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root/jsr166/jsr166/src/jsr166y/ForkJoinPool.java
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Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.2 by dl, Wed Jan 7 16:07:37 2009 UTC vs.
Revision 1.10 by jsr166, Mon Jul 20 23:07:43 2009 UTC

# Line 27 | Line 27 | import java.lang.reflect.*;
27   * (eventually blocking if none exist). This makes them efficient when
28   * most tasks spawn other subtasks (as do most ForkJoinTasks), as well
29   * as the mixed execution of some plain Runnable- or Callable- based
30 < * activities along with ForkJoinTasks. Otherwise, other
30 > * activities along with ForkJoinTasks. When setting
31 > * {@code setAsyncMode}, a ForkJoinPools may also be appropriate for
32 > * use with fine-grained tasks that are never joined. Otherwise, other
33   * ExecutorService implementations are typically more appropriate
34   * choices.
35   *
# Line 36 | Line 38 | import java.lang.reflect.*;
38   * adding, suspending, or resuming threads, even if some tasks are
39   * waiting to join others. However, no such adjustments are performed
40   * in the face of blocked IO or other unmanaged synchronization. The
41 < * nested <code>ManagedBlocker</code> interface enables extension of
41 > * nested {@code ManagedBlocker} interface enables extension of
42   * the kinds of synchronization accommodated.  The target parallelism
43 < * level may also be changed dynamically (<code>setParallelism</code>)
44 < * and dynamically thread construction can be limited using methods
45 < * <code>setMaximumPoolSize</code> and/or
46 < * <code>setMaintainsParallelism</code>.
43 > * level may also be changed dynamically ({@code setParallelism})
44 > * and thread construction can be limited using methods
45 > * {@code setMaximumPoolSize} and/or
46 > * {@code setMaintainsParallelism}.
47   *
48   * <p>In addition to execution and lifecycle control methods, this
49   * class provides status check methods (for example
50 < * <code>getStealCount</code>) that are intended to aid in developing,
50 > * {@code getStealCount}) that are intended to aid in developing,
51   * tuning, and monitoring fork/join applications. Also, method
52 < * <code>toString</code> returns indications of pool state in a
52 > * {@code toString} returns indications of pool state in a
53   * convenient form for informal monitoring.
54   *
55   * <p><b>Implementation notes</b>: This implementation restricts the
# Line 131 | Line 133 | public class ForkJoinPool extends Abstra
133          new AtomicInteger();
134  
135      /**
136 <     * Array holding all worker threads in the pool. Array size must
137 <     * be a power of two.  Updates and replacements are protected by
138 <     * workerLock, but it is always kept in a consistent enough state
139 <     * to be randomly accessed without locking by workers performing
140 <     * work-stealing.
136 >     * Array holding all worker threads in the pool. Initialized upon
137 >     * first use. Array size must be a power of two.  Updates and
138 >     * replacements are protected by workerLock, but it is always kept
139 >     * in a consistent enough state to be randomly accessed without
140 >     * locking by workers performing work-stealing.
141       */
142      volatile ForkJoinWorkerThread[] workers;
143  
# Line 151 | Line 153 | public class ForkJoinPool extends Abstra
153  
154      /**
155       * The uncaught exception handler used when any worker
156 <     * abrupty terminates
156 >     * abruptly terminates
157       */
158      private Thread.UncaughtExceptionHandler ueh;
159  
# Line 181 | Line 183 | public class ForkJoinPool extends Abstra
183      /**
184       * Head of Treiber stack for barrier sync. See below for explanation
185       */
186 <    private volatile WaitQueueNode barrierStack;
186 >    private volatile WaitQueueNode syncStack;
187  
188      /**
189       * The count for event barrier
# Line 204 | Line 206 | public class ForkJoinPool extends Abstra
206      private volatile int parallelism;
207  
208      /**
209 +     * True if use local fifo, not default lifo, for local polling
210 +     */
211 +    private volatile boolean locallyFifo;
212 +
213 +    /**
214       * Holds number of total (i.e., created and not yet terminated)
215       * and running (i.e., not blocked on joins or other managed sync)
216       * threads, packed into one int to ensure consistent snapshot when
# Line 219 | Line 226 | public class ForkJoinPool extends Abstra
226      private static int workerCountsFor(int t, int r) { return (t << 16) + r; }
227  
228      /**
229 <     * Add delta (which may be negative) to running count.  This must
229 >     * Adds delta (which may be negative) to running count.  This must
230       * be called before (with negative arg) and after (with positive)
231 <     * any managed synchronization (i.e., mainly, joins)
231 >     * any managed synchronization (i.e., mainly, joins).
232       * @param delta the number to add
233       */
234      final void updateRunningCount(int delta) {
# Line 230 | Line 237 | public class ForkJoinPool extends Abstra
237      }
238  
239      /**
240 <     * Add delta (which may be negative) to both total and running
240 >     * Adds delta (which may be negative) to both total and running
241       * count.  This must be called upon creation and termination of
242       * worker threads.
243       * @param delta the number to add
# Line 264 | Line 271 | public class ForkJoinPool extends Abstra
271      private static int runControlFor(int r, int a)   { return (r << 16) + a; }
272  
273      /**
274 <     * Increment active count. Called by workers before/during
275 <     * executing tasks.
274 >     * Try incrementing active count; fail on contention. Called by
275 >     * workers before/during executing tasks.
276 >     * @return true on success;
277       */
278 <    final void incrementActiveCount() {
279 <        int c;
280 <        do;while (!casRunControl(c = runControl, c+1));
278 >    final boolean tryIncrementActiveCount() {
279 >        int c = runControl;
280 >        return casRunControl(c, c+1);
281      }
282  
283      /**
284 <     * Decrement active count; possibly trigger termination.
284 >     * Tries decrementing active count; fails on contention.
285 >     * Possibly triggers termination on success.
286       * Called by workers when they can't find tasks.
287 +     * @return true on success
288       */
289 <    final void decrementActiveCount() {
290 <        int c, nextc;
291 <        do;while (!casRunControl(c = runControl, nextc = c-1));
289 >    final boolean tryDecrementActiveCount() {
290 >        int c = runControl;
291 >        int nextc = c - 1;
292 >        if (!casRunControl(c, nextc))
293 >            return false;
294          if (canTerminateOnShutdown(nextc))
295              terminateOnShutdown();
296 +        return true;
297      }
298  
299      /**
300 <     * Return true if argument represents zero active count and
300 >     * Returns true if argument represents zero active count and
301       * nonzero runstate, which is the triggering condition for
302       * terminating on shutdown.
303       */
# Line 320 | Line 333 | public class ForkJoinPool extends Abstra
333       * @throws SecurityException if a security manager exists and
334       *         the caller is not permitted to modify threads
335       *         because it does not hold {@link
336 <     *         java.lang.RuntimePermission}<code>("modifyThread")</code>,
336 >     *         java.lang.RuntimePermission}{@code ("modifyThread")},
337       */
338      public ForkJoinPool() {
339          this(Runtime.getRuntime().availableProcessors(),
# Line 328 | Line 341 | public class ForkJoinPool extends Abstra
341      }
342  
343      /**
344 <     * Creates a ForkJoinPool with the indicated parellelism level
344 >     * Creates a ForkJoinPool with the indicated parallelism level
345       * threads, and using the default ForkJoinWorkerThreadFactory,
346       * @param parallelism the number of worker threads
347       * @throws IllegalArgumentException if parallelism less than or
# Line 336 | Line 349 | public class ForkJoinPool extends Abstra
349       * @throws SecurityException if a security manager exists and
350       *         the caller is not permitted to modify threads
351       *         because it does not hold {@link
352 <     *         java.lang.RuntimePermission}<code>("modifyThread")</code>,
352 >     *         java.lang.RuntimePermission}{@code ("modifyThread")},
353       */
354      public ForkJoinPool(int parallelism) {
355          this(parallelism, defaultForkJoinWorkerThreadFactory);
# Line 351 | Line 364 | public class ForkJoinPool extends Abstra
364       * @throws SecurityException if a security manager exists and
365       *         the caller is not permitted to modify threads
366       *         because it does not hold {@link
367 <     *         java.lang.RuntimePermission}<code>("modifyThread")</code>,
367 >     *         java.lang.RuntimePermission}{@code ("modifyThread")},
368       */
369      public ForkJoinPool(ForkJoinWorkerThreadFactory factory) {
370          this(Runtime.getRuntime().availableProcessors(), factory);
# Line 368 | Line 381 | public class ForkJoinPool extends Abstra
381       * @throws SecurityException if a security manager exists and
382       *         the caller is not permitted to modify threads
383       *         because it does not hold {@link
384 <     *         java.lang.RuntimePermission}<code>("modifyThread")</code>,
384 >     *         java.lang.RuntimePermission}{@code ("modifyThread")},
385       */
386      public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) {
387          if (parallelism <= 0 || parallelism > MAX_THREADS)
# Line 385 | Line 398 | public class ForkJoinPool extends Abstra
398          this.termination = workerLock.newCondition();
399          this.stealCount = new AtomicLong();
400          this.submissionQueue = new LinkedTransferQueue<ForkJoinTask<?>>();
401 <        createAndStartInitialWorkers(parallelism);
401 >        // worker array and workers are lazily constructed
402      }
403  
404      /**
# Line 399 | Line 412 | public class ForkJoinPool extends Abstra
412          if (w != null) {
413              w.poolIndex = index;
414              w.setDaemon(true);
415 +            w.setAsyncMode(locallyFifo);
416              w.setName("ForkJoinPool-" + poolNumber + "-worker-" + index);
417              if (h != null)
418                  w.setUncaughtExceptionHandler(h);
# Line 407 | Line 421 | public class ForkJoinPool extends Abstra
421      }
422  
423      /**
424 <     * Return a good size for worker array given pool size.
424 >     * Returns a good size for worker array given pool size.
425       * Currently requires size to be a power of two.
426       */
427      private static int arraySizeFor(int ps) {
# Line 415 | Line 429 | public class ForkJoinPool extends Abstra
429      }
430  
431      /**
432 <     * Create or resize array if necessary to hold newLength
432 >     * Creates or resizes array if necessary to hold newLength.
433 >     * Call only under exclusion or lock.
434       * @return the array
435       */
436      private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
# Line 433 | Line 448 | public class ForkJoinPool extends Abstra
448       */
449      private void tryShrinkWorkerArray() {
450          ForkJoinWorkerThread[] ws = workers;
451 <        int len = ws.length;
452 <        int last = len - 1;
453 <        while (last >= 0 && ws[last] == null)
454 <            --last;
455 <        int newLength = arraySizeFor(last+1);
456 <        if (newLength < len)
457 <            workers = Arrays.copyOf(ws, newLength);
451 >        if (ws != null) {
452 >            int len = ws.length;
453 >            int last = len - 1;
454 >            while (last >= 0 && ws[last] == null)
455 >                --last;
456 >            int newLength = arraySizeFor(last+1);
457 >            if (newLength < len)
458 >                workers = Arrays.copyOf(ws, newLength);
459 >        }
460      }
461  
462      /**
463 <     * Initial worker array and worker creation and startup. (This
447 <     * must be done under lock to avoid interference by some of the
448 <     * newly started threads while creating others.)
463 >     * Initialize workers if necessary
464       */
465 <    private void createAndStartInitialWorkers(int ps) {
466 <        final ReentrantLock lock = this.workerLock;
467 <        lock.lock();
468 <        try {
469 <            ForkJoinWorkerThread[] ws = ensureWorkerArrayCapacity(ps);
470 <            for (int i = 0; i < ps; ++i) {
471 <                ForkJoinWorkerThread w = createWorker(i);
472 <                if (w != null) {
473 <                    ws[i] = w;
474 <                    w.start();
475 <                    updateWorkerCount(1);
465 >    final void ensureWorkerInitialization() {
466 >        ForkJoinWorkerThread[] ws = workers;
467 >        if (ws == null) {
468 >            final ReentrantLock lock = this.workerLock;
469 >            lock.lock();
470 >            try {
471 >                ws = workers;
472 >                if (ws == null) {
473 >                    int ps = parallelism;
474 >                    ws = ensureWorkerArrayCapacity(ps);
475 >                    for (int i = 0; i < ps; ++i) {
476 >                        ForkJoinWorkerThread w = createWorker(i);
477 >                        if (w != null) {
478 >                            ws[i] = w;
479 >                            w.start();
480 >                            updateWorkerCount(1);
481 >                        }
482 >                    }
483                  }
484 +            } finally {
485 +                lock.unlock();
486              }
463        } finally {
464            lock.unlock();
487          }
488      }
489  
# Line 507 | Line 529 | public class ForkJoinPool extends Abstra
529      private <T> void doSubmit(ForkJoinTask<T> task) {
530          if (isShutdown())
531              throw new RejectedExecutionException();
532 +        if (workers == null)
533 +            ensureWorkerInitialization();
534          submissionQueue.offer(task);
535 <        signalIdleWorkers(true);
535 >        signalIdleWorkers();
536      }
537  
538      /**
# Line 665 | Line 689 | public class ForkJoinPool extends Abstra
689       * @throws SecurityException if a security manager exists and
690       *         the caller is not permitted to modify threads
691       *         because it does not hold {@link
692 <     *         java.lang.RuntimePermission}<code>("modifyThread")</code>,
692 >     *         java.lang.RuntimePermission}{@code ("modifyThread")},
693       */
694      public Thread.UncaughtExceptionHandler
695          setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
# Line 677 | Line 701 | public class ForkJoinPool extends Abstra
701              old = ueh;
702              ueh = h;
703              ForkJoinWorkerThread[] ws = workers;
704 <            for (int i = 0; i < ws.length; ++i) {
705 <                ForkJoinWorkerThread w = ws[i];
706 <                if (w != null)
707 <                    w.setUncaughtExceptionHandler(h);
704 >            if (ws != null) {
705 >                for (int i = 0; i < ws.length; ++i) {
706 >                    ForkJoinWorkerThread w = ws[i];
707 >                    if (w != null)
708 >                        w.setUncaughtExceptionHandler(h);
709 >                }
710              }
711          } finally {
712              lock.unlock();
# Line 690 | Line 716 | public class ForkJoinPool extends Abstra
716  
717  
718      /**
719 <     * Sets the target paralleism level of this pool.
719 >     * Sets the target parallelism level of this pool.
720       * @param parallelism the target parallelism
721       * @throws IllegalArgumentException if parallelism less than or
722       * equal to zero or greater than maximum size bounds.
723       * @throws SecurityException if a security manager exists and
724       *         the caller is not permitted to modify threads
725       *         because it does not hold {@link
726 <     *         java.lang.RuntimePermission}<code>("modifyThread")</code>,
726 >     *         java.lang.RuntimePermission}{@code ("modifyThread")},
727       */
728      public void setParallelism(int parallelism) {
729          checkPermission();
# Line 717 | Line 743 | public class ForkJoinPool extends Abstra
743          } finally {
744              lock.unlock();
745          }
746 <        signalIdleWorkers(false);
746 >        signalIdleWorkers();
747      }
748  
749      /**
# Line 732 | Line 758 | public class ForkJoinPool extends Abstra
758      /**
759       * Returns the number of worker threads that have started but not
760       * yet terminated.  This result returned by this method may differ
761 <     * from <code>getParallelism</code> when threads are created to
761 >     * from {@code getParallelism} when threads are created to
762       * maintain parallelism when others are cooperatively blocked.
763       *
764       * @return the number of worker threads
# Line 787 | Line 813 | public class ForkJoinPool extends Abstra
813      }
814  
815      /**
816 +     * Establishes local first-in-first-out scheduling mode for forked
817 +     * tasks that are never joined. This mode may be more appropriate
818 +     * than default locally stack-based mode in applications in which
819 +     * worker threads only process asynchronous tasks.  This method is
820 +     * designed to be invoked only when pool is quiescent, and
821 +     * typically only before any tasks are submitted. The effects of
822 +     * invocations at other times may be unpredictable.
823 +     *
824 +     * @param async if true, use locally FIFO scheduling
825 +     * @return the previous mode.
826 +     */
827 +    public boolean setAsyncMode(boolean async) {
828 +        boolean oldMode = locallyFifo;
829 +        locallyFifo = async;
830 +        ForkJoinWorkerThread[] ws = workers;
831 +        if (ws != null) {
832 +            for (int i = 0; i < ws.length; ++i) {
833 +                ForkJoinWorkerThread t = ws[i];
834 +                if (t != null)
835 +                    t.setAsyncMode(async);
836 +            }
837 +        }
838 +        return oldMode;
839 +    }
840 +
841 +    /**
842 +     * Returns true if this pool uses local first-in-first-out
843 +     * scheduling mode for forked tasks that are never joined.
844 +     *
845 +     * @return true if this pool uses async mode.
846 +     */
847 +    public boolean getAsyncMode() {
848 +        return locallyFifo;
849 +    }
850 +
851 +    /**
852       * Returns an estimate of the number of worker threads that are
853       * not blocked waiting to join tasks or for other managed
854       * synchronization.
# Line 868 | Line 930 | public class ForkJoinPool extends Abstra
930      public long getQueuedTaskCount() {
931          long count = 0;
932          ForkJoinWorkerThread[] ws = workers;
933 <        for (int i = 0; i < ws.length; ++i) {
934 <            ForkJoinWorkerThread t = ws[i];
935 <            if (t != null)
936 <                count += t.getQueueSize();
933 >        if (ws != null) {
934 >            for (int i = 0; i < ws.length; ++i) {
935 >                ForkJoinWorkerThread t = ws[i];
936 >                if (t != null)
937 >                    count += t.getQueueSize();
938 >            }
939          }
940          return count;
941      }
# Line 889 | Line 953 | public class ForkJoinPool extends Abstra
953      /**
954       * Returns true if there are any tasks submitted to this pool
955       * that have not yet begun executing.
956 <     * @return <code>true</code> if there are any queued submissions.
956 >     * @return {@code true} if there are any queued submissions.
957       */
958      public boolean hasQueuedSubmissions() {
959          return !submissionQueue.isEmpty();
# Line 906 | Line 970 | public class ForkJoinPool extends Abstra
970      }
971  
972      /**
973 +     * Removes all available unexecuted submitted and forked tasks
974 +     * from scheduling queues and adds them to the given collection,
975 +     * without altering their execution status. These may include
976 +     * artificially generated or wrapped tasks. This method is designed
977 +     * to be invoked only when the pool is known to be
978 +     * quiescent. Invocations at other times may not remove all
979 +     * tasks. A failure encountered while attempting to add elements
980 +     * to collection {@code c} may result in elements being in
981 +     * neither, either or both collections when the associated
982 +     * exception is thrown.  The behavior of this operation is
983 +     * undefined if the specified collection is modified while the
984 +     * operation is in progress.
985 +     * @param c the collection to transfer elements into
986 +     * @return the number of elements transferred
987 +     */
988 +    protected int drainTasksTo(Collection<ForkJoinTask<?>> c) {
989 +        int n = submissionQueue.drainTo(c);
990 +        ForkJoinWorkerThread[] ws = workers;
991 +        if (ws != null) {
992 +            for (int i = 0; i < ws.length; ++i) {
993 +                ForkJoinWorkerThread w = ws[i];
994 +                if (w != null)
995 +                    n += w.drainTasksTo(c);
996 +            }
997 +        }
998 +        return n;
999 +    }
1000 +
1001 +    /**
1002       * Returns a string identifying this pool, as well as its state,
1003       * including indications of run state, parallelism level, and
1004       * worker and task counts.
# Line 952 | Line 1045 | public class ForkJoinPool extends Abstra
1045       * @throws SecurityException if a security manager exists and
1046       *         the caller is not permitted to modify threads
1047       *         because it does not hold {@link
1048 <     *         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1048 >     *         java.lang.RuntimePermission}{@code ("modifyThread")},
1049       */
1050      public void shutdown() {
1051          checkPermission();
# Line 966 | Line 1059 | public class ForkJoinPool extends Abstra
1059       * waiting tasks.  Tasks that are in the process of being
1060       * submitted or executed concurrently during the course of this
1061       * method may or may not be rejected. Unlike some other executors,
1062 <     * this method cancels rather than collects non-executed tasks,
1063 <     * so always returns an empty list.
1062 >     * this method cancels rather than collects non-executed tasks
1063 >     * upon termination, so always returns an empty list. However, you
1064 >     * can use method {@code drainTasksTo} before invoking this
1065 >     * method to transfer unexecuted tasks to another collection.
1066       * @return an empty list
1067       * @throws SecurityException if a security manager exists and
1068       *         the caller is not permitted to modify threads
1069       *         because it does not hold {@link
1070 <     *         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1070 >     *         java.lang.RuntimePermission}{@code ("modifyThread")},
1071       */
1072      public List<Runnable> shutdownNow() {
1073          checkPermission();
# Line 981 | Line 1076 | public class ForkJoinPool extends Abstra
1076      }
1077  
1078      /**
1079 <     * Returns <code>true</code> if all tasks have completed following shut down.
1079 >     * Returns {@code true} if all tasks have completed following shut down.
1080       *
1081 <     * @return <code>true</code> if all tasks have completed following shut down
1081 >     * @return {@code true} if all tasks have completed following shut down
1082       */
1083      public boolean isTerminated() {
1084          return runStateOf(runControl) == TERMINATED;
1085      }
1086  
1087      /**
1088 <     * Returns <code>true</code> if the process of termination has
1088 >     * Returns {@code true} if the process of termination has
1089       * commenced but possibly not yet completed.
1090       *
1091 <     * @return <code>true</code> if terminating
1091 >     * @return {@code true} if terminating
1092       */
1093      public boolean isTerminating() {
1094          return runStateOf(runControl) >= TERMINATING;
1095      }
1096  
1097      /**
1098 <     * Returns <code>true</code> if this pool has been shut down.
1098 >     * Returns {@code true} if this pool has been shut down.
1099       *
1100 <     * @return <code>true</code> if this pool has been shut down
1100 >     * @return {@code true} if this pool has been shut down
1101       */
1102      public boolean isShutdown() {
1103          return runStateOf(runControl) >= SHUTDOWN;
# Line 1015 | Line 1110 | public class ForkJoinPool extends Abstra
1110       *
1111       * @param timeout the maximum time to wait
1112       * @param unit the time unit of the timeout argument
1113 <     * @return <code>true</code> if this executor terminated and
1114 <     *         <code>false</code> if the timeout elapsed before termination
1113 >     * @return {@code true} if this executor terminated and
1114 >     *         {@code false} if the timeout elapsed before termination
1115       * @throws InterruptedException if interrupted while waiting
1116       */
1117      public boolean awaitTermination(long timeout, TimeUnit unit)
# Line 1052 | Line 1147 | public class ForkJoinPool extends Abstra
1147          lock.lock();
1148          try {
1149              ForkJoinWorkerThread[] ws = workers;
1150 <            int idx = w.poolIndex;
1151 <            if (idx >= 0 && idx < ws.length && ws[idx] == w)
1152 <                ws[idx] = null;
1153 <            if (totalCountOf(workerCounts) == 0) {
1154 <                terminate(); // no-op if already terminating
1155 <                transitionRunStateTo(TERMINATED);
1156 <                termination.signalAll();
1157 <            }
1158 <            else if (!isTerminating()) {
1159 <                tryShrinkWorkerArray();
1160 <                tryResumeSpare(true); // allow replacement
1150 >            if (ws != null) {
1151 >                int idx = w.poolIndex;
1152 >                if (idx >= 0 && idx < ws.length && ws[idx] == w)
1153 >                    ws[idx] = null;
1154 >                if (totalCountOf(workerCounts) == 0) {
1155 >                    terminate(); // no-op if already terminating
1156 >                    transitionRunStateTo(TERMINATED);
1157 >                    termination.signalAll();
1158 >                }
1159 >                else if (!isTerminating()) {
1160 >                    tryShrinkWorkerArray();
1161 >                    tryResumeSpare(true); // allow replacement
1162 >                }
1163              }
1164          } finally {
1165              lock.unlock();
1166          }
1167 <        signalIdleWorkers(false);
1167 >        signalIdleWorkers();
1168      }
1169  
1170      /**
# Line 1077 | Line 1174 | public class ForkJoinPool extends Abstra
1174          if (transitionRunStateTo(TERMINATING)) {
1175              stopAllWorkers();
1176              resumeAllSpares();
1177 <            signalIdleWorkers(true);
1177 >            signalIdleWorkers();
1178              cancelQueuedSubmissions();
1179              cancelQueuedWorkerTasks();
1180              interruptUnterminatedWorkers();
1181 <            signalIdleWorkers(true); // resignal after interrupt
1181 >            signalIdleWorkers(); // resignal after interrupt
1182          }
1183      }
1184  
1185      /**
1186 <     * Possibly terminate when on shutdown state
1186 >     * Possibly terminates when on shutdown state.
1187       */
1188      private void terminateOnShutdown() {
1189          if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
# Line 1094 | Line 1191 | public class ForkJoinPool extends Abstra
1191      }
1192  
1193      /**
1194 <     * Clear out and cancel submissions
1194 >     * Clears out and cancels submissions.
1195       */
1196      private void cancelQueuedSubmissions() {
1197          ForkJoinTask<?> task;
# Line 1103 | Line 1200 | public class ForkJoinPool extends Abstra
1200      }
1201  
1202      /**
1203 <     * Clean out worker queues.
1203 >     * Cleans out worker queues.
1204       */
1205      private void cancelQueuedWorkerTasks() {
1206          final ReentrantLock lock = this.workerLock;
1207          lock.lock();
1208          try {
1209              ForkJoinWorkerThread[] ws = workers;
1210 <            for (int i = 0; i < ws.length; ++i) {
1211 <                ForkJoinWorkerThread t = ws[i];
1212 <                if (t != null)
1213 <                    t.cancelTasks();
1210 >            if (ws != null) {
1211 >                for (int i = 0; i < ws.length; ++i) {
1212 >                    ForkJoinWorkerThread t = ws[i];
1213 >                    if (t != null)
1214 >                        t.cancelTasks();
1215 >                }
1216              }
1217          } finally {
1218              lock.unlock();
# Line 1121 | Line 1220 | public class ForkJoinPool extends Abstra
1220      }
1221  
1222      /**
1223 <     * Set each worker's status to terminating. Requires lock to avoid
1224 <     * conflicts with add/remove
1223 >     * Sets each worker's status to terminating. Requires lock to avoid
1224 >     * conflicts with add/remove.
1225       */
1226      private void stopAllWorkers() {
1227          final ReentrantLock lock = this.workerLock;
1228          lock.lock();
1229          try {
1230              ForkJoinWorkerThread[] ws = workers;
1231 <            for (int i = 0; i < ws.length; ++i) {
1232 <                ForkJoinWorkerThread t = ws[i];
1233 <                if (t != null)
1234 <                    t.shutdownNow();
1231 >            if (ws != null) {
1232 >                for (int i = 0; i < ws.length; ++i) {
1233 >                    ForkJoinWorkerThread t = ws[i];
1234 >                    if (t != null)
1235 >                        t.shutdownNow();
1236 >                }
1237              }
1238          } finally {
1239              lock.unlock();
# Line 1140 | Line 1241 | public class ForkJoinPool extends Abstra
1241      }
1242  
1243      /**
1244 <     * Interrupt all unterminated workers.  This is not required for
1244 >     * Interrupts all unterminated workers.  This is not required for
1245       * sake of internal control, but may help unstick user code during
1246       * shutdown.
1247       */
# Line 1149 | Line 1250 | public class ForkJoinPool extends Abstra
1250          lock.lock();
1251          try {
1252              ForkJoinWorkerThread[] ws = workers;
1253 <            for (int i = 0; i < ws.length; ++i) {
1254 <                ForkJoinWorkerThread t = ws[i];
1255 <                if (t != null && !t.isTerminated()) {
1256 <                    try {
1257 <                        t.interrupt();
1258 <                    } catch (SecurityException ignore) {
1253 >            if (ws != null) {
1254 >                for (int i = 0; i < ws.length; ++i) {
1255 >                    ForkJoinWorkerThread t = ws[i];
1256 >                    if (t != null && !t.isTerminated()) {
1257 >                        try {
1258 >                            t.interrupt();
1259 >                        } catch (SecurityException ignore) {
1260 >                        }
1261                      }
1262                  }
1263              }
# Line 1165 | Line 1268 | public class ForkJoinPool extends Abstra
1268  
1269  
1270      /*
1271 <     * Nodes for event barrier to manage idle threads.
1271 >     * Nodes for event barrier to manage idle threads.  Queue nodes
1272 >     * are basic Treiber stack nodes, also used for spare stack.
1273       *
1274       * The event barrier has an event count and a wait queue (actually
1275       * a Treiber stack).  Workers are enabled to look for work when
1276 <     * the eventCount is incremented. If they fail to find some,
1277 <     * they may wait for next count. Synchronization events occur only
1278 <     * in enough contexts to maintain overall liveness:
1276 >     * the eventCount is incremented. If they fail to find work, they
1277 >     * may wait for next count. Upon release, threads help others wake
1278 >     * up.
1279 >     *
1280 >     * Synchronization events occur only in enough contexts to
1281 >     * maintain overall liveness:
1282       *
1283       *   - Submission of a new task to the pool
1284 <     *   - Creation or termination of a worker
1284 >     *   - Resizes or other changes to the workers array
1285       *   - pool termination
1286       *   - A worker pushing a task on an empty queue
1287       *
1288 <     * The last case (pushing a task) occurs often enough, and is
1289 <     * heavy enough compared to simple stack pushes to require some
1290 <     * special handling: Method signalNonEmptyWorkerQueue returns
1291 <     * without advancing count if the queue appears to be empty.  This
1292 <     * would ordinarily result in races causing some queued waiters
1293 <     * not to be woken up. To avoid this, a worker in sync
1294 <     * rescans for tasks after being enqueued if it was the first to
1295 <     * enqueue, and aborts the wait if finding one, also helping to
1296 <     * signal others. This works well because the worker has nothing
1297 <     * better to do anyway, and so might as well help alleviate the
1298 <     * overhead and contention on the threads actually doing work.
1299 <     *
1300 <     * Queue nodes are basic Treiber stack nodes, also used for spare
1301 <     * stack.
1288 >     * The case of pushing a task occurs often enough, and is heavy
1289 >     * enough compared to simple stack pushes, to require special
1290 >     * handling: Method signalWork returns without advancing count if
1291 >     * the queue appears to be empty.  This would ordinarily result in
1292 >     * races causing some queued waiters not to be woken up. To avoid
1293 >     * this, the first worker enqueued in method sync (see
1294 >     * syncIsReleasable) rescans for tasks after being enqueued, and
1295 >     * helps signal if any are found. This works well because the
1296 >     * worker has nothing better to do, and so might as well help
1297 >     * alleviate the overhead and contention on the threads actually
1298 >     * doing work.  Also, since event counts increments on task
1299 >     * availability exist to maintain liveness (rather than to force
1300 >     * refreshes etc), it is OK for callers to exit early if
1301 >     * contending with another signaller.
1302       */
1303      static final class WaitQueueNode {
1304          WaitQueueNode next; // only written before enqueued
1305          volatile ForkJoinWorkerThread thread; // nulled to cancel wait
1306          final long count; // unused for spare stack
1307 <        WaitQueueNode(ForkJoinWorkerThread w, long c) {
1307 >
1308 >        WaitQueueNode(long c, ForkJoinWorkerThread w) {
1309              count = c;
1310              thread = w;
1311          }
1312 <        final boolean signal() {
1312 >
1313 >        /**
1314 >         * Wakes up waiter, returning false if known to already
1315 >         */
1316 >        boolean signal() {
1317              ForkJoinWorkerThread t = thread;
1318 +            if (t == null)
1319 +                return false;
1320              thread = null;
1321 <            if (t != null) {
1322 <                LockSupport.unpark(t);
1323 <                return true;
1321 >            LockSupport.unpark(t);
1322 >            return true;
1323 >        }
1324 >
1325 >        /**
1326 >         * Awaits release on sync.
1327 >         */
1328 >        void awaitSyncRelease(ForkJoinPool p) {
1329 >            while (thread != null && !p.syncIsReleasable(this))
1330 >                LockSupport.park(this);
1331 >        }
1332 >
1333 >        /**
1334 >         * Awaits resumption as spare.
1335 >         */
1336 >        void awaitSpareRelease() {
1337 >            while (thread != null) {
1338 >                if (!Thread.interrupted())
1339 >                    LockSupport.park(this);
1340              }
1211            return false;
1341          }
1342      }
1343  
1344      /**
1345 <     * Release at least one thread waiting for event count to advance,
1346 <     * if one exists. If initial attempt fails, release all threads.
1347 <     * @param all if false, at first try to only release one thread
1348 <     * @return current event
1345 >     * Ensures that no thread is waiting for count to advance from the
1346 >     * current value of eventCount read on entry to this method, by
1347 >     * releasing waiting threads if necessary.
1348 >     * @return the count
1349       */
1350 <    private long releaseIdleWorkers(boolean all) {
1351 <        long c;
1352 <        for (;;) {
1353 <            WaitQueueNode q = barrierStack;
1354 <            c = eventCount;
1226 <            long qc;
1227 <            if (q == null || (qc = q.count) >= c)
1228 <                break;
1229 <            if (!all) {
1230 <                if (casBarrierStack(q, q.next) && q.signal())
1231 <                    break;
1232 <                all = true;
1233 <            }
1234 <            else if (casBarrierStack(q, null)) {
1350 >    final long ensureSync() {
1351 >        long c = eventCount;
1352 >        WaitQueueNode q;
1353 >        while ((q = syncStack) != null && q.count < c) {
1354 >            if (casBarrierStack(q, null)) {
1355                  do {
1356 <                 q.signal();
1356 >                    q.signal();
1357                  } while ((q = q.next) != null);
1358                  break;
1359              }
# Line 1242 | Line 1362 | public class ForkJoinPool extends Abstra
1362      }
1363  
1364      /**
1365 <     * Returns current barrier event count
1246 <     * @return current barrier event count
1365 >     * Increments event count and releases waiting threads.
1366       */
1367 <    final long getEventCount() {
1249 <        long ec = eventCount;
1250 <        releaseIdleWorkers(true); // release to ensure accurate result
1251 <        return ec;
1252 <    }
1253 <
1254 <    /**
1255 <     * Increment event count and release at least one waiting thread,
1256 <     * if one exists (released threads will in turn wake up others).
1257 <     * @param all if true, try to wake up all
1258 <     */
1259 <    final void signalIdleWorkers(boolean all) {
1367 >    private void signalIdleWorkers() {
1368          long c;
1369          do;while (!casEventCount(c = eventCount, c+1));
1370 <        releaseIdleWorkers(all);
1370 >        ensureSync();
1371      }
1372  
1373      /**
1374 <     * Wake up threads waiting to steal a task. Because method
1375 <     * sync rechecks availability, it is OK to only proceed if
1376 <     * queue appears to be non-empty.
1374 >     * Signals threads waiting to poll a task. Because method sync
1375 >     * rechecks availability, it is OK to only proceed if queue
1376 >     * appears to be non-empty, and OK to skip under contention to
1377 >     * increment count (since some other thread succeeded).
1378       */
1379 <    final void signalNonEmptyWorkerQueue() {
1271 <        // If CAS fails another signaller must have succeeded
1379 >    final void signalWork() {
1380          long c;
1381 <        if (barrierStack != null && casEventCount(c = eventCount, c+1))
1382 <            releaseIdleWorkers(false);
1381 >        WaitQueueNode q;
1382 >        if (syncStack != null &&
1383 >            casEventCount(c = eventCount, c+1) &&
1384 >            (((q = syncStack) != null && q.count <= c) &&
1385 >             (!casBarrierStack(q, q.next) || !q.signal())))
1386 >            ensureSync();
1387      }
1388  
1389      /**
1390 <     * Waits until event count advances from count, or some thread is
1391 <     * waiting on a previous count, or there is stealable work
1392 <     * available. Help wake up others on release.
1390 >     * Waits until event count advances from last value held by
1391 >     * caller, or if excess threads, caller is resumed as spare, or
1392 >     * caller or pool is terminating. Updates caller's event on exit.
1393       * @param w the calling worker thread
1282     * @param prev previous value returned by sync (or 0)
1283     * @return current event count
1394       */
1395 <    final long sync(ForkJoinWorkerThread w, long prev) {
1396 <        updateStealCount(w);
1395 >    final void sync(ForkJoinWorkerThread w) {
1396 >        updateStealCount(w); // Transfer w's count while it is idle
1397  
1398 <        while (!w.isShutdown() && !isTerminating() &&
1399 <               (parallelism >= runningCountOf(workerCounts) ||
1290 <                !suspendIfSpare(w))) { // prefer suspend to waiting here
1398 >        while (!w.isShutdown() && !isTerminating() && !suspendIfSpare(w)) {
1399 >            long prev = w.lastEventCount;
1400              WaitQueueNode node = null;
1401 <            boolean queued = false;
1402 <            for (;;) {
1403 <                if (!queued) {
1404 <                    if (eventCount != prev)
1405 <                        break;
1406 <                    WaitQueueNode h = barrierStack;
1407 <                    if (h != null && h.count != prev)
1299 <                        break; // release below and maybe retry
1300 <                    if (node == null)
1301 <                        node = new WaitQueueNode(w, prev);
1302 <                    queued = casBarrierStack(node.next = h, node);
1303 <                }
1304 <                else if (Thread.interrupted() ||
1305 <                         node.thread == null ||
1306 <                         (node.next == null && w.prescan()) ||
1307 <                         eventCount != prev) {
1308 <                    node.thread = null;
1309 <                    if (eventCount == prev) // help trigger
1310 <                        casEventCount(prev, prev+1);
1401 >            WaitQueueNode h;
1402 >            while (eventCount == prev &&
1403 >                   ((h = syncStack) == null || h.count == prev)) {
1404 >                if (node == null)
1405 >                    node = new WaitQueueNode(prev, w);
1406 >                if (casBarrierStack(node.next = h, node)) {
1407 >                    node.awaitSyncRelease(this);
1408                      break;
1409                  }
1313                else
1314                    LockSupport.park(this);
1410              }
1411 +            long ec = ensureSync();
1412 +            if (ec != prev) {
1413 +                w.lastEventCount = ec;
1414 +                break;
1415 +            }
1416 +        }
1417 +    }
1418 +
1419 +    /**
1420 +     * Returns true if worker waiting on sync can proceed:
1421 +     *  - on signal (thread == null)
1422 +     *  - on event count advance (winning race to notify vs signaller)
1423 +     *  - on Interrupt
1424 +     *  - if the first queued node, we find work available
1425 +     * If node was not signalled and event count not advanced on exit,
1426 +     * then we also help advance event count.
1427 +     * @return true if node can be released
1428 +     */
1429 +    final boolean syncIsReleasable(WaitQueueNode node) {
1430 +        long prev = node.count;
1431 +        if (!Thread.interrupted() && node.thread != null &&
1432 +            (node.next != null ||
1433 +             !ForkJoinWorkerThread.hasQueuedTasks(workers)) &&
1434 +            eventCount == prev)
1435 +            return false;
1436 +        if (node.thread != null) {
1437 +            node.thread = null;
1438              long ec = eventCount;
1439 <            if (releaseIdleWorkers(false) != prev)
1440 <                return ec;
1439 >            if (prev <= ec) // help signal
1440 >                casEventCount(ec, ec+1);
1441          }
1442 <        return prev; // return old count if aborted
1442 >        return true;
1443 >    }
1444 >
1445 >    /**
1446 >     * Returns true if a new sync event occurred since last call to
1447 >     * sync or this method, if so, updating caller's count.
1448 >     */
1449 >    final boolean hasNewSyncEvent(ForkJoinWorkerThread w) {
1450 >        long lc = w.lastEventCount;
1451 >        long ec = ensureSync();
1452 >        if (ec == lc)
1453 >            return false;
1454 >        w.lastEventCount = ec;
1455 >        return true;
1456      }
1457  
1458      //  Parallelism maintenance
1459  
1460      /**
1461 <     * Decrement running count; if too low, add spare.
1461 >     * Decrements running count; if too low, adds spare.
1462       *
1463       * Conceptually, all we need to do here is add or resume a
1464       * spare thread when one is about to block (and remove or
# Line 1343 | Line 1478 | public class ForkJoinPool extends Abstra
1478       * only be suspended or removed when they are idle, not
1479       * immediately when they aren't needed. So adding threads will
1480       * raise parallelism level for longer than necessary.  Also,
1481 <     * FJ applications often enounter highly transient peaks when
1481 >     * FJ applications often encounter highly transient peaks when
1482       * many threads are blocked joining, but for less time than it
1483       * takes to create or resume spares.
1484       *
# Line 1408 | Line 1543 | public class ForkJoinPool extends Abstra
1543          return (tc < maxPoolSize &&
1544                  (rc == 0 || totalSurplus < 0 ||
1545                   (maintainParallelism &&
1546 <                  runningDeficit > totalSurplus && mayHaveQueuedWork())));
1547 <    }
1413 <
1414 <    /**
1415 <     * Returns true if at least one worker queue appears to be
1416 <     * nonempty. This is expensive but not often called. It is not
1417 <     * critical that this be accurate, but if not, more or fewer
1418 <     * running threads than desired might be maintained.
1419 <     */
1420 <    private boolean mayHaveQueuedWork() {
1421 <        ForkJoinWorkerThread[] ws = workers;
1422 <        int len = ws.length;
1423 <        ForkJoinWorkerThread v;
1424 <        for (int i = 0; i < len; ++i) {
1425 <            if ((v = ws[i]) != null && v.getRawQueueSize() > 0) {
1426 <                releaseIdleWorkers(false); // help wake up stragglers
1427 <                return true;
1428 <            }
1429 <        }
1430 <        return false;
1546 >                  runningDeficit > totalSurplus &&
1547 >                  ForkJoinWorkerThread.hasQueuedTasks(workers))));
1548      }
1549  
1550      /**
1551 <     * Add a spare worker if lock available and no more than the
1552 <     * expected numbers of threads exist
1551 >     * Adds a spare worker if lock available and no more than the
1552 >     * expected numbers of threads exist.
1553       * @return true if successful
1554       */
1555      private boolean tryAddSpare(int expectedCounts) {
# Line 1465 | Line 1582 | public class ForkJoinPool extends Abstra
1582      }
1583  
1584      /**
1585 <     * Add the kth spare worker. On entry, pool coounts are already
1585 >     * Adds the kth spare worker. On entry, pool counts are already
1586       * adjusted to reflect addition.
1587       */
1588      private void createAndStartSpare(int k) {
# Line 1477 | Line 1594 | public class ForkJoinPool extends Abstra
1594              for (k = 0; k < len && ws[k] != null; ++k)
1595                  ;
1596          }
1597 <        if (k < len && (w = createWorker(k)) != null) {
1597 >        if (k < len && !isTerminating() && (w = createWorker(k)) != null) {
1598              ws[k] = w;
1599              w.start();
1600          }
1601          else
1602              updateWorkerCount(-1); // adjust on failure
1603 <        signalIdleWorkers(false);
1603 >        signalIdleWorkers();
1604      }
1605  
1606      /**
1607 <     * Suspend calling thread w if there are excess threads.  Called
1608 <     * only from sync.  Spares are enqueued in a Treiber stack
1609 <     * using the same WaitQueueNodes as barriers.  They are resumed
1610 <     * mainly in preJoin, but are also woken on pool events that
1611 <     * require all threads to check run state.
1607 >     * Suspends calling thread w if there are excess threads.  Called
1608 >     * only from sync.  Spares are enqueued in a Treiber stack using
1609 >     * the same WaitQueueNodes as barriers.  They are resumed mainly
1610 >     * in preJoin, but are also woken on pool events that require all
1611 >     * threads to check run state.
1612       * @param w the caller
1613       */
1614      private boolean suspendIfSpare(ForkJoinWorkerThread w) {
# Line 1499 | Line 1616 | public class ForkJoinPool extends Abstra
1616          int s;
1617          while (parallelism < runningCountOf(s = workerCounts)) {
1618              if (node == null)
1619 <                node = new WaitQueueNode(w, 0);
1619 >                node = new WaitQueueNode(0, w);
1620              if (casWorkerCounts(s, s-1)) { // representation-dependent
1621                  // push onto stack
1622                  do;while (!casSpareStack(node.next = spareStack, node));
1506
1623                  // block until released by resumeSpare
1624 <                while (node.thread != null) {
1509 <                    if (!Thread.interrupted())
1510 <                        LockSupport.park(this);
1511 <                }
1512 <                w.activate(); // help warm up
1624 >                node.awaitSpareRelease();
1625                  return true;
1626              }
1627          }
# Line 1517 | Line 1629 | public class ForkJoinPool extends Abstra
1629      }
1630  
1631      /**
1632 <     * Try to pop and resume a spare thread.
1632 >     * Tries to pop and resume a spare thread.
1633       * @param updateCount if true, increment running count on success
1634       * @return true if successful
1635       */
# Line 1535 | Line 1647 | public class ForkJoinPool extends Abstra
1647      }
1648  
1649      /**
1650 <     * Pop and resume all spare threads. Same idea as
1539 <     * releaseIdleWorkers.
1650 >     * Pops and resumes all spare threads. Same idea as ensureSync.
1651       * @return true if any spares released
1652       */
1653      private boolean resumeAllSpares() {
# Line 1554 | Line 1665 | public class ForkJoinPool extends Abstra
1665      }
1666  
1667      /**
1668 <     * Pop and shutdown excessive spare threads. Call only while
1668 >     * Pops and shuts down excessive spare threads. Call only while
1669       * holding lock. This is not guaranteed to eliminate all excess
1670       * threads, only those suspended as spares, which are the ones
1671       * unlikely to be needed in the future.
# Line 1577 | Line 1688 | public class ForkJoinPool extends Abstra
1688      }
1689  
1690      /**
1580     * Returns approximate number of spares, just for diagnostics.
1581     */
1582    private int countSpares() {
1583        int sum = 0;
1584        for (WaitQueueNode q = spareStack; q != null; q = q.next)
1585            ++sum;
1586        return sum;
1587    }
1588
1589    /**
1691       * Interface for extending managed parallelism for tasks running
1692       * in ForkJoinPools. A ManagedBlocker provides two methods.
1693 <     * Method <code>isReleasable</code> must return true if blocking is not
1694 <     * necessary. Method <code>block</code> blocks the current thread
1693 >     * Method {@code isReleasable} must return true if blocking is not
1694 >     * necessary. Method {@code block} blocks the current thread
1695       * if necessary (perhaps internally invoking isReleasable before
1696       * actually blocking.).
1697       * <p>For example, here is a ManagedBlocker based on a
# Line 1618 | Line 1719 | public class ForkJoinPool extends Abstra
1719           * @return true if no additional blocking is necessary (i.e.,
1720           * if isReleasable would return true).
1721           * @throws InterruptedException if interrupted while waiting
1722 <         * (the method is not required to do so, but is allowe to).
1722 >         * (the method is not required to do so, but is allowed to).
1723           */
1724          boolean block() throws InterruptedException;
1725  
# Line 1633 | Line 1734 | public class ForkJoinPool extends Abstra
1734       * is a ForkJoinWorkerThread, this method possibly arranges for a
1735       * spare thread to be activated if necessary to ensure parallelism
1736       * while the current thread is blocked.  If
1737 <     * <code>maintainParallelism</code> is true and the pool supports
1737 >     * {@code maintainParallelism} is true and the pool supports
1738       * it ({@link #getMaintainsParallelism}), this method attempts to
1739       * maintain the pool's nominal parallelism. Otherwise if activates
1740       * a thread only if necessary to avoid complete starvation. This
# Line 1692 | Line 1793 | public class ForkJoinPool extends Abstra
1793  
1794  
1795      // Temporary Unsafe mechanics for preliminary release
1796 +    private static Unsafe getUnsafe() throws Throwable {
1797 +        try {
1798 +            return Unsafe.getUnsafe();
1799 +        } catch (SecurityException se) {
1800 +            try {
1801 +                return java.security.AccessController.doPrivileged
1802 +                    (new java.security.PrivilegedExceptionAction<Unsafe>() {
1803 +                        public Unsafe run() throws Exception {
1804 +                            return getUnsafePrivileged();
1805 +                        }});
1806 +            } catch (java.security.PrivilegedActionException e) {
1807 +                throw e.getCause();
1808 +            }
1809 +        }
1810 +    }
1811 +
1812 +    private static Unsafe getUnsafePrivileged()
1813 +            throws NoSuchFieldException, IllegalAccessException {
1814 +        Field f = Unsafe.class.getDeclaredField("theUnsafe");
1815 +        f.setAccessible(true);
1816 +        return (Unsafe) f.get(null);
1817 +    }
1818 +
1819 +    private static long fieldOffset(String fieldName)
1820 +            throws NoSuchFieldException {
1821 +        return _unsafe.objectFieldOffset
1822 +            (ForkJoinPool.class.getDeclaredField(fieldName));
1823 +    }
1824  
1825      static final Unsafe _unsafe;
1826      static final long eventCountOffset;
1827      static final long workerCountsOffset;
1828      static final long runControlOffset;
1829 <    static final long barrierStackOffset;
1829 >    static final long syncStackOffset;
1830      static final long spareStackOffset;
1831  
1832      static {
1833          try {
1834 <            if (ForkJoinPool.class.getClassLoader() != null) {
1835 <                Field f = Unsafe.class.getDeclaredField("theUnsafe");
1836 <                f.setAccessible(true);
1837 <                _unsafe = (Unsafe)f.get(null);
1838 <            }
1839 <            else
1840 <                _unsafe = Unsafe.getUnsafe();
1712 <            eventCountOffset = _unsafe.objectFieldOffset
1713 <                (ForkJoinPool.class.getDeclaredField("eventCount"));
1714 <            workerCountsOffset = _unsafe.objectFieldOffset
1715 <                (ForkJoinPool.class.getDeclaredField("workerCounts"));
1716 <            runControlOffset = _unsafe.objectFieldOffset
1717 <                (ForkJoinPool.class.getDeclaredField("runControl"));
1718 <            barrierStackOffset = _unsafe.objectFieldOffset
1719 <                (ForkJoinPool.class.getDeclaredField("barrierStack"));
1720 <            spareStackOffset = _unsafe.objectFieldOffset
1721 <                (ForkJoinPool.class.getDeclaredField("spareStack"));
1722 <        } catch (Exception e) {
1834 >            _unsafe = getUnsafe();
1835 >            eventCountOffset = fieldOffset("eventCount");
1836 >            workerCountsOffset = fieldOffset("workerCounts");
1837 >            runControlOffset = fieldOffset("runControl");
1838 >            syncStackOffset = fieldOffset("syncStack");
1839 >            spareStackOffset = fieldOffset("spareStack");
1840 >        } catch (Throwable e) {
1841              throw new RuntimeException("Could not initialize intrinsics", e);
1842          }
1843      }
# Line 1737 | Line 1855 | public class ForkJoinPool extends Abstra
1855          return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val);
1856      }
1857      private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1858 <        return _unsafe.compareAndSwapObject(this, barrierStackOffset, cmp, val);
1858 >        return _unsafe.compareAndSwapObject(this, syncStackOffset, cmp, val);
1859      }
1860   }

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