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

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.142 by jsr166, Wed Nov 14 19:05:03 2012 UTC vs.
Revision 1.165 by dl, Thu Dec 20 17:14:39 2012 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 62 | 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 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
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 238 | 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 247 | 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 315 | 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 392 | 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 524 | 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 597 | 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 623 | 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
630	<	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 639 | 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
642	–	// Heuristic padding to ameliorate unfortunate memory placements
643	–	Object p00, p01, p02, p03, p04, p05, p06, p07;
644	–	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.
656	<	* Cases needing resizing or rejection are relayed to fullPush
657	<	* (that also handles shared queues).
658	<	*
659	<	* @param task the task. Caller must ensure non-null.
660	<	* @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
679	<	* specialization of a common fast path of this method is in
680	<	* ForkJoinPool.externalPush. When called from a FJWT queue,
681	<	* this can fail only if the pool has been shut down or
682	<	* 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 {
696	<	int s = top, oldLen, len;
697	<	if ((a = array) == null)
698	<	a = array = new ForkJoinTask<?>[len=INITIAL_QUEUE_CAPACITY];
699	<	else if ((oldLen = a.length) > s + 1 - base)
700	<	len = oldLen;
701	<	else if ((len = oldLen << 1) > MAXIMUM_QUEUE_CAPACITY)
702	<	throw new RejectedExecutionException("Capacity exceeded");
703	<	else {
704	<	int oldMask, b;
705	<	ForkJoinTask<?>[] oldA = a;
706	<	a = array = new ForkJoinTask<?>[len];
707	<	if ((oldMask = oldLen - 1) >= 0 && s - (b = base) > 0) {
708	<	int mask = len - 1;
709	<	do {
710	<	ForkJoinTask<?> x;
711	<	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
712	<	int j    = ((b &    mask) << ASHIFT) + ABASE;
713	<	x = (ForkJoinTask<?>)
714	<	U.getObjectVolatile(oldA, oldj);
715	<	if (x != null &&
716	<	U.compareAndSwapObject(oldA, oldj, x, null))
717	<	U.putObjectVolatile(a, j, x);
718	<	} while (++b != s);
719	<	}
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);
723	<	top = s + 1;
724	<	} finally {
725	<	if (!owned)
726	<	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 851 | Line 874 | public class ForkJoinPool extends Abstra
874		return seed = r ^= r << 5;
875		}
876
854	–	/**
855	–	* Provides a more accurate estimate of size than (top - base)
856	–	* by ordering reads and checking whether a near-empty queue
857	–	* has at least one unclaimed task.
858	–	*/
859	–	final int queueSize() {
860	–	ForkJoinTask<?>[] a; int k, s, n;
861	–	return ((n = base - (s = top)) < 0 &&
862	–	(n != -1 ||
863	–	((a = array) != null && (k = a.length) > 0 &&
864	–	U.getObject
865	–	(a, (long)((((k - 1) & (s - 1)) << ASHIFT) + ABASE)) != null))) ?
866	–	-n : 0;
867	–	}
868	–
877		// Specialized execution methods
878
879		/**
#	Line 979 | 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;
984	<	if ((p = pool) != null)
985	<	p.collectStealCount(this);
986	<	}
987	<	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 1016 | Line 1020 | public class ForkJoinPool extends Abstra
1020		s != Thread.State.TIMED_WAITING);
1021		}
1022
1019	–	/**
1020	–	* If this owned and is not already interrupted, try to
1021	–	* interrupt and/or unpark, ignoring exceptions.
1022	–	*/
1023	–	final void interruptOwner() {
1024	–	Thread wt, p;
1025	–	if ((wt = owner) != null && !wt.isInterrupted()) {
1026	–	try {
1027	–	wt.interrupt();
1028	–	} catch (SecurityException ignore) {
1029	–	}
1030	–	}
1031	–	if ((p = parker) != null)
1032	–	U.unpark(p);
1033	–	}
1034	–
1023		// Unsafe mechanics
1024		private static final sun.misc.Unsafe U;
1025		private static final long QLOCK;
#	Line 1056 | Line 1044 | public class ForkJoinPool extends Abstra
1044		}
1045		}
1046
1059	–	/**
1060	–	* Per-thread records for threads that submit to pools. Currently
1061	–	* holds only pseudo-random seed / index that is used to choose
1062	–	* submission queues in method externalPush. In the future, this may
1063	–	* also incorporate a means to implement different task rejection
1064	–	* and resubmission policies.
1065	–	*
1066	–	* Seeds for submitters and workers/workQueues work in basically
1067	–	* the same way but are initialized and updated using slightly
1068	–	* different mechanics. Both are initialized using the same
1069	–	* approach as in class ThreadLocal, where successive values are
1070	–	* unlikely to collide with previous values. Seeds are then
1071	–	* randomly modified upon collisions using xorshifts, which
1072	–	* requires a non-zero seed.
1073	–	*/
1074	–	static final class Submitter {
1075	–	int seed;
1076	–	Submitter(int s) { seed = s; }
1077	–	}
1078	–
1079	–	/** Property prefix for constructing common pool */
1080	–	private static final String propPrefix =
1081	–	"java.util.concurrent.ForkJoinPool.common.";
1082	–
1047		// static fields (initialized in static initializer below)
1048
1049		/**
#	Line 1090 | 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 1104 | 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
1111	<	* 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 1148 | 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 1247 | 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
1260	–	final int parallelism;                     // parallelism level
1261	–	final int localMode;                       // per-worker scheduling mode
1262	–	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
1276	<	* internal ConcurrentHashMap documentation for further
1277	<	* 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 1282 | 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 1317 | Line 1302 | public class ForkJoinPool extends Abstra
1302		synchronized (this) { notifyAll(); }
1303		}
1304
1305	+	/**
1306	+	* Tries to create and start one worker if fewer than target
1307	+	* parallelism level exist. Adjusts counts etc on failure.
1308	+	*/
1309	+	private void tryAddWorker() {
1310	+	long c; int u;
1311	+	while ((u = (int)((c = ctl) >>> 32)) < 0 &&
1312	+	(u & SHORT_SIGN) != 0 && (int)c == 0) {
1313	+	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
1314	+	((u + UAC_UNIT) & UAC_MASK)) << 32;
1315	+	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1316	+	ForkJoinWorkerThreadFactory fac;
1317	+	Throwable ex = null;
1318	+	ForkJoinWorkerThread wt = null;
1319	+	try {
1320	+	if ((fac = factory) != null &&
1321	+	(wt = fac.newThread(this)) != null) {
1322	+	wt.start();
1323	+	break;
1324	+	}
1325	+	} catch (Throwable e) {
1326	+	ex = e;
1327	+	}
1328	+	deregisterWorker(wt, ex);
1329	+	break;
1330	+	}
1331	+	}
1332	+	}
1333	+
1334		//  Registering and deregistering workers
1335
1336		/**
1337	<	* Callback from ForkJoinWorkerThread constructor to establish its
1338	<	* poolIndex and record its WorkQueue. To avoid scanning bias due
1339	<	* to packing entries in front of the workQueues array, we treat
1340	<	* the array as a simple power-of-two hash table using per-thread
1341	<	* seed as hash, expanding as needed.
1342	<	*
1343	<	* @param w the worker's queue
1344	<	*/
1345	<	final void registerWorker(WorkQueue w) {
1346	<	int s, ps; // generate a rarely colliding candidate index seed
1347	<	do {} while (!U.compareAndSwapInt(this, INDEXSEED,
1348	<	s = indexSeed, s += SEED_INCREMENT) ||
1337	>	* Callback from ForkJoinWorkerThread to establish and record its
1338	>	* WorkQueue. To avoid scanning bias due to packing entries in
1339	>	* front of the workQueues array, we treat the array as a simple
1340	>	* power-of-two hash table using per-thread seed as hash,
1341	>	* expanding as needed.
1342	>	*
1343	>	* @param wt the worker thread
1344	>	* @return the worker's queue
1345	>	*/
1346	>	final WorkQueue registerWorker(ForkJoinWorkerThread wt) {
1347	>	Thread.UncaughtExceptionHandler handler; WorkQueue[] ws; int s, ps;
1348	>	wt.setDaemon(true);
1349	>	if ((handler = ueh) != null)
1350	>	wt.setUncaughtExceptionHandler(handler);
1351	>	do {} while (!U.compareAndSwapInt(this, INDEXSEED, s = indexSeed,
1352	>	s += SEED_INCREMENT) ||
1353		s == 0); // skip 0
1354	+	WorkQueue w = new WorkQueue(this, wt, config >>> 16, s);
1355		if (((ps = plock) & PL_LOCK) != 0 ||
1356		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1357		ps = acquirePlock();
1358		int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1359		try {
1360	<	WorkQueue[] ws;
1342	<	if (w != null && (ws = workQueues) != null) {
1343	<	w.seed = s;
1360	>	if ((ws = workQueues) != null) {    // skip if shutting down
1361		int n = ws.length, m = n - 1;
1362	<	int r = (s << 1) | 1;               // use odd-numbered indices
1363	<	if (ws[r &= m] != null) {           // collision
1364	<	int probes = 0;                 // step by approx half size
1362	>	int r = (s << 1) | 1;           // use odd-numbered indices
1363	>	if (ws[r &= m] != null) {       // collision
1364	>	int probes = 0;             // step by approx half size
1365		int step = (n <= 4) ? 2 : ((n >>> 1) & EVENMASK) + 2;
1366		while (ws[r = (r + step) & m] != null) {
1367		if (++probes >= n) {
#	Line 1354 | Line 1371 | public class ForkJoinPool extends Abstra
1371		}
1372		}
1373		}
1374	<	w.eventCount = w.poolIndex = r;     // establish before recording
1374	>	w.eventCount = w.poolIndex = r; // volatile write orders
1375		ws[r] = w;
1376		}
1377		} finally {
1378		if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1379		releasePlock(nps);
1380		}
1381	+	wt.setName(workerNamePrefix.concat(Integer.toString(w.poolIndex)));
1382	+	return w;
1383		}
1384
1385		/**
#	Line 1376 | Line 1395 | public class ForkJoinPool extends Abstra
1395		WorkQueue w = null;
1396		if (wt != null && (w = wt.workQueue) != null) {
1397		int ps;
1379	–	collectStealCount(w);
1398		w.qlock = -1;                // ensure set
1399	+	long ns = w.nsteals, sc;     // collect steal count
1400	+	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1401	+	sc = stealCount, sc + ns));
1402		if (((ps = plock) & PL_LOCK) != 0 ||
1403		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1404		ps = acquirePlock();
#	Line 1393 | Line 1414 | public class ForkJoinPool extends Abstra
1414		}
1415		}
1416
1417	<	long c;                             // adjust ctl counts
1417	>	long c;                          // adjust ctl counts
1418		do {} while (!U.compareAndSwapLong
1419		(this, CTL, c = ctl, (((c - AC_UNIT) & AC_MASK) |
1420		((c - TC_UNIT) & TC_MASK) |
1421		(c & ~(AC_MASK|TC_MASK)))));
1422
1423	<	if (!tryTerminate(false, false) && w != null) {
1424	<	w.cancelAll();                  // cancel remaining tasks
1425	<	if (w.array != null)            // suppress signal if never ran
1426	<	signalWork(null, 1);        // wake up or create replacement
1427	<	if (ex == null)                 // help clean refs on way out
1428	<	ForkJoinTask.helpExpungeStaleExceptions();
1423	>	if (!tryTerminate(false, false) && w != null && w.array != null) {
1424	>	w.cancelAll();               // cancel remaining tasks
1425	>	WorkQueue[] ws; WorkQueue v; Thread p; int u, i, e;
1426	>	while ((u = (int)((c = ctl) >>> 32)) < 0 && (e = (int)c) >= 0) {
1427	>	if (e > 0) {             // activate or create replacement
1428	>	if ((ws = workQueues) == null ||
1429	>	(i = e & SMASK) >= ws.length ||
1430	>	(v = ws[i]) == null)
1431	>	break;
1432	>	long nc = (((long)(v.nextWait & E_MASK)) |
1433	>	((long)(u + UAC_UNIT) << 32));
1434	>	if (v.eventCount != (e | INT_SIGN))
1435	>	break;
1436	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1437	>	v.eventCount = (e + E_SEQ) & E_MASK;
1438	>	if ((p = v.parker) != null)
1439	>	U.unpark(p);
1440	>	break;
1441	>	}
1442	>	}
1443	>	else {
1444	>	if ((short)u < 0)
1445	>	tryAddWorker();
1446	>	break;
1447	>	}
1448	>	}
1449		}
1450	<
1451	<	if (ex != null)                     // rethrow
1450	>	if (ex == null)                     // help clean refs on way out
1451	>	ForkJoinTask.helpExpungeStaleExceptions();
1452	>	else                                // rethrow
1453		ForkJoinTask.rethrow(ex);
1454		}
1455
1414	–	/**
1415	–	* Collect worker steal count into total. Called on termination
1416	–	* and upon int overflow of local count. (There is a possible race
1417	–	* in the latter case vs any caller of getStealCount, which can
1418	–	* make its results less accurate than usual.)
1419	–	*/
1420	–	final void collectStealCount(WorkQueue w) {
1421	–	if (w != null) {
1422	–	long sc;
1423	–	int ns = w.nsteals;
1424	–	w.nsteals = 0; // handle overflow
1425	–	long steals = (ns >= 0) ? ns : 1L + (long)(Integer.MAX_VALUE);
1426	–	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1427	–	sc = stealCount, sc + steals));
1428	–	}
1429	–	}
1430	–
1456		// Submissions
1457
1458		/**
#	Line 1444 | Line 1469 | public class ForkJoinPool extends Abstra
1469		(ws = workQueues) != null && (m = (ws.length - 1)) >= 0 &&
1470		(q = ws[m & z.seed & SQMASK]) != null &&
1471		U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock
1472	<	int s = q.top, n;
1473	<	if ((a = q.array) != null && a.length > (n = s + 1 - q.base)) {
1474	<	U.putObject(a, (long)(((a.length - 1) & s) << ASHIFT) + ABASE,
1475	<	task);
1472	>	int b = q.base, s = q.top, n, an;
1473	>	if ((a = q.array) != null && (an = a.length) > (n = s + 1 - b)) {
1474	>	int j = (((an - 1) & s) << ASHIFT) + ABASE;
1475	>	U.putOrderedObject(a, j, task);
1476		q.top = s + 1;                     // push on to deque
1477		q.qlock = 0;
1478	<	if (n <= 1)
1479	<	signalWork(q, 1);
1478	>	if (n <= 2)
1479	>	signalWork(q);
1480		return;
1481		}
1482		q.qlock = 0;
#	Line 1462 | Line 1487 | public class ForkJoinPool extends Abstra
1487		/**
1488		* Full version of externalPush. This method is called, among
1489		* other times, upon the first submission of the first task to the
1490	<	* pool, so must perform secondary initialization: creating
1466	<	* workQueue array and setting plock to a valid value. It also
1490	>	* pool, so must perform secondary initialization.  It also
1491		* detects first submission by an external thread by looking up
1492		* its ThreadLocal, and creates a new shared queue if the one at
1493	<	* index if empty or contended. The lock bodies must be
1493	>	* index if empty or contended. The plock lock body must be
1494		* exception-free (so no try/finally) so we optimistically
1495	<	* allocate new queues/arrays outside the locks and throw them
1496	<	* away if (very rarely) not needed. Note that the plock seq value
1497	<	* can eventually wrap around zero, but if so harmlessly fails to
1498	<	* reinitialize.
1495	>	* allocate new queues outside the lock and throw them away if
1496	>	* (very rarely) not needed.
1497	>	*
1498	>	* Secondary initialization occurs when plock is zero, to create
1499	>	* workQueue array and set plock to a valid value.  This lock body
1500	>	* must also be exception-free. Because the plock seq value can
1501	>	* eventually wrap around zero, this method harmlessly fails to
1502	>	* reinitialize if workQueues exists, while still advancing plock.
1503		*/
1504		private void fullExternalPush(ForkJoinTask<?> task) {
1505	<	for (Submitter z = null;;) {
1506	<	WorkQueue[] ws; WorkQueue q; int ps, m, r, s;
1507	<	if ((ps = plock) < 0)
1505	>	int r = 0; // random index seed
1506	>	for (Submitter z = submitters.get();;) {
1507	>	WorkQueue[] ws; WorkQueue q; int ps, m, k;
1508	>	if (z == null) {
1509	>	if (U.compareAndSwapInt(this, INDEXSEED, r = indexSeed,
1510	>	r += SEED_INCREMENT) && r != 0)
1511	>	submitters.set(z = new Submitter(r));
1512	>	}
1513	>	else if (r == 0) {                  // move to a different index
1514	>	r = z.seed;
1515	>	r ^= r << 13;                   // same xorshift as WorkQueues
1516	>	r ^= r >>> 17;
1517	>	z.seed = r ^ (r << 5);
1518	>	}
1519	>	else if ((ps = plock) < 0)
1520		throw new RejectedExecutionException();
1521	<	else if ((ws = workQueues) == null || (m = ws.length - 1) < 0) {
1522	<	int n = parallelism - 1; n |= n >>> 1; n |= n >>> 2;
1523	<	n |= n >>> 4; n |= n >>> 8; n |= n >>> 16;
1524	<	WorkQueue[] nws = new WorkQueue[(n + 1) << 1]; // power of two
1525	<	if ((ps & PL_LOCK) != 0 ||
1521	>	else if (ps == 0 || (ws = workQueues) == null ||
1522	>	(m = ws.length - 1) < 0) { // initialize workQueues
1523	>	int p = config & SMASK;         // find power of two table size
1524	>	int n = (p > 1) ? p - 1 : 1;    // ensure at least 2 slots
1525	>	n |= n >>> 1; n |= n >>> 2;  n |= n >>> 4;
1526	>	n |= n >>> 8; n |= n >>> 16; n = (n + 1) << 1;
1527	>	WorkQueue[] nws = ((ws = workQueues) == null || ws.length == 0 ?
1528	>	new WorkQueue[n] : null);
1529	>	if (((ps = plock) & PL_LOCK) != 0 ||
1530		!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1531		ps = acquirePlock();
1532	<	if ((ws = workQueues) == null)
1532	>	if (((ws = workQueues) == null || ws.length == 0) && nws != null)
1533		workQueues = nws;
1534		int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1535		if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1536		releasePlock(nps);
1537		}
1538	<	else if (z == null && (z = submitters.get()) == null) {
1539	<	if (U.compareAndSwapInt(this, INDEXSEED,
1540	<	s = indexSeed, s += SEED_INCREMENT) &&
1541	<	s != 0) // skip 0
1542	<	submitters.set(z = new Submitter(s));
1538	>	else if ((q = ws[k = r & m & SQMASK]) != null) {
1539	>	if (q.qlock == 0 && U.compareAndSwapInt(q, QLOCK, 0, 1)) {
1540	>	ForkJoinTask<?>[] a = q.array;
1541	>	int s = q.top;
1542	>	boolean submitted = false;
1543	>	try {                      // locked version of push
1544	>	if ((a != null && a.length > s + 1 - q.base) ||
1545	>	(a = q.growArray()) != null) {   // must presize
1546	>	int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
1547	>	U.putOrderedObject(a, j, task);
1548	>	q.top = s + 1;
1549	>	submitted = true;
1550	>	}
1551	>	} finally {
1552	>	q.qlock = 0;  // unlock
1553	>	}
1554	>	if (submitted) {
1555	>	signalWork(q);
1556	>	return;
1557	>	}
1558	>	}
1559	>	r = 0; // move on failure
1560		}
1561	<	else {
1562	<	int k = (r = z.seed) & m & SQMASK;
1563	<	if ((q = ws[k]) == null && (ps & PL_LOCK) == 0) {
1564	<	(q = new WorkQueue(this, null, SHARED_QUEUE)).poolIndex = k;
1565	<	if (((ps = plock) & PL_LOCK) != 0 ||
1566	<	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1567	<	ps = acquirePlock();
1568	<	WorkQueue w = null;
1569	<	if ((ws = workQueues) != null && k < ws.length &&
1570	<	(w = ws[k]) == null)
1510	<	ws[k] = q;
1511	<	else
1512	<	q = w;
1513	<	int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1514	<	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1515	<	releasePlock(nps);
1516	<	}
1517	<	if (q != null && q.qlock == 0 && q.fullPush(task, false))
1518	<	return;
1519	<	r ^= r << 13;                // same xorshift as WorkQueues
1520	<	r ^= r >>> 17;
1521	<	z.seed = r ^= r << 5;        // move to a different index
1561	>	else if (((ps = plock) & PL_LOCK) == 0) { // create new queue
1562	>	q = new WorkQueue(this, null, SHARED_QUEUE, r);
1563	>	if (((ps = plock) & PL_LOCK) != 0 ||
1564	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1565	>	ps = acquirePlock();
1566	>	if ((ws = workQueues) != null && k < ws.length && ws[k] == null)
1567	>	ws[k] = q;
1568	>	int nps = (ps & SHUTDOWN) | ((ps + PL_LOCK) & ~SHUTDOWN);
1569	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1570	>	releasePlock(nps);
1571		}
1572	+	else
1573	+	r = 0; // try elsewhere while lock held
1574		}
1575		}
1576
#	Line 1534 | Line 1585 | public class ForkJoinPool extends Abstra
1585		}
1586
1587		/**
1588	<	* Tries to create (at most one) or activate (possibly several)
1538	<	* workers if too few are active. On contention failure, continues
1539	<	* until at least one worker is signalled or the given queue is
1540	<	* empty or all workers are active.
1588	>	* Tries to create or activate a worker if too few are active.
1589		*
1590	<	* @param q if non-null, the queue holding tasks to be signalled
1543	<	* @param signals the target number of signals.
1590	>	* @param q the (non-null) queue holding tasks to be signalled
1591		*/
1592	<	final void signalWork(WorkQueue q, int signals) {
1593	<	long c; int e, u, i; WorkQueue[] ws; WorkQueue w; Thread p;
1592	>	final void signalWork(WorkQueue q) {
1593	>	int hint = q.poolIndex;
1594	>	long c; int e, u, i, n; WorkQueue[] ws; WorkQueue w; Thread p;
1595		while ((u = (int)((c = ctl) >>> 32)) < 0) {
1596		if ((e = (int)c) > 0) {
1597		if ((ws = workQueues) != null && ws.length > (i = e & SMASK) &&
#	Line 1551 | Line 1599 | public class ForkJoinPool extends Abstra
1599		long nc = (((long)(w.nextWait & E_MASK)) |
1600		((long)(u + UAC_UNIT) << 32));
1601		if (U.compareAndSwapLong(this, CTL, c, nc)) {
1602	+	w.hint = hint;
1603		w.eventCount = (e + E_SEQ) & E_MASK;
1604		if ((p = w.parker) != null)
1605		U.unpark(p);
1606	<	if (--signals <= 0)
1558	<	break;
1606	>	break;
1607		}
1608	<	else
1561	<	signals = 1;
1562	<	if ((q != null && q.queueSize() == 0))
1608	>	if (q.top - q.base <= 0)
1609		break;
1610		}
1611		else
1612		break;
1613		}
1614	<	else if (e == 0 && (u & SHORT_SIGN) != 0) {
1615	<	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) |
1616	<	((u + UAC_UNIT) & UAC_MASK)) << 32;
1571	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1572	<	ForkJoinWorkerThread wt = null;
1573	<	Throwable ex = null;
1574	<	boolean started = false;
1575	<	try {
1576	<	ForkJoinWorkerThreadFactory fac;
1577	<	if ((fac = factory) != null &&
1578	<	(wt = fac.newThread(this)) != null) {
1579	<	wt.start();
1580	<	started = true;
1581	<	}
1582	<	} catch (Throwable rex) {
1583	<	ex = rex;
1584	<	}
1585	<	if (!started)
1586	<	deregisterWorker(wt, ex); // adjust counts on failure
1587	<	break;
1588	<	}
1589	<	}
1590	<	else
1614	>	else {
1615	>	if ((short)u < 0)
1616	>	tryAddWorker();
1617		break;
1618	+	}
1619		}
1620		}
1621
#	Line 1598 | Line 1625 | public class ForkJoinPool extends Abstra
1625		* Top-level runloop for workers, called by ForkJoinWorkerThread.run.
1626		*/
1627		final void runWorker(WorkQueue w) {
1628	<	// initialize queue array in this thread
1602	<	w.array = new ForkJoinTask<?>[WorkQueue.INITIAL_QUEUE_CAPACITY];
1628	>	w.growArray(); // allocate queue
1629		do { w.runTask(scan(w)); } while (w.qlock >= 0);
1630		}
1631
#	Line 1611 | Line 1637 | public class ForkJoinPool extends Abstra
1637		* contention, or state changes that indicate possible success on
1638		* re-invocation.
1639		*
1640	<	* The scan searches for tasks across a random permutation of
1641	<	* queues (starting at a random index and stepping by a random
1642	<	* relative prime, checking each at least once).  The scan
1643	<	* terminates upon either finding a non-empty queue, or completing
1644	<	* the sweep. If the worker is not inactivated, it takes and
1645	<	* returns a task from this queue. Otherwise, if not activated, it
1646	<	* signals workers (that may include itself) and returns so caller
1647	<	* can retry. Also returns for trtry if the worker array may have
1648	<	* changed during an empty scan.  On failure to find a task, we
1649	<	* take one of the following actions, after which the caller will
1650	<	* retry calling this method unless terminated.
1640	>	* The scan searches for tasks across queues (starting at a random
1641	>	* index, and relying on registerWorker to irregularly scatter
1642	>	* them within array to avoid bias), checking each at least twice.
1643	>	* The scan terminates upon either finding a non-empty queue, or
1644	>	* completing the sweep. If the worker is not inactivated, it
1645	>	* takes and returns a task from this queue. Otherwise, if not
1646	>	* activated, it signals workers (that may include itself) and
1647	>	* returns so caller can retry. Also returns for true if the
1648	>	* worker array may have changed during an empty scan.  On failure
1649	>	* to find a task, we take one of the following actions, after
1650	>	* which the caller will retry calling this method unless
1651	>	* terminated.
1652		*
1653		* * If pool is terminating, terminate the worker.
1654		*
1655		* * If not already enqueued, try to inactivate and enqueue the
1656		* worker on wait queue. Or, if inactivating has caused the pool
1657	<	* to be quiescent, relay to idleAwaitWork to check for
1658	<	* termination and possibly shrink pool.
1657	>	* to be quiescent, relay to idleAwaitWork to possibly shrink
1658	>	* pool.
1659		*
1660		* * If already enqueued and none of the above apply, possibly
1661	<	* (with 1/2 probability) park awaiting signal, else lingering to
1662	<	* help scan and signal.
1661	>	* park awaiting signal, else lingering to help scan and signal.
1662	>	*
1663	>	* * If a non-empty queue discovered or left as a hint,
1664	>	* help wake up other workers before return
1665		*
1666		* @param w the worker (via its WorkQueue)
1667		* @return a task or null if none found
1668		*/
1669		private final ForkJoinTask<?> scan(WorkQueue w) {
1670	<	WorkQueue[] ws; WorkQueue q;           // first update random seed
1671	<	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1672	<	int ps = plock, m;                     // volatile read order matters
1673	<	if ((ws = workQueues) != null && (m = ws.length - 1) > 0) {
1674	<	int ec = w.eventCount;             // ec is negative if inactive
1675	<	int step = (r >>> 16) | 1;         // relatively prime
1676	<	for (int j = (m + 1) << 2;  ; --j, r += step) {
1677	<	ForkJoinTask<?> t; ForkJoinTask<?>[] a; int b, n;
1678	<	if ((q = ws[r & m]) != null && (b = q.base) - q.top < 0 &&
1679	<	(a = q.array) != null) {   // probably nonempty
1670	>	WorkQueue[] ws; int m;
1671	>	int ps = plock;                          // read plock before ws
1672	>	if (w != null && (ws = workQueues) != null && (m = ws.length - 1) >= 0) {
1673	>	int ec = w.eventCount;               // ec is negative if inactive
1674	>	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1675	>	w.hint = -1;                         // update seed and clear hint
1676	>	int j = ((m + m + 1) | MIN_SCAN) & MAX_SCAN;
1677	>	do {
1678	>	WorkQueue q; ForkJoinTask<?>[] a; int b;
1679	>	if ((q = ws[(r + j) & m]) != null && (b = q.base) - q.top < 0 &&
1680	>	(a = q.array) != null) {     // probably nonempty
1681		int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1682	<	t = (ForkJoinTask<?>)U.getObjectVolatile(a, i);
1682	>	ForkJoinTask<?> t = (ForkJoinTask<?>)
1683	>	U.getObjectVolatile(a, i);
1684		if (q.base == b && ec >= 0 && t != null &&
1685		U.compareAndSwapObject(a, i, t, null)) {
1686	<	if ((n = q.top - (q.base = b + 1)) > 0)
1687	<	signalWork(q, n);
1688	<	return t;              // taken
1689	<	}
1690	<	if (j < m || (ec < 0 && (ec = w.eventCount) < 0)) {
1691	<	if ((n = q.queueSize() - 1) > 0)
1692	<	signalWork(q, n);
1693	<	break;                 // let caller retry after signal
1694	<	}
1695	<	}
1696	<	else if (j < 0) {              // end of scan
1697	<	long c = ctl; int e;
1698	<	if (plock != ps)           // incomplete sweep
1699	<	break;
1700	<	if ((e = (int)c) < 0)      // pool is terminating
1701	<	w.qlock = -1;
1702	<	else if (ec >= 0) {        // try to enqueue/inactivate
1703	<	long nc = ((long)ec |
1704	<	((c - AC_UNIT) & (AC_MASK|TC_MASK)));
1705	<	w.nextWait = e;
1706	<	w.eventCount = ec | INT_SIGN; // mark as inactive
1707	<	if (ctl != c ||
1708	<	!U.compareAndSwapLong(this, CTL, c, nc))
1709	<	w.eventCount = ec; // unmark on CAS failure
1710	<	else if ((int)(c >> AC_SHIFT) == 1 - parallelism)
1711	<	idleAwaitWork(w, nc, c);  // quiescent
1686	>	if ((q.base = b + 1) - q.top < 0)
1687	>	signalWork(q);
1688	>	return t;                // taken
1689	>	}
1690	>	else if ((ec < 0 || j < m) && (int)(ctl >> AC_SHIFT) <= 0) {
1691	>	w.hint = (r + j) & m;    // help signal below
1692	>	break;                   // cannot take
1693	>	}
1694	>	}
1695	>	} while (--j >= 0);
1696	>
1697	>	int h, e, ns; long c, sc; WorkQueue q;
1698	>	if ((ns = w.nsteals) != 0) {
1699	>	if (U.compareAndSwapLong(this, STEALCOUNT,
1700	>	sc = stealCount, sc + ns))
1701	>	w.nsteals = 0;               // collect steals and rescan
1702	>	}
1703	>	else if (plock != ps)                // consistency check
1704	>	;                                // skip
1705	>	else if ((e = (int)(c = ctl)) < 0)
1706	>	w.qlock = -1;                    // pool is terminating
1707	>	else {
1708	>	if ((h = w.hint) < 0) {
1709	>	if (ec >= 0) {               // try to enqueue/inactivate
1710	>	long nc = (((long)ec |
1711	>	((c - AC_UNIT) & (AC_MASK|TC_MASK))));
1712	>	w.nextWait = e;          // link and mark inactive
1713	>	w.eventCount = ec | INT_SIGN;
1714	>	if (ctl != c || !U.compareAndSwapLong(this, CTL, c, nc))
1715	>	w.eventCount = ec;   // unmark on CAS failure
1716	>	else if ((int)(c >> AC_SHIFT) == 1 - (config & SMASK))
1717	>	idleAwaitWork(w, nc, c);
1718		}
1719	<	else if (w.seed >= 0 && w.eventCount < 0) {
1719	>	else if (w.eventCount < 0 && ctl == c) {
1720		Thread wt = Thread.currentThread();
1721	<	Thread.interrupted();  // clear status
1721	>	Thread.interrupted();    // clear status
1722		U.putObject(wt, PARKBLOCKER, this);
1723	<	w.parker = wt;         // emulate LockSupport.park
1724	<	if (w.eventCount < 0)  // recheck
1725	<	U.park(false, 0L);
1723	>	w.parker = wt;           // emulate LockSupport.park
1724	>	if (w.eventCount < 0)    // recheck
1725	>	U.park(false, 0L);   // block
1726		w.parker = null;
1727		U.putObject(wt, PARKBLOCKER, null);
1728		}
1729	<	break;
1729	>	}
1730	>	if ((h >= 0 || (h = w.hint) >= 0) &&
1731	>	(ws = workQueues) != null && h < ws.length &&
1732	>	(q = ws[h]) != null) {      // signal others before retry
1733	>	WorkQueue v; Thread p; int u, i, s;
1734	>	for (int n = (config & SMASK) - 1;;) {
1735	>	int idleCount = (w.eventCount < 0) ? 0 : -1;
1736	>	if (((s = idleCount - q.base + q.top) <= n &&
1737	>	(n = s) <= 0) ||
1738	>	(u = (int)((c = ctl) >>> 32)) >= 0 ||
1739	>	(e = (int)c) <= 0 || m < (i = e & SMASK) ||
1740	>	(v = ws[i]) == null)
1741	>	break;
1742	>	long nc = (((long)(v.nextWait & E_MASK)) |
1743	>	((long)(u + UAC_UNIT) << 32));
1744	>	if (v.eventCount != (e | INT_SIGN) ||
1745	>	!U.compareAndSwapLong(this, CTL, c, nc))
1746	>	break;
1747	>	v.hint = h;
1748	>	v.eventCount = (e + E_SEQ) & E_MASK;
1749	>	if ((p = v.parker) != null)
1750	>	U.unpark(p);
1751	>	if (--n <= 0)
1752	>	break;
1753	>	}
1754		}
1755		}
1756		}
#	Line 1709 | Line 1770 | public class ForkJoinPool extends Abstra
1770		* @param prevCtl the ctl value to restore if thread is terminated
1771		*/
1772		private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) {
1773	<	if (w.eventCount < 0 &&
1774	<	(this == commonPool || !tryTerminate(false, false)) &&
1775	<	(int)prevCtl != 0) {
1773	>	if (w != null && w.eventCount < 0 &&
1774	>	!tryTerminate(false, false) && (int)prevCtl != 0 &&
1775	>	ctl == currentCtl) {
1776		int dc = -(short)(currentCtl >>> TC_SHIFT);
1777		long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT;
1778	<	long deadline = System.nanoTime() + parkTime - 100000L; // 1ms slop
1778	>	long deadline = System.nanoTime() + parkTime - TIMEOUT_SLOP;
1779		Thread wt = Thread.currentThread();
1780		while (ctl == currentCtl) {
1781		Thread.interrupted();  // timed variant of version in scan()
#	Line 1729 | Line 1790 | public class ForkJoinPool extends Abstra
1790		if (deadline - System.nanoTime() <= 0L &&
1791		U.compareAndSwapLong(this, CTL, currentCtl, prevCtl)) {
1792		w.eventCount = (w.eventCount + E_SEQ) | E_MASK;
1793	+	w.hint = -1;
1794		w.qlock = -1;   // shrink
1795		break;
1796		}
#	Line 1737 | Line 1799 | public class ForkJoinPool extends Abstra
1799		}
1800
1801		/**
1802	<	* Scans through queues looking for work while joining a task;
1803	<	* if any are present, signals.
1802	>	* Scans through queues looking for work while joining a task; if
1803	>	* any present, signals. May return early if more signalling is
1804	>	* detectably unneeded.
1805		*
1806	<	* @param task to return early if done
1806	>	* @param task return early if done
1807		* @param origin an index to start scan
1808		*/
1809	<	final int helpSignal(ForkJoinTask<?> task, int origin) {
1810	<	WorkQueue[] ws; WorkQueue q; int m, n, s;
1811	<	if (task != null && (ws = workQueues) != null &&
1812	<	(m = ws.length - 1) >= 0) {
1813	<	for (int i = 0; i <= m; ++i) {
1814	<	if ((s = task.status) < 0)
1815	<	return s;
1816	<	if ((q = ws[(i + origin) & m]) != null &&
1817	<	(n = q.queueSize()) > 0) {
1818	<	signalWork(q, n);
1819	<	if ((int)(ctl >> AC_SHIFT) >= 0)
1809	>	private void helpSignal(ForkJoinTask<?> task, int origin) {
1810	>	WorkQueue[] ws; WorkQueue w; Thread p; long c; int m, u, e, i, s;
1811	>	if (task != null && task.status >= 0 &&
1812	>	(u = (int)(ctl >>> 32)) < 0 && (u >> UAC_SHIFT) < 0 &&
1813	>	(ws = workQueues) != null && (m = ws.length - 1) >= 0) {
1814	>	outer: for (int k = origin, j = m; j >= 0; --j) {
1815	>	WorkQueue q = ws[k++ & m];
1816	>	for (int n = m;;) { // limit to at most m signals
1817	>	if (task.status < 0)
1818	>	break outer;
1819	>	if (q == null ||
1820	>	((s = -q.base + q.top) <= n && (n = s) <= 0))
1821		break;
1822	+	if ((u = (int)((c = ctl) >>> 32)) >= 0 ||
1823	+	(e = (int)c) <= 0 || m < (i = e & SMASK) ||
1824	+	(w = ws[i]) == null)
1825	+	break outer;
1826	+	long nc = (((long)(w.nextWait & E_MASK)) |
1827	+	((long)(u + UAC_UNIT) << 32));
1828	+	if (w.eventCount != (e | INT_SIGN))
1829	+	break outer;
1830	+	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1831	+	w.eventCount = (e + E_SEQ) & E_MASK;
1832	+	if ((p = w.parker) != null)
1833	+	U.unpark(p);
1834	+	if (--n <= 0)
1835	+	break;
1836	+	}
1837		}
1838		}
1839		}
1761	–	return 0;
1840		}
1841
1842		/**
#	Line 1792 | Line 1870 | public class ForkJoinPool extends Abstra
1870		}
1871		if ((ws = workQueues) == null || (m = ws.length - 1) <= 0)
1872		break restart;              // shutting down
1873	<	if ((v = ws[h = (j.stealHint | 1) & m]) == null ||
1873	>	if ((v = ws[h = (j.hint | 1) & m]) == null ||
1874		v.currentSteal != subtask) {
1875		for (int origin = h;;) {    // find stealer
1876		if (((h = (h + 2) & m) & 15) == 1 &&
#	Line 1800 | Line 1878 | public class ForkJoinPool extends Abstra
1878		continue restart;   // occasional staleness check
1879		if ((v = ws[h]) != null &&
1880		v.currentSteal == subtask) {
1881	<	j.stealHint = h;    // save hint
1881	>	j.hint = h;        // save hint
1882		break;
1883		}
1884		if (h == origin)
#	Line 1849 | Line 1927 | public class ForkJoinPool extends Abstra
1927
1928		/**
1929		* Analog of tryHelpStealer for CountedCompleters. Tries to steal
1930	<	* and run tasks within the target's computation
1930	>	* and run tasks within the target's computation.
1931		*
1932		* @param task the task to join
1933		* @param mode if shared, exit upon completing any task
#	Line 1857 | Line 1935 | public class ForkJoinPool extends Abstra
1935		*
1936		*/
1937		private int helpComplete(ForkJoinTask<?> task, int mode) {
1938	<	WorkQueue[] ws; WorkQueue q; int m, n, s;
1938	>	WorkQueue[] ws; WorkQueue q; int m, n, s, u;
1939		if (task != null && (ws = workQueues) != null &&
1940		(m = ws.length - 1) >= 0) {
1941		for (int j = 1, origin = j;;) {
#	Line 1865 | Line 1943 | public class ForkJoinPool extends Abstra
1943		return s;
1944		if ((q = ws[j & m]) != null && q.pollAndExecCC(task)) {
1945		origin = j;
1946	<	if (mode == SHARED_QUEUE && (int)(ctl >> AC_SHIFT) >= 0)
1946	>	if (mode == SHARED_QUEUE &&
1947	>	((u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0))
1948		break;
1949		}
1950		else if ((j = (j + 2) & m) == origin)
#	Line 1883 | Line 1962 | public class ForkJoinPool extends Abstra
1962		* may become starved.
1963		*/
1964		final boolean tryCompensate() {
1965	<	int pc = parallelism, e, u, i, tc; long c;
1965	>	int pc = config & SMASK, e, i, tc; long c;
1966		WorkQueue[] ws; WorkQueue w; Thread p;
1967	<	if ((e = (int)(c = ctl)) >= 0 && (ws = workQueues) != null) {
1967	>	if ((ws = workQueues) != null && (e = (int)(c = ctl)) >= 0) {
1968		if (e != 0 && (i = e & SMASK) < ws.length &&
1969		(w = ws[i]) != null && w.eventCount == (e | INT_SIGN)) {
1970		long nc = ((long)(w.nextWait & E_MASK) |
#	Line 1897 | Line 1976 | public class ForkJoinPool extends Abstra
1976		return true;   // replace with idle worker
1977		}
1978		}
1979	<	else if ((short)((u = (int)(c >>> 32)) >>> UTC_SHIFT) >= 0 &&
1980	<	(u >> UAC_SHIFT) + pc > 1) {
1979	>	else if ((tc = (short)(c >>> TC_SHIFT)) >= 0 &&
1980	>	(int)(c >> AC_SHIFT) + pc > 1) {
1981		long nc = ((c - AC_UNIT) & AC_MASK) | (c & ~AC_MASK);
1982		if (U.compareAndSwapLong(this, CTL, c, nc))
1983	<	return true;    // no compensation
1983	>	return true;   // no compensation
1984		}
1985	<	else if ((tc = u + pc) < MAX_CAP) {
1985	>	else if (tc + pc < MAX_CAP) {
1986		long nc = ((c + TC_UNIT) & TC_MASK) | (c & ~TC_MASK);
1987		if (U.compareAndSwapLong(this, CTL, c, nc)) {
1988	+	ForkJoinWorkerThreadFactory fac;
1989		Throwable ex = null;
1990		ForkJoinWorkerThread wt = null;
1991		try {
1912	–	ForkJoinWorkerThreadFactory fac;
1992		if ((fac = factory) != null &&
1993		(wt = fac.newThread(this)) != null) {
1994		wt.start();
#	Line 1918 | Line 1997 | public class ForkJoinPool extends Abstra
1997		} catch (Throwable rex) {
1998		ex = rex;
1999		}
2000	<	deregisterWorker(wt, ex); // adjust counts etc
2000	>	deregisterWorker(wt, ex); // clean up and return false
2001		}
2002		}
2003		}
#	Line 1937 | Line 2016 | public class ForkJoinPool extends Abstra
2016		if (joiner != null && task != null && (s = task.status) >= 0) {
2017		ForkJoinTask<?> prevJoin = joiner.currentJoin;
2018		joiner.currentJoin = task;
2019	<	do {} while ((s = task.status) >= 0 &&
1941	<	joiner.queueSize() > 0 &&
2019	>	do {} while ((s = task.status) >= 0 && !joiner.isEmpty() &&
2020		joiner.tryRemoveAndExec(task)); // process local tasks
2021	<	if (s >= 0 && (s = task.status) >= 0 &&
2022	<	(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
2023	<	(task instanceof CountedCompleter))
2024	<	s = helpComplete(task, LIFO_QUEUE);
2021	>	if (s >= 0 && (s = task.status) >= 0) {
2022	>	helpSignal(task, joiner.poolIndex);
2023	>	if ((s = task.status) >= 0 &&
2024	>	(task instanceof CountedCompleter))
2025	>	s = helpComplete(task, LIFO_QUEUE);
2026	>	}
2027		while (s >= 0 && (s = task.status) >= 0) {
2028	<	if ((joiner.queueSize() > 0 ||           // try helping
2028	>	if ((!joiner.isEmpty() ||           // try helping
2029		(s = tryHelpStealer(joiner, task)) == 0) &&
2030	<	(s = task.status) >= 0 && tryCompensate()) {
2031	<	if (task.trySetSignal() && (s = task.status) >= 0) {
2032	<	synchronized (task) {
2033	<	if (task.status >= 0) {
2034	<	try {                // see ForkJoinTask
2035	<	task.wait();     //  for explanation
2036	<	} catch (InterruptedException ie) {
2030	>	(s = task.status) >= 0) {
2031	>	helpSignal(task, joiner.poolIndex);
2032	>	if ((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) {
2039	>	}
2040		}
2041	+	else
2042	+	task.notifyAll();
2043		}
1959	–	else
1960	–	task.notifyAll();
2044		}
2045	+	long c;                          // re-activate
2046	+	do {} while (!U.compareAndSwapLong
2047	+	(this, CTL, c = ctl, c + AC_UNIT));
2048		}
1963	–	long c;                          // re-activate
1964	–	do {} while (!U.compareAndSwapLong
1965	–	(this, CTL, c = ctl, c + AC_UNIT));
2049		}
2050		}
2051		joiner.currentJoin = prevJoin;
#	Line 1983 | Line 2066 | public class ForkJoinPool extends Abstra
2066		if (joiner != null && task != null && (s = task.status) >= 0) {
2067		ForkJoinTask<?> prevJoin = joiner.currentJoin;
2068		joiner.currentJoin = task;
2069	<	do {} while ((s = task.status) >= 0 &&
1987	<	joiner.queueSize() > 0 &&
2069	>	do {} while ((s = task.status) >= 0 && !joiner.isEmpty() &&
2070		joiner.tryRemoveAndExec(task));
2071	<	if (s >= 0 && (s = task.status) >= 0 &&
2072	<	(s = helpSignal(task, joiner.poolIndex)) >= 0 &&
2073	<	(task instanceof CountedCompleter))
2074	<	s = helpComplete(task, LIFO_QUEUE);
2075	<	if (s >= 0 && joiner.queueSize() == 0) {
2071	>	if (s >= 0 && (s = task.status) >= 0) {
2072	>	helpSignal(task, joiner.poolIndex);
2073	>	if ((s = task.status) >= 0 &&
2074	>	(task instanceof CountedCompleter))
2075	>	s = helpComplete(task, LIFO_QUEUE);
2076	>	}
2077	>	if (s >= 0 && joiner.isEmpty()) {
2078		do {} while (task.status >= 0 &&
2079		tryHelpStealer(joiner, task) > 0);
2080		}
#	Line 2000 | Line 2084 | public class ForkJoinPool extends Abstra
2084
2085		/**
2086		* Returns a (probably) non-empty steal queue, if one is found
2087	<	* during a random, then cyclic scan, else null.  This method must
2088	<	* be retried by caller if, by the time it tries to use the queue,
2005	<	* it is empty.
2087	>	* during a scan, else null.  This method must be retried by
2088	>	* caller if, by the time it tries to use the queue, it is empty.
2089		* @param r a (random) seed for scanning
2090		*/
2091		private WorkQueue findNonEmptyStealQueue(int r) {
2092	<	int step = (r >>> 16) | 1;
2093	<	for (WorkQueue[] ws;;) {
2094	<	int ps = plock, m;
2095	<	if ((ws = workQueues) == null || (m = ws.length - 1) < 1)
2096	<	return null;
2097	<	for (int j = (m + 1) << 2; ; r += step) {
2098	<	WorkQueue q = ws[((r << 1) | 1) & m];
2016	<	if (q != null && q.queueSize() > 0)
2017	<	return q;
2018	<	else if (--j < 0) {
2019	<	if (plock == ps)
2020	<	return null;
2021	<	break;
2092	>	for (;;) {
2093	>	int ps = plock, m; WorkQueue[] ws; WorkQueue q;
2094	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
2095	>	for (int j = (m + 1) << 2; j >= 0; --j) {
2096	>	if ((q = ws[(((r + j) << 1) | 1) & m]) != null &&
2097	>	q.base - q.top < 0)
2098	>	return q;
2099		}
2100		}
2101	+	if (plock == ps)
2102	+	return null;
2103		}
2104		}
2105
#	Line 2032 | Line 2111 | public class ForkJoinPool extends Abstra
2111		*/
2112		final void helpQuiescePool(WorkQueue w) {
2113		for (boolean active = true;;) {
2114	<	ForkJoinTask<?> localTask; // exhaust local queue
2115	<	while ((localTask = w.nextLocalTask()) != null)
2116	<	localTask.doExec();
2117	<	// Similar to loop in scan(), but ignoring submissions
2118	<	WorkQueue q = findNonEmptyStealQueue(w.nextSeed());
2119	<	if (q != null) {
2120	<	ForkJoinTask<?> t; int b;
2114	>	long c; WorkQueue q; ForkJoinTask<?> t; int b;
2115	>	while ((t = w.nextLocalTask()) != null) {
2116	>	if (w.base - w.top < 0)
2117	>	signalWork(w);
2118	>	t.doExec();
2119	>	}
2120	>	if ((q = findNonEmptyStealQueue(w.nextSeed())) != null) {
2121		if (!active) {      // re-establish active count
2043	–	long c;
2122		active = true;
2123		do {} while (!U.compareAndSwapLong
2124		(this, CTL, c = ctl, c + AC_UNIT));
2125		}
2126	<	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2126	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) {
2127	>	if (q.base - q.top < 0)
2128	>	signalWork(q);
2129		w.runSubtask(t);
2130	+	}
2131		}
2132	<	else {
2133	<	long c;
2134	<	if (active) {       // decrement active count without queuing
2132	>	else if (active) {       // decrement active count without queuing
2133	>	long nc = (c = ctl) - AC_UNIT;
2134	>	if ((int)(nc >> AC_SHIFT) + (config & SMASK) == 0)
2135	>	return;          // bypass decrement-then-increment
2136	>	if (U.compareAndSwapLong(this, CTL, c, nc))
2137		active = false;
2055	–	do {} while (!U.compareAndSwapLong
2056	–	(this, CTL, c = ctl, c -= AC_UNIT));
2057	–	}
2058	–	else
2059	–	c = ctl;        // re-increment on exit
2060	–	if ((int)(c >> AC_SHIFT) + parallelism == 0) {
2061	–	do {} while (!U.compareAndSwapLong
2062	–	(this, CTL, c = ctl, c + AC_UNIT));
2063	–	break;
2064	–	}
2138		}
2139	+	else if ((int)((c = ctl) >> AC_SHIFT) + (config & SMASK) == 0 &&
2140	+	U.compareAndSwapLong(this, CTL, c, c + AC_UNIT))
2141	+	return;
2142		}
2143		}
2144
#	Line 2078 | Line 2154 | public class ForkJoinPool extends Abstra
2154		return t;
2155		if ((q = findNonEmptyStealQueue(w.nextSeed())) == null)
2156		return null;
2157	<	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2157	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) {
2158	>	if (q.base - q.top < 0)
2159	>	signalWork(q);
2160		return t;
2161	+	}
2162		}
2163		}
2164
#	Line 2132 | Line 2211 | public class ForkJoinPool extends Abstra
2211		static int getSurplusQueuedTaskCount() {
2212		Thread t; ForkJoinWorkerThread wt; ForkJoinPool pool; WorkQueue q;
2213		if (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)) {
2214	<	int b = (q = (wt = (ForkJoinWorkerThread)t).workQueue).base;
2215	<	int p = (pool = wt.pool).parallelism;
2214	>	int p = (pool = (wt = (ForkJoinWorkerThread)t).pool).config & SMASK;
2215	>	int n = (q = wt.workQueue).top - q.base;
2216		int a = (int)(pool.ctl >> AC_SHIFT) + p;
2217	<	return q.top - b - (a > (p >>>= 1) ? 0 :
2218	<	a > (p >>>= 1) ? 1 :
2219	<	a > (p >>>= 1) ? 2 :
2220	<	a > (p >>>= 1) ? 4 :
2221	<	8);
2217	>	return n - (a > (p >>>= 1) ? 0 :
2218	>	a > (p >>>= 1) ? 1 :
2219	>	a > (p >>>= 1) ? 2 :
2220	>	a > (p >>>= 1) ? 4 :
2221	>	8);
2222		}
2223		return 0;
2224		}
#	Line 2161 | Line 2240 | public class ForkJoinPool extends Abstra
2240		* @return true if now terminating or terminated
2241		*/
2242		private boolean tryTerminate(boolean now, boolean enable) {
2243	<	if (this == commonPool)                     // cannot shut down
2243	>	int ps;
2244	>	if (this == commonPool)                    // cannot shut down
2245		return false;
2246	+	if ((ps = plock) >= 0) {                   // enable by setting plock
2247	+	if (!enable)
2248	+	return false;
2249	+	if ((ps & PL_LOCK) != 0 ||
2250	+	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
2251	+	ps = acquirePlock();
2252	+	int nps = ((ps + PL_LOCK) & ~SHUTDOWN) | SHUTDOWN;
2253	+	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
2254	+	releasePlock(nps);
2255	+	}
2256		for (long c;;) {
2257	<	if (((c = ctl) & STOP_BIT) != 0) {      // already terminating
2258	<	if ((short)(c >>> TC_SHIFT) == -parallelism) {
2257	>	if (((c = ctl) & STOP_BIT) != 0) {     // already terminating
2258	>	if ((short)(c >>> TC_SHIFT) == -(config & SMASK)) {
2259		synchronized (this) {
2260	<	notifyAll();                // signal when 0 workers
2260	>	notifyAll();               // signal when 0 workers
2261		}
2262		}
2263		return true;
2264		}
2265	<	if (plock >= 0) {                       // not yet enabled
2266	<	int ps;
2267	<	if (!enable)
2178	<	return false;
2179	<	if (((ps = plock) & PL_LOCK) != 0 ||
2180	<	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
2181	<	ps = acquirePlock();
2182	<	int nps = SHUTDOWN;
2183	<	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
2184	<	releasePlock(nps);
2185	<	}
2186	<	if (!now) {                             // check if idle & no tasks
2187	<	if ((int)(c >> AC_SHIFT) != -parallelism ||
2188	<	hasQueuedSubmissions())
2265	>	if (!now) {                            // check if idle & no tasks
2266	>	WorkQueue[] ws; WorkQueue w;
2267	>	if ((int)(c >> AC_SHIFT) != -(config & SMASK))
2268		return false;
2269	<	// Check for unqueued inactive workers. One pass suffices.
2270	<	WorkQueue[] ws = workQueues; WorkQueue w;
2271	<	if (ws != null) {
2272	<	for (int i = 1; i < ws.length; i += 2) {
2273	<	if ((w = ws[i]) != null && w.eventCount >= 0)
2274	<	return false;
2269	>	if ((ws = workQueues) != null) {
2270	>	for (int i = 0; i < ws.length; ++i) {
2271	>	if ((w = ws[i]) != null) {
2272	>	if (!w.isEmpty()) {    // signal unprocessed tasks
2273	>	signalWork(w);
2274	>	return false;
2275	>	}
2276	>	if ((i & 1) != 0 && w.eventCount >= 0)
2277	>	return false;      // unqueued inactive worker
2278	>	}
2279		}
2280		}
2281		}
2282		if (U.compareAndSwapLong(this, CTL, c, c | STOP_BIT)) {
2283		for (int pass = 0; pass < 3; ++pass) {
2284	<	WorkQueue[] ws = workQueues;
2285	<	if (ws != null) {
2203	<	WorkQueue w;
2284	>	WorkQueue[] ws; WorkQueue w; Thread wt;
2285	>	if ((ws = workQueues) != null) {
2286		int n = ws.length;
2287		for (int i = 0; i < n; ++i) {
2288		if ((w = ws[i]) != null) {
2289		w.qlock = -1;
2290		if (pass > 0) {
2291		w.cancelAll();
2292	<	if (pass > 1)
2293	<	w.interruptOwner();
2292	>	if (pass > 1 && (wt = w.owner) != null) {
2293	>	if (!wt.isInterrupted()) {
2294	>	try {
2295	>	wt.interrupt();
2296	>	} catch (Throwable ignore) {
2297	>	}
2298	>	}
2299	>	U.unpark(wt);
2300	>	}
2301		}
2302		}
2303		}
2304		// Wake up workers parked on event queue
2305		int i, e; long cc; Thread p;
2306		while ((e = (int)(cc = ctl) & E_MASK) != 0 &&
2307	<	(i = e & SMASK) < n &&
2307	>	(i = e & SMASK) < n && i >= 0 &&
2308		(w = ws[i]) != null) {
2309		long nc = ((long)(w.nextWait & E_MASK) |
2310		((cc + AC_UNIT) & AC_MASK) |
#	Line 2254 | Line 2343 | public class ForkJoinPool extends Abstra
2343		*/
2344		static boolean tryExternalUnpush(ForkJoinTask<?> t) {
2345		ForkJoinPool p; WorkQueue[] ws; WorkQueue q; Submitter z;
2346	<	ForkJoinTask<?>[] a;  int m, s; long j;
2347	<	if ((z = submitters.get()) != null &&
2346	>	ForkJoinTask<?>[] a;  int m, s;
2347	>	if (t != null &&
2348	>	(z = submitters.get()) != null &&
2349		(p = commonPool) != null &&
2350		(ws = p.workQueues) != null &&
2351		(m = ws.length - 1) >= 0 &&
2352		(q = ws[m & z.seed & SQMASK]) != null &&
2353		(s = q.top) != q.base &&
2354	<	(a = q.array) != null &&
2355	<	U.getObjectVolatile
2356	<	(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
2357	<	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2358	<	if (q.array == a && q.top == s && // recheck
2359	<	U.compareAndSwapObject(a, j, t, null)) {
2360	<	q.top = s - 1;
2354	>	(a = q.array) != null) {
2355	>	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
2356	>	if (U.getObject(a, j) == t &&
2357	>	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2358	>	if (q.array == a && q.top == s && // recheck
2359	>	U.compareAndSwapObject(a, j, t, null)) {
2360	>	q.top = s - 1;
2361	>	q.qlock = 0;
2362	>	return true;
2363	>	}
2364		q.qlock = 0;
2272	–	return true;
2365		}
2274	–	q.qlock = 0;
2366		}
2367		return false;
2368		}
#	Line 2286 | Line 2377 | public class ForkJoinPool extends Abstra
2377		if (q != null && (a = q.array) != null && (m = (a.length - 1)) >= 0 &&
2378		root != null && root.status >= 0) {
2379		for (;;) {
2380	<	int s; Object o; CountedCompleter<?> task = null;
2380	>	int s, u; Object o; CountedCompleter<?> task = null;
2381		if ((s = q.top) - q.base > 0) {
2382		long j = ((m & (s - 1)) << ASHIFT) + ABASE;
2383		if ((o = U.getObject(a, j)) != null &&
#	Line 2309 | Line 2400 | public class ForkJoinPool extends Abstra
2400		}
2401		if (task != null)
2402		task.doExec();
2403	<	if (root.status < 0 || (int)(ctl >> AC_SHIFT) >= 0)
2403	>	if (root.status < 0 ||
2404	>	(u = (int)(ctl >>> 32)) >= 0 || (u >> UAC_SHIFT) >= 0)
2405		break;
2406		if (task == null) {
2407	<	if (helpSignal(root, q.poolIndex) >= 0)
2407	>	helpSignal(root, q.poolIndex);
2408	>	if (root.status >= 0)
2409		helpComplete(root, SHARED_QUEUE);
2410		break;
2411		}
#	Line 2327 | Line 2420 | public class ForkJoinPool extends Abstra
2420		static void externalHelpJoin(ForkJoinTask<?> t) {
2421		// Some hard-to-avoid overlap with tryExternalUnpush
2422		ForkJoinPool p; WorkQueue[] ws; WorkQueue q, w; Submitter z;
2423	<	ForkJoinTask<?>[] a;  int m, s, n; long j;
2424	<	if (t != null && t.status >= 0 &&
2423	>	ForkJoinTask<?>[] a;  int m, s, n;
2424	>	if (t != null &&
2425		(z = submitters.get()) != null &&
2426		(p = commonPool) != null &&
2427		(ws = p.workQueues) != null &&
2428		(m = ws.length - 1) >= 0 &&
2429		(q = ws[m & z.seed & SQMASK]) != null &&
2430		(a = q.array) != null) {
2431	<	if ((s = q.top) != q.base &&
2432	<	U.getObjectVolatile
2433	<	(a, j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE) == t &&
2434	<	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2435	<	if (q.array == a && q.top == s &&
2436	<	U.compareAndSwapObject(a, j, t, null)) {
2437	<	q.top = s - 1;
2438	<	q.qlock = 0;
2439	<	t.doExec();
2431	>	int am = a.length - 1;
2432	>	if ((s = q.top) != q.base) {
2433	>	long j = ((am & (s - 1)) << ASHIFT) + ABASE;
2434	>	if (U.getObject(a, j) == t &&
2435	>	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2436	>	if (q.array == a && q.top == s &&
2437	>	U.compareAndSwapObject(a, j, t, null)) {
2438	>	q.top = s - 1;
2439	>	q.qlock = 0;
2440	>	t.doExec();
2441	>	}
2442	>	else
2443	>	q.qlock = 0;
2444		}
2348	–	else
2349	–	q.qlock = 0;
2445		}
2446		if (t.status >= 0) {
2447		if (t instanceof CountedCompleter)
#	Line 2362 | Line 2457 | public class ForkJoinPool extends Abstra
2457		*/
2458		static void externalHelpQuiescePool() {
2459		ForkJoinPool p; ForkJoinTask<?> t; WorkQueue q; int b;
2365	–	int r = ThreadLocalRandom.current().nextInt();
2460		if ((p = commonPool) != null &&
2461	<	(q = p.findNonEmptyStealQueue(r)) != null &&
2461	>	(q = p.findNonEmptyStealQueue(1)) != null &&
2462		(b = q.base) - q.top < 0 &&
2463	<	(t = q.pollAt(b)) != null)
2463	>	(t = q.pollAt(b)) != null) {
2464	>	if (q.base - q.top < 0)
2465	>	p.signalWork(q);
2466		t.doExec();
2467	+	}
2468		}
2469
2470		// Exported methods
#	Line 2441 | Line 2538 | public class ForkJoinPool extends Abstra
2538		throw new NullPointerException();
2539		if (parallelism <= 0 || parallelism > MAX_CAP)
2540		throw new IllegalArgumentException();
2444	–	this.parallelism = parallelism;
2541		this.factory = factory;
2542		this.ueh = handler;
2543	<	this.localMode = asyncMode ? FIFO_QUEUE : LIFO_QUEUE;
2543	>	this.config = parallelism | (asyncMode ? (FIFO_QUEUE << 16) : 0);
2544		long np = (long)(-parallelism); // offset ctl counts
2545		this.ctl = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
2546		int pn = nextPoolId();
#	Line 2461 | Line 2557 | public class ForkJoinPool extends Abstra
2557		ForkJoinPool(int parallelism, long ctl,
2558		ForkJoinWorkerThreadFactory factory,
2559		Thread.UncaughtExceptionHandler handler) {
2560	<	this.parallelism = parallelism;
2560	>	this.config = parallelism;
2561		this.ctl = ctl;
2562		this.factory = factory;
2563		this.ueh = handler;
2468	–	this.localMode = LIFO_QUEUE;
2564		this.workerNamePrefix = "ForkJoinPool.commonPool-worker-";
2565		}
2566
2567		/**
2568	<	* Returns the common pool instance.
2568	>	* Returns the common pool instance. This pool is statically
2569	>	* constructed; its run state is unaffected by attempts to
2570	>	* {@link #shutdown} or {@link #shutdownNow}.
2571		*
2572		* @return the common pool instance
2573		*/
2574		public static ForkJoinPool commonPool() {
2575	<	return commonPool; // cannot be null (if so, a static init error)
2575	>	// assert commonPool != null : "static init error";
2576	>	return commonPool;
2577		}
2578
2579		// Execution methods
#	Line 2647 | Line 2745 | public class ForkJoinPool extends Abstra
2745		* @return the targeted parallelism level of this pool
2746		*/
2747		public int getParallelism() {
2748	<	return parallelism;
2748	>	return config & SMASK;
2749		}
2750
2751		/**
#	Line 2668 | Line 2766 | public class ForkJoinPool extends Abstra
2766		* @return the number of worker threads
2767		*/
2768		public int getPoolSize() {
2769	<	return parallelism + (short)(ctl >>> TC_SHIFT);
2769	>	return (config & SMASK) + (short)(ctl >>> TC_SHIFT);
2770		}
2771
2772		/**
#	Line 2678 | Line 2776 | public class ForkJoinPool extends Abstra
2776		* @return {@code true} if this pool uses async mode
2777		*/
2778		public boolean getAsyncMode() {
2779	<	return localMode != 0;
2779	>	return (config >>> 16) == FIFO_QUEUE;
2780		}
2781
2782		/**
#	Line 2709 | Line 2807 | public class ForkJoinPool extends Abstra
2807		* @return the number of active threads
2808		*/
2809		public int getActiveThreadCount() {
2810	<	int r = parallelism + (int)(ctl >> AC_SHIFT);
2810	>	int r = (config & SMASK) + (int)(ctl >> AC_SHIFT);
2811		return (r <= 0) ? 0 : r; // suppress momentarily negative values
2812		}
2813
#	Line 2725 | Line 2823 | public class ForkJoinPool extends Abstra
2823		* @return {@code true} if all threads are currently idle
2824		*/
2825		public boolean isQuiescent() {
2826	<	return (int)(ctl >> AC_SHIFT) + parallelism == 0;
2826	>	return (int)(ctl >> AC_SHIFT) + (config & SMASK) == 0;
2827		}
2828
2829		/**
#	Line 2802 | Line 2900 | public class ForkJoinPool extends Abstra
2900		WorkQueue[] ws; WorkQueue w;
2901		if ((ws = workQueues) != null) {
2902		for (int i = 0; i < ws.length; i += 2) {
2903	<	if ((w = ws[i]) != null && w.queueSize() != 0)
2903	>	if ((w = ws[i]) != null && !w.isEmpty())
2904		return true;
2905		}
2906		}
#	Line 2888 | Line 2986 | public class ForkJoinPool extends Abstra
2986		}
2987		}
2988		}
2989	<	int pc = parallelism;
2989	>	int pc = (config & SMASK);
2990		int tc = pc + (short)(c >>> TC_SHIFT);
2991		int ac = pc + (int)(c >> AC_SHIFT);
2992		if (ac < 0) // ignore transient negative
#	Line 2961 | Line 3059 | public class ForkJoinPool extends Abstra
3059		public boolean isTerminated() {
3060		long c = ctl;
3061		return ((c & STOP_BIT) != 0L &&
3062	<	(short)(c >>> TC_SHIFT) == -parallelism);
3062	>	(short)(c >>> TC_SHIFT) == -(config & SMASK));
3063		}
3064
3065		/**
#	Line 2969 | Line 3067 | public class ForkJoinPool extends Abstra
3067		* commenced but not yet completed.  This method may be useful for
3068		* debugging. A return of {@code true} reported a sufficient
3069		* period after shutdown may indicate that submitted tasks have
3070	<	* ignored or suppressed interruption, or are waiting for IO,
3070	>	* ignored or suppressed interruption, or are waiting for I/O,
3071		* causing this executor not to properly terminate. (See the
3072		* advisory notes for class {@link ForkJoinTask} stating that
3073		* tasks should not normally entail blocking operations.  But if
#	Line 2980 | Line 3078 | public class ForkJoinPool extends Abstra
3078		public boolean isTerminating() {
3079		long c = ctl;
3080		return ((c & STOP_BIT) != 0L &&
3081	<	(short)(c >>> TC_SHIFT) != -parallelism);
3081	>	(short)(c >>> TC_SHIFT) != -(config & SMASK));
3082		}
3083
3084		/**
#	Line 3124 | Line 3222 | public class ForkJoinPool extends Abstra
3222		if (t instanceof ForkJoinWorkerThread) {
3223		ForkJoinPool p = ((ForkJoinWorkerThread)t).pool;
3224		while (!blocker.isReleasable()) { // variant of helpSignal
3225	<	WorkQueue[] ws; WorkQueue q; int m, n;
3225	>	WorkQueue[] ws; WorkQueue q; int m, u;
3226		if ((ws = p.workQueues) != null && (m = ws.length - 1) >= 0) {
3227		for (int i = 0; i <= m; ++i) {
3228		if (blocker.isReleasable())
3229		return;
3230	<	if ((q = ws[i]) != null && (n = q.queueSize()) > 0) {
3231	<	p.signalWork(q, n);
3232	<	if ((int)(p.ctl >> AC_SHIFT) >= 0)
3230	>	if ((q = ws[i]) != null && q.base - q.top < 0) {
3231	>	p.signalWork(q);
3232	>	if ((u = (int)(p.ctl >>> 32)) >= 0 ||
3233	>	(u >> UAC_SHIFT) >= 0)
3234		break;
3235		}
3236		}
#	Line 3177 | Line 3276 | public class ForkJoinPool extends Abstra
3276		private static final long QLOCK;
3277
3278		static {
3180	–	// Establish common pool parameters
3181	–	// TBD: limit or report ignored exceptions?
3182	–
3183	–	int par = 0;
3184	–	ForkJoinWorkerThreadFactory fac = null;
3185	–	Thread.UncaughtExceptionHandler handler = null;
3186	–	try {
3187	–	String pp = System.getProperty(propPrefix + "parallelism");
3188	–	String hp = System.getProperty(propPrefix + "exceptionHandler");
3189	–	String fp = System.getProperty(propPrefix + "threadFactory");
3190	–	if (fp != null)
3191	–	fac = ((ForkJoinWorkerThreadFactory)ClassLoader.
3192	–	getSystemClassLoader().loadClass(fp).newInstance());
3193	–	if (hp != null)
3194	–	handler = ((Thread.UncaughtExceptionHandler)ClassLoader.
3195	–	getSystemClassLoader().loadClass(hp).newInstance());
3196	–	if (pp != null)
3197	–	par = Integer.parseInt(pp);
3198	–	} catch (Exception ignore) {
3199	–	}
3200	–
3279		int s; // initialize field offsets for CAS etc
3280		try {
3281		U = getUnsafe();
#	Line 3226 | Line 3304 | public class ForkJoinPool extends Abstra
3304		if ((s & (s-1)) != 0)
3305		throw new Error("data type scale not a power of two");
3306
3307	+	submitters = new ThreadLocal<Submitter>();
3308	+	ForkJoinWorkerThreadFactory fac = defaultForkJoinWorkerThreadFactory =
3309	+	new DefaultForkJoinWorkerThreadFactory();
3310	+	modifyThreadPermission = new RuntimePermission("modifyThread");
3311	+
3312		/*
3313	<	* For extra caution, computations to set up pool state are
3314	<	* here; the constructor just assigns these values to fields.
3313	>	* Establish common pool parameters.  For extra caution,
3314	>	* computations to set up common pool state are here; the
3315	>	* constructor just assigns these values to fields.
3316		*/
3317	<	ForkJoinWorkerThreadFactory defaultFac =
3318	<	defaultForkJoinWorkerThreadFactory =
3319	<	new DefaultForkJoinWorkerThreadFactory();
3320	<	if (fac == null)
3321	<	fac = defaultFac;
3317	>
3318	>	int par = 0;
3319	>	Thread.UncaughtExceptionHandler handler = null;
3320	>	try {  // TBD: limit or report ignored exceptions?
3321	>	String pp = System.getProperty
3322	>	("java.util.concurrent.ForkJoinPool.common.parallelism");
3323	>	String hp = System.getProperty
3324	>	("java.util.concurrent.ForkJoinPool.common.exceptionHandler");
3325	>	String fp = System.getProperty
3326	>	("java.util.concurrent.ForkJoinPool.common.threadFactory");
3327	>	if (fp != null)
3328	>	fac = ((ForkJoinWorkerThreadFactory)ClassLoader.
3329	>	getSystemClassLoader().loadClass(fp).newInstance());
3330	>	if (hp != null)
3331	>	handler = ((Thread.UncaughtExceptionHandler)ClassLoader.
3332	>	getSystemClassLoader().loadClass(hp).newInstance());
3333	>	if (pp != null)
3334	>	par = Integer.parseInt(pp);
3335	>	} catch (Exception ignore) {
3336	>	}
3337	>
3338		if (par <= 0)
3339		par = Runtime.getRuntime().availableProcessors();
3340		if (par > MAX_CAP)
3341		par = MAX_CAP;
3342	+	commonPoolParallelism = par;
3343		long np = (long)(-par); // precompute initial ctl value
3344		long ct = ((np << AC_SHIFT) & AC_MASK) | ((np << TC_SHIFT) & TC_MASK);
3345
3245	–	commonPoolParallelism = par;
3346		commonPool = new ForkJoinPool(par, ct, fac, handler);
3247	–	modifyThreadPermission = new RuntimePermission("modifyThread");
3248	–	submitters = new ThreadLocal<Submitter>();
3347		}
3348
3349	+
3350		/**
3351		* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
3352		* Replace with a simple call to Unsafe.getUnsafe when integrating

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