[ViewVC] Diff of: jsr166/jsr166/src/jsr166y/ForkJoinPool.java

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.125 by jsr166, Tue Feb 21 00:19:23 2012 UTC vs.
Revision 1.189 by jsr166, Sat Sep 12 19:16:45 2015 UTC

#	Line 5 \| Line 5
5		*/
6
7		package jsr166y;
8	+
9		import java.util.ArrayList;
10		import java.util.Arrays;
11		import java.util.Collection;
12		import java.util.Collections;
13		import java.util.List;
13	–	import java.util.Random;
14		import java.util.concurrent.AbstractExecutorService;
15		import java.util.concurrent.Callable;
16		import java.util.concurrent.ExecutorService;
#	Line 18 \| Line 18 \| import java.util.concurrent.Future;
18		import java.util.concurrent.RejectedExecutionException;
19		import java.util.concurrent.RunnableFuture;
20		import java.util.concurrent.TimeUnit;
21	–	import java.util.concurrent.atomic.AtomicInteger;
22	–	import java.util.concurrent.atomic.AtomicLong;
23	–	import java.util.concurrent.locks.AbstractQueuedSynchronizer;
24	–	import java.util.concurrent.locks.Condition;
21
22		/**
23		* An {@link ExecutorService} for running {@link ForkJoinTask}s.
#	Line 41 \| Line 37 \| import java.util.concurrent.locks.Condit
37		* ForkJoinPool}s may also be appropriate for use with event-style
38		* tasks that are never joined.
39		*
40	<	* <p>A {@code ForkJoinPool} is constructed with a given target
41	<	* parallelism level; by default, equal to the number of available
42	<	* processors. The pool attempts to maintain enough active (or
43	<	* available) threads by dynamically adding, suspending, or resuming
44	<	* internal worker threads, even if some tasks are stalled waiting to
45	<	* join others. However, no such adjustments are guaranteed in the
46	<	* face of blocked IO or other unmanaged synchronization. The nested
47	<	* {@link ManagedBlocker} interface enables extension of the kinds of
40	>	* <p>A static {@link #commonPool()} is available and appropriate for
41	>	* most applications. The common pool is used by any ForkJoinTask that
42	>	* is not explicitly submitted to a specified pool. Using the common
43	>	* pool normally reduces resource usage (its threads are slowly
44	>	* reclaimed during periods of non-use, and reinstated upon subsequent
45	>	* use).
46	>	*
47	>	* <p>For applications that require separate or custom pools, a {@code
48	>	* ForkJoinPool} may be constructed with a given target parallelism
49	>	* level; by default, equal to the number of available processors. The
50	>	* pool attempts to maintain enough active (or available) threads by
51	>	* dynamically adding, suspending, or resuming internal worker
52	>	* threads, even if some tasks are stalled waiting to join
53	>	* others. However, no such adjustments are guaranteed in the face of
54	>	* blocked I/O or other unmanaged synchronization. The nested {@link
55	>	* ManagedBlocker} interface enables extension of the kinds of
56		* synchronization accommodated.
57		*
58		* <p>In addition to execution and lifecycle control methods, this
#	Line 58 \| Line 62 \| import java.util.concurrent.locks.Condit
62		* {@link #toString} returns indications of pool state in a
63		* convenient form for informal monitoring.
64		*
65	<	* <p> As is the case with other ExecutorServices, there are three
65	>	* <p>As is the case with other ExecutorServices, there are three
66		* main task execution methods summarized in the following table.
67		* These are designed to be used primarily by clients not already
68		* engaged in fork/join computations in the current pool. The main
#	Line 93 \| Line 97 \| import java.util.concurrent.locks.Condit
97		* </tr>
98		* </table>
99		*
100	<	* <p><b>Sample Usage.</b> Normally a single {@code ForkJoinPool} is
101	<	* used for all parallel task execution in a program or subsystem.
102	<	* Otherwise, use would not usually outweigh the construction and
103	<	* bookkeeping overhead of creating a large set of threads. For
104	<	* example, a common pool could be used for the {@code SortTasks}
105	<	* illustrated in {@link RecursiveAction}. Because {@code
106	<	* ForkJoinPool} uses threads in {@linkplain java.lang.Thread#isDaemon
107	<	* daemon} mode, there is typically no need to explicitly {@link
108	<	* #shutdown} such a pool upon program exit.
109	<	*
106	<	* <pre> {@code
107	<	* static final ForkJoinPool mainPool = new ForkJoinPool();
108	<	* ...
109	<	* public void sort(long[] array) {
110	<	* mainPool.invoke(new SortTask(array, 0, array.length));
111	<	* }}</pre>
100	>	* <p>The common pool is by default constructed with default
101	>	* parameters, but these may be controlled by setting three {@link
102	>	* System#getProperty system properties} with prefix {@code
103	>	* java.util.concurrent.ForkJoinPool.common}: {@code parallelism} --
104	>	* an integer greater than zero, {@code threadFactory} -- the class
105	>	* name of a {@link ForkJoinWorkerThreadFactory}, and {@code
106	>	* exceptionHandler} -- the class name of a {@link
107	>	* java.lang.Thread.UncaughtExceptionHandler
108	>	* Thread.UncaughtExceptionHandler}. Upon any error in establishing
109	>	* these settings, default parameters are used.
110		*
111		* <p><b>Implementation notes</b>: This implementation restricts the
112		* maximum number of running threads to 32767. Attempts to create
#	Line 196 \| Line 194 \| public class ForkJoinPool extends Abstra
194		* WorkQueues are also used in a similar way for tasks submitted
195		* to the pool. We cannot mix these tasks in the same queues used
196		* for work-stealing (this would contaminate lifo/fifo
197	<	* processing). Instead, we loosely associate submission queues
197	>	* processing). Instead, we randomly associate submission queues
198		* with submitting threads, using a form of hashing. The
199		* ThreadLocal Submitter class contains a value initially used as
200		* a hash code for choosing existing queues, but may be randomly
201		* repositioned upon contention with other submitters. In
202	<	* essence, submitters act like workers except that they never
203	<	* take tasks, and they are multiplexed on to a finite number of
204	<	* shared work queues. However, classes are set up so that future
205	<	* extensions could allow submitters to optionally help perform
206	<	* tasks as well. Insertion of tasks in shared mode requires a
207	<	* lock (mainly to protect in the case of resizing) but we use
208	<	* only a simple spinlock (using bits in field runState), because
209	<	* submitters encountering a busy queue move on to try or create
210	<	* other queues -- they block only when creating and registering
211	<	* new queues.
202	>	* essence, submitters act like workers except that they are
203	>	* restricted to executing local tasks that they submitted (or in
204	>	* the case of CountedCompleters, others with the same root task).
205	>	* However, because most shared/external queue operations are more
206	>	* expensive than internal, and because, at steady state, external
207	>	* submitters will compete for CPU with workers, ForkJoinTask.join
208	>	* and related methods disable them from repeatedly helping to
209	>	* process tasks if all workers are active. Insertion of tasks in
210	>	* shared mode requires a lock (mainly to protect in the case of
211	>	* resizing) but we use only a simple spinlock (using bits in
212	>	* field qlock), because submitters encountering a busy queue move
213	>	* on to try or create other queues -- they block only when
214	>	* creating and registering new queues.
215		*
216		* Management
217		* ==========
#	Line 232 \| Line 233 \| public class ForkJoinPool extends Abstra
233		* and their negations (used for thresholding) to fit into 16bit
234		* fields.
235		*
236	<	* Field "runState" contains 32 bits needed to register and
237	<	* deregister WorkQueues, as well as to enable shutdown. It is
238	<	* only modified under a lock (normally briefly held, but
239	<	* occasionally protecting allocations and resizings) but even
240	<	* when locked remains available to check consistency.
236	>	* Field "plock" is a form of sequence lock with a saturating
237	>	* shutdown bit (similarly for per-queue "qlocks"), mainly
238	>	* protecting updates to the workQueues array, as well as to
239	>	* enable shutdown. When used as a lock, it is normally only very
240	>	* briefly held, so is nearly always available after at most a
241	>	* brief spin, but we use a monitor-based backup strategy to
242	>	* block when needed.
243		*
244		* Recording WorkQueues. WorkQueues are recorded in the
245	<	* "workQueues" array that is created upon pool construction and
246	<	* expanded if necessary. Updates to the array while recording
247	<	* new workers and unrecording terminated ones are protected from
248	<	* each other by a lock but the array is otherwise concurrently
249	<	* readable, and accessed directly. To simplify index-based
250	<	* operations, the array size is always a power of two, and all
251	<	* readers must tolerate null slots. Shared (submission) queues
252	<	* are at even indices, worker queues at odd indices. Grouping
253	<	* them together in this way simplifies and speeds up task
254	<	* scanning.
245	>	* "workQueues" array that is created upon first use and expanded
246	>	* if necessary. Updates to the array while recording new workers
247	>	* and unrecording terminated ones are protected from each other
248	>	* by a lock but the array is otherwise concurrently readable, and
249	>	* accessed directly. To simplify index-based operations, the
250	>	* array size is always a power of two, and all readers must
251	>	* tolerate null slots. Worker queues are at odd indices. Shared
252	>	* (submission) queues are at even indices, up to a maximum of 64
253	>	* slots, to limit growth even if array needs to expand to add
254	>	* more workers. Grouping them together in this way simplifies and
255	>	* speeds up task scanning.
256		*
257		* All worker thread creation is on-demand, triggered by task
258		* submissions, replacement of terminated workers, and/or
#	Line 309 \| Line 313 \| public class ForkJoinPool extends Abstra
313		*
314		* Signalling. We create or wake up workers only when there
315		* appears to be at least one task they might be able to find and
316	<	* execute. When a submission is added or another worker adds a
317	<	* task to a queue that previously had fewer than two tasks, they
318	<	* signal waiting workers (or trigger creation of new ones if
319	<	* fewer than the given parallelism level -- see signalWork).
320	<	* These primary signals are buttressed by signals during rescans;
321	<	* together these cover the signals needed in cases when more
322	<	* tasks are pushed but untaken, and improve performance compared
323	<	* to having one thread wake up all workers.
316	>	* execute. However, many other threads may notice the same task
317	>	* and each signal to wake up a thread that might take it. So in
318	>	* general, pools will be over-signalled. When a submission is
319	>	* added or another worker adds a task to a queue that has fewer
320	>	* than two tasks, they signal waiting workers (or trigger
321	>	* creation of new ones if fewer than the given parallelism level
322	>	* -- signalWork), and may leave a hint to the unparked worker to
323	>	* help signal others upon wakeup). These primary signals are
324	>	* buttressed by others (see method helpSignal) whenever other
325	>	* threads scan for work or do not have a task to process. On
326	>	* most platforms, signalling (unpark) overhead time is noticeably
327	>	* long, and the time between signalling a thread and it actually
328	>	* making progress can be very noticeably long, so it is worth
329	>	* offloading these delays from critical paths as much as
330	>	* possible.
331		*
332		* Trimming workers. To release resources after periods of lack of
333		* use, a worker starting to wait when the pool is quiescent will
334	<	* time out and terminate if the pool has remained quiescent for
335	<	* SHRINK_RATE nanosecs. This will slowly propagate, eventually
336	<	* terminating all workers after long periods of non-use.
334	>	* time out and terminate if the pool has remained quiescent for a
335	>	* given period -- a short period if there are more threads than
336	>	* parallelism, longer as the number of threads decreases. This
337	>	* will slowly propagate, eventually terminating all workers after
338	>	* periods of non-use.
339		*
340		* Shutdown and Termination. A call to shutdownNow atomically sets
341	<	* a runState bit and then (non-atomically) sets each worker's
342	<	* runState status, cancels all unprocessed tasks, and wakes up
341	>	* a plock bit and then (non-atomically) sets each worker's
342	>	* qlock status, cancels all unprocessed tasks, and wakes up
343		* all waiting workers. Detecting whether termination should
344		* commence after a non-abrupt shutdown() call requires more work
345		* and bookkeeping. We need consensus about quiescence (i.e., that
#	Line 354 \| Line 367 \| public class ForkJoinPool extends Abstra
367		* method tryCompensate() may create or re-activate a spare
368		* thread to compensate for blocked joiners until they unblock.
369		*
370	<	* A third form (implemented in tryRemoveAndExec and
371	<	* tryPollForAndExec) amounts to helping a hypothetical
372	<	* compensator: If we can readily tell that a possible action of a
373	<	* compensator is to steal and execute the task being joined, the
374	<	* joining thread can do so directly, without the need for a
375	<	* compensation thread (although at the expense of larger run-time
376	<	* stacks, but the tradeoff is typically worthwhile).
370	>	* A third form (implemented in tryRemoveAndExec) amounts to
371	>	* helping a hypothetical compensator: If we can readily tell that
372	>	* a possible action of a compensator is to steal and execute the
373	>	* task being joined, the joining thread can do so directly,
374	>	* without the need for a compensation thread (although at the
375	>	* expense of larger run-time stacks, but the tradeoff is
376	>	* typically worthwhile).
377		*
378		* The ManagedBlocker extension API can't use helping so relies
379		* only on compensation in method awaitBlocker.
#	Line 382 \| Line 395 \| public class ForkJoinPool extends Abstra
395		* steals, rather than use per-task bookkeeping. This sometimes
396		* requires a linear scan of workQueues array to locate stealers,
397		* but often doesn't because stealers leave hints (that may become
398	<	* stale/wrong) of where to locate them. A stealHint is only a
399	<	* hint because a worker might have had multiple steals and the
400	<	* hint records only one of them (usually the most current).
401	<	* Hinting isolates cost to when it is needed, rather than adding
402	<	* to per-task overhead. (2) It is "shallow", ignoring nesting
403	<	* and potentially cyclic mutual steals. (3) It is intentionally
398	>	* stale/wrong) of where to locate them. It is only a hint
399	>	* because a worker might have had multiple steals and the hint
400	>	* records only one of them (usually the most current). Hinting
401	>	* isolates cost to when it is needed, rather than adding to
402	>	* per-task overhead. (2) It is "shallow", ignoring nesting and
403	>	* potentially cyclic mutual steals. (3) It is intentionally
404		* racy: field currentJoin is updated only while actively joining,
405		* which means that we miss links in the chain during long-lived
406		* tasks, GC stalls etc (which is OK since blocking in such cases
#	Line 395 \| Line 408 \| public class ForkJoinPool extends Abstra
408		* to find work (see MAX_HELP) and fall back to suspending the
409		* worker and if necessary replacing it with another.
410		*
411	+	* Helping actions for CountedCompleters are much simpler: Method
412	+	* helpComplete can take and execute any task with the same root
413	+	* as the task being waited on. However, this still entails some
414	+	* traversal of completer chains, so is less efficient than using
415	+	* CountedCompleters without explicit joins.
416	+	*
417		* It is impossible to keep exactly the target parallelism number
418		* of threads running at any given time. Determining the
419		* existence of conservatively safe helping targets, the
#	Line 416 \| Line 435 \| public class ForkJoinPool extends Abstra
435		* intractable) game with an opponent that may choose the worst
436		* (for us) active thread to stall at any time. We take several
437		* precautions to bound losses (and thus bound gains), mainly in
438	<	* methods tryCompensate and awaitJoin: (1) We only try
439	<	* compensation after attempting enough helping steps (measured
440	<	* via counting and timing) that we have already consumed the
441	<	* estimated cost of creating and activating a new thread. (2) We
442	<	* allow up to 50% of threads to be blocked before initially
443	<	* adding any others, and unless completely saturated, check that
444	<	* some work is available for a new worker before adding. Also, we
445	<	* create up to only 50% more threads until entering a mode that
446	<	* only adds a thread if all others are possibly blocked. All
447	<	* together, this means that we might be half as fast to react,
448	<	* and create half as many threads as possible in the ideal case,
449	<	* but present vastly fewer anomalies in all other cases compared
450	<	* to both more aggressive and more conservative alternatives.
451	<	*
452	<	* Style notes: There is a lot of representation-level coupling
453	<	* among classes ForkJoinPool, ForkJoinWorkerThread, and
454	<	* ForkJoinTask. The fields of WorkQueue maintain data structures
455	<	* managed by ForkJoinPool, so are directly accessed. There is
456	<	* little point trying to reduce this, since any associated future
457	<	* changes in representations will need to be accompanied by
458	<	* algorithmic changes anyway. Several methods intrinsically
459	<	* sprawl because they must accumulate sets of consistent reads of
460	<	* volatiles held in local variables. Methods signalWork() and
461	<	* scan() are the main bottlenecks, so are especially heavily
438	>	* methods tryCompensate and awaitJoin.
439	>	*
440	>	* Common Pool
441	>	* ===========
442	>	*
443	>	* The static common Pool always exists after static
444	>	* initialization. Since it (or any other created pool) need
445	>	* never be used, we minimize initial construction overhead and
446	>	* footprint to the setup of about a dozen fields, with no nested
447	>	* allocation. Most bootstrapping occurs within method
448	>	* fullExternalPush during the first submission to the pool.
449	>	*
450	>	* When external threads submit to the common pool, they can
451	>	* perform some subtask processing (see externalHelpJoin and
452	>	* related methods). We do not need to record whether these
453	>	* submissions are to the common pool -- if not, externalHelpJoin
454	>	* returns quickly (at the most helping to signal some common pool
455	>	* workers). These submitters would otherwise be blocked waiting
456	>	* for completion, so the extra effort (with liberally sprinkled
457	>	* task status checks) in inapplicable cases amounts to an odd
458	>	* form of limited spin-wait before blocking in ForkJoinTask.join.
459	>	*
460	>	* Style notes
461	>	* ===========
462	>	*
463	>	* There is a lot of representation-level coupling among classes
464	>	* ForkJoinPool, ForkJoinWorkerThread, and ForkJoinTask. The
465	>	* fields of WorkQueue maintain data structures managed by
466	>	* ForkJoinPool, so are directly accessed. There is little point
467	>	* trying to reduce this, since any associated future changes in
468	>	* representations will need to be accompanied by algorithmic
469	>	* changes anyway. Several methods intrinsically sprawl because
470	>	* they must accumulate sets of consistent reads of volatiles held
471	>	* in local variables. Methods signalWork() and scan() are the
472	>	* main bottlenecks, so are especially heavily
473		* micro-optimized/mangled. There are lots of inline assignments
474		* (of form "while ((local = field) != 0)") which are usually the
475		* simplest way to ensure the required read orderings (which are
#	Line 447 \| Line 477 \| public class ForkJoinPool extends Abstra
477		* declarations of these locals at the heads of methods or blocks.
478		* There are several occurrences of the unusual "do {} while
479		* (!cas...)" which is the simplest way to force an update of a
480	<	* CAS'ed variable. There are also other coding oddities that help
480	>	* CAS'ed variable. There are also other coding oddities (including
481	>	* several unnecessary-looking hoisted null checks) that help
482		* some methods perform reasonably even when interpreted (not
483		* compiled).
484		*
#	Line 496 \| Line 527 \| public class ForkJoinPool extends Abstra
527		* Default ForkJoinWorkerThreadFactory implementation; creates a
528		* new ForkJoinWorkerThread.
529		*/
530	<	static class DefaultForkJoinWorkerThreadFactory
530	>	static final class DefaultForkJoinWorkerThreadFactory
531		implements ForkJoinWorkerThreadFactory {
532	<	public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
532	>	public final ForkJoinWorkerThread newThread(ForkJoinPool pool) {
533		return new ForkJoinWorkerThread(pool);
534		}
535		}
536
537		/**
538	<	* A simple non-reentrant lock used for exclusion when managing
539	<	* queues and workers. We use a custom lock so that we can readily
540	<	* probe lock state in constructions that check among alternative
541	<	* actions. The lock is normally only very briefly held, and
542	<	* sometimes treated as a spinlock, but other usages block to
543	<	* reduce overall contention in those cases where locked code
544	<	* bodies perform allocation/resizing.
545	<	*/
546	<	static final class Mutex extends AbstractQueuedSynchronizer {
547	<	public final boolean tryAcquire(int ignore) {
548	<	return compareAndSetState(0, 1);
549	<	}
550	<	public final boolean tryRelease(int ignore) {
551	<	setState(0);
552	<	return true;
553	<	}
554	<	public final void lock() { acquire(0); }
524	<	public final void unlock() { release(0); }
525	<	public final boolean isHeldExclusively() { return getState() == 1; }
526	<	public final Condition newCondition() { return new ConditionObject(); }
538	>	* Per-thread records for threads that submit to pools. Currently
539	>	* holds only pseudo-random seed / index that is used to choose
540	>	* submission queues in method externalPush. In the future, this may
541	>	* also incorporate a means to implement different task rejection
542	>	* and resubmission policies.
543	>	*
544	>	* Seeds for submitters and workers/workQueues work in basically
545	>	* the same way but are initialized and updated using slightly
546	>	* different mechanics. Both are initialized using the same
547	>	* approach as in class ThreadLocal, where successive values are
548	>	* unlikely to collide with previous values. Seeds are then
549	>	* randomly modified upon collisions using xorshifts, which
550	>	* requires a non-zero seed.
551	>	*/
552	>	static final class Submitter {
553	>	int seed;
554	>	Submitter(int s) { seed = s; }
555		}
556
557		/**
#	Line 533 \| Line 561 \| public class ForkJoinPool extends Abstra
561		* actually do anything beyond having a unique identity.
562		*/
563		static final class EmptyTask extends ForkJoinTask<Void> {
564	+	private static final long serialVersionUID = -7721805057305804111L;
565		EmptyTask() { status = ForkJoinTask.NORMAL; } // force done
566		public final Void getRawResult() { return null; }
567		public final void setRawResult(Void x) {}
#	Line 553 \| Line 582 \| public class ForkJoinPool extends Abstra
582		*
583		* Field "top" is the index (mod array.length) of the next queue
584		* slot to push to or pop from. It is written only by owner thread
585	<	* for push, or under lock for trySharedPush, and accessed by
586	<	* other threads only after reading (volatile) base. Both top and
587	<	* base are allowed to wrap around on overflow, but (top - base)
588	<	* (or more commonly -(base - top) to force volatile read of base
589	<	* before top) still estimates size.
585	>	* for push, or under lock for external/shared push, and accessed
586	>	* by other threads only after reading (volatile) base. Both top
587	>	* and base are allowed to wrap around on overflow, but (top -
588	>	* base) (or more commonly -(base - top) to force volatile read of
589	>	* base before top) still estimates size. The lock ("qlock") is
590	>	* forced to -1 on termination, causing all further lock attempts
591	>	* to fail. (Note: we don't need CAS for termination state because
592	>	* upon pool shutdown, all shared-queues will stop being used
593	>	* anyway.) Nearly all lock bodies are set up so that exceptions
594	>	* within lock bodies are "impossible" (modulo JVM errors that
595	>	* would cause failure anyway.)
596		*
597		* The array slots are read and written using the emulation of
598		* volatiles/atomics provided by Unsafe. Insertions must in
599		* general use putOrderedObject as a form of releasing store to
600		* ensure that all writes to the task object are ordered before
601	<	* its publication in the queue. (Although we can avoid one case
602	<	* of this when locked in trySharedPush.) All removals entail a
603	<	* CAS to null. The array is always a power of two. To ensure
604	<	* safety of Unsafe array operations, all accesses perform
570	<	* explicit null checks and implicit bounds checks via
571	<	* power-of-two masking.
601	>	* its publication in the queue. All removals entail a CAS to
602	>	* null. The array is always a power of two. To ensure safety of
603	>	* Unsafe array operations, all accesses perform explicit null
604	>	* checks and implicit bounds checks via power-of-two masking.
605		*
606		* In addition to basic queuing support, this class contains
607		* fields described elsewhere to control execution. It turns out
608	<	* to work better memory-layout-wise to include them in this
609	<	* class rather than a separate class.
608	>	* to work better memory-layout-wise to include them in this class
609	>	* rather than a separate class.
610		*
611		* Performance on most platforms is very sensitive to placement of
612		* instances of both WorkQueues and their arrays -- we absolutely
#	Line 587 \| Line 620 \| public class ForkJoinPool extends Abstra
620		* trades off slightly slower average field access for the sake of
621		* avoiding really bad worst-case access. (Until better JVM
622		* support is in place, this padding is dependent on transient
623	<	* properties of JVM field layout rules.) We also take care in
623	>	* properties of JVM field layout rules.) We also take care in
624		* allocating, sizing and resizing the array. Non-shared queue
625	<	* arrays are initialized (via method growArray) by workers before
626	<	* use. Others are allocated on first use.
625	>	* arrays are initialized by workers before use. Others are
626	>	* allocated on first use.
627		*/
628		static final class WorkQueue {
629		/**
#	Line 613 \| Line 646 \| public class ForkJoinPool extends Abstra
646		*/
647		static final int MAXIMUM_QUEUE_CAPACITY = 1 << 26; // 64M
648
649	<	volatile long totalSteals; // cumulative number of steals
649	>	// Heuristic padding to ameliorate unfortunate memory placements
650	>	volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
651	>
652		int seed; // for random scanning; initialize nonzero
653		volatile int eventCount; // encoded inactivation count; < 0 if inactive
654		int nextWait; // encoded record of next event waiter
655	<	int rescans; // remaining scans until block
621	<	int nsteals; // top-level task executions since last idle
622	<	final int mode; // lifo, fifo, or shared
655	>	int hint; // steal or signal hint (index)
656		int poolIndex; // index of this queue in pool (or 0)
657	<	int stealHint; // index of most recent known stealer
658	<	volatile int runState; // 1: locked, -1: terminate; else 0
657	>	final int mode; // 0: lifo, > 0: fifo, < 0: shared
658	>	int nsteals; // number of steals
659	>	volatile int qlock; // 1: locked, -1: terminate; else 0
660		volatile int base; // index of next slot for poll
661		int top; // index of next slot for push
662		ForkJoinTask<?>[] array; // the elements (initially unallocated)
663		final ForkJoinPool pool; // the containing pool (may be null)
664		final ForkJoinWorkerThread owner; // owning thread or null if shared
665		volatile Thread parker; // == owner during call to park; else null
666	<	ForkJoinTask<?> currentJoin; // task being joined in awaitJoin
666	>	volatile ForkJoinTask<?> currentJoin; // task being joined in awaitJoin
667		ForkJoinTask<?> currentSteal; // current non-local task being executed
634	–	// Heuristic padding to ameliorate unfortunate memory placements
635	–	Object p00, p01, p02, p03, p04, p05, p06, p07;
636	–	Object p08, p09, p0a, p0b, p0c, p0d, p0e;
668
669	<	WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode) {
670	<	this.mode = mode;
669	>	volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17;
670	>	volatile Object pad18, pad19, pad1a, pad1b, pad1c, pad1d;
671	>
672	>	WorkQueue(ForkJoinPool pool, ForkJoinWorkerThread owner, int mode,
673	>	int seed) {
674		this.pool = pool;
675		this.owner = owner;
676	+	this.mode = mode;
677	+	this.seed = seed;
678		// Place indices in the center of array (that is not yet allocated)
679		base = top = INITIAL_QUEUE_CAPACITY >>> 1;
680		}
#	Line 663 \| Line 699 \| public class ForkJoinPool extends Abstra
699		(n == -1 &&
700		((a = array) == null \|\|
701		(m = a.length - 1) < 0 \|\|
702	<	U.getObjectVolatile
703	<	(a, ((m & (s - 1)) << ASHIFT) + ABASE) == null)));
702	>	U.getObject
703	>	(a, (long)((m & (s - 1)) << ASHIFT) + ABASE) == null)));
704		}
705
706		/**
707	<	* Pushes a task. Call only by owner in unshared queues.
707	>	* Pushes a task. Call only by owner in unshared queues. (The
708	>	* shared-queue version is embedded in method externalPush.)
709		*
710		* @param task the task. Caller must ensure non-null.
711	<	* @throw RejectedExecutionException if array cannot be resized
711	>	* @throws RejectedExecutionException if array cannot be resized
712		*/
713		final void push(ForkJoinTask<?> task) {
714		ForkJoinTask<?>[] a; ForkJoinPool p;
715		int s = top, m, n;
716		if ((a = array) != null) { // ignore if queue removed
717	<	U.putOrderedObject
718	<	(a, (((m = a.length - 1) & s) << ASHIFT) + ABASE, task);
717	>	int j = (((m = a.length - 1) & s) << ASHIFT) + ABASE;
718	>	U.putOrderedObject(a, j, task);
719		if ((n = (top = s + 1) - base) <= 2) {
720		if ((p = pool) != null)
721	<	p.signalWork();
721	>	p.signalWork(this);
722		}
723		else if (n >= m)
724	<	growArray(true);
724	>	growArray();
725		}
726		}
727
728		/**
729	<	* Pushes a task if lock is free and array is either big
730	<	* enough or can be resized to be big enough.
731	<	*
695	<	* @param task the task. Caller must ensure non-null.
696	<	* @return true if submitted
729	>	* Initializes or doubles the capacity of array. Call either
730	>	* by owner or with lock held -- it is OK for base, but not
731	>	* top, to move while resizings are in progress.
732		*/
733	<	final boolean trySharedPush(ForkJoinTask<?> task) {
734	<	boolean submitted = false;
735	<	if (runState == 0 && U.compareAndSwapInt(this, RUNSTATE, 0, 1)) {
736	<	ForkJoinTask<?>[] a = array;
737	<	int s = top;
738	<	try {
739	<	if ((a != null && a.length > s + 1 - base) \|\|
740	<	(a = growArray(false)) != null) { // must presize
741	<	int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
742	<	U.putObject(a, (long)j, task); // don't need "ordered"
743	<	top = s + 1;
744	<	submitted = true;
745	<	}
746	<	} finally {
747	<	runState = 0; // unlock
748	<	}
733	>	final ForkJoinTask<?>[] growArray() {
734	>	ForkJoinTask<?>[] oldA = array;
735	>	int size = oldA != null ? oldA.length << 1 : INITIAL_QUEUE_CAPACITY;
736	>	if (size > MAXIMUM_QUEUE_CAPACITY)
737	>	throw new RejectedExecutionException("Queue capacity exceeded");
738	>	int oldMask, t, b;
739	>	ForkJoinTask<?>[] a = array = new ForkJoinTask<?>[size];
740	>	if (oldA != null && (oldMask = oldA.length - 1) >= 0 &&
741	>	(t = top) - (b = base) > 0) {
742	>	int mask = size - 1;
743	>	do {
744	>	ForkJoinTask<?> x;
745	>	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
746	>	int j = ((b & mask) << ASHIFT) + ABASE;
747	>	x = (ForkJoinTask<?>)U.getObjectVolatile(oldA, oldj);
748	>	if (x != null &&
749	>	U.compareAndSwapObject(oldA, oldj, x, null))
750	>	U.putObjectVolatile(a, j, x);
751	>	} while (++b != t);
752		}
753	<	return submitted;
753	>	return a;
754		}
755
756		/**
757		* Takes next task, if one exists, in LIFO order. Call only
758	<	* by owner in unshared queues. (We do not have a shared
721	<	* version of this method because it is never needed.)
758	>	* by owner in unshared queues.
759		*/
760		final ForkJoinTask<?> pop() {
761	<	ForkJoinTask<?> t; int m;
762	<	ForkJoinTask<?>[] a = array;
726	<	if (a != null && (m = a.length - 1) >= 0) {
761	>	ForkJoinTask<?>[] a; ForkJoinTask<?> t; int m;
762	>	if ((a = array) != null && (m = a.length - 1) >= 0) {
763		for (int s; (s = top - 1) - base >= 0;) {
764	<	int j = ((m & s) << ASHIFT) + ABASE;
765	<	if ((t = (ForkJoinTask<?>)U.getObjectVolatile(a, j)) == null)
764	>	long j = ((m & s) << ASHIFT) + ABASE;
765	>	if ((t = (ForkJoinTask<?>)U.getObject(a, j)) == null)
766		break;
767		if (U.compareAndSwapObject(a, j, t, null)) {
768		top = s;
#	Line 774 \| Line 810 \| public class ForkJoinPool extends Abstra
810		else if (base == b) {
811		if (b + 1 == top)
812		break;
813	<	Thread.yield(); // wait for lagging update
813	>	Thread.yield(); // wait for lagging update (very rare)
814		}
815		}
816		return null;
#	Line 801 \| Line 837 \| public class ForkJoinPool extends Abstra
837
838		/**
839		* Pops the given task only if it is at the current top.
840	+	* (A shared version is available only via FJP.tryExternalUnpush)
841		*/
842		final boolean tryUnpush(ForkJoinTask<?> t) {
843		ForkJoinTask<?>[] a; int s;
#	Line 814 \| Line 851 \| public class ForkJoinPool extends Abstra
851		}
852
853		/**
854	<	* Polls the given task only if it is at the current base.
854	>	* Removes and cancels all known tasks, ignoring any exceptions.
855		*/
856	<	final boolean pollFor(ForkJoinTask<?> task) {
857	<	ForkJoinTask<?>[] a; int b;
858	<	if ((b = base) - top < 0 && (a = array) != null) {
859	<	int j = (((a.length - 1) & b) << ASHIFT) + ABASE;
860	<	if (U.getObjectVolatile(a, j) == task && base == b &&
861	<	U.compareAndSwapObject(a, j, task, null)) {
862	<	base = b + 1;
863	<	return true;
856	>	final void cancelAll() {
857	>	ForkJoinTask.cancelIgnoringExceptions(currentJoin);
858	>	ForkJoinTask.cancelIgnoringExceptions(currentSteal);
859	>	for (ForkJoinTask<?> t; (t = poll()) != null; )
860	>	ForkJoinTask.cancelIgnoringExceptions(t);
861	>	}
862	>
863	>	/**
864	>	* Computes next value for random probes. Scans don't require
865	>	* a very high quality generator, but also not a crummy one.
866	>	* Marsaglia xor-shift is cheap and works well enough. Note:
867	>	* This is manually inlined in its usages in ForkJoinPool to
868	>	* avoid writes inside busy scan loops.
869	>	*/
870	>	final int nextSeed() {
871	>	int r = seed;
872	>	r ^= r << 13;
873	>	r ^= r >>> 17;
874	>	return seed = r ^= r << 5;
875	>	}
876	>
877	>	// Specialized execution methods
878	>
879	>	/**
880	>	* Pops and runs tasks until empty.
881	>	*/
882	>	private void popAndExecAll() {
883	>	// A bit faster than repeated pop calls
884	>	ForkJoinTask<?>[] a; int m, s; long j; ForkJoinTask<?> t;
885	>	while ((a = array) != null && (m = a.length - 1) >= 0 &&
886	>	(s = top - 1) - base >= 0 &&
887	>	(t = ((ForkJoinTask<?>)
888	>	U.getObject(a, j = ((m & s) << ASHIFT) + ABASE)))
889	>	!= null) {
890	>	if (U.compareAndSwapObject(a, j, t, null)) {
891	>	top = s;
892	>	t.doExec();
893		}
894		}
829	–	return false;
895		}
896
897		/**
898	<	* If present, removes from queue and executes the given task, or
899	<	* any other cancelled task. Returns (true) immediately on any CAS
898	>	* Polls and runs tasks until empty.
899	>	*/
900	>	private void pollAndExecAll() {
901	>	for (ForkJoinTask<?> t; (t = poll()) != null;)
902	>	t.doExec();
903	>	}
904	>
905	>	/**
906	>	* If present, removes from queue and executes the given task,
907	>	* or any other cancelled task. Returns (true) on any CAS
908		* or consistency check failure so caller can retry.
909		*
910	<	* @return false if no progress can be made
910	>	* @return false if no progress can be made, else true
911		*/
912		final boolean tryRemoveAndExec(ForkJoinTask<?> task) {
913	<	boolean removed = false, empty = true, progress = true;
913	>	boolean stat = true, removed = false, empty = true;
914		ForkJoinTask<?>[] a; int m, s, b, n;
915		if ((a = array) != null && (m = a.length - 1) >= 0 &&
916		(n = (s = top) - (b = base)) > 0) {
#	Line 867 \| Line 940 \| public class ForkJoinPool extends Abstra
940		}
941		if (--n == 0) {
942		if (!empty && base == b)
943	<	progress = false;
943	>	stat = false;
944		break;
945		}
946		}
947		}
948		if (removed)
949		task.doExec();
950	<	return progress;
950	>	return stat;
951		}
952
953		/**
954	<	* Initializes or doubles the capacity of array. Call either
955	<	* by owner or with lock held -- it is OK for base, but not
883	<	* top, to move while resizings are in progress.
884	<	*
885	<	* @param rejectOnFailure if true, throw exception if capacity
886	<	* exceeded (relayed ultimately to user); else return null.
954	>	* Polls for and executes the given task or any other task in
955	>	* its CountedCompleter computation.
956		*/
957	<	final ForkJoinTask<?>[] growArray(boolean rejectOnFailure) {
958	<	ForkJoinTask<?>[] oldA = array;
959	<	int size = oldA != null ? oldA.length << 1 : INITIAL_QUEUE_CAPACITY;
960	<	if (size <= MAXIMUM_QUEUE_CAPACITY) {
961	<	int oldMask, t, b;
962	<	ForkJoinTask<?>[] a = array = new ForkJoinTask<?>[size];
963	<	if (oldA != null && (oldMask = oldA.length - 1) >= 0 &&
964	<	(t = top) - (b = base) > 0) {
965	<	int mask = size - 1;
966	<	do {
967	<	ForkJoinTask<?> x;
968	<	int oldj = ((b & oldMask) << ASHIFT) + ABASE;
969	<	int j = ((b & mask) << ASHIFT) + ABASE;
970	<	x = (ForkJoinTask<?>)U.getObjectVolatile(oldA, oldj);
902	<	if (x != null &&
903	<	U.compareAndSwapObject(oldA, oldj, x, null))
904	<	U.putObjectVolatile(a, j, x);
905	<	} while (++b != t);
906	<	}
907	<	return a;
908	<	}
909	<	else if (!rejectOnFailure)
910	<	return null;
911	<	else
912	<	throw new RejectedExecutionException("Queue capacity exceeded");
913	<	}
914	<
915	<	/**
916	<	* Removes and cancels all known tasks, ignoring any exceptions.
917	<	*/
918	<	final void cancelAll() {
919	<	ForkJoinTask.cancelIgnoringExceptions(currentJoin);
920	<	ForkJoinTask.cancelIgnoringExceptions(currentSteal);
921	<	for (ForkJoinTask<?> t; (t = poll()) != null; )
922	<	ForkJoinTask.cancelIgnoringExceptions(t);
923	<	}
924	<
925	<	/**
926	<	* Computes next value for random probes. Scans don't require
927	<	* a very high quality generator, but also not a crummy one.
928	<	* Marsaglia xor-shift is cheap and works well enough. Note:
929	<	* This is manually inlined in its usages in ForkJoinPool to
930	<	* avoid writes inside busy scan loops.
931	<	*/
932	<	final int nextSeed() {
933	<	int r = seed;
934	<	r ^= r << 13;
935	<	r ^= r >>> 17;
936	<	return seed = r ^= r << 5;
937	<	}
938	<
939	<	// Execution methods
940	<
941	<	/**
942	<	* Removes and runs tasks until empty, using local mode
943	<	* ordering. Normally called only after checking for apparent
944	<	* non-emptiness.
945	<	*/
946	<	final void runLocalTasks() {
947	<	// hoist checks from repeated pop/poll
948	<	ForkJoinTask<?>[] a; int m;
949	<	if ((a = array) != null && (m = a.length - 1) >= 0) {
950	<	if (mode == 0) {
951	<	for (int s; (s = top - 1) - base >= 0;) {
952	<	int j = ((m & s) << ASHIFT) + ABASE;
953	<	ForkJoinTask<?> t =
954	<	(ForkJoinTask<?>)U.getObjectVolatile(a, j);
955	<	if (t != null) {
956	<	if (U.compareAndSwapObject(a, j, t, null)) {
957	<	top = s;
958	<	t.doExec();
959	<	}
957	>	final boolean pollAndExecCC(ForkJoinTask<?> root) {
958	>	ForkJoinTask<?>[] a; int b; Object o;
959	>	outer: while ((b = base) - top < 0 && (a = array) != null) {
960	>	long j = (((a.length - 1) & b) << ASHIFT) + ABASE;
961	>	if ((o = U.getObject(a, j)) == null \|\|
962	>	!(o instanceof CountedCompleter))
963	>	break;
964	>	for (CountedCompleter<?> t = (CountedCompleter<?>)o, r = t;;) {
965	>	if (r == root) {
966	>	if (base == b &&
967	>	U.compareAndSwapObject(a, j, t, null)) {
968	>	base = b + 1;
969	>	t.doExec();
970	>	return true;
971		}
972		else
973	<	break;
963	<	}
964	<	}
965	<	else {
966	<	for (int b; (b = base) - top < 0;) {
967	<	int j = ((m & b) << ASHIFT) + ABASE;
968	<	ForkJoinTask<?> t =
969	<	(ForkJoinTask<?>)U.getObjectVolatile(a, j);
970	<	if (t != null) {
971	<	if (base == b &&
972	<	U.compareAndSwapObject(a, j, t, null)) {
973	<	base = b + 1;
974	<	t.doExec();
975	<	}
976	<	} else if (base == b) {
977	<	if (b + 1 == top)
978	<	break;
979	<	Thread.yield(); // wait for lagging update
980	<	}
973	>	break; // restart
974		}
975	+	if ((r = r.completer) == null)
976	+	break outer; // not part of root computation
977		}
978		}
979	+	return false;
980		}
981
982		/**
983		* Executes a top-level task and any local tasks remaining
984		* after execution.
989	–	*
990	–	* @return true unless terminating
985		*/
986	<	final boolean runTask(ForkJoinTask<?> t) {
993	<	boolean alive = true;
986	>	final void runTask(ForkJoinTask<?> t) {
987		if (t != null) {
988	<	currentSteal = t;
996	<	t.doExec();
997	<	if (top != base) // conservative guard
998	<	runLocalTasks();
999	<	++nsteals;
988	>	(currentSteal = t).doExec();
989		currentSteal = null;
990	+	++nsteals;
991	+	if (base - top < 0) { // process remaining local tasks
992	+	if (mode == 0)
993	+	popAndExecAll();
994	+	else
995	+	pollAndExecAll();
996	+	}
997		}
1002	–	else if (runState < 0) // terminating
1003	–	alive = false;
1004	–	return alive;
998		}
999
1000		/**
#	Line 1010 \| Line 1003 \| public class ForkJoinPool extends Abstra
1003		final void runSubtask(ForkJoinTask<?> t) {
1004		if (t != null) {
1005		ForkJoinTask<?> ps = currentSteal;
1006	<	currentSteal = t;
1014	<	t.doExec();
1006	>	(currentSteal = t).doExec();
1007		currentSteal = ps;
1008		}
1009		}
#	Line 1028 \| Line 1020 \| public class ForkJoinPool extends Abstra
1020		s != Thread.State.TIMED_WAITING);
1021		}
1022
1031	–	/**
1032	–	* If this owned and is not already interrupted, try to
1033	–	* interrupt and/or unpark, ignoring exceptions.
1034	–	*/
1035	–	final void interruptOwner() {
1036	–	Thread wt, p;
1037	–	if ((wt = owner) != null && !wt.isInterrupted()) {
1038	–	try {
1039	–	wt.interrupt();
1040	–	} catch (SecurityException ignore) {
1041	–	}
1042	–	}
1043	–	if ((p = parker) != null)
1044	–	U.unpark(p);
1045	–	}
1046	–
1023		// Unsafe mechanics
1024		private static final sun.misc.Unsafe U;
1025	<	private static final long RUNSTATE;
1025	>	private static final long QLOCK;
1026		private static final int ABASE;
1027		private static final int ASHIFT;
1028		static {
1053	–	int s;
1029		try {
1030		U = getUnsafe();
1031		Class<?> k = WorkQueue.class;
1032		Class<?> ak = ForkJoinTask[].class;
1033	<	RUNSTATE = U.objectFieldOffset
1034	<	(k.getDeclaredField("runState"));
1033	>	QLOCK = U.objectFieldOffset
1034	>	(k.getDeclaredField("qlock"));
1035		ABASE = U.arrayBaseOffset(ak);
1036	<	s = U.arrayIndexScale(ak);
1036	>	int scale = U.arrayIndexScale(ak);
1037	>	if ((scale & (scale - 1)) != 0)
1038	>	throw new Error("data type scale not a power of two");
1039	>	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
1040		} catch (Exception e) {
1041		throw new Error(e);
1042		}
1065	–	if ((s & (s-1)) != 0)
1066	–	throw new Error("data type scale not a power of two");
1067	–	ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
1043		}
1044		}
1045
1071	–	/**
1072	–	* Per-thread records for threads that submit to pools. Currently
1073	–	* holds only pseudo-random seed / index that is used to choose
1074	–	* submission queues in method doSubmit. In the future, this may
1075	–	* also incorporate a means to implement different task rejection
1076	–	* and resubmission policies.
1077	–	*
1078	–	* Seeds for submitters and workers/workQueues work in basically
1079	–	* the same way but are initialized and updated using slightly
1080	–	* different mechanics. Both are initialized using the same
1081	–	* approach as in class ThreadLocal, where successive values are
1082	–	* unlikely to collide with previous values. This is done during
1083	–	* registration for workers, but requires a separate AtomicInteger
1084	–	* for submitters. Seeds are then randomly modified upon
1085	–	* collisions using xorshifts, which requires a non-zero seed.
1086	–	*/
1087	–	static final class Submitter {
1088	–	int seed;
1089	–	Submitter() {
1090	–	int s = nextSubmitterSeed.getAndAdd(SEED_INCREMENT);
1091	–	seed = (s == 0) ? 1 : s; // ensure non-zero
1092	–	}
1093	–	}
1094	–
1095	–	/** ThreadLocal class for Submitters */
1096	–	static final class ThreadSubmitter extends ThreadLocal<Submitter> {
1097	–	public Submitter initialValue() { return new Submitter(); }
1098	–	}
1099	–
1046		// static fields (initialized in static initializer below)
1047
1048		/**
#	Line 1107 \| Line 1053 \| public class ForkJoinPool extends Abstra
1053		defaultForkJoinWorkerThreadFactory;
1054
1055		/**
1056	<	* Generator for assigning sequence numbers as pool names.
1057	<	*/
1058	<	private static final AtomicInteger poolNumberGenerator;
1059	<
1060	<	/**
1115	<	* Generator for initial hashes/seeds for submitters. Accessed by
1116	<	* Submitter class constructor.
1056	>	* Per-thread submission bookkeeping. Shared across all pools
1057	>	* to reduce ThreadLocal pollution and because random motion
1058	>	* to avoid contention in one pool is likely to hold for others.
1059	>	* Lazily initialized on first submission (but null-checked
1060	>	* in other contexts to avoid unnecessary initialization).
1061		*/
1062	<	static final AtomicInteger nextSubmitterSeed;
1062	>	static final ThreadLocal<Submitter> submitters;
1063
1064		/**
1065		* Permission required for callers of methods that may start or
#	Line 1124 \| Line 1068 \| public class ForkJoinPool extends Abstra
1068		private static final RuntimePermission modifyThreadPermission;
1069
1070		/**
1071	<	* Per-thread submission bookeeping. Shared across all pools
1072	<	* to reduce ThreadLocal pollution and because random motion
1073	<	* to avoid contention in one pool is likely to hold for others.
1071	>	* Common (static) pool. Non-null for public use unless a static
1072	>	* construction exception, but internal usages null-check on use
1073	>	* to paranoically avoid potential initialization circularities
1074	>	* as well as to simplify generated code.
1075	>	*/
1076	>	static final ForkJoinPool common;
1077	>
1078	>	/**
1079	>	* Common pool parallelism. Must equal common.parallelism.
1080	>	*/
1081	>	static final int commonParallelism;
1082	>
1083	>	/**
1084	>	* Sequence number for creating workerNamePrefix.
1085	>	*/
1086	>	private static int poolNumberSequence;
1087	>
1088	>	/**
1089	>	* Returns the next sequence number. We don't expect this to
1090	>	* ever contend, so use simple builtin sync.
1091		*/
1092	<	private static final ThreadSubmitter submitters;
1092	>	private static final synchronized int nextPoolId() {
1093	>	return ++poolNumberSequence;
1094	>	}
1095
1096		// static constants
1097
1098		/**
1099	<	* The wakeup interval (in nanoseconds) for a worker waiting for a
1100	<	* task when the pool is quiescent to instead try to shrink the
1101	<	* number of workers. The exact value does not matter too
1102	<	* much. It must be short enough to release resources during
1103	<	* sustained periods of idleness, but not so short that threads
1104	<	* are continually re-created.
1099	>	* Initial timeout value (in nanoseconds) for the thread
1100	>	* triggering quiescence to park waiting for new work. On timeout,
1101	>	* the thread will instead try to shrink the number of
1102	>	* workers. The value should be large enough to avoid overly
1103	>	* aggressive shrinkage during most transient stalls (long GCs
1104	>	* etc).
1105	>	*/
1106	>	private static final long IDLE_TIMEOUT = 2000L * 1000L * 1000L; // 2sec
1107	>
1108	>	/**
1109	>	* Timeout value when there are more threads than parallelism level
1110		*/
1111	<	private static final long SHRINK_RATE =
1144	<	4L * 1000L * 1000L * 1000L; // 4 seconds
1111	>	private static final long FAST_IDLE_TIMEOUT = 200L * 1000L * 1000L;
1112
1113		/**
1114	<	* The timeout value for attempted shrinkage, includes
1148	<	* some slop to cope with system timer imprecision.
1114	>	* Tolerance for idle timeouts, to cope with timer undershoots
1115		*/
1116	<	private static final long SHRINK_TIMEOUT = SHRINK_RATE - (SHRINK_RATE / 10);
1116	>	private static final long TIMEOUT_SLOP = 2000000L;
1117
1118		/**
1119		* The maximum stolen->joining link depth allowed in method
1120	<	* tryHelpStealer. Must be a power of two. This value also
1155	<	* controls the maximum number of times to try to help join a task
1156	<	* without any apparent progress or change in pool state before
1157	<	* giving up and blocking (see awaitJoin). Depths for legitimate
1120	>	* tryHelpStealer. Must be a power of two. Depths for legitimate
1121		* chains are unbounded, but we use a fixed constant to avoid
1122		* (otherwise unchecked) cycles and to bound staleness of
1123		* traversal parameters at the expense of sometimes blocking when
1124		* we could be helping.
1125		*/
1126	<	private static final int MAX_HELP = 32;
1164	<
1165	<	/**
1166	<	* Secondary time-based bound (in nanosecs) for helping attempts
1167	<	* before trying compensated blocking in awaitJoin. Used in
1168	<	* conjunction with MAX_HELP to reduce variance due to different
1169	<	* polling rates associated with different helping options. The
1170	<	* value should roughly approximate the time required to create
1171	<	* and/or activate a worker thread.
1172	<	*/
1173	<	private static final long COMPENSATION_DELAY = 100L * 1000L; // 0.1 millisec
1126	>	private static final int MAX_HELP = 64;
1127
1128		/**
1129		* Increment for seed generators. See class ThreadLocal for
#	Line 1178 \| Line 1131 \| public class ForkJoinPool extends Abstra
1131		*/
1132		private static final int SEED_INCREMENT = 0x61c88647;
1133
1134	<	/**
1134	>	/*
1135		* Bits and masks for control variables
1136		*
1137		* Field ctl is a long packed with:
#	Line 1206 \| Line 1159 \| public class ForkJoinPool extends Abstra
1159		* scan for them to avoid queuing races. Note however that
1160		* eventCount updates lag releases so usage requires care.
1161		*
1162	<	* Field runState is an int packed with:
1162	>	* Field plock is an int packed with:
1163		* SHUTDOWN: true if shutdown is enabled (1 bit)
1164	<	* SEQ: a sequence number updated upon (de)registering workers (30 bits)
1165	<	* INIT: set true after workQueues array construction (1 bit)
1164	>	* SEQ: a sequence lock, with PL_LOCK bit set if locked (30 bits)
1165	>	* SIGNAL: set when threads may be waiting on the lock (1 bit)
1166		*
1167		* The sequence number enables simple consistency checks:
1168		* Staleness of read-only operations on the workQueues array can
1169	<	* be checked by comparing runState before vs after the reads.
1169	>	* be checked by comparing plock before vs after the reads.
1170		*/
1171
1172		// bit positions/shifts for fields
#	Line 1225 \| Line 1178 \| public class ForkJoinPool extends Abstra
1178		// bounds
1179		private static final int SMASK = 0xffff; // short bits
1180		private static final int MAX_CAP = 0x7fff; // max #workers - 1
1181	<	private static final int SQMASK = 0xfffe; // even short bits
1181	>	private static final int EVENMASK = 0xfffe; // even short bits
1182	>	private static final int SQMASK = 0x007e; // max 64 (even) slots
1183		private static final int SHORT_SIGN = 1 << 15;
1184		private static final int INT_SIGN = 1 << 31;
1185
#	Line 1250 \| Line 1204 \| public class ForkJoinPool extends Abstra
1204		private static final int E_MASK = 0x7fffffff; // no STOP_BIT
1205		private static final int E_SEQ = 1 << EC_SHIFT;
1206
1207	<	// runState bits
1207	>	// plock bits
1208		private static final int SHUTDOWN = 1 << 31;
1209	+	private static final int PL_LOCK = 2;
1210	+	private static final int PL_SIGNAL = 1;
1211	+	private static final int PL_SPINS = 1 << 8;
1212
1213		// access mode for WorkQueue
1214		static final int LIFO_QUEUE = 0;
1215		static final int FIFO_QUEUE = 1;
1216		static final int SHARED_QUEUE = -1;
1217
1218	+	// bounds for #steps in scan loop -- must be power 2 minus 1
1219	+	private static final int MIN_SCAN = 0x1ff; // cover estimation slop
1220	+	private static final int MAX_SCAN = 0x1ffff; // 4 * max workers
1221	+
1222		// Instance fields
1223
1224		/*
1225	<	* Field layout order in this class tends to matter more than one
1226	<	* would like. Runtime layout order is only loosely related to
1225	>	* Field layout of this class tends to matter more than one would
1226	>	* like. Runtime layout order is only loosely related to
1227		* declaration order and may differ across JVMs, but the following
1228		* empirically works OK on current JVMs.
1229		*/
1230
1231	+	// Heuristic padding to ameliorate unfortunate memory placements
1232	+	volatile long pad00, pad01, pad02, pad03, pad04, pad05, pad06;
1233	+
1234	+	volatile long stealCount; // collects worker counts
1235		volatile long ctl; // main pool control
1236	<	final int parallelism; // parallelism level
1237	<	final int localMode; // per-worker scheduling mode
1238	<	final int submitMask; // submit queue index bound
1274	<	int nextSeed; // for initializing worker seeds
1275	<	volatile int runState; // shutdown status and seq
1236	>	volatile int plock; // shutdown status and seqLock
1237	>	volatile int indexSeed; // worker/submitter index seed
1238	>	final int config; // mode and parallelism level
1239		WorkQueue[] workQueues; // main registry
1240	<	final Mutex lock; // for registration
1278	<	final Condition termination; // for awaitTermination
1279	<	final ForkJoinWorkerThreadFactory factory; // factory for new workers
1240	>	final ForkJoinWorkerThreadFactory factory;
1241		final Thread.UncaughtExceptionHandler ueh; // per-worker UEH
1281	–	final AtomicLong stealCount; // collect counts when terminated
1282	–	final AtomicInteger nextWorkerNumber; // to create worker name string
1242		final String workerNamePrefix; // to create worker name string
1243
1244	<	// Creating, registering, and deregistering workers
1244	>	volatile Object pad10, pad11, pad12, pad13, pad14, pad15, pad16, pad17;
1245	>	volatile Object pad18, pad19, pad1a, pad1b;
1246
1247		/**
1248	<	* Tries to create and start a worker
1249	<	*/
1250	<	private void addWorker() {
1251	<	Throwable ex = null;
1252	<	ForkJoinWorkerThread wt = null;
1253	<	try {
1254	<	if ((wt = factory.newThread(this)) != null) {
1255	<	wt.start();
1256	<	return;
1248	>	* Acquires the plock lock to protect worker array and related
1249	>	* updates. This method is called only if an initial CAS on plock
1250	>	* fails. This acts as a spinlock for normal cases, but falls back
1251	>	* to builtin monitor to block when (rarely) needed. This would be
1252	>	* a terrible idea for a highly contended lock, but works fine as
1253	>	* a more conservative alternative to a pure spinlock.
1254	>	*/
1255	>	private int acquirePlock() {
1256	>	int spins = PL_SPINS, r = 0, ps, nps;
1257	>	for (;;) {
1258	>	if (((ps = plock) & PL_LOCK) == 0 &&
1259	>	U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK))
1260	>	return nps;
1261	>	else if (r == 0) { // randomize spins if possible
1262	>	Thread t = Thread.currentThread(); WorkQueue w; Submitter z;
1263	>	if ((t instanceof ForkJoinWorkerThread) &&
1264	>	(w = ((ForkJoinWorkerThread)t).workQueue) != null)
1265	>	r = w.seed;
1266	>	else if ((z = submitters.get()) != null)
1267	>	r = z.seed;
1268	>	else
1269	>	r = 1;
1270	>	}
1271	>	else if (spins >= 0) {
1272	>	r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
1273	>	if (r >= 0)
1274	>	--spins;
1275	>	}
1276	>	else if (U.compareAndSwapInt(this, PLOCK, ps, ps \| PL_SIGNAL)) {
1277	>	synchronized (this) {
1278	>	if ((plock & PL_SIGNAL) != 0) {
1279	>	try {
1280	>	wait();
1281	>	} catch (InterruptedException ie) {
1282	>	try {
1283	>	Thread.currentThread().interrupt();
1284	>	} catch (SecurityException ignore) {
1285	>	}
1286	>	}
1287	>	}
1288	>	else
1289	>	notifyAll();
1290	>	}
1291		}
1298	–	} catch (Throwable e) {
1299	–	ex = e;
1292		}
1301	–	deregisterWorker(wt, ex); // adjust counts etc on failure
1293		}
1294
1295		/**
1296	<	* Callback from ForkJoinWorkerThread constructor to assign a
1297	<	* public name. This must be separate from registerWorker because
1307	<	* it is called during the "super" constructor call in
1308	<	* ForkJoinWorkerThread.
1296	>	* Unlocks and signals any thread waiting for plock. Called only
1297	>	* when CAS of seq value for unlock fails.
1298		*/
1299	<	final String nextWorkerName() {
1300	<	return workerNamePrefix.concat
1301	<	(Integer.toString(nextWorkerNumber.addAndGet(1)));
1299	>	private void releasePlock(int ps) {
1300	>	plock = ps;
1301	>	synchronized (this) { notifyAll(); }
1302		}
1303
1304		/**
1305	<	* Callback from ForkJoinWorkerThread constructor to establish its
1306	<	* poolIndex and record its WorkQueue. To avoid scanning bias due
1318	<	* to packing entries in front of the workQueues array, we treat
1319	<	* the array as a simple power-of-two hash table using per-thread
1320	<	* seed as hash, expanding as needed.
1321	<	*
1322	<	* @param w the worker's queue
1305	>	* Tries to create and start one worker if fewer than target
1306	>	* parallelism level exist. Adjusts counts etc on failure.
1307		*/
1308	<	final void registerWorker(WorkQueue w) {
1309	<	Mutex lock = this.lock;
1310	<	lock.lock();
1308	>	private void tryAddWorker() {
1309	>	long c; int u;
1310	>	while ((u = (int)((c = ctl) >>> 32)) < 0 &&
1311	>	(u & SHORT_SIGN) != 0 && (int)c == 0) {
1312	>	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) \|
1313	>	((u + UAC_UNIT) & UAC_MASK)) << 32;
1314	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1315	>	ForkJoinWorkerThreadFactory fac;
1316	>	Throwable ex = null;
1317	>	ForkJoinWorkerThread wt = null;
1318	>	try {
1319	>	if ((fac = factory) != null &&
1320	>	(wt = fac.newThread(this)) != null) {
1321	>	wt.start();
1322	>	break;
1323	>	}
1324	>	} catch (Throwable e) {
1325	>	ex = e;
1326	>	}
1327	>	deregisterWorker(wt, ex);
1328	>	break;
1329	>	}
1330	>	}
1331	>	}
1332	>
1333	>	// Registering and deregistering workers
1334	>
1335	>	/**
1336	>	* Callback from ForkJoinWorkerThread to establish and record its
1337	>	* WorkQueue. To avoid scanning bias due to packing entries in
1338	>	* front of the workQueues array, we treat the array as a simple
1339	>	* power-of-two hash table using per-thread seed as hash,
1340	>	* expanding as needed.
1341	>	*
1342	>	* @param wt the worker thread
1343	>	* @return the worker's queue
1344	>	*/
1345	>	final WorkQueue registerWorker(ForkJoinWorkerThread wt) {
1346	>	Thread.UncaughtExceptionHandler handler; WorkQueue[] ws; int s, ps;
1347	>	wt.setDaemon(true);
1348	>	if ((handler = ueh) != null)
1349	>	wt.setUncaughtExceptionHandler(handler);
1350	>	do {} while (!U.compareAndSwapInt(this, INDEXSEED, s = indexSeed,
1351	>	s += SEED_INCREMENT) \|\|
1352	>	s == 0); // skip 0
1353	>	WorkQueue w = new WorkQueue(this, wt, config >>> 16, s);
1354	>	if (((ps = plock) & PL_LOCK) != 0 \|\|
1355	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1356	>	ps = acquirePlock();
1357	>	int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1358		try {
1359	<	WorkQueue[] ws = workQueues;
1360	<	if (w != null && ws != null) { // skip on shutdown/failure
1361	<	int rs, n;
1362	<	while ((n = ws.length) < // ensure can hold total
1363	<	(parallelism + (short)(ctl >>> TC_SHIFT) << 1))
1364	<	workQueues = ws = Arrays.copyOf(ws, n << 1);
1365	<	int m = n - 1;
1366	<	int s = nextSeed += SEED_INCREMENT; // rarely-colliding sequence
1367	<	w.seed = (s == 0) ? 1 : s; // ensure non-zero seed
1368	<	int r = (s << 1) \| 1; // use odd-numbered indices
1369	<	while (ws[r &= m] != null) // step by approx half size
1370	<	r += ((n >>> 1) & SQMASK) + 2;
1371	<	w.eventCount = w.poolIndex = r; // establish before recording
1372	<	ws[r] = w; // also update seq
1373	<	runState = ((rs = runState) & SHUTDOWN) \| ((rs + 2) & ~SHUTDOWN);
1359	>	if ((ws = workQueues) != null) { // skip if shutting down
1360	>	int n = ws.length, m = n - 1;
1361	>	int r = (s << 1) \| 1; // use odd-numbered indices
1362	>	if (ws[r &= m] != null) { // collision
1363	>	int probes = 0; // step by approx half size
1364	>	int step = (n <= 4) ? 2 : ((n >>> 1) & EVENMASK) + 2;
1365	>	while (ws[r = (r + step) & m] != null) {
1366	>	if (++probes >= n) {
1367	>	workQueues = ws = Arrays.copyOf(ws, n <<= 1);
1368	>	m = n - 1;
1369	>	probes = 0;
1370	>	}
1371	>	}
1372	>	}
1373	>	w.eventCount = w.poolIndex = r; // volatile write orders
1374	>	ws[r] = w;
1375		}
1376		} finally {
1377	<	lock.unlock();
1377	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1378	>	releasePlock(nps);
1379		}
1380	+	wt.setName(workerNamePrefix.concat(Integer.toString(w.poolIndex)));
1381	+	return w;
1382		}
1383
1384		/**
1385		* Final callback from terminating worker, as well as upon failure
1386	<	* to construct or start a worker in addWorker. Removes record of
1387	<	* worker from array, and adjusts counts. If pool is shutting
1388	<	* down, tries to complete termination.
1386	>	* to construct or start a worker. Removes record of worker from
1387	>	* array, and adjusts counts. If pool is shutting down, tries to
1388	>	* complete termination.
1389		*
1390	<	* @param wt the worker thread or null if addWorker failed
1390	>	* @param wt the worker thread or null if construction failed
1391		* @param ex the exception causing failure, or null if none
1392		*/
1393		final void deregisterWorker(ForkJoinWorkerThread wt, Throwable ex) {
1359	–	Mutex lock = this.lock;
1394		WorkQueue w = null;
1395		if (wt != null && (w = wt.workQueue) != null) {
1396	<	w.runState = -1; // ensure runState is set
1397	<	stealCount.getAndAdd(w.totalSteals + w.nsteals);
1398	<	int idx = w.poolIndex;
1399	<	lock.lock();
1400	<	try { // remove record from array
1396	>	int ps;
1397	>	w.qlock = -1; // ensure set
1398	>	long ns = w.nsteals, sc; // collect steal count
1399	>	do {} while (!U.compareAndSwapLong(this, STEALCOUNT,
1400	>	sc = stealCount, sc + ns));
1401	>	if (((ps = plock) & PL_LOCK) != 0 \|\|
1402	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1403	>	ps = acquirePlock();
1404	>	int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1405	>	try {
1406	>	int idx = w.poolIndex;
1407		WorkQueue[] ws = workQueues;
1408		if (ws != null && idx >= 0 && idx < ws.length && ws[idx] == w)
1409		ws[idx] = null;
1410		} finally {
1411	<	lock.unlock();
1411	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1412	>	releasePlock(nps);
1413		}
1414		}
1415
1416	<	long c; // adjust ctl counts
1416	>	long c; // adjust ctl counts
1417		do {} while (!U.compareAndSwapLong
1418		(this, CTL, c = ctl, (((c - AC_UNIT) & AC_MASK) \|
1419		((c - TC_UNIT) & TC_MASK) \|
1420		(c & ~(AC_MASK\|TC_MASK)))));
1421
1422	<	if (!tryTerminate(false, false) && w != null) {
1423	<	w.cancelAll(); // cancel remaining tasks
1424	<	if (w.array != null) // suppress signal if never ran
1425	<	signalWork(); // wake up or create replacement
1426	<	if (ex == null) // help clean refs on way out
1427	<	ForkJoinTask.helpExpungeStaleExceptions();
1422	>	if (!tryTerminate(false, false) && w != null && w.array != null) {
1423	>	w.cancelAll(); // cancel remaining tasks
1424	>	WorkQueue[] ws; WorkQueue v; Thread p; int u, i, e;
1425	>	while ((u = (int)((c = ctl) >>> 32)) < 0 && (e = (int)c) >= 0) {
1426	>	if (e > 0) { // activate or create replacement
1427	>	if ((ws = workQueues) == null \|\|
1428	>	(i = e & SMASK) >= ws.length \|\|
1429	>	(v = ws[i]) == null)
1430	>	break;
1431	>	long nc = (((long)(v.nextWait & E_MASK)) \|
1432	>	((long)(u + UAC_UNIT) << 32));
1433	>	if (v.eventCount != (e \| INT_SIGN))
1434	>	break;
1435	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1436	>	v.eventCount = (e + E_SEQ) & E_MASK;
1437	>	if ((p = v.parker) != null)
1438	>	U.unpark(p);
1439	>	break;
1440	>	}
1441	>	}
1442	>	else {
1443	>	if ((short)u < 0)
1444	>	tryAddWorker();
1445	>	break;
1446	>	}
1447	>	}
1448		}
1449	<
1450	<	if (ex != null) // rethrow
1451	<	U.throwException(ex);
1449	>	if (ex == null) // help clean refs on way out
1450	>	ForkJoinTask.helpExpungeStaleExceptions();
1451	>	else // rethrow
1452	>	ForkJoinTask.rethrow(ex);
1453		}
1454
1393	–
1455		// Submissions
1456
1457		/**
1458		* Unless shutting down, adds the given task to a submission queue
1459		* at submitter's current queue index (modulo submission
1460	<	* range). If no queue exists at the index, one is created. If
1461	<	* the queue is busy, another index is randomly chosen. The
1401	<	* submitMask bounds the effective number of queues to the
1402	<	* (nearest power of two for) parallelism level.
1460	>	* range). Only the most common path is directly handled in this
1461	>	* method. All others are relayed to fullExternalPush.
1462		*
1463		* @param task the task. Caller must ensure non-null.
1464		*/
1465	<	private void doSubmit(ForkJoinTask<?> task) {
1466	<	Submitter s = submitters.get();
1467	<	for (int r = s.seed, m = submitMask;;) {
1468	<	WorkQueue[] ws; WorkQueue q;
1469	<	int k = r & m & SQMASK; // use only even indices
1470	<	if (runState < 0 \|\| (ws = workQueues) == null \|\| ws.length <= k)
1471	<	throw new RejectedExecutionException(); // shutting down
1472	<	else if ((q = ws[k]) == null) { // create new queue
1473	<	WorkQueue nq = new WorkQueue(this, null, SHARED_QUEUE);
1474	<	Mutex lock = this.lock; // construct outside lock
1475	<	lock.lock();
1476	<	try { // recheck under lock
1477	<	int rs = runState; // to update seq
1478	<	if (ws == workQueues && ws[k] == null) {
1420	<	ws[k] = nq;
1421	<	runState = ((rs & SHUTDOWN) \| ((rs + 2) & ~SHUTDOWN));
1422	<	}
1423	<	} finally {
1424	<	lock.unlock();
1425	<	}
1426	<	}
1427	<	else if (q.trySharedPush(task)) {
1428	<	signalWork();
1465	>	final void externalPush(ForkJoinTask<?> task) {
1466	>	WorkQueue[] ws; WorkQueue q; Submitter z; int m; ForkJoinTask<?>[] a;
1467	>	if ((z = submitters.get()) != null && plock > 0 &&
1468	>	(ws = workQueues) != null && (m = (ws.length - 1)) >= 0 &&
1469	>	(q = ws[m & z.seed & SQMASK]) != null &&
1470	>	U.compareAndSwapInt(q, QLOCK, 0, 1)) { // lock
1471	>	int b = q.base, s = q.top, n, an;
1472	>	if ((a = q.array) != null && (an = a.length) > (n = s + 1 - b)) {
1473	>	int j = (((an - 1) & s) << ASHIFT) + ABASE;
1474	>	U.putOrderedObject(a, j, task);
1475	>	q.top = s + 1; // push on to deque
1476	>	q.qlock = 0;
1477	>	if (n <= 2)
1478	>	signalWork(q);
1479		return;
1480		}
1481	<	else if (m > 1) { // move to a different index
1482	<	r ^= r << 13; // same xorshift as WorkQueues
1481	>	q.qlock = 0;
1482	>	}
1483	>	fullExternalPush(task);
1484	>	}
1485	>
1486	>	/**
1487	>	* Full version of externalPush. This method is called, among
1488	>	* other times, upon the first submission of the first task to the
1489	>	* pool, so must perform secondary initialization. It also
1490	>	* detects first submission by an external thread by looking up
1491	>	* its ThreadLocal, and creates a new shared queue if the one at
1492	>	* index if empty or contended. The plock lock body must be
1493	>	* exception-free (so no try/finally) so we optimistically
1494	>	* allocate new queues outside the lock and throw them away if
1495	>	* (very rarely) not needed.
1496	>	*
1497	>	* Secondary initialization occurs when plock is zero, to create
1498	>	* workQueue array and set plock to a valid value. This lock body
1499	>	* must also be exception-free. Because the plock seq value can
1500	>	* eventually wrap around zero, this method harmlessly fails to
1501	>	* reinitialize if workQueues exists, while still advancing plock.
1502	>	*/
1503	>	private void fullExternalPush(ForkJoinTask<?> task) {
1504	>	int r = 0; // random index seed
1505	>	for (Submitter z = submitters.get();;) {
1506	>	WorkQueue[] ws; WorkQueue q; int ps, m, k;
1507	>	if (z == null) {
1508	>	if (U.compareAndSwapInt(this, INDEXSEED, r = indexSeed,
1509	>	r += SEED_INCREMENT) && r != 0)
1510	>	submitters.set(z = new Submitter(r));
1511	>	}
1512	>	else if (r == 0) { // move to a different index
1513	>	r = z.seed;
1514	>	r ^= r << 13; // same xorshift as WorkQueues
1515		r ^= r >>> 17;
1516	<	s.seed = r ^= r << 5;
1516	>	z.seed = r ^ (r << 5);
1517	>	}
1518	>	else if ((ps = plock) < 0)
1519	>	throw new RejectedExecutionException();
1520	>	else if (ps == 0 \|\| (ws = workQueues) == null \|\|
1521	>	(m = ws.length - 1) < 0) { // initialize workQueues
1522	>	int p = config & SMASK; // find power of two table size
1523	>	int n = (p > 1) ? p - 1 : 1; // ensure at least 2 slots
1524	>	n \|= n >>> 1;
1525	>	n \|= n >>> 2;
1526	>	n \|= n >>> 4;
1527	>	n \|= n >>> 8;
1528	>	n \|= n >>> 16;
1529	>	n = (n + 1) << 1;
1530	>	WorkQueue[] nws = ((ws = workQueues) == null \|\| ws.length == 0 ?
1531	>	new WorkQueue[n] : null);
1532	>	if (((ps = plock) & PL_LOCK) != 0 \|\|
1533	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1534	>	ps = acquirePlock();
1535	>	if (((ws = workQueues) == null \|\| ws.length == 0) && nws != null)
1536	>	workQueues = nws;
1537	>	int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1538	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1539	>	releasePlock(nps);
1540	>	}
1541	>	else if ((q = ws[k = r & m & SQMASK]) != null) {
1542	>	if (q.qlock == 0 && U.compareAndSwapInt(q, QLOCK, 0, 1)) {
1543	>	ForkJoinTask<?>[] a = q.array;
1544	>	int s = q.top;
1545	>	boolean submitted = false;
1546	>	try { // locked version of push
1547	>	if ((a != null && a.length > s + 1 - q.base) \|\|
1548	>	(a = q.growArray()) != null) { // must presize
1549	>	int j = (((a.length - 1) & s) << ASHIFT) + ABASE;
1550	>	U.putOrderedObject(a, j, task);
1551	>	q.top = s + 1;
1552	>	submitted = true;
1553	>	}
1554	>	} finally {
1555	>	q.qlock = 0; // unlock
1556	>	}
1557	>	if (submitted) {
1558	>	signalWork(q);
1559	>	return;
1560	>	}
1561	>	}
1562	>	r = 0; // move on failure
1563	>	}
1564	>	else if (((ps = plock) & PL_LOCK) == 0) { // create new queue
1565	>	q = new WorkQueue(this, null, SHARED_QUEUE, r);
1566	>	if (((ps = plock) & PL_LOCK) != 0 \|\|
1567	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
1568	>	ps = acquirePlock();
1569	>	if ((ws = workQueues) != null && k < ws.length && ws[k] == null)
1570	>	ws[k] = q;
1571	>	int nps = (ps & SHUTDOWN) \| ((ps + PL_LOCK) & ~SHUTDOWN);
1572	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
1573	>	releasePlock(nps);
1574		}
1575		else
1576	<	Thread.yield(); // yield if no alternatives
1576	>	r = 0; // try elsewhere while lock held
1577		}
1578		}
1579
#	Line 1449 \| Line 1588 \| public class ForkJoinPool extends Abstra
1588		}
1589
1590		/**
1591	<	* Tries to activate or create a worker if too few are active.
1591	>	* Tries to create or activate a worker if too few are active.
1592	>	*
1593	>	* @param q the (non-null) queue holding tasks to be signalled
1594		*/
1595	<	final void signalWork() {
1596	<	long c; int u;
1597	<	while ((u = (int)((c = ctl) >>> 32)) < 0) { // too few active
1598	<	WorkQueue[] ws = workQueues; int e, i; WorkQueue w; Thread p;
1599	<	if ((e = (int)c) > 0) { // at least one waiting
1600	<	if (ws != null && (i = e & SMASK) < ws.length &&
1595	>	final void signalWork(WorkQueue q) {
1596	>	int hint = q.poolIndex;
1597	>	long c; int e, u, i, n; WorkQueue[] ws; WorkQueue w; Thread p;
1598	>	while ((u = (int)((c = ctl) >>> 32)) < 0) {
1599	>	if ((e = (int)c) > 0) {
1600	>	if ((ws = workQueues) != null && ws.length > (i = e & SMASK) &&
1601		(w = ws[i]) != null && w.eventCount == (e \| INT_SIGN)) {
1602		long nc = (((long)(w.nextWait & E_MASK)) \|
1603		((long)(u + UAC_UNIT) << 32));
1604		if (U.compareAndSwapLong(this, CTL, c, nc)) {
1605	+	w.hint = hint;
1606		w.eventCount = (e + E_SEQ) & E_MASK;
1607		if ((p = w.parker) != null)
1608	<	U.unpark(p); // activate and release
1608	>	U.unpark(p);
1609		break;
1610		}
1611	+	if (q.top - q.base <= 0)
1612	+	break;
1613		}
1614		else
1615		break;
1616		}
1617	<	else if (e == 0 && (u & SHORT_SIGN) != 0) { // too few total
1618	<	long nc = (long)(((u + UTC_UNIT) & UTC_MASK) \|
1619	<	((u + UAC_UNIT) & UAC_MASK)) << 32;
1476	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1477	<	addWorker();
1478	<	break;
1479	<	}
1480	<	}
1481	<	else
1617	>	else {
1618	>	if ((short)u < 0)
1619	>	tryAddWorker();
1620		break;
1621	+	}
1622		}
1623		}
1624
1486	–
1625		// Scanning for tasks
1626
1627		/**
1628		* Top-level runloop for workers, called by ForkJoinWorkerThread.run.
1629		*/
1630		final void runWorker(WorkQueue w) {
1631	<	w.growArray(false); // initialize queue array in this thread
1632	<	do {} while (w.runTask(scan(w)));
1631	>	w.growArray(); // allocate queue
1632	>	do { w.runTask(scan(w)); } while (w.qlock >= 0);
1633		}
1634
1635		/**
#	Line 1502 \| Line 1640 \| public class ForkJoinPool extends Abstra
1640		* contention, or state changes that indicate possible success on
1641		* re-invocation.
1642		*
1643	<	* The scan searches for tasks across a random permutation of
1644	<	* queues (starting at a random index and stepping by a random
1645	<	* relative prime, checking each at least once). The scan
1646	<	* terminates upon either finding a non-empty queue, or completing
1647	<	* the sweep. If the worker is not inactivated, it takes and
1648	<	* returns a task from this queue. On failure to find a task, we
1649	<	* take one of the following actions, after which the caller will
1650	<	* retry calling this method unless terminated.
1643	>	* The scan searches for tasks across queues (starting at a random
1644	>	* index, and relying on registerWorker to irregularly scatter
1645	>	* them within array to avoid bias), checking each at least twice.
1646	>	* The scan terminates upon either finding a non-empty queue, or
1647	>	* completing the sweep. If the worker is not inactivated, it
1648	>	* takes and returns a task from this queue. Otherwise, if not
1649	>	* activated, it signals workers (that may include itself) and
1650	>	* returns so caller can retry. Also returns for true if the
1651	>	* worker array may have changed during an empty scan. On failure
1652	>	* to find a task, we take one of the following actions, after
1653	>	* which the caller will retry calling this method unless
1654	>	* terminated.
1655		*
1656		* * If pool is terminating, terminate the worker.
1657		*
1516	–	* * If not a complete sweep, try to release a waiting worker. If
1517	–	* the scan terminated because the worker is inactivated, then the
1518	–	* released worker will often be the calling worker, and it can
1519	–	* succeed obtaining a task on the next call. Or maybe it is
1520	–	* another worker, but with same net effect. Releasing in other
1521	–	* cases as well ensures that we have enough workers running.
1522	–	*
1658		* * If not already enqueued, try to inactivate and enqueue the
1659		* worker on wait queue. Or, if inactivating has caused the pool
1660	<	* to be quiescent, relay to idleAwaitWork to check for
1661	<	* termination and possibly shrink pool.
1660	>	* to be quiescent, relay to idleAwaitWork to possibly shrink
1661	>	* pool.
1662		*
1663	<	* * If already inactive, and the caller has run a task since the
1664	<	* last empty scan, return (to allow rescan) unless others are
1530	<	* also inactivated. Field WorkQueue.rescans counts down on each
1531	<	* scan to ensure eventual inactivation and blocking.
1663	>	* * If already enqueued and none of the above apply, possibly
1664	>	* park awaiting signal, else lingering to help scan and signal.
1665		*
1666	<	* * If already enqueued and none of the above apply, park
1667	<	* awaiting signal,
1666	>	* * If a non-empty queue discovered or left as a hint,
1667	>	* help wake up other workers before return.
1668		*
1669		* @param w the worker (via its WorkQueue)
1670	<	* @return a task or null of none found
1670	>	* @return a task or null if none found
1671		*/
1672		private final ForkJoinTask<?> scan(WorkQueue w) {
1673	<	WorkQueue[] ws; // first update random seed
1674	<	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1675	<	int rs = runState, m; // volatile read order matters
1676	<	if ((ws = workQueues) != null && (m = ws.length - 1) > 0) {
1677	<	int ec = w.eventCount; // ec is negative if inactive
1678	<	int step = (r >>> 16) \| 1; // relative prime
1679	<	for (int j = (m + 1) << 2; ; r += step) {
1680	<	WorkQueue q; ForkJoinTask<?> t; ForkJoinTask<?>[] a; int b;
1681	<	if ((q = ws[r & m]) != null && (b = q.base) - q.top < 0 &&
1682	<	(a = q.array) != null) { // probably nonempty
1673	>	WorkQueue[] ws; int m;
1674	>	int ps = plock; // read plock before ws
1675	>	if (w != null && (ws = workQueues) != null && (m = ws.length - 1) >= 0) {
1676	>	int ec = w.eventCount; // ec is negative if inactive
1677	>	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
1678	>	w.hint = -1; // update seed and clear hint
1679	>	int j = ((m + m + 1) \| MIN_SCAN) & MAX_SCAN;
1680	>	do {
1681	>	WorkQueue q; ForkJoinTask<?>[] a; int b;
1682	>	if ((q = ws[(r + j) & m]) != null && (b = q.base) - q.top < 0 &&
1683	>	(a = q.array) != null) { // probably nonempty
1684		int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1685	<	t = (ForkJoinTask<?>)U.getObjectVolatile(a, i);
1685	>	ForkJoinTask<?> t = (ForkJoinTask<?>)
1686	>	U.getObjectVolatile(a, i);
1687		if (q.base == b && ec >= 0 && t != null &&
1688		U.compareAndSwapObject(a, i, t, null)) {
1689	<	q.base = b + 1; // specialization of pollAt
1690	<	return t;
1691	<	}
1692	<	else if ((t != null \|\| b + 1 != q.top) &&
1693	<	(ec < 0 \|\| j <= m)) {
1694	<	rs = 0; // mark scan as imcomplete
1695	<	break; // caller can retry after release
1696	<	}
1697	<	}
1698	<	if (--j < 0)
1699	<	break;
1700	<	}
1701	<	long c = ctl; int e = (int)c, a = (int)(c >> AC_SHIFT), nr, ns;
1702	<	if (e < 0) // decode ctl on empty scan
1703	<	w.runState = -1; // pool is terminating
1704	<	else if (rs == 0 \|\| rs != runState) { // incomplete scan
1705	<	WorkQueue v; Thread p; // try to release a waiter
1706	<	if (e > 0 && a < 0 && w.eventCount == ec &&
1707	<	(v = ws[e & m]) != null && v.eventCount == (e \| INT_SIGN)) {
1708	<	long nc = ((long)(v.nextWait & E_MASK) \|
1709	<	((c + AC_UNIT) & (AC_MASK\|TC_MASK)));
1710	<	if (ctl == c && U.compareAndSwapLong(this, CTL, c, nc)) {
1689	>	if ((q.base = b + 1) - q.top < 0)
1690	>	signalWork(q);
1691	>	return t; // taken
1692	>	}
1693	>	else if ((ec < 0 \|\| j < m) && (int)(ctl >> AC_SHIFT) <= 0) {
1694	>	w.hint = (r + j) & m; // help signal below
1695	>	break; // cannot take
1696	>	}
1697	>	}
1698	>	} while (--j >= 0);
1699	>
1700	>	int h, e, ns; long c, sc; WorkQueue q;
1701	>	if ((ns = w.nsteals) != 0) {
1702	>	if (U.compareAndSwapLong(this, STEALCOUNT,
1703	>	sc = stealCount, sc + ns))
1704	>	w.nsteals = 0; // collect steals and rescan
1705	>	}
1706	>	else if (plock != ps) // consistency check
1707	>	; // skip
1708	>	else if ((e = (int)(c = ctl)) < 0)
1709	>	w.qlock = -1; // pool is terminating
1710	>	else {
1711	>	if ((h = w.hint) < 0) {
1712	>	if (ec >= 0) { // try to enqueue/inactivate
1713	>	long nc = (((long)ec \|
1714	>	((c - AC_UNIT) & (AC_MASK\|TC_MASK))));
1715	>	w.nextWait = e; // link and mark inactive
1716	>	w.eventCount = ec \| INT_SIGN;
1717	>	if (ctl != c \|\| !U.compareAndSwapLong(this, CTL, c, nc))
1718	>	w.eventCount = ec; // unmark on CAS failure
1719	>	else if ((int)(c >> AC_SHIFT) == 1 - (config & SMASK))
1720	>	idleAwaitWork(w, nc, c);
1721	>	}
1722	>	else if (w.eventCount < 0 && ctl == c) {
1723	>	Thread wt = Thread.currentThread();
1724	>	Thread.interrupted(); // clear status
1725	>	U.putObject(wt, PARKBLOCKER, this);
1726	>	w.parker = wt; // emulate LockSupport.park
1727	>	if (w.eventCount < 0) // recheck
1728	>	U.park(false, 0L); // block
1729	>	w.parker = null;
1730	>	U.putObject(wt, PARKBLOCKER, null);
1731	>	}
1732	>	}
1733	>	if ((h >= 0 \|\| (h = w.hint) >= 0) &&
1734	>	(ws = workQueues) != null && h < ws.length &&
1735	>	(q = ws[h]) != null) { // signal others before retry
1736	>	WorkQueue v; Thread p; int u, i, s;
1737	>	for (int n = (config & SMASK) - 1;;) {
1738	>	int idleCount = (w.eventCount < 0) ? 0 : -1;
1739	>	if (((s = idleCount - q.base + q.top) <= n &&
1740	>	(n = s) <= 0) \|\|
1741	>	(u = (int)((c = ctl) >>> 32)) >= 0 \|\|
1742	>	(e = (int)c) <= 0 \|\| m < (i = e & SMASK) \|\|
1743	>	(v = ws[i]) == null)
1744	>	break;
1745	>	long nc = (((long)(v.nextWait & E_MASK)) \|
1746	>	((long)(u + UAC_UNIT) << 32));
1747	>	if (v.eventCount != (e \| INT_SIGN) \|\|
1748	>	!U.compareAndSwapLong(this, CTL, c, nc))
1749	>	break;
1750	>	v.hint = h;
1751		v.eventCount = (e + E_SEQ) & E_MASK;
1752		if ((p = v.parker) != null)
1753		U.unpark(p);
1754	+	if (--n <= 0)
1755	+	break;
1756		}
1757		}
1758		}
1582	–	else if (ec >= 0) { // try to enqueue/inactivate
1583	–	long nc = (long)ec \| ((c - AC_UNIT) & (AC_MASK\|TC_MASK));
1584	–	w.nextWait = e;
1585	–	w.eventCount = ec \| INT_SIGN; // mark as inactive
1586	–	if (ctl != c \|\| !U.compareAndSwapLong(this, CTL, c, nc))
1587	–	w.eventCount = ec; // unmark on CAS failure
1588	–	else {
1589	–	if ((ns = w.nsteals) != 0) {
1590	–	w.nsteals = 0; // set rescans if ran task
1591	–	w.rescans = (a > 0) ? 0 : a + parallelism;
1592	–	w.totalSteals += ns;
1593	–	}
1594	–	if (a == 1 - parallelism) // quiescent
1595	–	idleAwaitWork(w, nc, c);
1596	–	}
1597	–	}
1598	–	else if (w.eventCount < 0) { // already queued
1599	–	if ((nr = w.rescans) > 0) { // continue rescanning
1600	–	int ac = a + parallelism;
1601	–	if (((w.rescans = (ac < nr) ? ac : nr - 1) & 3) == 0)
1602	–	Thread.yield(); // yield before block
1603	–	}
1604	–	else {
1605	–	Thread.interrupted(); // clear status
1606	–	Thread wt = Thread.currentThread();
1607	–	U.putObject(wt, PARKBLOCKER, this);
1608	–	w.parker = wt; // emulate LockSupport.park
1609	–	if (w.eventCount < 0) // recheck
1610	–	U.park(false, 0L);
1611	–	w.parker = null;
1612	–	U.putObject(wt, PARKBLOCKER, null);
1613	–	}
1614	–	}
1759		}
1760		return null;
1761		}
#	Line 1619 \| Line 1763 \| public class ForkJoinPool extends Abstra
1763		/**
1764		* If inactivating worker w has caused the pool to become
1765		* quiescent, checks for pool termination, and, so long as this is
1766	<	* not the only worker, waits for event for up to SHRINK_RATE
1767	<	* nanosecs. On timeout, if ctl has not changed, terminates the
1766	>	* not the only worker, waits for event for up to a given
1767	>	* duration. On timeout, if ctl has not changed, terminates the
1768		* worker, which will in turn wake up another worker to possibly
1769		* repeat this process.
1770		*
#	Line 1629 \| Line 1773 \| public class ForkJoinPool extends Abstra
1773		* @param prevCtl the ctl value to restore if thread is terminated
1774		*/
1775		private void idleAwaitWork(WorkQueue w, long currentCtl, long prevCtl) {
1776	<	if (w.eventCount < 0 && !tryTerminate(false, false) &&
1777	<	(int)prevCtl != 0 && ctl == currentCtl) {
1776	>	if (w != null && w.eventCount < 0 &&
1777	>	!tryTerminate(false, false) && (int)prevCtl != 0 &&
1778	>	ctl == currentCtl) {
1779	>	int dc = -(short)(currentCtl >>> TC_SHIFT);
1780	>	long parkTime = dc < 0 ? FAST_IDLE_TIMEOUT: (dc + 1) * IDLE_TIMEOUT;
1781	>	long deadline = System.nanoTime() + parkTime - TIMEOUT_SLOP;
1782		Thread wt = Thread.currentThread();
1635	–	Thread.yield(); // yield before block
1783		while (ctl == currentCtl) {
1637	–	long startTime = System.nanoTime();
1784		Thread.interrupted(); // timed variant of version in scan()
1785		U.putObject(wt, PARKBLOCKER, this);
1786		w.parker = wt;
1787		if (ctl == currentCtl)
1788	<	U.park(false, SHRINK_RATE);
1788	>	U.park(false, parkTime);
1789		w.parker = null;
1790		U.putObject(wt, PARKBLOCKER, null);
1791		if (ctl != currentCtl)
1792		break;
1793	<	if (System.nanoTime() - startTime >= SHRINK_TIMEOUT &&
1793	>	if (deadline - System.nanoTime() <= 0L &&
1794		U.compareAndSwapLong(this, CTL, currentCtl, prevCtl)) {
1795		w.eventCount = (w.eventCount + E_SEQ) \| E_MASK;
1796	<	w.runState = -1; // shrink
1796	>	w.hint = -1;
1797	>	w.qlock = -1; // shrink
1798		break;
1799		}
1800		}
#	Line 1655 \| Line 1802 \| public class ForkJoinPool extends Abstra
1802		}
1803
1804		/**
1805	+	* Scans through queues looking for work while joining a task; if
1806	+	* any present, signals. May return early if more signalling is
1807	+	* detectably unneeded.
1808	+	*
1809	+	* @param task return early if done
1810	+	* @param origin an index to start scan
1811	+	*/
1812	+	private void helpSignal(ForkJoinTask<?> task, int origin) {
1813	+	WorkQueue[] ws; WorkQueue w; Thread p; long c; int m, u, e, i, s;
1814	+	if (task != null && task.status >= 0 &&
1815	+	(u = (int)(ctl >>> 32)) < 0 && (u >> UAC_SHIFT) < 0 &&
1816	+	(ws = workQueues) != null && (m = ws.length - 1) >= 0) {
1817	+	outer: for (int k = origin, j = m; j >= 0; --j) {
1818	+	WorkQueue q = ws[k++ & m];
1819	+	for (int n = m;;) { // limit to at most m signals
1820	+	if (task.status < 0)
1821	+	break outer;
1822	+	if (q == null \|\|
1823	+	((s = -q.base + q.top) <= n && (n = s) <= 0))
1824	+	break;
1825	+	if ((u = (int)((c = ctl) >>> 32)) >= 0 \|\|
1826	+	(e = (int)c) <= 0 \|\| m < (i = e & SMASK) \|\|
1827	+	(w = ws[i]) == null)
1828	+	break outer;
1829	+	long nc = (((long)(w.nextWait & E_MASK)) \|
1830	+	((long)(u + UAC_UNIT) << 32));
1831	+	if (w.eventCount != (e \| INT_SIGN))
1832	+	break outer;
1833	+	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1834	+	w.eventCount = (e + E_SEQ) & E_MASK;
1835	+	if ((p = w.parker) != null)
1836	+	U.unpark(p);
1837	+	if (--n <= 0)
1838	+	break;
1839	+	}
1840	+	}
1841	+	}
1842	+	}
1843	+	}
1844	+
1845	+	/**
1846		* Tries to locate and execute tasks for a stealer of the given
1847		* task, or in turn one of its stealers, Traces currentSteal ->
1848		* currentJoin links looking for a thread working on a descendant
#	Line 1665 \| Line 1853 \| public class ForkJoinPool extends Abstra
1853		* leaves hints in workers to speed up subsequent calls. The
1854		* implementation is very branchy to cope with potential
1855		* inconsistencies or loops encountering chains that are stale,
1856	<	* unknown, or so long that they are likely cyclic. All of these
1669	<	* cases are dealt with by just retrying by caller.
1856	>	* unknown, or so long that they are likely cyclic.
1857		*
1858		* @param joiner the joining worker
1859		* @param task the task to join
1860	<	* @return true if found or ran a task (and so is immediately retryable)
1860	>	* @return 0 if no progress can be made, negative if task
1861	>	* known complete, else positive
1862		*/
1863	<	private boolean tryHelpStealer(WorkQueue joiner, ForkJoinTask<?> task) {
1864	<	WorkQueue[] ws;
1865	<	int m, depth = MAX_HELP; // remaining chain depth
1866	<	boolean progress = false;
1867	<	if ((ws = workQueues) != null && (m = ws.length - 1) > 0 &&
1868	<	task.status >= 0) {
1869	<	ForkJoinTask<?> subtask = task; // current target
1870	<	outer: for (WorkQueue j = joiner;;) {
1871	<	WorkQueue stealer = null; // find stealer of subtask
1872	<	WorkQueue v = ws[j.stealHint & m]; // try hint
1873	<	if (v != null && v.currentSteal == subtask)
1874	<	stealer = v;
1875	<	else { // scan
1876	<	for (int i = 1; i <= m; i += 2) {
1877	<	if ((v = ws[i]) != null && v.currentSteal == subtask &&
1878	<	v != joiner) {
1879	<	stealer = v;
1880	<	j.stealHint = i; // save hint
1881	<	break;
1863	>	private int tryHelpStealer(WorkQueue joiner, ForkJoinTask<?> task) {
1864	>	int stat = 0, steps = 0; // bound to avoid cycles
1865	>	if (joiner != null && task != null) { // hoist null checks
1866	>	restart: for (;;) {
1867	>	ForkJoinTask<?> subtask = task; // current target
1868	>	for (WorkQueue j = joiner, v;;) { // v is stealer of subtask
1869	>	WorkQueue[] ws; int m, s, h;
1870	>	if ((s = task.status) < 0) {
1871	>	stat = s;
1872	>	break restart;
1873	>	}
1874	>	if ((ws = workQueues) == null \|\| (m = ws.length - 1) <= 0)
1875	>	break restart; // shutting down
1876	>	if ((v = ws[h = (j.hint \| 1) & m]) == null \|\|
1877	>	v.currentSteal != subtask) {
1878	>	for (int origin = h;;) { // find stealer
1879	>	if (((h = (h + 2) & m) & 15) == 1 &&
1880	>	(subtask.status < 0 \|\| j.currentJoin != subtask))
1881	>	continue restart; // occasional staleness check
1882	>	if ((v = ws[h]) != null &&
1883	>	v.currentSteal == subtask) {
1884	>	j.hint = h; // save hint
1885	>	break;
1886	>	}
1887	>	if (h == origin)
1888	>	break restart; // cannot find stealer
1889		}
1890		}
1891	<	if (stealer == null)
1892	<	break;
1893	<	}
1894	<
1895	<	for (WorkQueue q = stealer;;) { // try to help stealer
1896	<	ForkJoinTask[] a; ForkJoinTask<?> t; int b;
1897	<	if (task.status < 0)
1898	<	break outer;
1899	<	if ((b = q.base) - q.top < 0 && (a = q.array) != null) {
1900	<	progress = true;
1901	<	int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1902	<	t = (ForkJoinTask<?>)U.getObjectVolatile(a, i);
1903	<	if (subtask.status < 0) // must recheck before taking
1904	<	break outer;
1905	<	if (t != null &&
1906	<	q.base == b &&
1907	<	U.compareAndSwapObject(a, i, t, null)) {
1908	<	q.base = b + 1;
1909	<	joiner.runSubtask(t);
1891	>	for (;;) { // help stealer or descend to its stealer
1892	>	ForkJoinTask[] a; int b;
1893	>	if (subtask.status < 0) // surround probes with
1894	>	continue restart; // consistency checks
1895	>	if ((b = v.base) - v.top < 0 && (a = v.array) != null) {
1896	>	int i = (((a.length - 1) & b) << ASHIFT) + ABASE;
1897	>	ForkJoinTask<?> t =
1898	>	(ForkJoinTask<?>)U.getObjectVolatile(a, i);
1899	>	if (subtask.status < 0 \|\| j.currentJoin != subtask \|\|
1900	>	v.currentSteal != subtask)
1901	>	continue restart; // stale
1902	>	stat = 1; // apparent progress
1903	>	if (t != null && v.base == b &&
1904	>	U.compareAndSwapObject(a, i, t, null)) {
1905	>	v.base = b + 1; // help stealer
1906	>	joiner.runSubtask(t);
1907	>	}
1908	>	else if (v.base == b && ++steps == MAX_HELP)
1909	>	break restart; // v apparently stalled
1910	>	}
1911	>	else { // empty -- try to descend
1912	>	ForkJoinTask<?> next = v.currentJoin;
1913	>	if (subtask.status < 0 \|\| j.currentJoin != subtask \|\|
1914	>	v.currentSteal != subtask)
1915	>	continue restart; // stale
1916	>	else if (next == null \|\| ++steps == MAX_HELP)
1917	>	break restart; // dead-end or maybe cyclic
1918	>	else {
1919	>	subtask = next;
1920	>	j = v;
1921	>	break;
1922	>	}
1923		}
1716	–	else if (q.base == b)
1717	–	break outer; // possibly stalled
1718	–	}
1719	–	else { // descend
1720	–	ForkJoinTask<?> next = stealer.currentJoin;
1721	–	if (--depth <= 0 \|\| subtask.status < 0 \|\|
1722	–	next == null \|\| next == subtask)
1723	–	break outer; // stale, dead-end, or cyclic
1724	–	subtask = next;
1725	–	j = stealer;
1726	–	break;
1924		}
1925		}
1926		}
1927		}
1928	<	return progress;
1928	>	return stat;
1929		}
1930
1931		/**
1932	<	* If task is at base of some steal queue, steals and executes it.
1932	>	* Analog of tryHelpStealer for CountedCompleters. Tries to steal
1933	>	* and run tasks within the target's computation.
1934		*
1935	<	* @param joiner the joining worker
1936	<	* @param task the task
1935	>	* @param task the task to join
1936	>	* @param mode if shared, exit upon completing any task
1937	>	* if all workers are active
1938		*/
1939	<	private void tryPollForAndExec(WorkQueue joiner, ForkJoinTask<?> task) {
1940	<	WorkQueue[] ws;
1941	<	if ((ws = workQueues) != null) {
1942	<	for (int j = 1; j < ws.length && task.status >= 0; j += 2) {
1943	<	WorkQueue q = ws[j];
1944	<	if (q != null && q.pollFor(task)) {
1945	<	joiner.runSubtask(task);
1946	<	break;
1939	>	private int helpComplete(ForkJoinTask<?> task, int mode) {
1940	>	WorkQueue[] ws; WorkQueue q; int m, n, s, u;
1941	>	if (task != null && (ws = workQueues) != null &&
1942	>	(m = ws.length - 1) >= 0) {
1943	>	for (int j = 1, origin = j;;) {
1944	>	if ((s = task.status) < 0)
1945	>	return s;
1946	>	if ((q = ws[j & m]) != null && q.pollAndExecCC(task)) {
1947	>	origin = j;
1948	>	if (mode == SHARED_QUEUE &&
1949	>	((u = (int)(ctl >>> 32)) >= 0 \|\| (u >> UAC_SHIFT) >= 0))
1950	>	break;
1951		}
1952	+	else if ((j = (j + 2) & m) == origin)
1953	+	break;
1954		}
1955		}
1956	+	return 0;
1957		}
1958
1959		/**
1960		* Tries to decrement active count (sometimes implicitly) and
1961		* possibly release or create a compensating worker in preparation
1962		* for blocking. Fails on contention or termination. Otherwise,
1963	<	* adds a new thread if no idle workers are available and either
1964	<	* pool would become completely starved or: (at least half
1759	<	* starved, and fewer than 50% spares exist, and there is at least
1760	<	* one task apparently available). Even though the availability
1761	<	* check requires a full scan, it is worthwhile in reducing false
1762	<	* alarms.
1763	<	*
1764	<	* @param task if nonnull, a task being waited for
1765	<	* @param blocker if nonnull, a blocker being waited for
1766	<	* @return true if the caller can block, else should recheck and retry
1963	>	* adds a new thread if no idle workers are available and pool
1964	>	* may become starved.
1965		*/
1966	<	final boolean tryCompensate(ForkJoinTask<?> task, ManagedBlocker blocker) {
1967	<	int pc = parallelism, e;
1968	<	long c = ctl;
1969	<	WorkQueue[] ws = workQueues;
1970	<	if ((e = (int)c) >= 0 && ws != null) {
1971	<	int u, a, ac, hc;
1972	<	int tc = (short)((u = (int)(c >>> 32)) >>> UTC_SHIFT) + pc;
1973	<	boolean replace = false;
1974	<	if ((a = u >> UAC_SHIFT) <= 0) {
1975	<	if ((ac = a + pc) <= 1)
1976	<	replace = true;
1977	<	else if ((e > 0 \|\| (task != null &&
1978	<	ac <= (hc = pc >>> 1) && tc < pc + hc))) {
1781	<	WorkQueue w;
1782	<	for (int j = 0; j < ws.length; ++j) {
1783	<	if ((w = ws[j]) != null && !w.isEmpty()) {
1784	<	replace = true;
1785	<	break; // in compensation range and tasks available
1786	<	}
1787	<	}
1966	>	final boolean tryCompensate() {
1967	>	int pc = config & SMASK, e, i, tc; long c;
1968	>	WorkQueue[] ws; WorkQueue w; Thread p;
1969	>	if ((ws = workQueues) != null && (e = (int)(c = ctl)) >= 0) {
1970	>	if (e != 0 && (i = e & SMASK) < ws.length &&
1971	>	(w = ws[i]) != null && w.eventCount == (e \| INT_SIGN)) {
1972	>	long nc = ((long)(w.nextWait & E_MASK) \|
1973	>	(c & (AC_MASK\|TC_MASK)));
1974	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1975	>	w.eventCount = (e + E_SEQ) & E_MASK;
1976	>	if ((p = w.parker) != null)
1977	>	U.unpark(p);
1978	>	return true; // replace with idle worker
1979		}
1980		}
1981	<	if ((task == null \|\| task.status >= 0) && // recheck need to block
1982	<	(blocker == null \|\| !blocker.isReleasable()) && ctl == c) {
1983	<	if (!replace) { // no compensation
1984	<	long nc = ((c - AC_UNIT) & AC_MASK) \| (c & ~AC_MASK);
1985	<	if (U.compareAndSwapLong(this, CTL, c, nc))
1986	<	return true;
1987	<	}
1988	<	else if (e != 0) { // release an idle worker
1989	<	WorkQueue w; Thread p; int i;
1990	<	if ((i = e & SMASK) < ws.length && (w = ws[i]) != null) {
1991	<	long nc = ((long)(w.nextWait & E_MASK) \|
1992	<	(c & (AC_MASK\|TC_MASK)));
1993	<	if (w.eventCount == (e \| INT_SIGN) &&
1994	<	U.compareAndSwapLong(this, CTL, c, nc)) {
1995	<	w.eventCount = (e + E_SEQ) & E_MASK;
1996	<	if ((p = w.parker) != null)
1806	<	U.unpark(p);
1981	>	else if ((tc = (short)(c >>> TC_SHIFT)) >= 0 &&
1982	>	(int)(c >> AC_SHIFT) + pc > 1) {
1983	>	long nc = ((c - AC_UNIT) & AC_MASK) \| (c & ~AC_MASK);
1984	>	if (U.compareAndSwapLong(this, CTL, c, nc))
1985	>	return true; // no compensation
1986	>	}
1987	>	else if (tc + pc < MAX_CAP) {
1988	>	long nc = ((c + TC_UNIT) & TC_MASK) \| (c & ~TC_MASK);
1989	>	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1990	>	ForkJoinWorkerThreadFactory fac;
1991	>	Throwable ex = null;
1992	>	ForkJoinWorkerThread wt = null;
1993	>	try {
1994	>	if ((fac = factory) != null &&
1995	>	(wt = fac.newThread(this)) != null) {
1996	>	wt.start();
1997		return true;
1998		}
1999	+	} catch (Throwable rex) {
2000	+	ex = rex;
2001		}
2002	<	}
1811	<	else if (tc < MAX_CAP) { // create replacement
1812	<	long nc = ((c + TC_UNIT) & TC_MASK) \| (c & ~TC_MASK);
1813	<	if (U.compareAndSwapLong(this, CTL, c, nc)) {
1814	<	addWorker();
1815	<	return true;
1816	<	}
2002	>	deregisterWorker(wt, ex); // clean up and return false
2003		}
2004		}
2005		}
#	Line 1821 \| Line 2007 \| public class ForkJoinPool extends Abstra
2007		}
2008
2009		/**
2010	<	* Helps and/or blocks until the given task is done
2010	>	* Helps and/or blocks until the given task is done.
2011		*
2012		* @param joiner the joining worker
2013		* @param task the task
2014		* @return task status on exit
2015		*/
2016		final int awaitJoin(WorkQueue joiner, ForkJoinTask<?> task) {
2017	<	ForkJoinTask<?> prevJoin = joiner.currentJoin;
2018	<	joiner.currentJoin = task;
2019	<	long startTime = 0L;
2020	<	for (int k = 0, s; ; ++k) {
2021	<	if ((joiner.isEmpty() ? // try to help
2022	<	!tryHelpStealer(joiner, task) :
2023	<	!joiner.tryRemoveAndExec(task))) {
2024	<	if (k == 0) {
2025	<	startTime = System.nanoTime();
2026	<	tryPollForAndExec(joiner, task); // check uncommon case
2027	<	}
2028	<	else if ((k & (MAX_HELP - 1)) == 0 &&
2029	<	System.nanoTime() - startTime >= COMPENSATION_DELAY &&
2030	<	tryCompensate(task, null)) {
2031	<	if (task.trySetSignal() && task.status >= 0) {
2032	<	synchronized (task) {
2033	<	if (task.status >= 0) {
2034	<	try { // see ForkJoinTask
2035	<	task.wait(); // for explanation
2036	<	} catch (InterruptedException ie) {
2017	>	int s = 0;
2018	>	if (joiner != null && task != null && (s = task.status) >= 0) {
2019	>	ForkJoinTask<?> prevJoin = joiner.currentJoin;
2020	>	joiner.currentJoin = task;
2021	>	do {} while ((s = task.status) >= 0 && !joiner.isEmpty() &&
2022	>	joiner.tryRemoveAndExec(task)); // process local tasks
2023	>	if (s >= 0 && (s = task.status) >= 0) {
2024	>	helpSignal(task, joiner.poolIndex);
2025	>	if ((s = task.status) >= 0 &&
2026	>	(task instanceof CountedCompleter))
2027	>	s = helpComplete(task, LIFO_QUEUE);
2028	>	}
2029	>	while (s >= 0 && (s = task.status) >= 0) {
2030	>	if ((!joiner.isEmpty() \|\| // try helping
2031	>	(s = tryHelpStealer(joiner, task)) == 0) &&
2032	>	(s = task.status) >= 0) {
2033	>	helpSignal(task, joiner.poolIndex);
2034	>	if ((s = task.status) >= 0 && tryCompensate()) {
2035	>	if (task.trySetSignal() && (s = task.status) >= 0) {
2036	>	synchronized (task) {
2037	>	if (task.status >= 0) {
2038	>	try { // see ForkJoinTask
2039	>	task.wait(); // for explanation
2040	>	} catch (InterruptedException ie) {
2041	>	}
2042		}
2043	+	else
2044	+	task.notifyAll();
2045		}
1853	–	else
1854	–	task.notifyAll();
2046		}
2047	+	long c; // re-activate
2048	+	do {} while (!U.compareAndSwapLong
2049	+	(this, CTL, c = ctl, c + AC_UNIT));
2050		}
1857	–	long c; // re-activate
1858	–	do {} while (!U.compareAndSwapLong
1859	–	(this, CTL, c = ctl, c + AC_UNIT));
2051		}
2052		}
2053	<	if ((s = task.status) < 0) {
1863	<	joiner.currentJoin = prevJoin;
1864	<	return s;
1865	<	}
1866	<	else if ((k & (MAX_HELP - 1)) == MAX_HELP >>> 1)
1867	<	Thread.yield(); // for politeness
2053	>	joiner.currentJoin = prevJoin;
2054		}
2055	+	return s;
2056		}
2057
2058		/**
#	Line 1875 \| Line 2062 \| public class ForkJoinPool extends Abstra
2062		*
2063		* @param joiner the joining worker
2064		* @param task the task
1878	–	* @return task status on exit
2065		*/
2066	<	final int helpJoinOnce(WorkQueue joiner, ForkJoinTask<?> task) {
2066	>	final void helpJoinOnce(WorkQueue joiner, ForkJoinTask<?> task) {
2067		int s;
2068	<	while ((s = task.status) >= 0 &&
2069	<	(joiner.isEmpty() ?
2070	<	tryHelpStealer(joiner, task) :
2071	<	joiner.tryRemoveAndExec(task)))
2072	<	;
2073	<	return s;
2068	>	if (joiner != null && task != null && (s = task.status) >= 0) {
2069	>	ForkJoinTask<?> prevJoin = joiner.currentJoin;
2070	>	joiner.currentJoin = task;
2071	>	do {} while ((s = task.status) >= 0 && !joiner.isEmpty() &&
2072	>	joiner.tryRemoveAndExec(task));
2073	>	if (s >= 0 && (s = task.status) >= 0) {
2074	>	helpSignal(task, joiner.poolIndex);
2075	>	if ((s = task.status) >= 0 &&
2076	>	(task instanceof CountedCompleter))
2077	>	s = helpComplete(task, LIFO_QUEUE);
2078	>	}
2079	>	if (s >= 0 && joiner.isEmpty()) {
2080	>	do {} while (task.status >= 0 &&
2081	>	tryHelpStealer(joiner, task) > 0);
2082	>	}
2083	>	joiner.currentJoin = prevJoin;
2084	>	}
2085		}
2086
2087		/**
2088		* Returns a (probably) non-empty steal queue, if one is found
2089	<	* during a random, then cyclic scan, else null. This method must
2090	<	* be retried by caller if, by the time it tries to use the queue,
2091	<	* it is empty.
2092	<	*/
2093	<	private WorkQueue findNonEmptyStealQueue(WorkQueue w) {
2094	<	// Similar to loop in scan(), but ignoring submissions
2095	<	int r = w.seed; r ^= r << 13; r ^= r >>> 17; w.seed = r ^= r << 5;
2096	<	int step = (r >>> 16) \| 1;
2097	<	for (WorkQueue[] ws;;) {
2098	<	int rs = runState, m;
2099	<	if ((ws = workQueues) == null \|\| (m = ws.length - 1) < 1)
2100	<	return null;
1904	<	for (int j = (m + 1) << 2; ; r += step) {
1905	<	WorkQueue q = ws[((r << 1) \| 1) & m];
1906	<	if (q != null && !q.isEmpty())
1907	<	return q;
1908	<	else if (--j < 0) {
1909	<	if (runState == rs)
1910	<	return null;
1911	<	break;
2089	>	* during a scan, else null. This method must be retried by
2090	>	* caller if, by the time it tries to use the queue, it is empty.
2091	>	* @param r a (random) seed for scanning
2092	>	*/
2093	>	private WorkQueue findNonEmptyStealQueue(int r) {
2094	>	for (;;) {
2095	>	int ps = plock, m; WorkQueue[] ws; WorkQueue q;
2096	>	if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
2097	>	for (int j = (m + 1) << 2; j >= 0; --j) {
2098	>	if ((q = ws[(((r + j) << 1) \| 1) & m]) != null &&
2099	>	q.base - q.top < 0)
2100	>	return q;
2101		}
2102		}
2103	+	if (plock == ps)
2104	+	return null;
2105		}
2106		}
2107
#	Line 1922 \| Line 2113 \| public class ForkJoinPool extends Abstra
2113		*/
2114		final void helpQuiescePool(WorkQueue w) {
2115		for (boolean active = true;;) {
2116	<	if (w.base - w.top < 0)
2117	<	w.runLocalTasks(); // exhaust local queue
2118	<	WorkQueue q = findNonEmptyStealQueue(w);
2119	<	if (q != null) {
2120	<	ForkJoinTask<?> t; int b;
2116	>	long c; WorkQueue q; ForkJoinTask<?> t; int b;
2117	>	while ((t = w.nextLocalTask()) != null) {
2118	>	if (w.base - w.top < 0)
2119	>	signalWork(w);
2120	>	t.doExec();
2121	>	}
2122	>	if ((q = findNonEmptyStealQueue(w.nextSeed())) != null) {
2123		if (!active) { // re-establish active count
1931	–	long c;
2124		active = true;
2125		do {} while (!U.compareAndSwapLong
2126		(this, CTL, c = ctl, c + AC_UNIT));
2127		}
2128	<	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2128	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) {
2129	>	if (q.base - q.top < 0)
2130	>	signalWork(q);
2131		w.runSubtask(t);
2132	+	}
2133		}
2134	<	else {
2135	<	long c;
2136	<	if (active) { // decrement active count without queuing
2134	>	else if (active) { // decrement active count without queuing
2135	>	long nc = (c = ctl) - AC_UNIT;
2136	>	if ((int)(nc >> AC_SHIFT) + (config & SMASK) == 0)
2137	>	return; // bypass decrement-then-increment
2138	>	if (U.compareAndSwapLong(this, CTL, c, nc))
2139		active = false;
1943	–	do {} while (!U.compareAndSwapLong
1944	–	(this, CTL, c = ctl, c -= AC_UNIT));
1945	–	}
1946	–	else
1947	–	c = ctl; // re-increment on exit
1948	–	if ((int)(c >> AC_SHIFT) + parallelism == 0) {
1949	–	do {} while (!U.compareAndSwapLong
1950	–	(this, CTL, c = ctl, c + AC_UNIT));
1951	–	break;
1952	–	}
2140		}
2141	+	else if ((int)((c = ctl) >> AC_SHIFT) + (config & SMASK) == 0 &&
2142	+	U.compareAndSwapLong(this, CTL, c, c + AC_UNIT))
2143	+	return;
2144		}
2145		}
2146
#	Line 1964 \| Line 2154 \| public class ForkJoinPool extends Abstra
2154		WorkQueue q; int b;
2155		if ((t = w.nextLocalTask()) != null)
2156		return t;
2157	<	if ((q = findNonEmptyStealQueue(w)) == null)
2157	>	if ((q = findNonEmptyStealQueue(w.nextSeed())) == null)
2158		return null;
2159	<	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null)
2159	>	if ((b = q.base) - q.top < 0 && (t = q.pollAt(b)) != null) {
2160	>	if (q.base - q.top < 0)
2161	>	signalWork(q);
2162		return t;
2163	+	}
2164		}
2165		}
2166
2167		/**
2168	<	* Returns the approximate (non-atomic) number of idle threads per
2169	<	* active thread to offset steal queue size for method
2170	<	* ForkJoinTask.getSurplusQueuedTaskCount().
2171	<	*/
2172	<	final int idlePerActive() {
2173	<	// Approximate at powers of two for small values, saturate past 4
2174	<	int p = parallelism;
2175	<	int a = p + (int)(ctl >> AC_SHIFT);
2176	<	return (a > (p >>>= 1) ? 0 :
2177	<	a > (p >>>= 1) ? 1 :
2178	<	a > (p >>>= 1) ? 2 :
2179	<	a > (p >>>= 1) ? 4 :
2180	<	8);
2168	>	* Returns a cheap heuristic guide for task partitioning when
2169	>	* programmers, frameworks, tools, or languages have little or no
2170	>	* idea about task granularity. In essence by offering this
2171	>	* method, we ask users only about tradeoffs in overhead vs
2172	>	* expected throughput and its variance, rather than how finely to
2173	>	* partition tasks.
2174	>	*
2175	>	* In a steady state strict (tree-structured) computation, each
2176	>	* thread makes available for stealing enough tasks for other
2177	>	* threads to remain active. Inductively, if all threads play by
2178	>	* the same rules, each thread should make available only a
2179	>	* constant number of tasks.
2180	>	*
2181	>	* The minimum useful constant is just 1. But using a value of 1
2182	>	* would require immediate replenishment upon each steal to
2183	>	* maintain enough tasks, which is infeasible. Further,
2184	>	* partitionings/granularities of offered tasks should minimize
2185	>	* steal rates, which in general means that threads nearer the top
2186	>	* of computation tree should generate more than those nearer the
2187	>	* bottom. In perfect steady state, each thread is at
2188	>	* approximately the same level of computation tree. However,
2189	>	* producing extra tasks amortizes the uncertainty of progress and
2190	>	* diffusion assumptions.
2191	>	*
2192	>	* So, users will want to use values larger (but not much larger)
2193	>	* than 1 to both smooth over transient shortages and hedge
2194	>	* against uneven progress; as traded off against the cost of
2195	>	* extra task overhead. We leave the user to pick a threshold
2196	>	* value to compare with the results of this call to guide
2197	>	* decisions, but recommend values such as 3.
2198	>	*
2199	>	* When all threads are active, it is on average OK to estimate
2200	>	* surplus strictly locally. In steady-state, if one thread is
2201	>	* maintaining say 2 surplus tasks, then so are others. So we can
2202	>	* just use estimated queue length. However, this strategy alone
2203	>	* leads to serious mis-estimates in some non-steady-state
2204	>	* conditions (ramp-up, ramp-down, other stalls). We can detect
2205	>	* many of these by further considering the number of "idle"
2206	>	* threads, that are known to have zero queued tasks, so
2207	>	* compensate by a factor of (#idle/#active) threads.
2208	>	*
2209	>	* Note: The approximation of #busy workers as #active workers is
2210	>	* not very good under current signalling scheme, and should be
2211	>	* improved.
2212	>	*/
2213	>	static int getSurplusQueuedTaskCount() {
2214	>	Thread t; ForkJoinWorkerThread wt; ForkJoinPool pool; WorkQueue q;
2215	>	if (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)) {
2216	>	int p = (pool = (wt = (ForkJoinWorkerThread)t).pool).config & SMASK;
2217	>	int n = (q = wt.workQueue).top - q.base;
2218	>	int a = (int)(pool.ctl >> AC_SHIFT) + p;
2219	>	return n - (a > (p >>>= 1) ? 0 :
2220	>	a > (p >>>= 1) ? 1 :
2221	>	a > (p >>>= 1) ? 2 :
2222	>	a > (p >>>= 1) ? 4 :
2223	>	8);
2224	>	}
2225	>	return 0;
2226		}
2227
2228		// Termination
#	Line 2004 \| Line 2242 \| public class ForkJoinPool extends Abstra
2242		* @return true if now terminating or terminated
2243		*/
2244		private boolean tryTerminate(boolean now, boolean enable) {
2245	<	Mutex lock = this.lock;
2245	>	int ps;
2246	>	if (this == common) // cannot shut down
2247	>	return false;
2248	>	if ((ps = plock) >= 0) { // enable by setting plock
2249	>	if (!enable)
2250	>	return false;
2251	>	if ((ps & PL_LOCK) != 0 \|\|
2252	>	!U.compareAndSwapInt(this, PLOCK, ps, ps += PL_LOCK))
2253	>	ps = acquirePlock();
2254	>	int nps = ((ps + PL_LOCK) & ~SHUTDOWN) \| SHUTDOWN;
2255	>	if (!U.compareAndSwapInt(this, PLOCK, ps, nps))
2256	>	releasePlock(nps);
2257	>	}
2258		for (long c;;) {
2259	<	if (((c = ctl) & STOP_BIT) != 0) { // already terminating
2260	<	if ((short)(c >>> TC_SHIFT) == -parallelism) {
2261	<	lock.lock(); // don't need try/finally
2262	<	termination.signalAll(); // signal when 0 workers
2263	<	lock.unlock();
2259	>	if (((c = ctl) & STOP_BIT) != 0) { // already terminating
2260	>	if ((short)(c >>> TC_SHIFT) == -(config & SMASK)) {
2261	>	synchronized (this) {
2262	>	notifyAll(); // signal when 0 workers
2263	>	}
2264		}
2265		return true;
2266		}
2267	<	if (runState >= 0) { // not yet enabled
2268	<	if (!enable)
2269	<	return false;
2020	<	lock.lock();
2021	<	runState \|= SHUTDOWN;
2022	<	lock.unlock();
2023	<	}
2024	<	if (!now) { // check if idle & no tasks
2025	<	if ((int)(c >> AC_SHIFT) != -parallelism \|\|
2026	<	hasQueuedSubmissions())
2267	>	if (!now) { // check if idle & no tasks
2268	>	WorkQueue[] ws; WorkQueue w;
2269	>	if ((int)(c >> AC_SHIFT) != -(config & SMASK))
2270		return false;
2271	<	// Check for unqueued inactive workers. One pass suffices.
2272	<	WorkQueue[] ws = workQueues; WorkQueue w;
2273	<	if (ws != null) {
2274	<	for (int i = 1; i < ws.length; i += 2) {
2275	<	if ((w = ws[i]) != null && w.eventCount >= 0)
2276	<	return false;
2271	>	if ((ws = workQueues) != null) {
2272	>	for (int i = 0; i < ws.length; ++i) {
2273	>	if ((w = ws[i]) != null) {
2274	>	if (!w.isEmpty()) { // signal unprocessed tasks
2275	>	signalWork(w);
2276	>	return false;
2277	>	}
2278	>	if ((i & 1) != 0 && w.eventCount >= 0)
2279	>	return false; // unqueued inactive worker
2280	>	}
2281		}
2282		}
2283		}
2284		if (U.compareAndSwapLong(this, CTL, c, c \| STOP_BIT)) {
2285		for (int pass = 0; pass < 3; ++pass) {
2286	<	WorkQueue[] ws = workQueues;
2287	<	if (ws != null) {
2041	<	WorkQueue w;
2286	>	WorkQueue[] ws; WorkQueue w; Thread wt;
2287	>	if ((ws = workQueues) != null) {
2288		int n = ws.length;
2289		for (int i = 0; i < n; ++i) {
2290		if ((w = ws[i]) != null) {
2291	<	w.runState = -1;
2291	>	w.qlock = -1;
2292		if (pass > 0) {
2293		w.cancelAll();
2294	<	if (pass > 1)
2295	<	w.interruptOwner();
2294	>	if (pass > 1 && (wt = w.owner) != null) {
2295	>	if (!wt.isInterrupted()) {
2296	>	try {
2297	>	wt.interrupt();
2298	>	} catch (Throwable ignore) {
2299	>	}
2300	>	}
2301	>	U.unpark(wt);
2302	>	}
2303		}
2304		}
2305		}
2306		// Wake up workers parked on event queue
2307		int i, e; long cc; Thread p;
2308		while ((e = (int)(cc = ctl) & E_MASK) != 0 &&
2309	<	(i = e & SMASK) < n &&
2309	>	(i = e & SMASK) < n && i >= 0 &&
2310		(w = ws[i]) != null) {
2311		long nc = ((long)(w.nextWait & E_MASK) \|
2312		((cc + AC_UNIT) & AC_MASK) \|
#	Line 2061 \| Line 2314 \| public class ForkJoinPool extends Abstra
2314		if (w.eventCount == (e \| INT_SIGN) &&
2315		U.compareAndSwapLong(this, CTL, cc, nc)) {
2316		w.eventCount = (e + E_SEQ) & E_MASK;
2317	<	w.runState = -1;
2317	>	w.qlock = -1;
2318		if ((p = w.parker) != null)
2319		U.unpark(p);
2320		}
#	Line 2072 \| Line 2325 \| public class ForkJoinPool extends Abstra
2325		}
2326		}
2327
2328	+	// external operations on common pool
2329	+
2330	+	/**
2331	+	* Returns common pool queue for a thread that has submitted at
2332	+	* least one task.
2333	+	*/
2334	+	static WorkQueue commonSubmitterQueue() {
2335	+	ForkJoinPool p; WorkQueue[] ws; int m; Submitter z;
2336	+	return ((z = submitters.get()) != null &&
2337	+	(p = common) != null &&
2338	+	(ws = p.workQueues) != null &&
2339	+	(m = ws.length - 1) >= 0) ?
2340	+	ws[m & z.seed & SQMASK] : null;
2341	+	}
2342	+
2343	+	/**
2344	+	* Tries to pop the given task from submitter's queue in common pool.
2345	+	*/
2346	+	static boolean tryExternalUnpush(ForkJoinTask<?> t) {
2347	+	ForkJoinPool p; WorkQueue[] ws; WorkQueue q; Submitter z;
2348	+	ForkJoinTask<?>[] a; int m, s;
2349	+	if (t != null &&
2350	+	(z = submitters.get()) != null &&
2351	+	(p = common) != null &&
2352	+	(ws = p.workQueues) != null &&
2353	+	(m = ws.length - 1) >= 0 &&
2354	+	(q = ws[m & z.seed & SQMASK]) != null &&
2355	+	(s = q.top) != q.base &&
2356	+	(a = q.array) != null) {
2357	+	long j = (((a.length - 1) & (s - 1)) << ASHIFT) + ABASE;
2358	+	if (U.getObject(a, j) == t &&
2359	+	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2360	+	if (q.array == a && q.top == s && // recheck
2361	+	U.compareAndSwapObject(a, j, t, null)) {
2362	+	q.top = s - 1;
2363	+	q.qlock = 0;
2364	+	return true;
2365	+	}
2366	+	q.qlock = 0;
2367	+	}
2368	+	}
2369	+	return false;
2370	+	}
2371	+
2372	+	/**
2373	+	* Tries to pop and run local tasks within the same computation
2374	+	* as the given root. On failure, tries to help complete from
2375	+	* other queues via helpComplete.
2376	+	*/
2377	+	private void externalHelpComplete(WorkQueue q, ForkJoinTask<?> root) {
2378	+	ForkJoinTask<?>[] a; int m;
2379	+	if (q != null && (a = q.array) != null && (m = (a.length - 1)) >= 0 &&
2380	+	root != null && root.status >= 0) {
2381	+	for (;;) {
2382	+	int s, u; Object o; CountedCompleter<?> task = null;
2383	+	if ((s = q.top) - q.base > 0) {
2384	+	long j = ((m & (s - 1)) << ASHIFT) + ABASE;
2385	+	if ((o = U.getObject(a, j)) != null &&
2386	+	(o instanceof CountedCompleter)) {
2387	+	CountedCompleter<?> t = (CountedCompleter<?>)o, r = t;
2388	+	do {
2389	+	if (r == root) {
2390	+	if (U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2391	+	if (q.array == a && q.top == s &&
2392	+	U.compareAndSwapObject(a, j, t, null)) {
2393	+	q.top = s - 1;
2394	+	task = t;
2395	+	}
2396	+	q.qlock = 0;
2397	+	}
2398	+	break;
2399	+	}
2400	+	} while ((r = r.completer) != null);
2401	+	}
2402	+	}
2403	+	if (task != null)
2404	+	task.doExec();
2405	+	if (root.status < 0 \|\|
2406	+	(u = (int)(ctl >>> 32)) >= 0 \|\| (u >> UAC_SHIFT) >= 0)
2407	+	break;
2408	+	if (task == null) {
2409	+	helpSignal(root, q.poolIndex);
2410	+	if (root.status >= 0)
2411	+	helpComplete(root, SHARED_QUEUE);
2412	+	break;
2413	+	}
2414	+	}
2415	+	}
2416	+	}
2417	+
2418	+	/**
2419	+	* Tries to help execute or signal availability of the given task
2420	+	* from submitter's queue in common pool.
2421	+	*/
2422	+	static void externalHelpJoin(ForkJoinTask<?> t) {
2423	+	// Some hard-to-avoid overlap with tryExternalUnpush
2424	+	ForkJoinPool p; WorkQueue[] ws; WorkQueue q, w; Submitter z;
2425	+	ForkJoinTask<?>[] a; int m, s, n;
2426	+	if (t != null &&
2427	+	(z = submitters.get()) != null &&
2428	+	(p = common) != null &&
2429	+	(ws = p.workQueues) != null &&
2430	+	(m = ws.length - 1) >= 0 &&
2431	+	(q = ws[m & z.seed & SQMASK]) != null &&
2432	+	(a = q.array) != null) {
2433	+	int am = a.length - 1;
2434	+	if ((s = q.top) != q.base) {
2435	+	long j = ((am & (s - 1)) << ASHIFT) + ABASE;
2436	+	if (U.getObject(a, j) == t &&
2437	+	U.compareAndSwapInt(q, QLOCK, 0, 1)) {
2438	+	if (q.array == a && q.top == s &&
2439	+	U.compareAndSwapObject(a, j, t, null)) {
2440	+	q.top = s - 1;
2441	+	q.qlock = 0;
2442	+	t.doExec();
2443	+	}
2444	+	else
2445	+	q.qlock = 0;
2446	+	}
2447	+	}
2448	+	if (t.status >= 0) {
2449	+	if (t instanceof CountedCompleter)
2450	+	p.externalHelpComplete(q, t);
2451	+	else
2452	+	p.helpSignal(t, q.poolIndex);
2453	+	}
2454	+	}
2455	+	}
2456	+
2457		// Exported methods
2458
2459		// Constructors
#	Line 2088 \| Line 2470 \| public class ForkJoinPool extends Abstra
2470		* java.lang.RuntimePermission}{@code ("modifyThread")}
2471		*/
2472		public ForkJoinPool() {
2473	<	this(Runtime.getRuntime().availableProcessors(),
2473	>	this(Math.min(MAX_CAP, Runtime.getRuntime().availableProcessors()),
2474		defaultForkJoinWorkerThreadFactory, null, false);
2475		}
2476
#	Line 2143 \| Line 2525 \| public class ForkJoinPool extends Abstra
2525		throw new NullPointerException();
2526		if (parallelism <= 0 \|\| parallelism > MAX_CAP)
2527		throw new IllegalArgumentException();
2146	–	this.parallelism = parallelism;
2528		this.factory = factory;
2529		this.ueh = handler;
2530	<	this.localMode = asyncMode ? FIFO_QUEUE : LIFO_QUEUE;
2530	>	this.config = parallelism \| (asyncMode ? (FIFO_QUEUE << 16) : 0);
2531		long np = (long)(-parallelism); // offset ctl counts
2532		this.ctl = ((np << AC_SHIFT) & AC_MASK) \| ((np << TC_SHIFT) & TC_MASK);
2533	<	// Use nearest power 2 for workQueues size. See Hackers Delight sec 3.2.
2153	<	int n = parallelism - 1;
2154	<	n \|= n >>> 1; n \|= n >>> 2; n \|= n >>> 4; n \|= n >>> 8; n \|= n >>> 16;
2155	<	int size = (n + 1) << 1; // #slots = 2*#workers
2156	<	this.submitMask = size - 1; // room for max # of submit queues
2157	<	this.workQueues = new WorkQueue[size];
2158	<	this.termination = (this.lock = new Mutex()).newCondition();
2159	<	this.stealCount = new AtomicLong();
2160	<	this.nextWorkerNumber = new AtomicInteger();
2161	<	int pn = poolNumberGenerator.incrementAndGet();
2533	>	int pn = nextPoolId();
2534		StringBuilder sb = new StringBuilder("ForkJoinPool-");
2535		sb.append(Integer.toString(pn));
2536		sb.append("-worker-");
2537		this.workerNamePrefix = sb.toString();
2538	<	lock.lock();
2539	<	this.runState = 1; // set init flag
2540	<	lock.unlock();
2538	>	}
2539	>
2540	>	/**
2541	>	* Constructor for common pool, suitable only for static initialization.
2542	>	* Basically the same as above, but uses smallest possible initial footprint.
2543	>	*/
2544	>	ForkJoinPool(int parallelism, long ctl,
2545	>	ForkJoinWorkerThreadFactory factory,
2546	>	Thread.UncaughtExceptionHandler handler) {
2547	>	this.config = parallelism;
2548	>	this.ctl = ctl;
2549	>	this.factory = factory;
2550	>	this.ueh = handler;
2551	>	this.workerNamePrefix = "ForkJoinPool.commonPool-worker-";
2552	>	}
2553	>
2554	>	/**
2555	>	* Returns the common pool instance. This pool is statically
2556	>	* constructed; its run state is unaffected by attempts to {@link
2557	>	* #shutdown} or {@link #shutdownNow}. However this pool and any
2558	>	* ongoing processing are automatically terminated upon program
2559	>	* {@link System#exit}. Any program that relies on asynchronous
2560	>	* task processing to complete before program termination should
2561	>	* invoke {@code commonPool().}{@link #awaitQuiescence}, before
2562	>	* exit.
2563	>	*
2564	>	* @return the common pool instance
2565	>	* @since 1.8
2566	>	*/
2567	>	public static ForkJoinPool commonPool() {
2568	>	// assert common != null : "static init error";
2569	>	return common;
2570		}
2571
2572		// Execution methods
#	Line 2189 \| Line 2590 \| public class ForkJoinPool extends Abstra
2590		public <T> T invoke(ForkJoinTask<T> task) {
2591		if (task == null)
2592		throw new NullPointerException();
2593	<	doSubmit(task);
2593	>	externalPush(task);
2594		return task.join();
2595		}
2596
#	Line 2204 \| Line 2605 \| public class ForkJoinPool extends Abstra
2605		public void execute(ForkJoinTask<?> task) {
2606		if (task == null)
2607		throw new NullPointerException();
2608	<	doSubmit(task);
2608	>	externalPush(task);
2609		}
2610
2611		// AbstractExecutorService methods
#	Line 2222 \| Line 2623 \| public class ForkJoinPool extends Abstra
2623		job = (ForkJoinTask<?>) task;
2624		else
2625		job = new ForkJoinTask.AdaptedRunnableAction(task);
2626	<	doSubmit(job);
2626	>	externalPush(job);
2627		}
2628
2629		/**
#	Line 2237 \| Line 2638 \| public class ForkJoinPool extends Abstra
2638		public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) {
2639		if (task == null)
2640		throw new NullPointerException();
2641	<	doSubmit(task);
2641	>	externalPush(task);
2642		return task;
2643		}
2644
#	Line 2248 \| Line 2649 \| public class ForkJoinPool extends Abstra
2649		*/
2650		public <T> ForkJoinTask<T> submit(Callable<T> task) {
2651		ForkJoinTask<T> job = new ForkJoinTask.AdaptedCallable<T>(task);
2652	<	doSubmit(job);
2652	>	externalPush(job);
2653		return job;
2654		}
2655
#	Line 2259 \| Line 2660 \| public class ForkJoinPool extends Abstra
2660		*/
2661		public <T> ForkJoinTask<T> submit(Runnable task, T result) {
2662		ForkJoinTask<T> job = new ForkJoinTask.AdaptedRunnable<T>(task, result);
2663	<	doSubmit(job);
2663	>	externalPush(job);
2664		return job;
2665		}
2666
#	Line 2276 \| Line 2677 \| public class ForkJoinPool extends Abstra
2677		job = (ForkJoinTask<?>) task;
2678		else
2679		job = new ForkJoinTask.AdaptedRunnableAction(task);
2680	<	doSubmit(job);
2680	>	externalPush(job);
2681		return job;
2682		}
2683
#	Line 2288 \| Line 2689 \| public class ForkJoinPool extends Abstra
2689		// In previous versions of this class, this method constructed
2690		// a task to run ForkJoinTask.invokeAll, but now external
2691		// invocation of multiple tasks is at least as efficient.
2692	<	List<ForkJoinTask<T>> fs = new ArrayList<ForkJoinTask<T>>(tasks.size());
2292	<	// Workaround needed because method wasn't declared with
2293	<	// wildcards in return type but should have been.
2294	<	@SuppressWarnings({"unchecked", "rawtypes"})
2295	<	List<Future<T>> futures = (List<Future<T>>) (List) fs;
2692	>	ArrayList<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
2693
2694		boolean done = false;
2695		try {
2696		for (Callable<T> t : tasks) {
2697		ForkJoinTask<T> f = new ForkJoinTask.AdaptedCallable<T>(t);
2698	<	doSubmit(f);
2699	<	fs.add(f);
2698	>	futures.add(f);
2699	>	externalPush(f);
2700		}
2701	<	for (ForkJoinTask<T> f : fs)
2702	<	f.quietlyJoin();
2701	>	for (int i = 0, size = futures.size(); i < size; i++)
2702	>	((ForkJoinTask<?>)futures.get(i)).quietlyJoin();
2703		done = true;
2704		return futures;
2705		} finally {
2706		if (!done)
2707	<	for (ForkJoinTask<T> f : fs)
2708	<	f.cancel(false);
2707	>	for (int i = 0, size = futures.size(); i < size; i++)
2708	>	futures.get(i).cancel(false);
2709		}
2710		}
2711
#	Line 2337 \| Line 2734 \| public class ForkJoinPool extends Abstra
2734		* @return the targeted parallelism level of this pool
2735		*/
2736		public int getParallelism() {
2737	<	return parallelism;
2737	>	return config & SMASK;
2738	>	}
2739	>
2740	>	/**
2741	>	* Returns the targeted parallelism level of the common pool.
2742	>	*
2743	>	* @return the targeted parallelism level of the common pool
2744	>	* @since 1.8
2745	>	*/
2746	>	public static int getCommonPoolParallelism() {
2747	>	return commonParallelism;
2748		}
2749
2750		/**
#	Line 2349 \| Line 2756 \| public class ForkJoinPool extends Abstra
2756		* @return the number of worker threads
2757		*/
2758		public int getPoolSize() {
2759	<	return parallelism + (short)(ctl >>> TC_SHIFT);
2759	>	return (config & SMASK) + (short)(ctl >>> TC_SHIFT);
2760		}
2761
2762		/**
#	Line 2359 \| Line 2766 \| public class ForkJoinPool extends Abstra
2766		* @return {@code true} if this pool uses async mode
2767		*/
2768		public boolean getAsyncMode() {
2769	<	return localMode != 0;
2769	>	return (config >>> 16) == FIFO_QUEUE;
2770		}
2771
2772		/**
#	Line 2390 \| Line 2797 \| public class ForkJoinPool extends Abstra
2797		* @return the number of active threads
2798		*/
2799		public int getActiveThreadCount() {
2800	<	int r = parallelism + (int)(ctl >> AC_SHIFT);
2800	>	int r = (config & SMASK) + (int)(ctl >> AC_SHIFT);
2801		return (r <= 0) ? 0 : r; // suppress momentarily negative values
2802		}
2803
#	Line 2406 \| Line 2813 \| public class ForkJoinPool extends Abstra
2813		* @return {@code true} if all threads are currently idle
2814		*/
2815		public boolean isQuiescent() {
2816	<	return (int)(ctl >> AC_SHIFT) + parallelism == 0;
2816	>	return (int)(ctl >> AC_SHIFT) + (config & SMASK) == 0;
2817		}
2818
2819		/**
#	Line 2421 \| Line 2828 \| public class ForkJoinPool extends Abstra
2828		* @return the number of steals
2829		*/
2830		public long getStealCount() {
2831	<	long count = stealCount.get();
2831	>	long count = stealCount;
2832		WorkQueue[] ws; WorkQueue w;
2833		if ((ws = workQueues) != null) {
2834		for (int i = 1; i < ws.length; i += 2) {
2835		if ((w = ws[i]) != null)
2836	<	count += w.totalSteals;
2836	>	count += w.nsteals;
2837		}
2838		}
2839		return count;
#	Line 2551 \| Line 2958 \| public class ForkJoinPool extends Abstra
2958		public String toString() {
2959		// Use a single pass through workQueues to collect counts
2960		long qt = 0L, qs = 0L; int rc = 0;
2961	<	long st = stealCount.get();
2961	>	long st = stealCount;
2962		long c = ctl;
2963		WorkQueue[] ws; WorkQueue w;
2964		if ((ws = workQueues) != null) {
#	Line 2562 \| Line 2969 \| public class ForkJoinPool extends Abstra
2969		qs += size;
2970		else {
2971		qt += size;
2972	<	st += w.totalSteals;
2972	>	st += w.nsteals;
2973		if (w.isApparentlyUnblocked())
2974		++rc;
2975		}
2976		}
2977		}
2978		}
2979	<	int pc = parallelism;
2979	>	int pc = (config & SMASK);
2980		int tc = pc + (short)(c >>> TC_SHIFT);
2981		int ac = pc + (int)(c >> AC_SHIFT);
2982		if (ac < 0) // ignore transient negative
#	Line 2578 \| Line 2985 \| public class ForkJoinPool extends Abstra
2985		if ((c & STOP_BIT) != 0)
2986		level = (tc == 0) ? "Terminated" : "Terminating";
2987		else
2988	<	level = runState < 0 ? "Shutting down" : "Running";
2988	>	level = plock < 0 ? "Shutting down" : "Running";
2989		return super.toString() +
2990		"[" + level +
2991		", parallelism = " + pc +
#	Line 2592 \| Line 2999 \| public class ForkJoinPool extends Abstra
2999		}
3000
3001		/**
3002	<	* Initiates an orderly shutdown in which previously submitted
3003	<	* tasks are executed, but no new tasks will be accepted.
3004	<	* Invocation has no additional effect if already shut down.
3005	<	* Tasks that are in the process of being submitted concurrently
3006	<	* during the course of this method may or may not be rejected.
3002	>	* Possibly initiates an orderly shutdown in which previously
3003	>	* submitted tasks are executed, but no new tasks will be
3004	>	* accepted. Invocation has no effect on execution state if this
3005	>	* is the {@link #commonPool()}, and no additional effect if
3006	>	* already shut down. Tasks that are in the process of being
3007	>	* submitted concurrently during the course of this method may or
3008	>	* may not be rejected.
3009		*
3010		* @throws SecurityException if a security manager exists and
3011		* the caller is not permitted to modify threads
#	Line 2609 \| Line 3018 \| public class ForkJoinPool extends Abstra
3018		}
3019
3020		/**
3021	<	* Attempts to cancel and/or stop all tasks, and reject all
3022	<	* subsequently submitted tasks. Tasks that are in the process of
3023	<	* being submitted or executed concurrently during the course of
3024	<	* this method may or may not be rejected. This method cancels
3025	<	* both existing and unexecuted tasks, in order to permit
3026	<	* termination in the presence of task dependencies. So the method
3027	<	* always returns an empty list (unlike the case for some other
3028	<	* Executors).
3021	>	* Possibly attempts to cancel and/or stop all tasks, and reject
3022	>	* all subsequently submitted tasks. Invocation has no effect on
3023	>	* execution state if this is the {@link #commonPool()}, and no
3024	>	* additional effect if already shut down. Otherwise, tasks that
3025	>	* are in the process of being submitted or executed concurrently
3026	>	* during the course of this method may or may not be
3027	>	* rejected. This method cancels both existing and unexecuted
3028	>	* tasks, in order to permit termination in the presence of task
3029	>	* dependencies. So the method always returns an empty list
3030	>	* (unlike the case for some other Executors).
3031		*
3032		* @return an empty list
3033		* @throws SecurityException if a security manager exists and
#	Line 2638 \| Line 3049 \| public class ForkJoinPool extends Abstra
3049		public boolean isTerminated() {
3050		long c = ctl;
3051		return ((c & STOP_BIT) != 0L &&
3052	<	(short)(c >>> TC_SHIFT) == -parallelism);
3052	>	(short)(c >>> TC_SHIFT) == -(config & SMASK));
3053		}
3054
3055		/**
#	Line 2646 \| Line 3057 \| public class ForkJoinPool extends Abstra
3057		* commenced but not yet completed. This method may be useful for
3058		* debugging. A return of {@code true} reported a sufficient
3059		* period after shutdown may indicate that submitted tasks have
3060	<	* ignored or suppressed interruption, or are waiting for IO,
3060	>	* ignored or suppressed interruption, or are waiting for I/O,
3061		* causing this executor not to properly terminate. (See the
3062		* advisory notes for class {@link ForkJoinTask} stating that
3063		* tasks should not normally entail blocking operations. But if
#	Line 2657 \| Line 3068 \| public class ForkJoinPool extends Abstra
3068		public boolean isTerminating() {
3069		long c = ctl;
3070		return ((c & STOP_BIT) != 0L &&
3071	<	(short)(c >>> TC_SHIFT) != -parallelism);
3071	>	(short)(c >>> TC_SHIFT) != -(config & SMASK));
3072		}
3073
3074		/**
#	Line 2666 \| Line 3077 \| public class ForkJoinPool extends Abstra
3077		* @return {@code true} if this pool has been shut down
3078		*/
3079		public boolean isShutdown() {
3080	<	return runState < 0;
3080	>	return plock < 0;
3081		}
3082
3083		/**
3084	<	* Blocks until all tasks have completed execution after a shutdown
3085	<	* request, or the timeout occurs, or the current thread is
3086	<	* interrupted, whichever happens first.
3084	>	* Blocks until all tasks have completed execution after a
3085	>	* shutdown request, or the timeout occurs, or the current thread
3086	>	* is interrupted, whichever happens first. Because the {@link
3087	>	* #commonPool()} never terminates until program shutdown, when
3088	>	* applied to the common pool, this method is equivalent to {@link
3089	>	* #awaitQuiescence} but always returns {@code false}.
3090		*
3091		* @param timeout the maximum time to wait
3092		* @param unit the time unit of the timeout argument
#	Line 2682 \| Line 3096 \| public class ForkJoinPool extends Abstra
3096		*/
3097		public boolean awaitTermination(long timeout, TimeUnit unit)
3098		throws InterruptedException {
3099	+	if (Thread.interrupted())
3100	+	throw new InterruptedException();
3101	+	if (this == common) {
3102	+	awaitQuiescence(timeout, unit);
3103	+	return false;
3104	+	}
3105		long nanos = unit.toNanos(timeout);
3106	<	final Mutex lock = this.lock;
3107	<	lock.lock();
3108	<	try {
3109	<	for (;;) {
3110	<	if (isTerminated())
3111	<	return true;
3112	<	if (nanos <= 0)
3106	>	if (isTerminated())
3107	>	return true;
3108	>	long startTime = System.nanoTime();
3109	>	boolean terminated = false;
3110	>	synchronized (this) {
3111	>	for (long waitTime = nanos, millis = 0L;;) {
3112	>	if (terminated = isTerminated() \|\|
3113	>	waitTime <= 0L \|\|
3114	>	(millis = unit.toMillis(waitTime)) <= 0L)
3115	>	break;
3116	>	wait(millis);
3117	>	waitTime = nanos - (System.nanoTime() - startTime);
3118	>	}
3119	>	}
3120	>	return terminated;
3121	>	}
3122	>
3123	>	/**
3124	>	* If called by a ForkJoinTask operating in this pool, equivalent
3125	>	* in effect to {@link ForkJoinTask#helpQuiesce}. Otherwise,
3126	>	* waits and/or attempts to assist performing tasks until this
3127	>	* pool {@link #isQuiescent} or the indicated timeout elapses.
3128	>	*
3129	>	* @param timeout the maximum time to wait
3130	>	* @param unit the time unit of the timeout argument
3131	>	* @return {@code true} if quiescent; {@code false} if the
3132	>	* timeout elapsed.
3133	>	*/
3134	>	public boolean awaitQuiescence(long timeout, TimeUnit unit) {
3135	>	long nanos = unit.toNanos(timeout);
3136	>	ForkJoinWorkerThread wt;
3137	>	Thread thread = Thread.currentThread();
3138	>	if ((thread instanceof ForkJoinWorkerThread) &&
3139	>	(wt = (ForkJoinWorkerThread)thread).pool == this) {
3140	>	helpQuiescePool(wt.workQueue);
3141	>	return true;
3142	>	}
3143	>	long startTime = System.nanoTime();
3144	>	WorkQueue[] ws;
3145	>	int r = 0, m;
3146	>	boolean found = true;
3147	>	while (!isQuiescent() && (ws = workQueues) != null &&
3148	>	(m = ws.length - 1) >= 0) {
3149	>	if (!found) {
3150	>	if ((System.nanoTime() - startTime) > nanos)
3151		return false;
3152	<	nanos = termination.awaitNanos(nanos);
3152	>	Thread.yield(); // cannot block
3153	>	}
3154	>	found = false;
3155	>	for (int j = (m + 1) << 2; j >= 0; --j) {
3156	>	ForkJoinTask<?> t; WorkQueue q; int b;
3157	>	if ((q = ws[r++ & m]) != null && (b = q.base) - q.top < 0) {
3158	>	found = true;
3159	>	if ((t = q.pollAt(b)) != null) {
3160	>	if (q.base - q.top < 0)
3161	>	signalWork(q);
3162	>	t.doExec();
3163	>	}
3164	>	break;
3165	>	}
3166		}
2696	–	} finally {
2697	–	lock.unlock();
3167		}
3168	+	return true;
3169	+	}
3170	+
3171	+	/**
3172	+	* Waits and/or attempts to assist performing tasks indefinitely
3173	+	* until the {@link #commonPool()} {@link #isQuiescent}.
3174	+	*/
3175	+	static void quiesceCommonPool() {
3176	+	common.awaitQuiescence(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
3177		}
3178
3179		/**
#	Line 2794 \| Line 3272 \| public class ForkJoinPool extends Abstra
3272		public static void managedBlock(ManagedBlocker blocker)
3273		throws InterruptedException {
3274		Thread t = Thread.currentThread();
3275	<	ForkJoinPool p = ((t instanceof ForkJoinWorkerThread) ?
3276	<	((ForkJoinWorkerThread)t).pool : null);
3277	<	while (!blocker.isReleasable()) {
3278	<	if (p == null \|\| p.tryCompensate(null, blocker)) {
3279	<	try {
3280	<	do {} while (!blocker.isReleasable() && !blocker.block());
3281	<	} finally {
3282	<	if (p != null)
3275	>	if (t instanceof ForkJoinWorkerThread) {
3276	>	ForkJoinPool p = ((ForkJoinWorkerThread)t).pool;
3277	>	while (!blocker.isReleasable()) { // variant of helpSignal
3278	>	WorkQueue[] ws; WorkQueue q; int m, u;
3279	>	if ((ws = p.workQueues) != null && (m = ws.length - 1) >= 0) {
3280	>	for (int i = 0; i <= m; ++i) {
3281	>	if (blocker.isReleasable())
3282	>	return;
3283	>	if ((q = ws[i]) != null && q.base - q.top < 0) {
3284	>	p.signalWork(q);
3285	>	if ((u = (int)(p.ctl >>> 32)) >= 0 \|\|
3286	>	(u >> UAC_SHIFT) >= 0)
3287	>	break;
3288	>	}
3289	>	}
3290	>	}
3291	>	if (p.tryCompensate()) {
3292	>	try {
3293	>	do {} while (!blocker.isReleasable() &&
3294	>	!blocker.block());
3295	>	} finally {
3296		p.incrementActiveCount();
3297	+	}
3298	+	break;
3299		}
2807	–	break;
3300		}
3301		}
3302	+	else {
3303	+	do {} while (!blocker.isReleasable() &&
3304	+	!blocker.block());
3305	+	}
3306		}
3307
3308		// AbstractExecutorService overrides. These rely on undocumented
#	Line 2827 \| Line 3323 \| public class ForkJoinPool extends Abstra
3323		private static final long PARKBLOCKER;
3324		private static final int ABASE;
3325		private static final int ASHIFT;
3326	+	private static final long STEALCOUNT;
3327	+	private static final long PLOCK;
3328	+	private static final long INDEXSEED;
3329	+	private static final long QLOCK;
3330
3331		static {
3332	<	poolNumberGenerator = new AtomicInteger();
2833	<	nextSubmitterSeed = new AtomicInteger(0x55555555);
2834	<	modifyThreadPermission = new RuntimePermission("modifyThread");
2835	<	defaultForkJoinWorkerThreadFactory =
2836	<	new DefaultForkJoinWorkerThreadFactory();
2837	<	submitters = new ThreadSubmitter();
2838	<	int s;
3332	>	// initialize field offsets for CAS etc
3333		try {
3334		U = getUnsafe();
3335		Class<?> k = ForkJoinPool.class;
2842	–	Class<?> ak = ForkJoinTask[].class;
3336		CTL = U.objectFieldOffset
3337		(k.getDeclaredField("ctl"));
3338	+	STEALCOUNT = U.objectFieldOffset
3339	+	(k.getDeclaredField("stealCount"));
3340	+	PLOCK = U.objectFieldOffset
3341	+	(k.getDeclaredField("plock"));
3342	+	INDEXSEED = U.objectFieldOffset
3343	+	(k.getDeclaredField("indexSeed"));
3344		Class<?> tk = Thread.class;
3345		PARKBLOCKER = U.objectFieldOffset
3346		(tk.getDeclaredField("parkBlocker"));
3347	+	Class<?> wk = WorkQueue.class;
3348	+	QLOCK = U.objectFieldOffset
3349	+	(wk.getDeclaredField("qlock"));
3350	+	Class<?> ak = ForkJoinTask[].class;
3351		ABASE = U.arrayBaseOffset(ak);
3352	<	s = U.arrayIndexScale(ak);
3352	>	int scale = U.arrayIndexScale(ak);
3353	>	if ((scale & (scale - 1)) != 0)
3354	>	throw new Error("data type scale not a power of two");
3355	>	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
3356		} catch (Exception e) {
3357		throw new Error(e);
3358		}
3359	<	if ((s & (s-1)) != 0)
3360	<	throw new Error("data type scale not a power of two");
3361	<	ASHIFT = 31 - Integer.numberOfLeadingZeros(s);
3359	>
3360	>	submitters = new ThreadLocal<Submitter>();
3361	>	ForkJoinWorkerThreadFactory fac = defaultForkJoinWorkerThreadFactory =
3362	>	new DefaultForkJoinWorkerThreadFactory();
3363	>	modifyThreadPermission = new RuntimePermission("modifyThread");
3364	>
3365	>	/*
3366	>	* Establish common pool parameters. For extra caution,
3367	>	* computations to set up common pool state are here; the
3368	>	* constructor just assigns these values to fields.
3369	>	*/
3370	>
3371	>	int par = 0;
3372	>	Thread.UncaughtExceptionHandler handler = null;
3373	>	try { // TBD: limit or report ignored exceptions?
3374	>	String pp = System.getProperty
3375	>	("java.util.concurrent.ForkJoinPool.common.parallelism");
3376	>	String hp = System.getProperty
3377	>	("java.util.concurrent.ForkJoinPool.common.exceptionHandler");
3378	>	String fp = System.getProperty
3379	>	("java.util.concurrent.ForkJoinPool.common.threadFactory");
3380	>	if (fp != null)
3381	>	fac = ((ForkJoinWorkerThreadFactory)ClassLoader.
3382	>	getSystemClassLoader().loadClass(fp).newInstance());
3383	>	if (hp != null)
3384	>	handler = ((Thread.UncaughtExceptionHandler)ClassLoader.
3385	>	getSystemClassLoader().loadClass(hp).newInstance());
3386	>	if (pp != null)
3387	>	par = Integer.parseInt(pp);
3388	>	} catch (Exception ignore) {
3389	>	}
3390	>
3391	>	if (par <= 0)
3392	>	par = Runtime.getRuntime().availableProcessors();
3393	>	if (par > MAX_CAP)
3394	>	par = MAX_CAP;
3395	>	commonParallelism = par;
3396	>	long np = (long)(-par); // precompute initial ctl value
3397	>	long ct = ((np << AC_SHIFT) & AC_MASK) \| ((np << TC_SHIFT) & TC_MASK);
3398	>
3399	>	common = new ForkJoinPool(par, ct, fac, handler);
3400		}
3401
3402		/**
#	Line 2865 \| Line 3409 \| public class ForkJoinPool extends Abstra
3409		private static sun.misc.Unsafe getUnsafe() {
3410		try {
3411		return sun.misc.Unsafe.getUnsafe();
3412	<	} catch (SecurityException se) {
3413	<	try {
3414	<	return java.security.AccessController.doPrivileged
3415	<	(new java.security
3416	<	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
3417	<	public sun.misc.Unsafe run() throws Exception {
3418	<	java.lang.reflect.Field f = sun.misc
3419	<	.Unsafe.class.getDeclaredField("theUnsafe");
3420	<	f.setAccessible(true);
3421	<	return (sun.misc.Unsafe) f.get(null);
3422	<	}});
3423	<	} catch (java.security.PrivilegedActionException e) {
3424	<	throw new RuntimeException("Could not initialize intrinsics",
3425	<	e.getCause());
3426	<	}
3412	>	} catch (SecurityException tryReflectionInstead) {}
3413	>	try {
3414	>	return java.security.AccessController.doPrivileged
3415	>	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
3416	>	public sun.misc.Unsafe run() throws Exception {
3417	>	Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
3418	>	for (java.lang.reflect.Field f : k.getDeclaredFields()) {
3419	>	f.setAccessible(true);
3420	>	Object x = f.get(null);
3421	>	if (k.isInstance(x))
3422	>	return k.cast(x);
3423	>	}
3424	>	throw new NoSuchFieldError("the Unsafe");
3425	>	}});
3426	>	} catch (java.security.PrivilegedActionException e) {
3427	>	throw new RuntimeException("Could not initialize intrinsics",
3428	>	e.getCause());
3429		}
3430		}
2885	–
3431		}

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Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents): Revision 1.125 by jsr166, Tue Feb 21 00:19:23 2012 UTC vs. Revision 1.189 by jsr166, Sat Sep 12 19:16:45 2015 UTC

Diff Legend

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.125 by jsr166, Tue Feb 21 00:19:23 2012 UTC vs.
Revision 1.189 by jsr166, Sat Sep 12 19:16:45 2015 UTC