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 |
|
* |
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 |
81 |
|
* Returns a new worker thread operating in the given pool. |
82 |
|
* |
83 |
|
* @param pool the pool this thread works in |
84 |
< |
* @throws NullPointerException if pool is null; |
84 |
> |
* @throws NullPointerException if pool is null |
85 |
|
*/ |
86 |
|
public ForkJoinWorkerThread newThread(ForkJoinPool pool); |
87 |
|
} |
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 |
|
|
153 |
|
|
154 |
|
/** |
155 |
|
* The uncaught exception handler used when any worker |
156 |
< |
* abrupty terminates |
156 |
> |
* abruptly terminates |
157 |
|
*/ |
158 |
|
private Thread.UncaughtExceptionHandler ueh; |
159 |
|
|
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 |
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 |
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) { |
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 |
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 |
|
*/ |
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(), |
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 |
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); |
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); |
376 |
|
* @param parallelism the targeted number of worker threads |
377 |
|
* @param factory the factory for creating new threads |
378 |
|
* @throws IllegalArgumentException if parallelism less than or |
379 |
< |
* equal to zero, or greater than implementation limit. |
379 |
> |
* equal to zero, or greater than implementation limit |
380 |
|
* @throws NullPointerException if factory is null |
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) |
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 |
|
/** |
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); |
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) { |
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) { |
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 |
|
|
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 |
|
/** |
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) { |
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(); |
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. |
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(); |
743 |
|
} finally { |
744 |
|
lock.unlock(); |
745 |
|
} |
746 |
< |
signalIdleWorkers(false); |
746 |
> |
signalIdleWorkers(); |
747 |
|
} |
748 |
|
|
749 |
|
/** |
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 |
782 |
|
* Setting this value has no effect on current pool size. It |
783 |
|
* controls construction of new threads. |
784 |
|
* @throws IllegalArgumentException if negative or greater then |
785 |
< |
* internal implementation limit. |
785 |
> |
* internal implementation limit |
786 |
|
*/ |
787 |
|
public void setMaximumPoolSize(int newMax) { |
788 |
|
if (newMax < 0 || newMax > MAX_THREADS) |
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. |
863 |
|
* Returns an estimate of the number of threads that are currently |
864 |
|
* stealing or executing tasks. This method may overestimate the |
865 |
|
* number of active threads. |
866 |
< |
* @return the number of active threads. |
866 |
> |
* @return the number of active threads |
867 |
|
*/ |
868 |
|
public int getActiveThreadCount() { |
869 |
|
return activeCountOf(runControl); |
873 |
|
* Returns an estimate of the number of threads that are currently |
874 |
|
* idle waiting for tasks. This method may underestimate the |
875 |
|
* number of idle threads. |
876 |
< |
* @return the number of idle threads. |
876 |
> |
* @return the number of idle threads |
877 |
|
*/ |
878 |
|
final int getIdleThreadCount() { |
879 |
|
int c = runningCountOf(workerCounts) - activeCountOf(runControl); |
902 |
|
* tuning fork/join programs: In general, steal counts should be |
903 |
|
* high enough to keep threads busy, but low enough to avoid |
904 |
|
* overhead and contention across threads. |
905 |
< |
* @return the number of steals. |
905 |
> |
* @return the number of steals |
906 |
|
*/ |
907 |
|
public long getStealCount() { |
908 |
|
return stealCount.get(); |
925 |
|
* an approximation, obtained by iterating across all threads in |
926 |
|
* the pool. This method may be useful for tuning task |
927 |
|
* granularities. |
928 |
< |
* @return the number of queued tasks. |
928 |
> |
* @return the number of queued tasks |
929 |
|
*/ |
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 |
|
} |
944 |
|
* Returns an estimate of the number tasks submitted to this pool |
945 |
|
* that have not yet begun executing. This method takes time |
946 |
|
* proportional to the number of submissions. |
947 |
< |
* @return the number of queued submissions. |
947 |
> |
* @return the number of queued submissions |
948 |
|
*/ |
949 |
|
public int getQueuedSubmissionCount() { |
950 |
|
return submissionQueue.size(); |
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(); |
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. |
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(); |
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(); |
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; |
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) |
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 |
|
/** |
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)) |
1191 |
|
} |
1192 |
|
|
1193 |
|
/** |
1194 |
< |
* Clear out and cancel submissions |
1194 |
> |
* Clears out and cancels submissions. |
1195 |
|
*/ |
1196 |
|
private void cancelQueuedSubmissions() { |
1197 |
|
ForkJoinTask<?> task; |
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(); |
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(); |
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 |
|
*/ |
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 |
|
} |
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 |
|
} |
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 |
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 |
|
* |
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) { |
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) { |
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) { |
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 |
|
} |
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 |
|
*/ |
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() { |
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. |
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 |
1717 |
|
* Possibly blocks the current thread, for example waiting for |
1718 |
|
* a lock or condition. |
1719 |
|
* @return true if no additional blocking is necessary (i.e., |
1720 |
< |
* if isReleasable would return true). |
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 |
|
|
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 |
1756 |
|
* attempt to maintain the pool's nominal parallelism; otherwise |
1757 |
|
* activate a thread only if necessary to avoid complete |
1758 |
|
* starvation. |
1759 |
< |
* @throws InterruptedException if blocker.block did so. |
1759 |
> |
* @throws InterruptedException if blocker.block did so |
1760 |
|
*/ |
1761 |
|
public static void managedBlock(ManagedBlocker blocker, |
1762 |
|
boolean maintainParallelism) |
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 |
|
} |
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 |
|
} |