5 |
|
*/ |
6 |
|
|
7 |
|
package jsr166y; |
8 |
< |
import java.util.*; |
8 |
> |
|
9 |
|
import java.util.concurrent.*; |
10 |
< |
import java.util.concurrent.locks.*; |
11 |
< |
import java.util.concurrent.atomic.*; |
12 |
< |
import sun.misc.Unsafe; |
13 |
< |
import java.lang.reflect.*; |
10 |
> |
|
11 |
> |
import java.util.ArrayList; |
12 |
> |
import java.util.Arrays; |
13 |
> |
import java.util.Collection; |
14 |
> |
import java.util.Collections; |
15 |
> |
import java.util.List; |
16 |
> |
import java.util.concurrent.locks.Condition; |
17 |
> |
import java.util.concurrent.locks.LockSupport; |
18 |
> |
import java.util.concurrent.locks.ReentrantLock; |
19 |
> |
import java.util.concurrent.atomic.AtomicInteger; |
20 |
> |
import java.util.concurrent.atomic.AtomicLong; |
21 |
|
|
22 |
|
/** |
23 |
< |
* An {@link ExecutorService} for running {@link ForkJoinTask}s. A |
24 |
< |
* ForkJoinPool provides the entry point for submissions from |
23 |
> |
* An {@link ExecutorService} for running {@link ForkJoinTask}s. |
24 |
> |
* A ForkJoinPool provides the entry point for submissions from |
25 |
|
* non-ForkJoinTasks, as well as management and monitoring operations. |
26 |
|
* Normally a single ForkJoinPool is used for a large number of |
27 |
|
* submitted tasks. Otherwise, use would not usually outweigh the |
34 |
|
* (eventually blocking if none exist). This makes them efficient when |
35 |
|
* most tasks spawn other subtasks (as do most ForkJoinTasks), as well |
36 |
|
* as the mixed execution of some plain Runnable- or Callable- based |
37 |
< |
* activities along with ForkJoinTasks. When setting |
38 |
< |
* <tt>setAsyncMode</tt>, a ForkJoinPools may also be appropriate for |
39 |
< |
* use with fine-grained tasks that are never joined. Otherwise, other |
40 |
< |
* ExecutorService implementations are typically more appropriate |
41 |
< |
* choices. |
37 |
> |
* activities along with ForkJoinTasks. When setting {@linkplain |
38 |
> |
* #setAsyncMode async mode}, a ForkJoinPool may also be appropriate |
39 |
> |
* for use with fine-grained tasks that are never joined. Otherwise, |
40 |
> |
* other ExecutorService implementations are typically more |
41 |
> |
* appropriate choices. |
42 |
|
* |
43 |
|
* <p>A ForkJoinPool may be constructed with a given parallelism level |
44 |
|
* (target pool size), which it attempts to maintain by dynamically |
45 |
|
* adding, suspending, or resuming threads, even if some tasks are |
46 |
|
* waiting to join others. However, no such adjustments are performed |
47 |
|
* in the face of blocked IO or other unmanaged synchronization. The |
48 |
< |
* nested <code>ManagedBlocker</code> interface enables extension of |
48 |
> |
* nested {@link ManagedBlocker} interface enables extension of |
49 |
|
* the kinds of synchronization accommodated. The target parallelism |
50 |
< |
* level may also be changed dynamically (<code>setParallelism</code>) |
50 |
> |
* level may also be changed dynamically ({@link #setParallelism}) |
51 |
|
* and thread construction can be limited using methods |
52 |
< |
* <code>setMaximumPoolSize</code> and/or |
53 |
< |
* <code>setMaintainsParallelism</code>. |
52 |
> |
* {@link #setMaximumPoolSize} and/or |
53 |
> |
* {@link #setMaintainsParallelism}. |
54 |
|
* |
55 |
|
* <p>In addition to execution and lifecycle control methods, this |
56 |
|
* class provides status check methods (for example |
57 |
< |
* <code>getStealCount</code>) that are intended to aid in developing, |
57 |
> |
* {@link #getStealCount}) that are intended to aid in developing, |
58 |
|
* tuning, and monitoring fork/join applications. Also, method |
59 |
< |
* <code>toString</code> returns indications of pool state in a |
59 |
> |
* {@link #toString} returns indications of pool state in a |
60 |
|
* convenient form for informal monitoring. |
61 |
|
* |
62 |
|
* <p><b>Implementation notes</b>: This implementation restricts the |
63 |
|
* maximum number of running threads to 32767. Attempts to create |
64 |
|
* pools with greater than the maximum result in |
65 |
|
* IllegalArgumentExceptions. |
66 |
+ |
* |
67 |
+ |
* @since 1.7 |
68 |
+ |
* @author Doug Lea |
69 |
|
*/ |
70 |
|
public class ForkJoinPool extends AbstractExecutorService { |
71 |
|
|
91 |
|
* Returns a new worker thread operating in the given pool. |
92 |
|
* |
93 |
|
* @param pool the pool this thread works in |
94 |
< |
* @throws NullPointerException if pool is null; |
94 |
> |
* @throws NullPointerException if pool is null |
95 |
|
*/ |
96 |
|
public ForkJoinWorkerThread newThread(ForkJoinPool pool); |
97 |
|
} |
98 |
|
|
99 |
|
/** |
100 |
< |
* Default ForkJoinWorkerThreadFactory implementation, creates a |
100 |
> |
* Default ForkJoinWorkerThreadFactory implementation; creates a |
101 |
|
* new ForkJoinWorkerThread. |
102 |
|
*/ |
103 |
|
static class DefaultForkJoinWorkerThreadFactory |
163 |
|
|
164 |
|
/** |
165 |
|
* The uncaught exception handler used when any worker |
166 |
< |
* abrupty terminates |
166 |
> |
* abruptly terminates |
167 |
|
*/ |
168 |
|
private Thread.UncaughtExceptionHandler ueh; |
169 |
|
|
191 |
|
private final LinkedTransferQueue<ForkJoinTask<?>> submissionQueue; |
192 |
|
|
193 |
|
/** |
194 |
< |
* Head of Treiber stack for barrier sync. See below for explanation |
194 |
> |
* Head of Treiber stack for barrier sync. See below for explanation. |
195 |
|
*/ |
196 |
|
private volatile WaitQueueNode syncStack; |
197 |
|
|
226 |
|
* threads, packed into one int to ensure consistent snapshot when |
227 |
|
* making decisions about creating and suspending spare |
228 |
|
* threads. Updated only by CAS. Note: CASes in |
229 |
< |
* updateRunningCount and preJoin running active count is in low |
230 |
< |
* word, so need to be modified if this changes |
229 |
> |
* updateRunningCount and preJoin assume that running active count |
230 |
> |
* is in low word, so need to be modified if this changes. |
231 |
|
*/ |
232 |
|
private volatile int workerCounts; |
233 |
|
|
236 |
|
private static int workerCountsFor(int t, int r) { return (t << 16) + r; } |
237 |
|
|
238 |
|
/** |
239 |
< |
* Add delta (which may be negative) to running count. This must |
239 |
> |
* Adds delta (which may be negative) to running count. This must |
240 |
|
* be called before (with negative arg) and after (with positive) |
241 |
< |
* any managed synchronization (i.e., mainly, joins) |
241 |
> |
* any managed synchronization (i.e., mainly, joins). |
242 |
> |
* |
243 |
|
* @param delta the number to add |
244 |
|
*/ |
245 |
|
final void updateRunningCount(int delta) { |
246 |
|
int s; |
247 |
< |
do;while (!casWorkerCounts(s = workerCounts, s + delta)); |
247 |
> |
do {} while (!casWorkerCounts(s = workerCounts, s + delta)); |
248 |
|
} |
249 |
|
|
250 |
|
/** |
251 |
< |
* Add delta (which may be negative) to both total and running |
251 |
> |
* Adds delta (which may be negative) to both total and running |
252 |
|
* count. This must be called upon creation and termination of |
253 |
|
* worker threads. |
254 |
+ |
* |
255 |
|
* @param delta the number to add |
256 |
|
*/ |
257 |
|
private void updateWorkerCount(int delta) { |
258 |
|
int d = delta + (delta << 16); // add to both lo and hi parts |
259 |
|
int s; |
260 |
< |
do;while (!casWorkerCounts(s = workerCounts, s + d)); |
260 |
> |
do {} while (!casWorkerCounts(s = workerCounts, s + d)); |
261 |
|
} |
262 |
|
|
263 |
|
/** |
283 |
|
private static int runControlFor(int r, int a) { return (r << 16) + a; } |
284 |
|
|
285 |
|
/** |
286 |
< |
* Try incrementing active count; fail on contention. Called by |
287 |
< |
* workers before/during executing tasks. |
288 |
< |
* @return true on success; |
286 |
> |
* Tries incrementing active count; fails on contention. |
287 |
> |
* Called by workers before/during executing tasks. |
288 |
> |
* |
289 |
> |
* @return true on success |
290 |
|
*/ |
291 |
|
final boolean tryIncrementActiveCount() { |
292 |
|
int c = runControl; |
294 |
|
} |
295 |
|
|
296 |
|
/** |
297 |
< |
* Try decrementing active count; fail on contention. |
298 |
< |
* Possibly trigger termination on success |
297 |
> |
* Tries decrementing active count; fails on contention. |
298 |
> |
* Possibly triggers termination on success. |
299 |
|
* Called by workers when they can't find tasks. |
300 |
+ |
* |
301 |
|
* @return true on success |
302 |
|
*/ |
303 |
|
final boolean tryDecrementActiveCount() { |
311 |
|
} |
312 |
|
|
313 |
|
/** |
314 |
< |
* Return true if argument represents zero active count and |
315 |
< |
* nonzero runstate, which is the triggering condition for |
314 |
> |
* Returns {@code true} if argument represents zero active count |
315 |
> |
* and nonzero runstate, which is the triggering condition for |
316 |
|
* terminating on shutdown. |
317 |
|
*/ |
318 |
|
private static boolean canTerminateOnShutdown(int c) { |
319 |
< |
return ((c & -c) >>> 16) != 0; // i.e. least bit is nonzero runState bit |
319 |
> |
// i.e. least bit is nonzero runState bit |
320 |
> |
return ((c & -c) >>> 16) != 0; |
321 |
|
} |
322 |
|
|
323 |
|
/** |
343 |
|
|
344 |
|
/** |
345 |
|
* Creates a ForkJoinPool with a pool size equal to the number of |
346 |
< |
* processors available on the system and using the default |
347 |
< |
* ForkJoinWorkerThreadFactory, |
346 |
> |
* processors available on the system, using the default |
347 |
> |
* ForkJoinWorkerThreadFactory. |
348 |
> |
* |
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() { |
355 |
|
this(Runtime.getRuntime().availableProcessors(), |
357 |
|
} |
358 |
|
|
359 |
|
/** |
360 |
< |
* Creates a ForkJoinPool with the indicated parellelism level |
361 |
< |
* threads, and using the default ForkJoinWorkerThreadFactory, |
360 |
> |
* Creates a ForkJoinPool with the indicated parallelism level |
361 |
> |
* threads and using the default ForkJoinWorkerThreadFactory. |
362 |
> |
* |
363 |
|
* @param parallelism the number of worker threads |
364 |
|
* @throws IllegalArgumentException if parallelism less than or |
365 |
|
* equal to zero |
366 |
|
* @throws SecurityException if a security manager exists and |
367 |
|
* the caller is not permitted to modify threads |
368 |
|
* because it does not hold {@link |
369 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
369 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
370 |
|
*/ |
371 |
|
public ForkJoinPool(int parallelism) { |
372 |
|
this(parallelism, defaultForkJoinWorkerThreadFactory); |
375 |
|
/** |
376 |
|
* Creates a ForkJoinPool with parallelism equal to the number of |
377 |
|
* processors available on the system and using the given |
378 |
< |
* ForkJoinWorkerThreadFactory, |
378 |
> |
* ForkJoinWorkerThreadFactory. |
379 |
> |
* |
380 |
|
* @param factory the factory for creating new threads |
381 |
|
* @throws NullPointerException if factory is null |
382 |
|
* @throws SecurityException if a security manager exists and |
383 |
|
* the caller is not permitted to modify threads |
384 |
|
* because it does not hold {@link |
385 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
385 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
386 |
|
*/ |
387 |
|
public ForkJoinPool(ForkJoinWorkerThreadFactory factory) { |
388 |
|
this(Runtime.getRuntime().availableProcessors(), factory); |
394 |
|
* @param parallelism the targeted number of worker threads |
395 |
|
* @param factory the factory for creating new threads |
396 |
|
* @throws IllegalArgumentException if parallelism less than or |
397 |
< |
* equal to zero, or greater than implementation limit. |
397 |
> |
* equal to zero, or greater than implementation limit |
398 |
|
* @throws NullPointerException if factory is null |
399 |
|
* @throws SecurityException if a security manager exists and |
400 |
|
* the caller is not permitted to modify threads |
401 |
|
* because it does not hold {@link |
402 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
402 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
403 |
|
*/ |
404 |
|
public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) { |
405 |
|
if (parallelism <= 0 || parallelism > MAX_THREADS) |
420 |
|
} |
421 |
|
|
422 |
|
/** |
423 |
< |
* Create new worker using factory. |
423 |
> |
* Creates a new worker thread using factory. |
424 |
> |
* |
425 |
|
* @param index the index to assign worker |
426 |
|
* @return new worker, or null of factory failed |
427 |
|
*/ |
440 |
|
} |
441 |
|
|
442 |
|
/** |
443 |
< |
* Return a good size for worker array given pool size. |
443 |
> |
* Returns a good size for worker array given pool size. |
444 |
|
* Currently requires size to be a power of two. |
445 |
|
*/ |
446 |
< |
private static int arraySizeFor(int ps) { |
447 |
< |
return ps <= 1? 1 : (1 << (32 - Integer.numberOfLeadingZeros(ps-1))); |
446 |
> |
private static int arraySizeFor(int poolSize) { |
447 |
> |
return (poolSize <= 1) ? 1 : |
448 |
> |
(1 << (32 - Integer.numberOfLeadingZeros(poolSize-1))); |
449 |
|
} |
450 |
|
|
451 |
|
/** |
452 |
< |
* Create or resize array if necessary to hold newLength. |
453 |
< |
* Call only under exlusion or lock |
452 |
> |
* Creates or resizes array if necessary to hold newLength. |
453 |
> |
* Call only under exclusion. |
454 |
> |
* |
455 |
|
* @return the array |
456 |
|
*/ |
457 |
|
private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) { |
465 |
|
} |
466 |
|
|
467 |
|
/** |
468 |
< |
* Try to shrink workers into smaller array after one or more terminate |
468 |
> |
* Tries to shrink workers into smaller array after one or more terminate. |
469 |
|
*/ |
470 |
|
private void tryShrinkWorkerArray() { |
471 |
|
ForkJoinWorkerThread[] ws = workers; |
481 |
|
} |
482 |
|
|
483 |
|
/** |
484 |
< |
* Initialize workers if necessary |
484 |
> |
* Initializes workers if necessary. |
485 |
|
*/ |
486 |
|
final void ensureWorkerInitialization() { |
487 |
|
ForkJoinWorkerThread[] ws = workers; |
548 |
|
* Common code for execute, invoke and submit |
549 |
|
*/ |
550 |
|
private <T> void doSubmit(ForkJoinTask<T> task) { |
551 |
+ |
if (task == null) |
552 |
+ |
throw new NullPointerException(); |
553 |
|
if (isShutdown()) |
554 |
|
throw new RejectedExecutionException(); |
555 |
|
if (workers == null) |
559 |
|
} |
560 |
|
|
561 |
|
/** |
562 |
< |
* Performs the given task; returning its result upon completion |
562 |
> |
* Performs the given task, returning its result upon completion. |
563 |
> |
* |
564 |
|
* @param task the task |
565 |
|
* @return the task's result |
566 |
|
* @throws NullPointerException if task is null |
573 |
|
|
574 |
|
/** |
575 |
|
* Arranges for (asynchronous) execution of the given task. |
576 |
+ |
* |
577 |
|
* @param task the task |
578 |
|
* @throws NullPointerException if task is null |
579 |
|
* @throws RejectedExecutionException if pool is shut down |
585 |
|
// AbstractExecutorService methods |
586 |
|
|
587 |
|
public void execute(Runnable task) { |
588 |
< |
doSubmit(new AdaptedRunnable<Void>(task, null)); |
588 |
> |
ForkJoinTask<?> job; |
589 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
590 |
> |
job = (ForkJoinTask<?>) task; |
591 |
> |
else |
592 |
> |
job = ForkJoinTask.adapt(task, null); |
593 |
> |
doSubmit(job); |
594 |
|
} |
595 |
|
|
596 |
|
public <T> ForkJoinTask<T> submit(Callable<T> task) { |
597 |
< |
ForkJoinTask<T> job = new AdaptedCallable<T>(task); |
597 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task); |
598 |
|
doSubmit(job); |
599 |
|
return job; |
600 |
|
} |
601 |
|
|
602 |
|
public <T> ForkJoinTask<T> submit(Runnable task, T result) { |
603 |
< |
ForkJoinTask<T> job = new AdaptedRunnable<T>(task, result); |
603 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task, result); |
604 |
|
doSubmit(job); |
605 |
|
return job; |
606 |
|
} |
607 |
|
|
608 |
|
public ForkJoinTask<?> submit(Runnable task) { |
609 |
< |
ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null); |
609 |
> |
ForkJoinTask<?> job; |
610 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
611 |
> |
job = (ForkJoinTask<?>) task; |
612 |
> |
else |
613 |
> |
job = ForkJoinTask.adapt(task, null); |
614 |
|
doSubmit(job); |
615 |
|
return job; |
616 |
|
} |
617 |
|
|
618 |
|
/** |
619 |
< |
* Adaptor for Runnables. This implements RunnableFuture |
620 |
< |
* to be compliant with AbstractExecutorService constraints |
619 |
> |
* Submits a ForkJoinTask for execution. |
620 |
> |
* |
621 |
> |
* @param task the task to submit |
622 |
> |
* @return the task |
623 |
> |
* @throws RejectedExecutionException if the task cannot be |
624 |
> |
* scheduled for execution |
625 |
> |
* @throws NullPointerException if the task is null |
626 |
|
*/ |
627 |
< |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
628 |
< |
implements RunnableFuture<T> { |
629 |
< |
final Runnable runnable; |
591 |
< |
final T resultOnCompletion; |
592 |
< |
T result; |
593 |
< |
AdaptedRunnable(Runnable runnable, T result) { |
594 |
< |
if (runnable == null) throw new NullPointerException(); |
595 |
< |
this.runnable = runnable; |
596 |
< |
this.resultOnCompletion = result; |
597 |
< |
} |
598 |
< |
public T getRawResult() { return result; } |
599 |
< |
public void setRawResult(T v) { result = v; } |
600 |
< |
public boolean exec() { |
601 |
< |
runnable.run(); |
602 |
< |
result = resultOnCompletion; |
603 |
< |
return true; |
604 |
< |
} |
605 |
< |
public void run() { invoke(); } |
627 |
> |
public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) { |
628 |
> |
doSubmit(task); |
629 |
> |
return task; |
630 |
|
} |
631 |
|
|
608 |
– |
/** |
609 |
– |
* Adaptor for Callables |
610 |
– |
*/ |
611 |
– |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
612 |
– |
implements RunnableFuture<T> { |
613 |
– |
final Callable<T> callable; |
614 |
– |
T result; |
615 |
– |
AdaptedCallable(Callable<T> callable) { |
616 |
– |
if (callable == null) throw new NullPointerException(); |
617 |
– |
this.callable = callable; |
618 |
– |
} |
619 |
– |
public T getRawResult() { return result; } |
620 |
– |
public void setRawResult(T v) { result = v; } |
621 |
– |
public boolean exec() { |
622 |
– |
try { |
623 |
– |
result = callable.call(); |
624 |
– |
return true; |
625 |
– |
} catch (Error err) { |
626 |
– |
throw err; |
627 |
– |
} catch (RuntimeException rex) { |
628 |
– |
throw rex; |
629 |
– |
} catch (Exception ex) { |
630 |
– |
throw new RuntimeException(ex); |
631 |
– |
} |
632 |
– |
} |
633 |
– |
public void run() { invoke(); } |
634 |
– |
} |
632 |
|
|
633 |
|
public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) { |
634 |
< |
ArrayList<ForkJoinTask<T>> ts = |
634 |
> |
ArrayList<ForkJoinTask<T>> forkJoinTasks = |
635 |
|
new ArrayList<ForkJoinTask<T>>(tasks.size()); |
636 |
< |
for (Callable<T> c : tasks) |
637 |
< |
ts.add(new AdaptedCallable<T>(c)); |
638 |
< |
invoke(new InvokeAll<T>(ts)); |
639 |
< |
return (List<Future<T>>)(List)ts; |
636 |
> |
for (Callable<T> task : tasks) |
637 |
> |
forkJoinTasks.add(ForkJoinTask.adapt(task)); |
638 |
> |
invoke(new InvokeAll<T>(forkJoinTasks)); |
639 |
> |
|
640 |
> |
@SuppressWarnings({"unchecked", "rawtypes"}) |
641 |
> |
List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks; |
642 |
> |
return futures; |
643 |
|
} |
644 |
|
|
645 |
|
static final class InvokeAll<T> extends RecursiveAction { |
646 |
|
final ArrayList<ForkJoinTask<T>> tasks; |
647 |
|
InvokeAll(ArrayList<ForkJoinTask<T>> tasks) { this.tasks = tasks; } |
648 |
|
public void compute() { |
649 |
< |
try { invokeAll(tasks); } catch(Exception ignore) {} |
649 |
> |
try { invokeAll(tasks); } |
650 |
> |
catch (Exception ignore) {} |
651 |
|
} |
652 |
+ |
private static final long serialVersionUID = -7914297376763021607L; |
653 |
|
} |
654 |
|
|
655 |
|
// Configuration and status settings and queries |
656 |
|
|
657 |
|
/** |
658 |
< |
* Returns the factory used for constructing new workers |
658 |
> |
* Returns the factory used for constructing new workers. |
659 |
|
* |
660 |
|
* @return the factory used for constructing new workers |
661 |
|
*/ |
666 |
|
/** |
667 |
|
* Returns the handler for internal worker threads that terminate |
668 |
|
* due to unrecoverable errors encountered while executing tasks. |
669 |
< |
* @return the handler, or null if none |
669 |
> |
* |
670 |
> |
* @return the handler, or {@code null} if none |
671 |
|
*/ |
672 |
|
public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() { |
673 |
|
Thread.UncaughtExceptionHandler h; |
688 |
|
* as handler. |
689 |
|
* |
690 |
|
* @param h the new handler |
691 |
< |
* @return the old handler, or null if none |
691 |
> |
* @return the old handler, or {@code null} if none |
692 |
|
* @throws SecurityException if a security manager exists and |
693 |
|
* the caller is not permitted to modify threads |
694 |
|
* because it does not hold {@link |
695 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
695 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
696 |
|
*/ |
697 |
|
public Thread.UncaughtExceptionHandler |
698 |
|
setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) { |
719 |
|
|
720 |
|
|
721 |
|
/** |
722 |
< |
* Sets the target paralleism level of this pool. |
722 |
> |
* Sets the target parallelism level of this pool. |
723 |
> |
* |
724 |
|
* @param parallelism the target parallelism |
725 |
|
* @throws IllegalArgumentException if parallelism less than or |
726 |
< |
* equal to zero or greater than maximum size bounds. |
726 |
> |
* equal to zero or greater than maximum size bounds |
727 |
|
* @throws SecurityException if a security manager exists and |
728 |
|
* the caller is not permitted to modify threads |
729 |
|
* because it does not hold {@link |
730 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
730 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
731 |
|
*/ |
732 |
|
public void setParallelism(int parallelism) { |
733 |
|
checkPermission(); |
762 |
|
/** |
763 |
|
* Returns the number of worker threads that have started but not |
764 |
|
* yet terminated. This result returned by this method may differ |
765 |
< |
* from <code>getParallelism</code> when threads are created to |
765 |
> |
* from {@link #getParallelism} when threads are created to |
766 |
|
* maintain parallelism when others are cooperatively blocked. |
767 |
|
* |
768 |
|
* @return the number of worker threads |
774 |
|
/** |
775 |
|
* Returns the maximum number of threads allowed to exist in the |
776 |
|
* pool, even if there are insufficient unblocked running threads. |
777 |
+ |
* |
778 |
|
* @return the maximum |
779 |
|
*/ |
780 |
|
public int getMaximumPoolSize() { |
786 |
|
* pool, even if there are insufficient unblocked running threads. |
787 |
|
* Setting this value has no effect on current pool size. It |
788 |
|
* controls construction of new threads. |
789 |
+ |
* |
790 |
|
* @throws IllegalArgumentException if negative or greater then |
791 |
< |
* internal implementation limit. |
791 |
> |
* internal implementation limit |
792 |
|
*/ |
793 |
|
public void setMaximumPoolSize(int newMax) { |
794 |
|
if (newMax < 0 || newMax > MAX_THREADS) |
798 |
|
|
799 |
|
|
800 |
|
/** |
801 |
< |
* Returns true if this pool dynamically maintains its target |
802 |
< |
* parallelism level. If false, new threads are added only to |
803 |
< |
* avoid possible starvation. |
804 |
< |
* This setting is by default true; |
805 |
< |
* @return true if maintains parallelism |
801 |
> |
* Returns {@code true} if this pool dynamically maintains its |
802 |
> |
* target parallelism level. If false, new threads are added only |
803 |
> |
* to avoid possible starvation. This setting is by default true. |
804 |
> |
* |
805 |
> |
* @return {@code true} if maintains parallelism |
806 |
|
*/ |
807 |
|
public boolean getMaintainsParallelism() { |
808 |
|
return maintainsParallelism; |
812 |
|
* Sets whether this pool dynamically maintains its target |
813 |
|
* parallelism level. If false, new threads are added only to |
814 |
|
* avoid possible starvation. |
815 |
< |
* @param enable true to maintains parallelism |
815 |
> |
* |
816 |
> |
* @param enable {@code true} to maintain parallelism |
817 |
|
*/ |
818 |
|
public void setMaintainsParallelism(boolean enable) { |
819 |
|
maintainsParallelism = enable; |
824 |
|
* tasks that are never joined. This mode may be more appropriate |
825 |
|
* than default locally stack-based mode in applications in which |
826 |
|
* worker threads only process asynchronous tasks. This method is |
827 |
< |
* designed to be invoked only when pool is quiescent, and |
827 |
> |
* designed to be invoked only when the pool is quiescent, and |
828 |
|
* typically only before any tasks are submitted. The effects of |
829 |
< |
* invocations at ather times may be unpredictable. |
829 |
> |
* invocations at other times may be unpredictable. |
830 |
|
* |
831 |
< |
* @param async if true, use locally FIFO scheduling |
832 |
< |
* @return the previous mode. |
831 |
> |
* @param async if {@code true}, use locally FIFO scheduling |
832 |
> |
* @return the previous mode |
833 |
> |
* @see #getAsyncMode |
834 |
|
*/ |
835 |
|
public boolean setAsyncMode(boolean async) { |
836 |
|
boolean oldMode = locallyFifo; |
847 |
|
} |
848 |
|
|
849 |
|
/** |
850 |
< |
* Returns true if this pool uses local first-in-first-out |
851 |
< |
* scheduling mode for forked tasks that are never joined. |
850 |
> |
* Returns {@code true} if this pool uses local first-in-first-out |
851 |
> |
* scheduling mode for forked tasks that are never joined. |
852 |
|
* |
853 |
< |
* @return true if this pool uses async mode. |
853 |
> |
* @return {@code true} if this pool uses async mode |
854 |
> |
* @see #setAsyncMode |
855 |
|
*/ |
856 |
|
public boolean getAsyncMode() { |
857 |
|
return locallyFifo; |
872 |
|
* Returns an estimate of the number of threads that are currently |
873 |
|
* stealing or executing tasks. This method may overestimate the |
874 |
|
* number of active threads. |
875 |
< |
* @return the number of active threads. |
875 |
> |
* |
876 |
> |
* @return the number of active threads |
877 |
|
*/ |
878 |
|
public int getActiveThreadCount() { |
879 |
|
return activeCountOf(runControl); |
883 |
|
* Returns an estimate of the number of threads that are currently |
884 |
|
* idle waiting for tasks. This method may underestimate the |
885 |
|
* number of idle threads. |
886 |
< |
* @return the number of idle threads. |
886 |
> |
* |
887 |
> |
* @return the number of idle threads |
888 |
|
*/ |
889 |
|
final int getIdleThreadCount() { |
890 |
|
int c = runningCountOf(workerCounts) - activeCountOf(runControl); |
891 |
< |
return (c <= 0)? 0 : c; |
891 |
> |
return (c <= 0) ? 0 : c; |
892 |
|
} |
893 |
|
|
894 |
|
/** |
895 |
< |
* Returns true if all worker threads are currently idle. An idle |
896 |
< |
* worker is one that cannot obtain a task to execute because none |
897 |
< |
* are available to steal from other threads, and there are no |
898 |
< |
* pending submissions to the pool. This method is conservative: |
899 |
< |
* It might not return true immediately upon idleness of all |
900 |
< |
* threads, but will eventually become true if threads remain |
901 |
< |
* inactive. |
902 |
< |
* @return true if all threads are currently idle |
895 |
> |
* Returns {@code true} if all worker threads are currently idle. |
896 |
> |
* An idle worker is one that cannot obtain a task to execute |
897 |
> |
* because none are available to steal from other threads, and |
898 |
> |
* there are no pending submissions to the pool. This method is |
899 |
> |
* conservative; it might not return {@code true} immediately upon |
900 |
> |
* idleness of all threads, but will eventually become true if |
901 |
> |
* threads remain inactive. |
902 |
> |
* |
903 |
> |
* @return {@code true} if all threads are currently idle |
904 |
|
*/ |
905 |
|
public boolean isQuiescent() { |
906 |
|
return activeCountOf(runControl) == 0; |
911 |
|
* one thread's work queue by another. The reported value |
912 |
|
* underestimates the actual total number of steals when the pool |
913 |
|
* is not quiescent. This value may be useful for monitoring and |
914 |
< |
* tuning fork/join programs: In general, steal counts should be |
914 |
> |
* tuning fork/join programs: in general, steal counts should be |
915 |
|
* high enough to keep threads busy, but low enough to avoid |
916 |
|
* overhead and contention across threads. |
917 |
< |
* @return the number of steals. |
917 |
> |
* |
918 |
> |
* @return the number of steals |
919 |
|
*/ |
920 |
|
public long getStealCount() { |
921 |
|
return stealCount.get(); |
922 |
|
} |
923 |
|
|
924 |
|
/** |
925 |
< |
* Accumulate steal count from a worker. Call only |
926 |
< |
* when worker known to be idle. |
925 |
> |
* Accumulates steal count from a worker. |
926 |
> |
* Call only when worker known to be idle. |
927 |
|
*/ |
928 |
|
private void updateStealCount(ForkJoinWorkerThread w) { |
929 |
|
int sc = w.getAndClearStealCount(); |
938 |
|
* an approximation, obtained by iterating across all threads in |
939 |
|
* the pool. This method may be useful for tuning task |
940 |
|
* granularities. |
941 |
< |
* @return the number of queued tasks. |
941 |
> |
* |
942 |
> |
* @return the number of queued tasks |
943 |
|
*/ |
944 |
|
public long getQueuedTaskCount() { |
945 |
|
long count = 0; |
958 |
|
* Returns an estimate of the number tasks submitted to this pool |
959 |
|
* that have not yet begun executing. This method takes time |
960 |
|
* proportional to the number of submissions. |
961 |
< |
* @return the number of queued submissions. |
961 |
> |
* |
962 |
> |
* @return the number of queued submissions |
963 |
|
*/ |
964 |
|
public int getQueuedSubmissionCount() { |
965 |
|
return submissionQueue.size(); |
966 |
|
} |
967 |
|
|
968 |
|
/** |
969 |
< |
* Returns true if there are any tasks submitted to this pool |
970 |
< |
* that have not yet begun executing. |
971 |
< |
* @return <code>true</code> if there are any queued submissions. |
969 |
> |
* Returns {@code true} if there are any tasks submitted to this |
970 |
> |
* pool that have not yet begun executing. |
971 |
> |
* |
972 |
> |
* @return {@code true} if there are any queued submissions |
973 |
|
*/ |
974 |
|
public boolean hasQueuedSubmissions() { |
975 |
|
return !submissionQueue.isEmpty(); |
979 |
|
* Removes and returns the next unexecuted submission if one is |
980 |
|
* available. This method may be useful in extensions to this |
981 |
|
* class that re-assign work in systems with multiple pools. |
982 |
< |
* @return the next submission, or null if none |
982 |
> |
* |
983 |
> |
* @return the next submission, or {@code null} if none |
984 |
|
*/ |
985 |
|
protected ForkJoinTask<?> pollSubmission() { |
986 |
|
return submissionQueue.poll(); |
990 |
|
* Removes all available unexecuted submitted and forked tasks |
991 |
|
* from scheduling queues and adds them to the given collection, |
992 |
|
* without altering their execution status. These may include |
993 |
< |
* artifically generated or wrapped tasks. This method id designed |
993 |
> |
* artificially generated or wrapped tasks. This method is designed |
994 |
|
* to be invoked only when the pool is known to be |
995 |
|
* quiescent. Invocations at other times may not remove all |
996 |
|
* tasks. A failure encountered while attempting to add elements |
997 |
< |
* to collection <tt>c</tt> may result in elements being in |
997 |
> |
* to collection {@code c} may result in elements being in |
998 |
|
* neither, either or both collections when the associated |
999 |
|
* exception is thrown. The behavior of this operation is |
1000 |
|
* undefined if the specified collection is modified while the |
1001 |
|
* operation is in progress. |
1002 |
+ |
* |
1003 |
|
* @param c the collection to transfer elements into |
1004 |
|
* @return the number of elements transferred |
1005 |
|
*/ |
1006 |
< |
protected int drainTasksTo(Collection<ForkJoinTask<?>> c) { |
1006 |
> |
protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) { |
1007 |
|
int n = submissionQueue.drainTo(c); |
1008 |
|
ForkJoinWorkerThread[] ws = workers; |
1009 |
|
if (ws != null) { |
1060 |
|
* Invocation has no additional effect if already shut down. |
1061 |
|
* Tasks that are in the process of being submitted concurrently |
1062 |
|
* during the course of this method may or may not be rejected. |
1063 |
+ |
* |
1064 |
|
* @throws SecurityException if a security manager exists and |
1065 |
|
* the caller is not permitted to modify threads |
1066 |
|
* because it does not hold {@link |
1067 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
1067 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1068 |
|
*/ |
1069 |
|
public void shutdown() { |
1070 |
|
checkPermission(); |
1071 |
|
transitionRunStateTo(SHUTDOWN); |
1072 |
< |
if (canTerminateOnShutdown(runControl)) |
1072 |
> |
if (canTerminateOnShutdown(runControl)) { |
1073 |
> |
if (workers == null) { // shutting down before workers created |
1074 |
> |
final ReentrantLock lock = this.workerLock; |
1075 |
> |
lock.lock(); |
1076 |
> |
try { |
1077 |
> |
if (workers == null) { |
1078 |
> |
terminate(); |
1079 |
> |
transitionRunStateTo(TERMINATED); |
1080 |
> |
termination.signalAll(); |
1081 |
> |
} |
1082 |
> |
} finally { |
1083 |
> |
lock.unlock(); |
1084 |
> |
} |
1085 |
> |
} |
1086 |
|
terminateOnShutdown(); |
1087 |
+ |
} |
1088 |
|
} |
1089 |
|
|
1090 |
|
/** |
1094 |
|
* method may or may not be rejected. Unlike some other executors, |
1095 |
|
* this method cancels rather than collects non-executed tasks |
1096 |
|
* upon termination, so always returns an empty list. However, you |
1097 |
< |
* can use method <code>drainTasksTo</code> before invoking this |
1097 |
> |
* can use method {@link #drainTasksTo} before invoking this |
1098 |
|
* method to transfer unexecuted tasks to another collection. |
1099 |
+ |
* |
1100 |
|
* @return an empty list |
1101 |
|
* @throws SecurityException if a security manager exists and |
1102 |
|
* the caller is not permitted to modify threads |
1103 |
|
* because it does not hold {@link |
1104 |
< |
* java.lang.RuntimePermission}<code>("modifyThread")</code>, |
1104 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1105 |
|
*/ |
1106 |
|
public List<Runnable> shutdownNow() { |
1107 |
|
checkPermission(); |
1110 |
|
} |
1111 |
|
|
1112 |
|
/** |
1113 |
< |
* Returns <code>true</code> if all tasks have completed following shut down. |
1113 |
> |
* Returns {@code true} if all tasks have completed following shut down. |
1114 |
|
* |
1115 |
< |
* @return <code>true</code> if all tasks have completed following shut down |
1115 |
> |
* @return {@code true} if all tasks have completed following shut down |
1116 |
|
*/ |
1117 |
|
public boolean isTerminated() { |
1118 |
|
return runStateOf(runControl) == TERMINATED; |
1119 |
|
} |
1120 |
|
|
1121 |
|
/** |
1122 |
< |
* Returns <code>true</code> if the process of termination has |
1122 |
> |
* Returns {@code true} if the process of termination has |
1123 |
|
* commenced but possibly not yet completed. |
1124 |
|
* |
1125 |
< |
* @return <code>true</code> if terminating |
1125 |
> |
* @return {@code true} if terminating |
1126 |
|
*/ |
1127 |
|
public boolean isTerminating() { |
1128 |
|
return runStateOf(runControl) >= TERMINATING; |
1129 |
|
} |
1130 |
|
|
1131 |
|
/** |
1132 |
< |
* Returns <code>true</code> if this pool has been shut down. |
1132 |
> |
* Returns {@code true} if this pool has been shut down. |
1133 |
|
* |
1134 |
< |
* @return <code>true</code> if this pool has been shut down |
1134 |
> |
* @return {@code true} if this pool has been shut down |
1135 |
|
*/ |
1136 |
|
public boolean isShutdown() { |
1137 |
|
return runStateOf(runControl) >= SHUTDOWN; |
1144 |
|
* |
1145 |
|
* @param timeout the maximum time to wait |
1146 |
|
* @param unit the time unit of the timeout argument |
1147 |
< |
* @return <code>true</code> if this executor terminated and |
1148 |
< |
* <code>false</code> if the timeout elapsed before termination |
1147 |
> |
* @return {@code true} if this executor terminated and |
1148 |
> |
* {@code false} if the timeout elapsed before termination |
1149 |
|
* @throws InterruptedException if interrupted while waiting |
1150 |
|
*/ |
1151 |
|
public boolean awaitTermination(long timeout, TimeUnit unit) |
1169 |
|
// Shutdown and termination support |
1170 |
|
|
1171 |
|
/** |
1172 |
< |
* Callback from terminating worker. Null out the corresponding |
1173 |
< |
* workers slot, and if terminating, try to terminate, else try to |
1174 |
< |
* shrink workers array. |
1172 |
> |
* Callback from terminating worker. Nulls out the corresponding |
1173 |
> |
* workers slot, and if terminating, tries to terminate; else |
1174 |
> |
* tries to shrink workers array. |
1175 |
> |
* |
1176 |
|
* @param w the worker |
1177 |
|
*/ |
1178 |
|
final void workerTerminated(ForkJoinWorkerThread w) { |
1203 |
|
} |
1204 |
|
|
1205 |
|
/** |
1206 |
< |
* Initiate termination. |
1206 |
> |
* Initiates termination. |
1207 |
|
*/ |
1208 |
|
private void terminate() { |
1209 |
|
if (transitionRunStateTo(TERMINATING)) { |
1218 |
|
} |
1219 |
|
|
1220 |
|
/** |
1221 |
< |
* Possibly terminate when on shutdown state |
1221 |
> |
* Possibly terminates when on shutdown state. |
1222 |
|
*/ |
1223 |
|
private void terminateOnShutdown() { |
1224 |
|
if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl)) |
1226 |
|
} |
1227 |
|
|
1228 |
|
/** |
1229 |
< |
* Clear out and cancel submissions |
1229 |
> |
* Clears out and cancels submissions. |
1230 |
|
*/ |
1231 |
|
private void cancelQueuedSubmissions() { |
1232 |
|
ForkJoinTask<?> task; |
1235 |
|
} |
1236 |
|
|
1237 |
|
/** |
1238 |
< |
* Clean out worker queues. |
1238 |
> |
* Cleans out worker queues. |
1239 |
|
*/ |
1240 |
|
private void cancelQueuedWorkerTasks() { |
1241 |
|
final ReentrantLock lock = this.workerLock; |
1255 |
|
} |
1256 |
|
|
1257 |
|
/** |
1258 |
< |
* Set each worker's status to terminating. Requires lock to avoid |
1259 |
< |
* conflicts with add/remove |
1258 |
> |
* Sets each worker's status to terminating. Requires lock to avoid |
1259 |
> |
* conflicts with add/remove. |
1260 |
|
*/ |
1261 |
|
private void stopAllWorkers() { |
1262 |
|
final ReentrantLock lock = this.workerLock; |
1276 |
|
} |
1277 |
|
|
1278 |
|
/** |
1279 |
< |
* Interrupt all unterminated workers. This is not required for |
1279 |
> |
* Interrupts all unterminated workers. This is not required for |
1280 |
|
* sake of internal control, but may help unstick user code during |
1281 |
|
* shutdown. |
1282 |
|
*/ |
1346 |
|
} |
1347 |
|
|
1348 |
|
/** |
1349 |
< |
* Wake up waiter, returning false if known to already |
1349 |
> |
* Wakes up waiter, returning false if known to already |
1350 |
|
*/ |
1351 |
|
boolean signal() { |
1352 |
|
ForkJoinWorkerThread t = thread; |
1358 |
|
} |
1359 |
|
|
1360 |
|
/** |
1361 |
< |
* Await release on sync |
1361 |
> |
* Awaits release on sync. |
1362 |
|
*/ |
1363 |
|
void awaitSyncRelease(ForkJoinPool p) { |
1364 |
|
while (thread != null && !p.syncIsReleasable(this)) |
1366 |
|
} |
1367 |
|
|
1368 |
|
/** |
1369 |
< |
* Await resumption as spare |
1369 |
> |
* Awaits resumption as spare. |
1370 |
|
*/ |
1371 |
|
void awaitSpareRelease() { |
1372 |
|
while (thread != null) { |
1380 |
|
* Ensures that no thread is waiting for count to advance from the |
1381 |
|
* current value of eventCount read on entry to this method, by |
1382 |
|
* releasing waiting threads if necessary. |
1383 |
+ |
* |
1384 |
|
* @return the count |
1385 |
|
*/ |
1386 |
|
final long ensureSync() { |
1402 |
|
*/ |
1403 |
|
private void signalIdleWorkers() { |
1404 |
|
long c; |
1405 |
< |
do;while (!casEventCount(c = eventCount, c+1)); |
1405 |
> |
do {} while (!casEventCount(c = eventCount, c+1)); |
1406 |
|
ensureSync(); |
1407 |
|
} |
1408 |
|
|
1409 |
|
/** |
1410 |
< |
* Signal threads waiting to poll a task. Because method sync |
1410 |
> |
* Signals threads waiting to poll a task. Because method sync |
1411 |
|
* rechecks availability, it is OK to only proceed if queue |
1412 |
|
* appears to be non-empty, and OK to skip under contention to |
1413 |
|
* increment count (since some other thread succeeded). |
1426 |
|
* Waits until event count advances from last value held by |
1427 |
|
* caller, or if excess threads, caller is resumed as spare, or |
1428 |
|
* caller or pool is terminating. Updates caller's event on exit. |
1429 |
+ |
* |
1430 |
|
* @param w the calling worker thread |
1431 |
|
*/ |
1432 |
|
final void sync(ForkJoinWorkerThread w) { |
1454 |
|
} |
1455 |
|
|
1456 |
|
/** |
1457 |
< |
* Returns true if worker waiting on sync can proceed: |
1457 |
> |
* Returns {@code true} if worker waiting on sync can proceed: |
1458 |
|
* - on signal (thread == null) |
1459 |
|
* - on event count advance (winning race to notify vs signaller) |
1460 |
< |
* - on Interrupt |
1460 |
> |
* - on interrupt |
1461 |
|
* - if the first queued node, we find work available |
1462 |
|
* If node was not signalled and event count not advanced on exit, |
1463 |
|
* then we also help advance event count. |
1464 |
< |
* @return true if node can be released |
1464 |
> |
* |
1465 |
> |
* @return {@code true} if node can be released |
1466 |
|
*/ |
1467 |
|
final boolean syncIsReleasable(WaitQueueNode node) { |
1468 |
|
long prev = node.count; |
1481 |
|
} |
1482 |
|
|
1483 |
|
/** |
1484 |
< |
* Returns true if a new sync event occurred since last call to |
1485 |
< |
* sync or this method, if so, updating caller's count. |
1484 |
> |
* Returns {@code true} if a new sync event occurred since last |
1485 |
> |
* call to sync or this method, if so, updating caller's count. |
1486 |
|
*/ |
1487 |
|
final boolean hasNewSyncEvent(ForkJoinWorkerThread w) { |
1488 |
|
long lc = w.lastEventCount; |
1496 |
|
// Parallelism maintenance |
1497 |
|
|
1498 |
|
/** |
1499 |
< |
* Decrement running count; if too low, add spare. |
1499 |
> |
* Decrements running count; if too low, adds spare. |
1500 |
|
* |
1501 |
|
* Conceptually, all we need to do here is add or resume a |
1502 |
|
* spare thread when one is about to block (and remove or |
1503 |
|
* suspend it later when unblocked -- see suspendIfSpare). |
1504 |
|
* However, implementing this idea requires coping with |
1505 |
< |
* several problems: We have imperfect information about the |
1505 |
> |
* several problems: we have imperfect information about the |
1506 |
|
* states of threads. Some count updates can and usually do |
1507 |
|
* lag run state changes, despite arrangements to keep them |
1508 |
|
* accurate (for example, when possible, updating counts |
1516 |
|
* only be suspended or removed when they are idle, not |
1517 |
|
* immediately when they aren't needed. So adding threads will |
1518 |
|
* raise parallelism level for longer than necessary. Also, |
1519 |
< |
* FJ applications often enounter highly transient peaks when |
1519 |
> |
* FJ applications often encounter highly transient peaks when |
1520 |
|
* many threads are blocked joining, but for less time than it |
1521 |
|
* takes to create or resume spares. |
1522 |
|
* |
1525 |
|
* target counts, else create only to avoid starvation |
1526 |
|
* @return true if joinMe known to be done |
1527 |
|
*/ |
1528 |
< |
final boolean preJoin(ForkJoinTask<?> joinMe, boolean maintainParallelism) { |
1528 |
> |
final boolean preJoin(ForkJoinTask<?> joinMe, |
1529 |
> |
boolean maintainParallelism) { |
1530 |
|
maintainParallelism &= maintainsParallelism; // overrride |
1531 |
|
boolean dec = false; // true when running count decremented |
1532 |
|
while (spareStack == null || !tryResumeSpare(dec)) { |
1533 |
|
int counts = workerCounts; |
1534 |
< |
if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat |
1534 |
> |
if (dec || (dec = casWorkerCounts(counts, --counts))) { |
1535 |
> |
// CAS cheat |
1536 |
|
if (!needSpare(counts, maintainParallelism)) |
1537 |
|
break; |
1538 |
|
if (joinMe.status < 0) |
1547 |
|
/** |
1548 |
|
* Same idea as preJoin |
1549 |
|
*/ |
1550 |
< |
final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){ |
1550 |
> |
final boolean preBlock(ManagedBlocker blocker, |
1551 |
> |
boolean maintainParallelism) { |
1552 |
|
maintainParallelism &= maintainsParallelism; |
1553 |
|
boolean dec = false; |
1554 |
|
while (spareStack == null || !tryResumeSpare(dec)) { |
1566 |
|
} |
1567 |
|
|
1568 |
|
/** |
1569 |
< |
* Returns true if a spare thread appears to be needed. If |
1570 |
< |
* maintaining parallelism, returns true when the deficit in |
1569 |
> |
* Returns {@code true} if a spare thread appears to be needed. |
1570 |
> |
* If maintaining parallelism, returns true when the deficit in |
1571 |
|
* running threads is more than the surplus of total threads, and |
1572 |
|
* there is apparently some work to do. This self-limiting rule |
1573 |
|
* means that the more threads that have already been added, the |
1574 |
|
* less parallelism we will tolerate before adding another. |
1575 |
+ |
* |
1576 |
|
* @param counts current worker counts |
1577 |
|
* @param maintainParallelism try to maintain parallelism |
1578 |
|
*/ |
1590 |
|
} |
1591 |
|
|
1592 |
|
/** |
1593 |
< |
* Add a spare worker if lock available and no more than the |
1594 |
< |
* expected numbers of threads exist |
1593 |
> |
* Adds a spare worker if lock available and no more than the |
1594 |
> |
* expected numbers of threads exist. |
1595 |
> |
* |
1596 |
|
* @return true if successful |
1597 |
|
*/ |
1598 |
|
private boolean tryAddSpare(int expectedCounts) { |
1625 |
|
} |
1626 |
|
|
1627 |
|
/** |
1628 |
< |
* Add the kth spare worker. On entry, pool coounts are already |
1628 |
> |
* Adds the kth spare worker. On entry, pool counts are already |
1629 |
|
* adjusted to reflect addition. |
1630 |
|
*/ |
1631 |
|
private void createAndStartSpare(int k) { |
1647 |
|
} |
1648 |
|
|
1649 |
|
/** |
1650 |
< |
* Suspend calling thread w if there are excess threads. Called |
1651 |
< |
* only from sync. Spares are enqueued in a Treiber stack |
1652 |
< |
* using the same WaitQueueNodes as barriers. They are resumed |
1653 |
< |
* mainly in preJoin, but are also woken on pool events that |
1654 |
< |
* require all threads to check run state. |
1650 |
> |
* Suspends calling thread w if there are excess threads. Called |
1651 |
> |
* only from sync. Spares are enqueued in a Treiber stack using |
1652 |
> |
* the same WaitQueueNodes as barriers. They are resumed mainly |
1653 |
> |
* in preJoin, but are also woken on pool events that require all |
1654 |
> |
* threads to check run state. |
1655 |
> |
* |
1656 |
|
* @param w the caller |
1657 |
|
*/ |
1658 |
|
private boolean suspendIfSpare(ForkJoinWorkerThread w) { |
1663 |
|
node = new WaitQueueNode(0, w); |
1664 |
|
if (casWorkerCounts(s, s-1)) { // representation-dependent |
1665 |
|
// push onto stack |
1666 |
< |
do;while (!casSpareStack(node.next = spareStack, node)); |
1666 |
> |
do {} while (!casSpareStack(node.next = spareStack, node)); |
1667 |
|
// block until released by resumeSpare |
1668 |
|
node.awaitSpareRelease(); |
1669 |
|
return true; |
1673 |
|
} |
1674 |
|
|
1675 |
|
/** |
1676 |
< |
* Try to pop and resume a spare thread. |
1676 |
> |
* Tries to pop and resume a spare thread. |
1677 |
> |
* |
1678 |
|
* @param updateCount if true, increment running count on success |
1679 |
|
* @return true if successful |
1680 |
|
*/ |
1692 |
|
} |
1693 |
|
|
1694 |
|
/** |
1695 |
< |
* Pop and resume all spare threads. Same idea as ensureSync. |
1695 |
> |
* Pops and resumes all spare threads. Same idea as ensureSync. |
1696 |
> |
* |
1697 |
|
* @return true if any spares released |
1698 |
|
*/ |
1699 |
|
private boolean resumeAllSpares() { |
1711 |
|
} |
1712 |
|
|
1713 |
|
/** |
1714 |
< |
* Pop and shutdown excessive spare threads. Call only while |
1714 |
> |
* Pops and shuts down excessive spare threads. Call only while |
1715 |
|
* holding lock. This is not guaranteed to eliminate all excess |
1716 |
|
* threads, only those suspended as spares, which are the ones |
1717 |
|
* unlikely to be needed in the future. |
1736 |
|
/** |
1737 |
|
* Interface for extending managed parallelism for tasks running |
1738 |
|
* in ForkJoinPools. A ManagedBlocker provides two methods. |
1739 |
< |
* Method <code>isReleasable</code> must return true if blocking is not |
1740 |
< |
* necessary. Method <code>block</code> blocks the current thread |
1741 |
< |
* if necessary (perhaps internally invoking isReleasable before |
1742 |
< |
* actually blocking.). |
1739 |
> |
* Method {@code isReleasable} must return {@code true} if |
1740 |
> |
* blocking is not necessary. Method {@code block} blocks the |
1741 |
> |
* current thread if necessary (perhaps internally invoking |
1742 |
> |
* {@code isReleasable} before actually blocking.). |
1743 |
> |
* |
1744 |
|
* <p>For example, here is a ManagedBlocker based on a |
1745 |
|
* ReentrantLock: |
1746 |
< |
* <pre> |
1747 |
< |
* class ManagedLocker implements ManagedBlocker { |
1748 |
< |
* final ReentrantLock lock; |
1749 |
< |
* boolean hasLock = false; |
1750 |
< |
* ManagedLocker(ReentrantLock lock) { this.lock = lock; } |
1751 |
< |
* public boolean block() { |
1752 |
< |
* if (!hasLock) |
1753 |
< |
* lock.lock(); |
1754 |
< |
* return true; |
1755 |
< |
* } |
1756 |
< |
* public boolean isReleasable() { |
1757 |
< |
* return hasLock || (hasLock = lock.tryLock()); |
1711 |
< |
* } |
1746 |
> |
* <pre> {@code |
1747 |
> |
* class ManagedLocker implements ManagedBlocker { |
1748 |
> |
* final ReentrantLock lock; |
1749 |
> |
* boolean hasLock = false; |
1750 |
> |
* ManagedLocker(ReentrantLock lock) { this.lock = lock; } |
1751 |
> |
* public boolean block() { |
1752 |
> |
* if (!hasLock) |
1753 |
> |
* lock.lock(); |
1754 |
> |
* return true; |
1755 |
> |
* } |
1756 |
> |
* public boolean isReleasable() { |
1757 |
> |
* return hasLock || (hasLock = lock.tryLock()); |
1758 |
|
* } |
1759 |
< |
* </pre> |
1759 |
> |
* }}</pre> |
1760 |
|
*/ |
1761 |
|
public static interface ManagedBlocker { |
1762 |
|
/** |
1763 |
|
* Possibly blocks the current thread, for example waiting for |
1764 |
|
* a lock or condition. |
1765 |
< |
* @return true if no additional blocking is necessary (i.e., |
1766 |
< |
* if isReleasable would return true). |
1765 |
> |
* |
1766 |
> |
* @return {@code true} if no additional blocking is necessary |
1767 |
> |
* (i.e., if isReleasable would return true) |
1768 |
|
* @throws InterruptedException if interrupted while waiting |
1769 |
< |
* (the method is not required to do so, but is allowe to). |
1769 |
> |
* (the method is not required to do so, but is allowed to) |
1770 |
|
*/ |
1771 |
|
boolean block() throws InterruptedException; |
1772 |
|
|
1773 |
|
/** |
1774 |
< |
* Returns true if blocking is unnecessary. |
1774 |
> |
* Returns {@code true} if blocking is unnecessary. |
1775 |
|
*/ |
1776 |
|
boolean isReleasable(); |
1777 |
|
} |
1781 |
|
* is a ForkJoinWorkerThread, this method possibly arranges for a |
1782 |
|
* spare thread to be activated if necessary to ensure parallelism |
1783 |
|
* while the current thread is blocked. If |
1784 |
< |
* <code>maintainParallelism</code> is true and the pool supports |
1784 |
> |
* {@code maintainParallelism} is {@code true} and the pool supports |
1785 |
|
* it ({@link #getMaintainsParallelism}), this method attempts to |
1786 |
< |
* maintain the pool's nominal parallelism. Otherwise if activates |
1786 |
> |
* maintain the pool's nominal parallelism. Otherwise it activates |
1787 |
|
* a thread only if necessary to avoid complete starvation. This |
1788 |
|
* option may be preferable when blockages use timeouts, or are |
1789 |
|
* almost always brief. |
1790 |
|
* |
1791 |
|
* <p> If the caller is not a ForkJoinTask, this method is behaviorally |
1792 |
|
* equivalent to |
1793 |
< |
* <pre> |
1794 |
< |
* while (!blocker.isReleasable()) |
1795 |
< |
* if (blocker.block()) |
1796 |
< |
* return; |
1797 |
< |
* </pre> |
1793 |
> |
* <pre> {@code |
1794 |
> |
* while (!blocker.isReleasable()) |
1795 |
> |
* if (blocker.block()) |
1796 |
> |
* return; |
1797 |
> |
* }</pre> |
1798 |
|
* If the caller is a ForkJoinTask, then the pool may first |
1799 |
|
* be expanded to ensure parallelism, and later adjusted. |
1800 |
|
* |
1801 |
|
* @param blocker the blocker |
1802 |
< |
* @param maintainParallelism if true and supported by this pool, |
1803 |
< |
* attempt to maintain the pool's nominal parallelism; otherwise |
1804 |
< |
* activate a thread only if necessary to avoid complete |
1805 |
< |
* starvation. |
1806 |
< |
* @throws InterruptedException if blocker.block did so. |
1802 |
> |
* @param maintainParallelism if {@code true} and supported by |
1803 |
> |
* this pool, attempt to maintain the pool's nominal parallelism; |
1804 |
> |
* otherwise activate a thread only if necessary to avoid |
1805 |
> |
* complete starvation. |
1806 |
> |
* @throws InterruptedException if blocker.block did so |
1807 |
|
*/ |
1808 |
|
public static void managedBlock(ManagedBlocker blocker, |
1809 |
|
boolean maintainParallelism) |
1810 |
|
throws InterruptedException { |
1811 |
|
Thread t = Thread.currentThread(); |
1812 |
< |
ForkJoinPool pool = (t instanceof ForkJoinWorkerThread? |
1813 |
< |
((ForkJoinWorkerThread)t).pool : null); |
1812 |
> |
ForkJoinPool pool = ((t instanceof ForkJoinWorkerThread) ? |
1813 |
> |
((ForkJoinWorkerThread) t).pool : null); |
1814 |
|
if (!blocker.isReleasable()) { |
1815 |
|
try { |
1816 |
|
if (pool == null || |
1825 |
|
|
1826 |
|
private static void awaitBlocker(ManagedBlocker blocker) |
1827 |
|
throws InterruptedException { |
1828 |
< |
do;while (!blocker.isReleasable() && !blocker.block()); |
1828 |
> |
do {} while (!blocker.isReleasable() && !blocker.block()); |
1829 |
|
} |
1830 |
|
|
1831 |
< |
// AbstractExecutorService overrides |
1831 |
> |
// AbstractExecutorService overrides. These rely on undocumented |
1832 |
> |
// fact that ForkJoinTask.adapt returns ForkJoinTasks that also |
1833 |
> |
// implement RunnableFuture. |
1834 |
|
|
1835 |
|
protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) { |
1836 |
< |
return new AdaptedRunnable(runnable, value); |
1836 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(runnable, value); |
1837 |
|
} |
1838 |
|
|
1839 |
|
protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) { |
1840 |
< |
return new AdaptedCallable(callable); |
1840 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(callable); |
1841 |
|
} |
1842 |
|
|
1843 |
+ |
// Unsafe mechanics |
1844 |
|
|
1845 |
< |
// Temporary Unsafe mechanics for preliminary release |
1846 |
< |
private static Unsafe getUnsafe() throws Throwable { |
1847 |
< |
try { |
1848 |
< |
return Unsafe.getUnsafe(); |
1849 |
< |
} catch (SecurityException se) { |
1850 |
< |
try { |
1851 |
< |
return java.security.AccessController.doPrivileged |
1852 |
< |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
1853 |
< |
public Unsafe run() throws Exception { |
1854 |
< |
return getUnsafePrivileged(); |
1855 |
< |
}}); |
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 syncStackOffset; |
1830 |
< |
static final long spareStackOffset; |
1831 |
< |
|
1832 |
< |
static { |
1833 |
< |
try { |
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 |
< |
} |
1845 |
> |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1846 |
> |
private static final long eventCountOffset = |
1847 |
> |
objectFieldOffset("eventCount", ForkJoinPool.class); |
1848 |
> |
private static final long workerCountsOffset = |
1849 |
> |
objectFieldOffset("workerCounts", ForkJoinPool.class); |
1850 |
> |
private static final long runControlOffset = |
1851 |
> |
objectFieldOffset("runControl", ForkJoinPool.class); |
1852 |
> |
private static final long syncStackOffset = |
1853 |
> |
objectFieldOffset("syncStack",ForkJoinPool.class); |
1854 |
> |
private static final long spareStackOffset = |
1855 |
> |
objectFieldOffset("spareStack", ForkJoinPool.class); |
1856 |
|
|
1857 |
|
private boolean casEventCount(long cmp, long val) { |
1858 |
< |
return _unsafe.compareAndSwapLong(this, eventCountOffset, cmp, val); |
1858 |
> |
return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val); |
1859 |
|
} |
1860 |
|
private boolean casWorkerCounts(int cmp, int val) { |
1861 |
< |
return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val); |
1861 |
> |
return UNSAFE.compareAndSwapInt(this, workerCountsOffset, cmp, val); |
1862 |
|
} |
1863 |
|
private boolean casRunControl(int cmp, int val) { |
1864 |
< |
return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val); |
1864 |
> |
return UNSAFE.compareAndSwapInt(this, runControlOffset, cmp, val); |
1865 |
|
} |
1866 |
|
private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) { |
1867 |
< |
return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val); |
1867 |
> |
return UNSAFE.compareAndSwapObject(this, spareStackOffset, cmp, val); |
1868 |
|
} |
1869 |
|
private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) { |
1870 |
< |
return _unsafe.compareAndSwapObject(this, syncStackOffset, cmp, val); |
1870 |
> |
return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val); |
1871 |
> |
} |
1872 |
> |
|
1873 |
> |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1874 |
> |
try { |
1875 |
> |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1876 |
> |
} catch (NoSuchFieldException e) { |
1877 |
> |
// Convert Exception to corresponding Error |
1878 |
> |
NoSuchFieldError error = new NoSuchFieldError(field); |
1879 |
> |
error.initCause(e); |
1880 |
> |
throw error; |
1881 |
> |
} |
1882 |
> |
} |
1883 |
> |
|
1884 |
> |
/** |
1885 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1886 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1887 |
> |
* into a jdk. |
1888 |
> |
* |
1889 |
> |
* @return a sun.misc.Unsafe |
1890 |
> |
*/ |
1891 |
> |
private static sun.misc.Unsafe getUnsafe() { |
1892 |
> |
try { |
1893 |
> |
return sun.misc.Unsafe.getUnsafe(); |
1894 |
> |
} catch (SecurityException se) { |
1895 |
> |
try { |
1896 |
> |
return java.security.AccessController.doPrivileged |
1897 |
> |
(new java.security |
1898 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1899 |
> |
public sun.misc.Unsafe run() throws Exception { |
1900 |
> |
java.lang.reflect.Field f = sun.misc |
1901 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
1902 |
> |
f.setAccessible(true); |
1903 |
> |
return (sun.misc.Unsafe) f.get(null); |
1904 |
> |
}}); |
1905 |
> |
} catch (java.security.PrivilegedActionException e) { |
1906 |
> |
throw new RuntimeException("Could not initialize intrinsics", |
1907 |
> |
e.getCause()); |
1908 |
> |
} |
1909 |
> |
} |
1910 |
|
} |
1911 |
|
} |