| 110 |
|
* idea). (4) We bound the number of attempts to find work (see |
| 111 |
|
* MAX_HELP_DEPTH) and fall back to suspending the worker and if |
| 112 |
|
* necessary replacing it with a spare (see |
| 113 |
< |
* ForkJoinPool.tryAwaitJoin). |
| 113 |
> |
* ForkJoinPool.awaitJoin). |
| 114 |
|
* |
| 115 |
|
* Efficient implementation of these algorithms currently relies |
| 116 |
|
* on an uncomfortable amount of "Unsafe" mechanics. To maintain |
| 164 |
|
private static final int MAX_HELP_DEPTH = 8; |
| 165 |
|
|
| 166 |
|
/** |
| 167 |
– |
* The wakeup interval (in nanoseconds) for the oldest worker |
| 168 |
– |
* suspended as spare. On each wakeup not signalled by a |
| 169 |
– |
* resumption, it may ask the pool to reduce the number of spares. |
| 170 |
– |
*/ |
| 171 |
– |
private static final long TRIM_RATE_NANOS = |
| 172 |
– |
5L * 1000L * 1000L * 1000L; // 5sec |
| 173 |
– |
|
| 174 |
– |
/** |
| 167 |
|
* Capacity of work-stealing queue array upon initialization. |
| 168 |
|
* Must be a power of two. Initial size must be at least 4, but is |
| 169 |
|
* padded to minimize cache effects. |
| 172 |
|
|
| 173 |
|
/** |
| 174 |
|
* Maximum work-stealing queue array size. Must be less than or |
| 175 |
< |
* equal to 1 << 28 to ensure lack of index wraparound. (This |
| 176 |
< |
* is less than usual bounds, because we need leftshift by 3 |
| 177 |
< |
* to be in int range). |
| 175 |
> |
* equal to 1 << (31 - width of array entry) to ensure lack of |
| 176 |
> |
* index wraparound. The value is set in the static block |
| 177 |
> |
* at the end of this file after obtaining width. |
| 178 |
|
*/ |
| 179 |
< |
private static final int MAXIMUM_QUEUE_CAPACITY = 1 << 28; |
| 179 |
> |
private static final int MAXIMUM_QUEUE_CAPACITY; |
| 180 |
|
|
| 181 |
|
/** |
| 182 |
|
* The pool this thread works in. Accessed directly by ForkJoinTask. |
| 218 |
|
* tracks if this worker is suspended as a spare, and if it was |
| 219 |
|
* killed (trimmed) while suspended. However, "active" status is |
| 220 |
|
* maintained separately and modified only in conjunction with |
| 221 |
< |
* CASes of the pool's runState (which are currently sadly manually |
| 222 |
< |
* inlined for performance.) |
| 221 |
> |
* CASes of the pool's runState (which are currently sadly |
| 222 |
> |
* manually inlined for performance.) Accessed directly by pool |
| 223 |
> |
* to simplify checks for normal (zero) status. |
| 224 |
|
*/ |
| 225 |
< |
private volatile int runState; |
| 225 |
> |
volatile int runState; |
| 226 |
|
|
| 227 |
|
private static final int TERMINATING = 0x01; |
| 228 |
|
private static final int TERMINATED = 0x02; |
| 230 |
|
private static final int TRIMMED = 0x08; // killed while suspended |
| 231 |
|
|
| 232 |
|
/** |
| 233 |
< |
* Number of steals, transferred and reset in pool callbacks pool |
| 234 |
< |
* when idle Accessed directly by pool. |
| 233 |
> |
* Number of steals. Directly accessed (and reset) by |
| 234 |
> |
* pool.tryAccumulateStealCount when idle. |
| 235 |
|
*/ |
| 236 |
|
int stealCount; |
| 237 |
|
|
| 267 |
|
int lastEventCount; |
| 268 |
|
|
| 269 |
|
/** |
| 270 |
< |
* Encoded index and event count of next event waiter. Used only |
| 271 |
< |
* by ForkJoinPool for managing event waiters. |
| 270 |
> |
* Encoded index and event count of next event waiter. Accessed |
| 271 |
> |
* only by ForkJoinPool for managing event waiters. |
| 272 |
|
*/ |
| 273 |
|
volatile long nextWaiter; |
| 274 |
|
|
| 275 |
|
/** |
| 276 |
< |
* Number of times this thread suspended as spare |
| 276 |
> |
* Number of times this thread suspended as spare. Accessed only |
| 277 |
> |
* by pool. |
| 278 |
|
*/ |
| 279 |
|
int spareCount; |
| 280 |
|
|
| 281 |
|
/** |
| 282 |
< |
* Encoded index and count of next spare waiter. Used only |
| 282 |
> |
* Encoded index and count of next spare waiter. Accessed only |
| 283 |
|
* by ForkJoinPool for managing spares. |
| 284 |
|
*/ |
| 285 |
|
volatile int nextSpare; |
| 286 |
|
|
| 287 |
|
/** |
| 288 |
|
* The task currently being joined, set only when actively trying |
| 289 |
< |
* to helpStealer. Written only by current thread, but read by |
| 290 |
< |
* others. |
| 289 |
> |
* to help other stealers in helpJoinTask. Written only by this |
| 290 |
> |
* thread, but read by others. |
| 291 |
|
*/ |
| 292 |
|
private volatile ForkJoinTask<?> currentJoin; |
| 293 |
|
|
| 294 |
|
/** |
| 295 |
|
* The task most recently stolen from another worker (or |
| 296 |
< |
* submission queue). Not volatile because always read/written in |
| 297 |
< |
* presence of related volatiles in those cases where it matters. |
| 296 |
> |
* submission queue). Written only by this thread, but read by |
| 297 |
> |
* others. |
| 298 |
|
*/ |
| 299 |
< |
private ForkJoinTask<?> currentSteal; |
| 299 |
> |
private volatile ForkJoinTask<?> currentSteal; |
| 300 |
|
|
| 301 |
|
/** |
| 302 |
|
* Creates a ForkJoinWorkerThread operating in the given pool. |
| 313 |
|
} |
| 314 |
|
|
| 315 |
|
/** |
| 316 |
< |
* Performs additional initialization and starts this thread |
| 316 |
> |
* Performs additional initialization and starts this thread. |
| 317 |
|
*/ |
| 318 |
|
final void start(int poolIndex, UncaughtExceptionHandler ueh) { |
| 319 |
|
this.poolIndex = poolIndex; |
| 349 |
|
/** |
| 350 |
|
* Initializes internal state after construction but before |
| 351 |
|
* processing any tasks. If you override this method, you must |
| 352 |
< |
* invoke super.onStart() at the beginning of the method. |
| 352 |
> |
* invoke @code{super.onStart()} at the beginning of the method. |
| 353 |
|
* Initialization requires care: Most fields must have legal |
| 354 |
|
* default values, to ensure that attempted accesses from other |
| 355 |
|
* threads work correctly even before this thread starts |
| 381 |
|
if (active) { |
| 382 |
|
int a; // inline p.tryDecrementActiveCount |
| 383 |
|
active = false; |
| 384 |
< |
do {} while(!UNSAFE.compareAndSwapInt |
| 385 |
< |
(p, poolRunStateOffset, a = p.runState, a - 1)); |
| 384 |
> |
do {} while (!UNSAFE.compareAndSwapInt |
| 385 |
> |
(p, poolRunStateOffset, a = p.runState, a - 1)); |
| 386 |
|
} |
| 387 |
|
cancelTasks(); |
| 388 |
|
setTerminated(); |
| 416 |
|
// helpers for run() |
| 417 |
|
|
| 418 |
|
/** |
| 419 |
< |
* Find and execute tasks and check status while running |
| 419 |
> |
* Finds and executes tasks, and checks status while running. |
| 420 |
|
*/ |
| 421 |
|
private void mainLoop() { |
| 422 |
< |
int misses = 0; // track consecutive times failed to find work; max 2 |
| 422 |
> |
boolean ran = false; // true if ran a task on last step |
| 423 |
|
ForkJoinPool p = pool; |
| 424 |
|
for (;;) { |
| 425 |
< |
p.preStep(this, misses); |
| 425 |
> |
p.preStep(this, ran); |
| 426 |
|
if (runState != 0) |
| 427 |
|
break; |
| 428 |
< |
misses = ((tryExecSteal() || tryExecSubmission()) ? 0 : |
| 435 |
< |
(misses < 2 ? misses + 1 : 2)); |
| 428 |
> |
ran = tryExecSteal() || tryExecSubmission(); |
| 429 |
|
} |
| 430 |
|
} |
| 431 |
|
|
| 432 |
|
/** |
| 433 |
< |
* Try to steal a task and execute it |
| 433 |
> |
* Tries to steal a task and execute it. |
| 434 |
|
* |
| 435 |
|
* @return true if ran a task |
| 436 |
|
*/ |
| 437 |
|
private boolean tryExecSteal() { |
| 438 |
|
ForkJoinTask<?> t; |
| 439 |
< |
if ((t = scan()) != null) { |
| 439 |
> |
if ((t = scan()) != null) { |
| 440 |
|
t.quietlyExec(); |
| 441 |
< |
currentSteal = null; |
| 441 |
> |
UNSAFE.putOrderedObject(this, currentStealOffset, null); |
| 442 |
|
if (sp != base) |
| 443 |
|
execLocalTasks(); |
| 444 |
|
return true; |
| 447 |
|
} |
| 448 |
|
|
| 449 |
|
/** |
| 450 |
< |
* If a submission exists, try to activate and run it; |
| 450 |
> |
* If a submission exists, try to activate and run it. |
| 451 |
|
* |
| 452 |
|
* @return true if ran a task |
| 453 |
|
*/ |
| 454 |
|
private boolean tryExecSubmission() { |
| 455 |
|
ForkJoinPool p = pool; |
| 456 |
+ |
// This loop is needed in case attempt to activate fails, in |
| 457 |
+ |
// which case we only retry if there still appears to be a |
| 458 |
+ |
// submission. |
| 459 |
|
while (p.hasQueuedSubmissions()) { |
| 460 |
|
ForkJoinTask<?> t; int a; |
| 461 |
< |
if (active || // ugly/hacky: inline p.tryIncrementActiveCount |
| 461 |
> |
if (active || // inline p.tryIncrementActiveCount |
| 462 |
|
(active = UNSAFE.compareAndSwapInt(p, poolRunStateOffset, |
| 463 |
|
a = p.runState, a + 1))) { |
| 464 |
|
if ((t = p.pollSubmission()) != null) { |
| 465 |
< |
currentSteal = t; |
| 465 |
> |
UNSAFE.putOrderedObject(this, currentStealOffset, t); |
| 466 |
|
t.quietlyExec(); |
| 467 |
< |
currentSteal = null; |
| 467 |
> |
UNSAFE.putOrderedObject(this, currentStealOffset, null); |
| 468 |
|
if (sp != base) |
| 469 |
|
execLocalTasks(); |
| 470 |
|
return true; |
| 480 |
|
*/ |
| 481 |
|
private void execLocalTasks() { |
| 482 |
|
while (runState == 0) { |
| 483 |
< |
ForkJoinTask<?> t = locallyFifo? locallyDeqTask() : popTask(); |
| 483 |
> |
ForkJoinTask<?> t = locallyFifo ? locallyDeqTask() : popTask(); |
| 484 |
|
if (t != null) |
| 485 |
|
t.quietlyExec(); |
| 486 |
|
else if (sp == base) |
| 490 |
|
|
| 491 |
|
/* |
| 492 |
|
* Intrinsics-based atomic writes for queue slots. These are |
| 493 |
< |
* basically the same as methods in AtomicObjectArray, but |
| 493 |
> |
* basically the same as methods in AtomicReferenceArray, but |
| 494 |
|
* specialized for (1) ForkJoinTask elements (2) requirement that |
| 495 |
|
* nullness and bounds checks have already been performed by |
| 496 |
|
* callers and (3) effective offsets are known not to overflow |
| 497 |
|
* from int to long (because of MAXIMUM_QUEUE_CAPACITY). We don't |
| 498 |
|
* need corresponding version for reads: plain array reads are OK |
| 499 |
< |
* because they protected by other volatile reads and are |
| 499 |
> |
* because they are protected by other volatile reads and are |
| 500 |
|
* confirmed by CASes. |
| 501 |
|
* |
| 502 |
|
* Most uses don't actually call these methods, but instead contain |
| 520 |
|
* range. This method is used only during resets and backouts. |
| 521 |
|
*/ |
| 522 |
|
private static final void writeSlot(ForkJoinTask<?>[] q, int i, |
| 523 |
< |
ForkJoinTask<?> t) { |
| 523 |
> |
ForkJoinTask<?> t) { |
| 524 |
|
UNSAFE.putObjectVolatile(q, (i << qShift) + qBase, t); |
| 525 |
|
} |
| 526 |
|
|
| 565 |
|
|
| 566 |
|
/** |
| 567 |
|
* Tries to take a task from the base of own queue. Assumes active |
| 568 |
< |
* status. Called only by current thread. |
| 568 |
> |
* status. Called only by this thread. |
| 569 |
|
* |
| 570 |
|
* @return a task, or null if none |
| 571 |
|
*/ |
| 588 |
|
|
| 589 |
|
/** |
| 590 |
|
* Returns a popped task, or null if empty. Assumes active status. |
| 591 |
< |
* Called only by current thread. |
| 591 |
> |
* Called only by this thread. |
| 592 |
|
*/ |
| 593 |
|
private ForkJoinTask<?> popTask() { |
| 594 |
|
ForkJoinTask<?>[] q = queue; |
| 612 |
|
|
| 613 |
|
/** |
| 614 |
|
* Specialized version of popTask to pop only if topmost element |
| 615 |
< |
* is the given task. Called only by current thread while |
| 620 |
< |
* active. |
| 615 |
> |
* is the given task. Called only by this thread while active. |
| 616 |
|
* |
| 617 |
|
* @param t the task. Caller must ensure non-null. |
| 618 |
|
*/ |
| 622 |
|
if ((s = sp) != base && q != null && |
| 623 |
|
UNSAFE.compareAndSwapObject |
| 624 |
|
(q, (((q.length - 1) & --s) << qShift) + qBase, t, null)) { |
| 625 |
< |
sp = s; |
| 625 |
> |
sp = s; // putOrderedInt may encourage more timely write |
| 626 |
|
// UNSAFE.putOrderedInt(this, spOffset, s); |
| 627 |
|
return true; |
| 628 |
|
} |
| 630 |
|
} |
| 631 |
|
|
| 632 |
|
/** |
| 633 |
< |
* Returns next task or null if empty or contended |
| 633 |
> |
* Returns next task, or null if empty or contended. |
| 634 |
|
*/ |
| 635 |
|
final ForkJoinTask<?> peekTask() { |
| 636 |
|
ForkJoinTask<?>[] q = queue; |
| 672 |
|
* Computes next value for random victim probe in scan(). Scans |
| 673 |
|
* don't require a very high quality generator, but also not a |
| 674 |
|
* crummy one. Marsaglia xor-shift is cheap and works well enough. |
| 675 |
< |
* Note: This is manually inlined in scan() |
| 675 |
> |
* Note: This is manually inlined in scan(). |
| 676 |
|
*/ |
| 677 |
|
private static final int xorShift(int r) { |
| 678 |
|
r ^= r << 13; |
| 711 |
|
for (;;) { |
| 712 |
|
ForkJoinWorkerThread v = ws[k & mask]; |
| 713 |
|
r ^= r << 13; r ^= r >>> 17; r ^= r << 5; // inline xorshift |
| 714 |
< |
if (v != null && v.base != v.sp) { |
| 715 |
< |
ForkJoinTask<?>[] q; int b, a; |
| 716 |
< |
if ((canSteal || // Ugly/hacky: inline |
| 717 |
< |
(canSteal = active = // p.tryIncrementActiveCount |
| 718 |
< |
UNSAFE.compareAndSwapInt(p, poolRunStateOffset, |
| 719 |
< |
a = p.runState, a + 1))) && |
| 720 |
< |
(q = v.queue) != null && (b = v.base) != v.sp) { |
| 721 |
< |
int i = (q.length - 1) & b; |
| 722 |
< |
long u = (i << qShift) + qBase; // raw offset |
| 723 |
< |
ForkJoinTask<?> t = q[i]; |
| 724 |
< |
if (v.base == b && t != null && |
| 714 |
> |
ForkJoinTask<?>[] q; ForkJoinTask<?> t; int b, a; |
| 715 |
> |
if (v != null && (b = v.base) != v.sp && |
| 716 |
> |
(q = v.queue) != null) { |
| 717 |
> |
int i = (q.length - 1) & b; |
| 718 |
> |
long u = (i << qShift) + qBase; // raw offset |
| 719 |
> |
int pid = poolIndex; |
| 720 |
> |
if ((t = q[i]) != null) { |
| 721 |
> |
if (!canSteal && // inline p.tryIncrementActiveCount |
| 722 |
> |
UNSAFE.compareAndSwapInt(p, poolRunStateOffset, |
| 723 |
> |
a = p.runState, a + 1)) |
| 724 |
> |
canSteal = active = true; |
| 725 |
> |
if (canSteal && v.base == b++ && |
| 726 |
|
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
| 727 |
< |
int pid = poolIndex; |
| 732 |
< |
currentSteal = t; |
| 727 |
> |
v.base = b; |
| 728 |
|
v.stealHint = pid; |
| 729 |
< |
v.base = b + 1; |
| 729 |
> |
UNSAFE.putOrderedObject(this, |
| 730 |
> |
currentStealOffset, t); |
| 731 |
|
seed = r; |
| 732 |
|
++stealCount; |
| 733 |
|
return t; |
| 751 |
|
|
| 752 |
|
// status check methods used mainly by ForkJoinPool |
| 753 |
|
final boolean isRunning() { return runState == 0; } |
| 758 |
– |
final boolean isTerminating() { return (runState & TERMINATING) != 0; } |
| 754 |
|
final boolean isTerminated() { return (runState & TERMINATED) != 0; } |
| 755 |
|
final boolean isSuspended() { return (runState & SUSPENDED) != 0; } |
| 756 |
|
final boolean isTrimmed() { return (runState & TRIMMED) != 0; } |
| 757 |
|
|
| 758 |
+ |
final boolean isTerminating() { |
| 759 |
+ |
if ((runState & TERMINATING) != 0) |
| 760 |
+ |
return true; |
| 761 |
+ |
if (pool.isAtLeastTerminating()) { // propagate pool state |
| 762 |
+ |
shutdown(); |
| 763 |
+ |
return true; |
| 764 |
+ |
} |
| 765 |
+ |
return false; |
| 766 |
+ |
} |
| 767 |
+ |
|
| 768 |
|
/** |
| 769 |
|
* Sets state to TERMINATING. Does NOT unpark or interrupt |
| 770 |
< |
* to wake up if currently blocked. |
| 770 |
> |
* to wake up if currently blocked. Callers must do so if desired. |
| 771 |
|
*/ |
| 772 |
|
final void shutdown() { |
| 773 |
|
for (;;) { |
| 787 |
|
} |
| 788 |
|
|
| 789 |
|
/** |
| 790 |
< |
* Sets state to TERMINATED. Called only by onTermination() |
| 790 |
> |
* Sets state to TERMINATED. Called only by onTermination(). |
| 791 |
|
*/ |
| 792 |
|
private void setTerminated() { |
| 793 |
|
int s; |
| 798 |
|
|
| 799 |
|
/** |
| 800 |
|
* If suspended, tries to set status to unsuspended. |
| 801 |
+ |
* Does NOT wake up if blocked. |
| 802 |
|
* |
| 803 |
|
* @return true if successful |
| 804 |
|
*/ |
| 830 |
|
} |
| 831 |
|
ForkJoinPool p = pool; |
| 832 |
|
p.pushSpare(this); |
| 827 |
– |
lastEventCount = 0; // reset upon resume |
| 833 |
|
while ((runState & SUSPENDED) != 0) { |
| 834 |
|
if (p.tryAccumulateStealCount(this)) { |
| 830 |
– |
boolean untimed = nextSpare != 0; |
| 831 |
– |
long startTime = untimed? 0 : System.nanoTime(); |
| 835 |
|
interrupted(); // clear/ignore interrupts |
| 836 |
|
if ((runState & SUSPENDED) == 0) |
| 837 |
|
break; |
| 838 |
< |
if (untimed) // untimed |
| 836 |
< |
LockSupport.park(this); |
| 837 |
< |
else { |
| 838 |
< |
LockSupport.parkNanos(this, TRIM_RATE_NANOS); |
| 839 |
< |
if ((runState & SUSPENDED) == 0) |
| 840 |
< |
break; |
| 841 |
< |
if (System.nanoTime() - startTime >= TRIM_RATE_NANOS) |
| 842 |
< |
p.tryShutdownSpare(); |
| 843 |
< |
} |
| 838 |
> |
LockSupport.park(this); |
| 839 |
|
} |
| 840 |
|
} |
| 841 |
|
} |
| 908 |
|
if (active || |
| 909 |
|
(active = UNSAFE.compareAndSwapInt(p, poolRunStateOffset, |
| 910 |
|
a = p.runState, a + 1))) |
| 911 |
< |
return locallyFifo? locallyDeqTask() : popTask(); |
| 911 |
> |
return locallyFifo ? locallyDeqTask() : popTask(); |
| 912 |
|
} |
| 913 |
|
return null; |
| 914 |
|
} |
| 922 |
|
ForkJoinTask<?> t = pollLocalTask(); |
| 923 |
|
if (t == null) { |
| 924 |
|
t = scan(); |
| 925 |
< |
currentSteal = null; // cannot retain/track/help |
| 925 |
> |
// cannot retain/track/help steal |
| 926 |
> |
UNSAFE.putOrderedObject(this, currentStealOffset, null); |
| 927 |
|
} |
| 928 |
|
return t; |
| 929 |
|
} |
| 978 |
|
} |
| 979 |
|
|
| 980 |
|
/** |
| 981 |
< |
* Tries to locate and help perform tasks for a stealer of the |
| 982 |
< |
* given task, or in turn one of its stealers. Traces |
| 983 |
< |
* currentSteal->currentJoin links looking for a thread working on |
| 984 |
< |
* a descendant of the given task and with a non-empty queue to |
| 985 |
< |
* steal back and execute tasks from. |
| 981 |
> |
* Unless terminating, tries to locate and help perform tasks for |
| 982 |
> |
* a stealer of the given task, or in turn one of its stealers. |
| 983 |
> |
* Traces currentSteal->currentJoin links looking for a thread |
| 984 |
> |
* working on a descendant of the given task and with a non-empty |
| 985 |
> |
* queue to steal back and execute tasks from. |
| 986 |
|
* |
| 987 |
< |
* The implementation is very branchy to cope with the potential |
| 987 |
> |
* The implementation is very branchy to cope with potential |
| 988 |
|
* inconsistencies or loops encountering chains that are stale, |
| 989 |
|
* unknown, or of length greater than MAX_HELP_DEPTH links. All |
| 990 |
|
* of these cases are dealt with by just returning back to the |
| 994 |
|
* @param joinMe the task to join |
| 995 |
|
*/ |
| 996 |
|
final void helpJoinTask(ForkJoinTask<?> joinMe) { |
| 997 |
< |
ForkJoinWorkerThread[] ws = pool.workers; |
| 998 |
< |
int n; // need at least 2 workers |
| 999 |
< |
if (ws != null && (n = ws.length) > 1 && joinMe.status >= 0) { |
| 1000 |
< |
ForkJoinTask<?> task = joinMe; // base of chain |
| 1001 |
< |
ForkJoinWorkerThread thread = this; // thread with stolen task |
| 1002 |
< |
for (int d = 0; d < MAX_HELP_DEPTH; ++d) { // chain length |
| 1003 |
< |
// Try to find v, the stealer of task, by first using hint |
| 1004 |
< |
ForkJoinWorkerThread v = ws[thread.stealHint & (n - 1)]; |
| 1005 |
< |
if (v == null || v.currentSteal != task) { |
| 1006 |
< |
for (int j = 0; ; ++j) { // search array |
| 1007 |
< |
if (j < n) { |
| 1008 |
< |
if ((v = ws[j]) != null) { |
| 1009 |
< |
if (task.status < 0) |
| 1010 |
< |
return; // stale or done |
| 1011 |
< |
if (v.currentSteal == task) { |
| 1012 |
< |
thread.stealHint = j; |
| 1013 |
< |
break; // save hint for next time |
| 1014 |
< |
} |
| 997 |
> |
ForkJoinWorkerThread[] ws; |
| 998 |
> |
int n; |
| 999 |
> |
if (joinMe.status < 0) // already done |
| 1000 |
> |
return; |
| 1001 |
> |
if ((runState & TERMINATING) != 0) { // cancel if shutting down |
| 1002 |
> |
joinMe.cancelIgnoringExceptions(); |
| 1003 |
> |
return; |
| 1004 |
> |
} |
| 1005 |
> |
if ((ws = pool.workers) == null || (n = ws.length) <= 1) |
| 1006 |
> |
return; // need at least 2 workers |
| 1007 |
> |
|
| 1008 |
> |
ForkJoinTask<?> task = joinMe; // base of chain |
| 1009 |
> |
ForkJoinWorkerThread thread = this; // thread with stolen task |
| 1010 |
> |
for (int d = 0; d < MAX_HELP_DEPTH; ++d) { // chain length |
| 1011 |
> |
// Try to find v, the stealer of task, by first using hint |
| 1012 |
> |
ForkJoinWorkerThread v = ws[thread.stealHint & (n - 1)]; |
| 1013 |
> |
if (v == null || v.currentSteal != task) { |
| 1014 |
> |
for (int j = 0; ; ++j) { // search array |
| 1015 |
> |
if (j < n) { |
| 1016 |
> |
ForkJoinTask<?> vs; |
| 1017 |
> |
if ((v = ws[j]) != null && |
| 1018 |
> |
(vs = v.currentSteal) != null) { |
| 1019 |
> |
if (joinMe.status < 0 || task.status < 0) |
| 1020 |
> |
return; // stale or done |
| 1021 |
> |
if (vs == task) { |
| 1022 |
> |
thread.stealHint = j; |
| 1023 |
> |
break; // save hint for next time |
| 1024 |
|
} |
| 1025 |
|
} |
| 1021 |
– |
else |
| 1022 |
– |
return; // no stealer |
| 1026 |
|
} |
| 1027 |
+ |
else |
| 1028 |
+ |
return; // no stealer |
| 1029 |
|
} |
| 1030 |
< |
// Try to help v, using specialized form of deqTask |
| 1031 |
< |
int b; |
| 1032 |
< |
ForkJoinTask<?>[] q; |
| 1033 |
< |
while ((b = v.base) != v.sp && (q = v.queue) != null) { |
| 1034 |
< |
int i = (q.length - 1) & b; |
| 1035 |
< |
long u = (i << qShift) + qBase; |
| 1036 |
< |
ForkJoinTask<?> t = q[i]; |
| 1037 |
< |
if (task.status < 0) |
| 1038 |
< |
return; // stale or done |
| 1039 |
< |
if (v.base == b) { |
| 1040 |
< |
if (t == null) |
| 1041 |
< |
return; // producer stalled |
| 1042 |
< |
if (UNSAFE.compareAndSwapObject(q, u, t, null)) { |
| 1043 |
< |
if (joinMe.status < 0) { |
| 1044 |
< |
UNSAFE.putObjectVolatile(q, u, t); |
| 1045 |
< |
return; // back out on cancel |
| 1046 |
< |
} |
| 1047 |
< |
int pid = poolIndex; |
| 1048 |
< |
ForkJoinTask<?> prevSteal = currentSteal; |
| 1049 |
< |
currentSteal = t; |
| 1045 |
< |
v.stealHint = pid; |
| 1046 |
< |
v.base = b + 1; |
| 1047 |
< |
t.quietlyExec(); |
| 1048 |
< |
currentSteal = prevSteal; |
| 1049 |
< |
} |
| 1030 |
> |
} |
| 1031 |
> |
for (;;) { // Try to help v, using specialized form of deqTask |
| 1032 |
> |
if (joinMe.status < 0) |
| 1033 |
> |
return; |
| 1034 |
> |
int b = v.base; |
| 1035 |
> |
ForkJoinTask<?>[] q = v.queue; |
| 1036 |
> |
if (b == v.sp || q == null) |
| 1037 |
> |
break; |
| 1038 |
> |
int i = (q.length - 1) & b; |
| 1039 |
> |
long u = (i << qShift) + qBase; |
| 1040 |
> |
ForkJoinTask<?> t = q[i]; |
| 1041 |
> |
int pid = poolIndex; |
| 1042 |
> |
ForkJoinTask<?> ps = currentSteal; |
| 1043 |
> |
if (task.status < 0) |
| 1044 |
> |
return; // stale or done |
| 1045 |
> |
if (t != null && v.base == b++ && |
| 1046 |
> |
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
| 1047 |
> |
if (joinMe.status < 0) { |
| 1048 |
> |
UNSAFE.putObjectVolatile(q, u, t); |
| 1049 |
> |
return; // back out on cancel |
| 1050 |
|
} |
| 1051 |
< |
if (joinMe.status < 0) |
| 1052 |
< |
return; |
| 1051 |
> |
v.base = b; |
| 1052 |
> |
v.stealHint = pid; |
| 1053 |
> |
UNSAFE.putOrderedObject(this, currentStealOffset, t); |
| 1054 |
> |
t.quietlyExec(); |
| 1055 |
> |
UNSAFE.putOrderedObject(this, currentStealOffset, ps); |
| 1056 |
|
} |
| 1054 |
– |
// Try to descend to find v's stealer |
| 1055 |
– |
ForkJoinTask<?> next = v.currentJoin; |
| 1056 |
– |
if (task.status < 0 || next == null || next == task || |
| 1057 |
– |
joinMe.status < 0) |
| 1058 |
– |
return; |
| 1059 |
– |
task = next; |
| 1060 |
– |
thread = v; |
| 1057 |
|
} |
| 1058 |
+ |
// Try to descend to find v's stealer |
| 1059 |
+ |
ForkJoinTask<?> next = v.currentJoin; |
| 1060 |
+ |
if (task.status < 0 || next == null || next == task || |
| 1061 |
+ |
joinMe.status < 0) |
| 1062 |
+ |
return; |
| 1063 |
+ |
task = next; |
| 1064 |
+ |
thread = v; |
| 1065 |
|
} |
| 1066 |
|
} |
| 1067 |
|
|
| 1068 |
|
/** |
| 1069 |
+ |
* Implements ForkJoinTask.getSurplusQueuedTaskCount(). |
| 1070 |
|
* Returns an estimate of the number of tasks, offset by a |
| 1071 |
|
* function of number of idle workers. |
| 1072 |
|
* |
| 1121 |
|
* Runs tasks until {@code pool.isQuiescent()}. |
| 1122 |
|
*/ |
| 1123 |
|
final void helpQuiescePool() { |
| 1124 |
+ |
ForkJoinTask<?> ps = currentSteal; // to restore below |
| 1125 |
|
for (;;) { |
| 1126 |
|
ForkJoinTask<?> t = pollLocalTask(); |
| 1127 |
< |
if (t != null || (t = scan()) != null) { |
| 1127 |
> |
if (t != null || (t = scan()) != null) |
| 1128 |
|
t.quietlyExec(); |
| 1124 |
– |
currentSteal = null; |
| 1125 |
– |
} |
| 1129 |
|
else { |
| 1130 |
|
ForkJoinPool p = pool; |
| 1131 |
|
int a; // to inline CASes |
| 1134 |
|
(p, poolRunStateOffset, a = p.runState, a - 1)) |
| 1135 |
|
continue; // retry later |
| 1136 |
|
active = false; // inactivate |
| 1137 |
+ |
UNSAFE.putOrderedObject(this, currentStealOffset, ps); |
| 1138 |
|
} |
| 1139 |
|
if (p.isQuiescent()) { |
| 1140 |
|
active = true; // re-activate |
| 1141 |
< |
do {} while(!UNSAFE.compareAndSwapInt |
| 1142 |
< |
(p, poolRunStateOffset, a = p.runState, a+1)); |
| 1141 |
> |
do {} while (!UNSAFE.compareAndSwapInt |
| 1142 |
> |
(p, poolRunStateOffset, a = p.runState, a+1)); |
| 1143 |
|
return; |
| 1144 |
|
} |
| 1145 |
|
} |
| 1169 |
|
if ((s & (s-1)) != 0) |
| 1170 |
|
throw new Error("data type scale not a power of two"); |
| 1171 |
|
qShift = 31 - Integer.numberOfLeadingZeros(s); |
| 1172 |
+ |
MAXIMUM_QUEUE_CAPACITY = 1 << (31 - qShift); |
| 1173 |
|
} |
| 1174 |
|
|
| 1175 |
|
private static long objectFieldOffset(String field, Class<?> klazz) { |
