| 524 |
|
ws = workers; |
| 525 |
|
if (ws == null) { |
| 526 |
|
int ps = parallelism; |
| 527 |
+ |
updateWorkerCount(ps); |
| 528 |
|
ws = ensureWorkerArrayCapacity(ps); |
| 529 |
|
for (int i = 0; i < ps; ++i) { |
| 530 |
|
ForkJoinWorkerThread w = createWorker(i); |
| 531 |
|
if (w != null) { |
| 532 |
|
ws[i] = w; |
| 533 |
|
w.start(); |
| 533 |
– |
updateWorkerCount(1); |
| 534 |
|
} |
| 535 |
+ |
else |
| 536 |
+ |
updateWorkerCount(-1); |
| 537 |
|
} |
| 538 |
|
} |
| 539 |
|
} finally { |
| 799 |
|
if (isProcessingTasks()) { |
| 800 |
|
int p = this.parallelism; |
| 801 |
|
this.parallelism = parallelism; |
| 802 |
< |
if (parallelism > p) |
| 803 |
< |
createAndStartAddedWorkers(); |
| 804 |
< |
else |
| 805 |
< |
trimSpares(); |
| 802 |
> |
if (workers != null) { |
| 803 |
> |
if (parallelism > p) |
| 804 |
> |
createAndStartAddedWorkers(); |
| 805 |
> |
else |
| 806 |
> |
trimSpares(); |
| 807 |
> |
} |
| 808 |
|
} |
| 809 |
|
} finally { |
| 810 |
|
lock.unlock(); |
| 1378 |
|
} |
| 1379 |
|
} |
| 1380 |
|
|
| 1377 |
– |
|
| 1381 |
|
/* |
| 1382 |
|
* Nodes for event barrier to manage idle threads. Queue nodes |
| 1383 |
|
* are basic Treiber stack nodes, also used for spare stack. |
| 1401 |
|
* handling: Method signalWork returns without advancing count if |
| 1402 |
|
* the queue appears to be empty. This would ordinarily result in |
| 1403 |
|
* races causing some queued waiters not to be woken up. To avoid |
| 1404 |
< |
* this, the first worker enqueued in method sync (see |
| 1405 |
< |
* syncIsReleasable) rescans for tasks after being enqueued, and |
| 1406 |
< |
* helps signal if any are found. This works well because the |
| 1407 |
< |
* worker has nothing better to do, and so might as well help |
| 1408 |
< |
* alleviate the overhead and contention on the threads actually |
| 1409 |
< |
* doing work. Also, since event counts increments on task |
| 1410 |
< |
* availability exist to maintain liveness (rather than to force |
| 1411 |
< |
* refreshes etc), it is OK for callers to exit early if |
| 1409 |
< |
* contending with another signaller. |
| 1404 |
> |
* this, the first worker enqueued in method sync rescans for |
| 1405 |
> |
* tasks after being enqueued, and helps signal if any are |
| 1406 |
> |
* found. This works well because the worker has nothing better to |
| 1407 |
> |
* do, and so might as well help alleviate the overhead and |
| 1408 |
> |
* contention on the threads actually doing work. Also, since |
| 1409 |
> |
* event counts increments on task availability exist to maintain |
| 1410 |
> |
* liveness (rather than to force refreshes etc), it is OK for |
| 1411 |
> |
* callers to exit early if contending with another signaller. |
| 1412 |
|
*/ |
| 1413 |
|
static final class WaitQueueNode { |
| 1414 |
|
WaitQueueNode next; // only written before enqueued |
| 1421 |
|
} |
| 1422 |
|
|
| 1423 |
|
/** |
| 1424 |
< |
* Wakes up waiter, returning false if known to already |
| 1424 |
> |
* Wakes up waiter, also clearing thread field |
| 1425 |
|
*/ |
| 1426 |
< |
boolean signal() { |
| 1426 |
> |
void signal() { |
| 1427 |
|
ForkJoinWorkerThread t = thread; |
| 1428 |
< |
if (t == null) |
| 1429 |
< |
return false; |
| 1430 |
< |
thread = null; |
| 1429 |
< |
LockSupport.unpark(t); |
| 1430 |
< |
return true; |
| 1431 |
< |
} |
| 1432 |
< |
|
| 1433 |
< |
/** |
| 1434 |
< |
* Awaits release on sync. |
| 1435 |
< |
*/ |
| 1436 |
< |
void awaitSyncRelease(ForkJoinPool p) { |
| 1437 |
< |
while (thread != null && !p.syncIsReleasable(this)) |
| 1438 |
< |
LockSupport.park(this); |
| 1439 |
< |
} |
| 1440 |
< |
|
| 1441 |
< |
/** |
| 1442 |
< |
* Awaits resumption as spare. |
| 1443 |
< |
*/ |
| 1444 |
< |
void awaitSpareRelease() { |
| 1445 |
< |
while (thread != null) { |
| 1446 |
< |
if (!Thread.interrupted()) |
| 1447 |
< |
LockSupport.park(this); |
| 1428 |
> |
if (t != null) { |
| 1429 |
> |
thread = null; |
| 1430 |
> |
LockSupport.unpark(t); |
| 1431 |
|
} |
| 1432 |
|
} |
| 1433 |
|
} |
| 1436 |
|
* Ensures that no thread is waiting for count to advance from the |
| 1437 |
|
* current value of eventCount read on entry to this method, by |
| 1438 |
|
* releasing waiting threads if necessary. |
| 1456 |
– |
* |
| 1457 |
– |
* @return the count |
| 1439 |
|
*/ |
| 1440 |
< |
final long ensureSync() { |
| 1440 |
> |
final void ensureSync() { |
| 1441 |
|
long c = eventCount; |
| 1442 |
|
WaitQueueNode q; |
| 1443 |
|
while ((q = syncStack) != null && q.count < c) { |
| 1448 |
|
break; |
| 1449 |
|
} |
| 1450 |
|
} |
| 1470 |
– |
return c; |
| 1451 |
|
} |
| 1452 |
|
|
| 1453 |
|
/** |
| 1462 |
|
/** |
| 1463 |
|
* Signals threads waiting to poll a task. Because method sync |
| 1464 |
|
* rechecks availability, it is OK to only proceed if queue |
| 1465 |
< |
* appears to be non-empty, and OK to skip under contention to |
| 1466 |
< |
* increment count (since some other thread succeeded). |
| 1465 |
> |
* appears to be non-empty, and OK if CAS to increment count |
| 1466 |
> |
* fails (since some other thread succeeded). |
| 1467 |
|
*/ |
| 1468 |
|
final void signalWork() { |
| 1469 |
< |
long c; |
| 1470 |
< |
WaitQueueNode q; |
| 1471 |
< |
if (syncStack != null && |
| 1472 |
< |
casEventCount(c = eventCount, c+1) && |
| 1473 |
< |
(((q = syncStack) != null && q.count <= c) && |
| 1474 |
< |
(!casBarrierStack(q, q.next) || !q.signal()))) |
| 1475 |
< |
ensureSync(); |
| 1469 |
> |
if (syncStack != null) { |
| 1470 |
> |
long c = eventCount; |
| 1471 |
> |
casEventCount(c, c+1); |
| 1472 |
> |
WaitQueueNode q = syncStack; |
| 1473 |
> |
if (q != null && q.count <= c) { |
| 1474 |
> |
if (casBarrierStack(q, q.next)) |
| 1475 |
> |
q.signal(); |
| 1476 |
> |
else |
| 1477 |
> |
ensureSync(); // awaken all on contention |
| 1478 |
> |
} |
| 1479 |
> |
} |
| 1480 |
|
} |
| 1481 |
|
|
| 1482 |
|
/** |
| 1483 |
< |
* Waits until event count advances from last value held by |
| 1484 |
< |
* caller, or if excess threads, caller is resumed as spare, or |
| 1483 |
> |
* Possibly blocks until event count advances from last value held |
| 1484 |
> |
* by caller, or if excess threads, caller is resumed as spare, or |
| 1485 |
|
* caller or pool is terminating. Updates caller's event on exit. |
| 1486 |
|
* |
| 1487 |
|
* @param w the calling worker thread |
| 1489 |
|
final void sync(ForkJoinWorkerThread w) { |
| 1490 |
|
updateStealCount(w); // Transfer w's count while it is idle |
| 1491 |
|
|
| 1492 |
< |
while (!w.isShutdown() && isProcessingTasks() && !suspendIfSpare(w)) { |
| 1492 |
> |
if (!w.isShutdown() && isProcessingTasks() && !suspendIfSpare(w)) { |
| 1493 |
|
long prev = w.lastEventCount; |
| 1494 |
|
WaitQueueNode node = null; |
| 1495 |
|
WaitQueueNode h; |
| 1496 |
< |
while (eventCount == prev && |
| 1496 |
> |
long c; |
| 1497 |
> |
while ((c = eventCount) == prev && |
| 1498 |
|
((h = syncStack) == null || h.count == prev)) { |
| 1499 |
|
if (node == null) |
| 1500 |
|
node = new WaitQueueNode(prev, w); |
| 1501 |
|
if (casBarrierStack(node.next = h, node)) { |
| 1502 |
< |
node.awaitSyncRelease(this); |
| 1502 |
> |
if (!Thread.interrupted() && |
| 1503 |
> |
node.thread != null && |
| 1504 |
> |
eventCount == prev && |
| 1505 |
> |
(h != null || // cover signalWork race |
| 1506 |
> |
(!ForkJoinWorkerThread.hasQueuedTasks(workers) && |
| 1507 |
> |
eventCount == prev))) |
| 1508 |
> |
LockSupport.park(this); |
| 1509 |
> |
c = eventCount; |
| 1510 |
> |
if (node.thread != null) { // help signal if not unparked |
| 1511 |
> |
node.thread = null; |
| 1512 |
> |
if (c == prev) |
| 1513 |
> |
casEventCount(prev, prev + 1); |
| 1514 |
> |
} |
| 1515 |
|
break; |
| 1516 |
|
} |
| 1517 |
|
} |
| 1518 |
< |
long ec = ensureSync(); |
| 1519 |
< |
if (ec != prev) { |
| 1523 |
< |
w.lastEventCount = ec; |
| 1524 |
< |
break; |
| 1525 |
< |
} |
| 1526 |
< |
} |
| 1527 |
< |
} |
| 1528 |
< |
|
| 1529 |
< |
/** |
| 1530 |
< |
* Returns {@code true} if worker waiting on sync can proceed: |
| 1531 |
< |
* - on signal (thread == null) |
| 1532 |
< |
* - on event count advance (winning race to notify vs signaller) |
| 1533 |
< |
* - on interrupt |
| 1534 |
< |
* - if the first queued node, we find work available |
| 1535 |
< |
* If node was not signalled and event count not advanced on exit, |
| 1536 |
< |
* then we also help advance event count. |
| 1537 |
< |
* |
| 1538 |
< |
* @return {@code true} if node can be released |
| 1539 |
< |
*/ |
| 1540 |
< |
final boolean syncIsReleasable(WaitQueueNode node) { |
| 1541 |
< |
long prev = node.count; |
| 1542 |
< |
if (!Thread.interrupted() && node.thread != null && |
| 1543 |
< |
(node.next != null || |
| 1544 |
< |
!ForkJoinWorkerThread.hasQueuedTasks(workers)) && |
| 1545 |
< |
eventCount == prev) |
| 1546 |
< |
return false; |
| 1547 |
< |
if (node.thread != null) { |
| 1548 |
< |
node.thread = null; |
| 1549 |
< |
long ec = eventCount; |
| 1550 |
< |
if (prev <= ec) // help signal |
| 1551 |
< |
casEventCount(ec, ec+1); |
| 1518 |
> |
w.lastEventCount = c; |
| 1519 |
> |
ensureSync(); |
| 1520 |
|
} |
| 1553 |
– |
return true; |
| 1521 |
|
} |
| 1522 |
|
|
| 1523 |
|
/** |
| 1525 |
|
* call to sync or this method, if so, updating caller's count. |
| 1526 |
|
*/ |
| 1527 |
|
final boolean hasNewSyncEvent(ForkJoinWorkerThread w) { |
| 1528 |
< |
long lc = w.lastEventCount; |
| 1529 |
< |
long ec = ensureSync(); |
| 1530 |
< |
if (ec == lc) |
| 1531 |
< |
return false; |
| 1532 |
< |
w.lastEventCount = ec; |
| 1533 |
< |
return true; |
| 1528 |
> |
long wc = w.lastEventCount; |
| 1529 |
> |
long c = eventCount; |
| 1530 |
> |
if (wc != c) |
| 1531 |
> |
w.lastEventCount = c; |
| 1532 |
> |
ensureSync(); |
| 1533 |
> |
return wc != c || wc != eventCount; |
| 1534 |
|
} |
| 1535 |
|
|
| 1536 |
|
// Parallelism maintenance |
| 1696 |
|
*/ |
| 1697 |
|
private boolean suspendIfSpare(ForkJoinWorkerThread w) { |
| 1698 |
|
WaitQueueNode node = null; |
| 1699 |
< |
int s; |
| 1700 |
< |
while (parallelism < runningCountOf(s = workerCounts)) { |
| 1699 |
> |
for (;;) { |
| 1700 |
> |
int s = workerCounts; |
| 1701 |
> |
int rc = runningCountOf(s); |
| 1702 |
> |
int tc = totalCountOf(s); |
| 1703 |
> |
int ps = parallelism; |
| 1704 |
> |
// use tc as bound if rc transiently out of sync |
| 1705 |
> |
if (tc <= ps || rc <= ps) |
| 1706 |
> |
return false; // not a spare |
| 1707 |
|
if (node == null) |
| 1708 |
|
node = new WaitQueueNode(0, w); |
| 1709 |
< |
if (casWorkerCounts(s, s-1)) { // representation-dependent |
| 1710 |
< |
// push onto stack |
| 1738 |
< |
do {} while (!casSpareStack(node.next = spareStack, node)); |
| 1739 |
< |
// block until released by resumeSpare |
| 1740 |
< |
node.awaitSpareRelease(); |
| 1741 |
< |
return true; |
| 1742 |
< |
} |
| 1709 |
> |
if (casWorkerCounts(s, workerCountsFor(tc, rc - 1))) |
| 1710 |
> |
break; |
| 1711 |
|
} |
| 1712 |
< |
return false; |
| 1712 |
> |
// push onto stack |
| 1713 |
> |
do {} while (!casSpareStack(node.next = spareStack, node)); |
| 1714 |
> |
// block until released by resumeSpare |
| 1715 |
> |
while (!Thread.interrupted() && node.thread != null) |
| 1716 |
> |
LockSupport.park(this); |
| 1717 |
> |
return true; |
| 1718 |
|
} |
| 1719 |
|
|
| 1720 |
|
/** |
