASK) + (int)(ctl >> AC_SHIFT);
2823		return (r <= 0) ? 0 : r; // suppress momentarily negative values
2824		}
2825
#	Line 2726 | Line 2835 | public class ForkJoinPool extends Abstra
2835		* @return {@code true} if all threads are currently idle
2836		*/
2837		public boolean isQuiescent() {
2838	<	return (int)(ctl >> AC_SHIFT) + parallelism == 0;
2838	>	return (int)(ctl >> AC_SHIFT) + (config & SMASK) == 0;
2839		}
2840
2841		/**
#	Line 2803 | Line 2912 | public class ForkJoinPool extends Abstra
2912		WorkQueue[] ws; WorkQueue w;
2913		if ((ws = workQueues) != null) {
2914		for (int i = 0; i < ws.length; i += 2) {
2915	<	if ((w = ws[i]) != null && w.queueSize() != 0)
2915	>	if ((w = ws[i]) != null && !w.isEmpty())
2916		return true;
2917		}
2918		}
#	Line 2889 | Line 2998 | public class ForkJoinPool extends Abstra
2998		}
2999		}
3000		}
3001	<	int pc = parallelism;
3001	>	int pc = (config & SMASK);
3002		int tc = pc + (short)(c >>> TC_SHIFT);
3003		int ac = pc + (int)(c >> AC_SHIFT);
3004		if (ac < 0) // ignore transient negative
#	Line 2962 | Line 3071 | public class ForkJoinPool extends Abstra
3071		public boolean isTerminated() {
3072		long c = ctl;
3073		return ((c & STOP_BIT) != 0L &&
3074	<	(short)(c >>> TC_SHIFT) == -parallelism);
3074	>	(short)(c >>> TC_SHIFT) == -(config & SMASK));
3075		}
3076
3077		/**
#	Line 2970 | Line 3079 | public class ForkJoinPool extends Abstra
3079		* commenced but not yet completed.  This method may be useful for
3080		* debugging. A return of {@code true} reported a sufficient
3081		* period after shutdown may indicate that submitted tasks have
3082	<	* ignored or suppressed interruption, or are waiting for IO,
3082	>	* ignored or suppressed interruption, or are waiting for I/O,
3083		* causing this executor not to properly terminate. (See the
3084		* advisory notes for class {@link ForkJoinTask} stating that
3085		* tasks should not normally entail blocking operations.  But if
#	Line 2981 | Line 3090 | public class ForkJoinPool extends Abstra
3090		public boolean isTerminating() {
3091		long c = ctl;
3092		return ((c & STOP_BIT) != 0L &&
3093	<	(short)(c >>> TC_SHIFT) != -parallelism);
3093	>	(short)(c >>> TC_SHIFT) != -(config & SMASK));
3094		}
3095
3096		/**
#	Line 3125 | Line 3234 | public class ForkJoinPool extends Abstra
3234		if (t instanceof ForkJoinWorkerThread) {
3235		ForkJoinPool p = ((ForkJoinWorkerThread)t).pool;
3236		while (!blocker.isReleasable()) { // variant of helpSignal
3237	<	WorkQueue[] ws; WorkQueue q; int m, n;
3237	>	WorkQueue[] ws; WorkQueue q; int m, u;
3238		if ((ws = p.workQueues) != null && (m = ws.length - 1) >= 0) {
3239		for (int i = 0; i <= m; ++i) {
3240		if (blocker.isReleasable())
3241		return;
3242	<	if ((q = ws[i]) != null && (n = q.queueSize()) > 0) {
3243	<	p.signalWork(q, n);
3244	<	if ((int)(p.ctl >> AC_SHIFT) >= 0)
3242	>	if ((q = ws[i]) != null && q.base - q.top < 0) {
3243	>	p.signalWork(q);
3244	>	if ((u = (int)(p.ctl >>> 32)) >= 0 ||
3245	>	(u >> UAC_SHIFT) >= 0)
3246		break;
3247		}
3248		}
#	Line 3178 | Line 3288 | public class ForkJoinPool extends Abstra
3288		private static final long QLOCK;
3289
3290		static {
3181	–	// 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	–
3291		int s; // initialize field offsets for CAS etc
3292		try {
3293		U = getUnsafe();
#	Line 3227 | Line 3316 | public class ForkJoinPool extends Abstra
3316		if ((s & (s-1)) != 0)
3317		throw new Error("data type scale not a power of two");
3318
3319	+	submitters = new ThreadLocal<Submitter>();
3320	+	ForkJoinWorkerThreadFactory fac = defaultForkJoinWorkerThreadFactory =
3321	+	new DefaultForkJoinWorkerThreadFactory();
3322	+	modifyThreadPermission = new RuntimePermission("modifyThread");
3323	+
3324		/*
3325	<	* For extra caution, computations to set up pool state are
3326	<	* here; the constructor just assigns these values to fields.
3325	>	* Establish common pool parameters.  For extra caution,
3326	>	* computations to set up common pool state are here; the
3327	>	* constructor just assigns these values to fields.
3328		*/
3329	<	ForkJoinWorkerThreadFactory defaultFac =
3330	<	defaultForkJoinWorkerThreadFactory =
3331	<	new DefaultForkJoinWorkerThreadFactory();
3332	<	if (fac == null)
3333	<	fac = defaultFac;
3329	>
3330	>	int par = 0;
3331	>	Thread.UncaughtExceptionHandler handler = null;
3332	>	try {  // TBD: limit or report ignored exceptions?
3333	>	String pp = System.getProperty
3334	>	("java.util.concurrent.ForkJoinPool.common.parallelism");
3335	>	String hp = System.getProperty
3336	>	("java.util.concurrent.ForkJoinPool.common.exceptionHandler");
3337	>	String fp = System.getProperty
3338	>	("java.util.concurrent.ForkJoinPool.common.threadFactory");
3339	>	if (fp != null)
3340	>	fac = ((ForkJoinWorkerThreadFactory)ClassLoader.
3341	>	getSystemClassLoader().loadClass(fp).newInstance());
3342	>	if (hp != null)
3343	>	handler = ((Thread.UncaughtExceptionHandler)ClassLoader.
3344	>	getSystemClassLoader().loadClass(hp).newInstance());
3345	>	if (pp != null)
3346	>	par = Integer.parseInt(pp);
3347	>	} catch (Exception ignore) {
3348	>	}
3349	>
3350		if (par <= 0)
3351		par = Runtime.getRuntime().availableProcessors();
3352		if (par > MAX_CAP)
3353		par = MAX_CAP;
3354	+	commonPoolParallelism = par;
3355		long np = (long)(-par); // precompute initial ctl value
3356		long ct = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
3357
3246	–	commonPoolParallelism = par;
3358		commonPool = new ForkJoinPool(par, ct, fac, handler);
3248	–	modifyThreadPermission = new RuntimePermission("modifyThread");
3249	–	submitters = new ThreadLocal<Submitter>();
3359		}
3360
3361		/**

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