1 /*
2 * Copyright (c) 2002, 2007, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "incls/_precompiled.incl"
26 #include "incls/_gcTaskManager.cpp.incl"
27
28 //
29 // GCTask
30 //
31
32 const char* GCTask::Kind::to_string(kind value) {
33 const char* result = "unknown GCTask kind";
34 switch (value) {
35 default:
36 result = "unknown GCTask kind";
37 break;
38 case unknown_task:
39 result = "unknown task";
40 break;
41 case ordinary_task:
42 result = "ordinary task";
43 break;
44 case barrier_task:
45 result = "barrier task";
46 break;
47 case noop_task:
48 result = "noop task";
49 break;
50 }
51 return result;
52 };
53
54 GCTask::GCTask() :
55 _kind(Kind::ordinary_task),
56 _affinity(GCTaskManager::sentinel_worker()){
57 initialize();
58 }
59
60 GCTask::GCTask(Kind::kind kind) :
61 _kind(kind),
62 _affinity(GCTaskManager::sentinel_worker()) {
63 initialize();
64 }
65
66 GCTask::GCTask(uint affinity) :
67 _kind(Kind::ordinary_task),
68 _affinity(affinity) {
69 initialize();
70 }
71
72 GCTask::GCTask(Kind::kind kind, uint affinity) :
73 _kind(kind),
74 _affinity(affinity) {
75 initialize();
76 }
77
78 void GCTask::initialize() {
79 _older = NULL;
80 _newer = NULL;
81 }
82
83 void GCTask::destruct() {
84 assert(older() == NULL, "shouldn't have an older task");
85 assert(newer() == NULL, "shouldn't have a newer task");
86 // Nothing to do.
87 }
88
89 NOT_PRODUCT(
90 void GCTask::print(const char* message) const {
91 tty->print(INTPTR_FORMAT " <- " INTPTR_FORMAT "(%u) -> " INTPTR_FORMAT,
92 newer(), this, affinity(), older());
93 }
94 )
95
96 //
97 // GCTaskQueue
98 //
99
100 GCTaskQueue* GCTaskQueue::create() {
101 GCTaskQueue* result = new GCTaskQueue(false);
102 if (TraceGCTaskQueue) {
103 tty->print_cr("GCTaskQueue::create()"
104 " returns " INTPTR_FORMAT, result);
105 }
106 return result;
107 }
108
109 GCTaskQueue* GCTaskQueue::create_on_c_heap() {
110 GCTaskQueue* result = new(ResourceObj::C_HEAP) GCTaskQueue(true);
111 if (TraceGCTaskQueue) {
112 tty->print_cr("GCTaskQueue::create_on_c_heap()"
113 " returns " INTPTR_FORMAT,
114 result);
115 }
116 return result;
117 }
118
119 GCTaskQueue::GCTaskQueue(bool on_c_heap) :
120 _is_c_heap_obj(on_c_heap) {
121 initialize();
122 if (TraceGCTaskQueue) {
123 tty->print_cr("[" INTPTR_FORMAT "]"
124 " GCTaskQueue::GCTaskQueue() constructor",
125 this);
126 }
127 }
128
129 void GCTaskQueue::destruct() {
130 // Nothing to do.
131 }
132
133 void GCTaskQueue::destroy(GCTaskQueue* that) {
134 if (TraceGCTaskQueue) {
135 tty->print_cr("[" INTPTR_FORMAT "]"
136 " GCTaskQueue::destroy()"
137 " is_c_heap_obj: %s",
138 that,
139 that->is_c_heap_obj() ? "true" : "false");
140 }
141 // That instance may have been allocated as a CHeapObj,
142 // in which case we have to free it explicitly.
143 if (that != NULL) {
144 that->destruct();
145 assert(that->is_empty(), "should be empty");
146 if (that->is_c_heap_obj()) {
147 FreeHeap(that);
148 }
149 }
150 }
151
152 void GCTaskQueue::initialize() {
153 set_insert_end(NULL);
154 set_remove_end(NULL);
155 set_length(0);
156 }
157
158 // Enqueue one task.
159 void GCTaskQueue::enqueue(GCTask* task) {
160 if (TraceGCTaskQueue) {
161 tty->print_cr("[" INTPTR_FORMAT "]"
162 " GCTaskQueue::enqueue(task: "
163 INTPTR_FORMAT ")",
164 this, task);
165 print("before:");
166 }
167 assert(task != NULL, "shouldn't have null task");
168 assert(task->older() == NULL, "shouldn't be on queue");
169 assert(task->newer() == NULL, "shouldn't be on queue");
170 task->set_newer(NULL);
171 task->set_older(insert_end());
172 if (is_empty()) {
173 set_remove_end(task);
174 } else {
175 insert_end()->set_newer(task);
176 }
177 set_insert_end(task);
178 increment_length();
179 if (TraceGCTaskQueue) {
180 print("after:");
181 }
182 }
183
184 // Enqueue a whole list of tasks. Empties the argument list.
185 void GCTaskQueue::enqueue(GCTaskQueue* list) {
186 if (TraceGCTaskQueue) {
187 tty->print_cr("[" INTPTR_FORMAT "]"
188 " GCTaskQueue::enqueue(list: "
189 INTPTR_FORMAT ")",
190 this);
191 print("before:");
192 list->print("list:");
193 }
194 if (list->is_empty()) {
195 // Enqueuing the empty list: nothing to do.
196 return;
197 }
198 uint list_length = list->length();
199 if (is_empty()) {
200 // Enqueuing to empty list: just acquire elements.
201 set_insert_end(list->insert_end());
202 set_remove_end(list->remove_end());
203 set_length(list_length);
204 } else {
205 // Prepend argument list to our queue.
206 list->remove_end()->set_older(insert_end());
207 insert_end()->set_newer(list->remove_end());
208 set_insert_end(list->insert_end());
209 // empty the argument list.
210 }
211 set_length(length() + list_length);
212 list->initialize();
213 if (TraceGCTaskQueue) {
214 print("after:");
215 list->print("list:");
216 }
217 }
218
219 // Dequeue one task.
220 GCTask* GCTaskQueue::dequeue() {
221 if (TraceGCTaskQueue) {
222 tty->print_cr("[" INTPTR_FORMAT "]"
223 " GCTaskQueue::dequeue()", this);
224 print("before:");
225 }
226 assert(!is_empty(), "shouldn't dequeue from empty list");
227 GCTask* result = remove();
228 assert(result != NULL, "shouldn't have NULL task");
229 if (TraceGCTaskQueue) {
230 tty->print_cr(" return: " INTPTR_FORMAT, result);
231 print("after:");
232 }
233 return result;
234 }
235
236 // Dequeue one task, preferring one with affinity.
237 GCTask* GCTaskQueue::dequeue(uint affinity) {
238 if (TraceGCTaskQueue) {
239 tty->print_cr("[" INTPTR_FORMAT "]"
240 " GCTaskQueue::dequeue(%u)", this, affinity);
241 print("before:");
242 }
243 assert(!is_empty(), "shouldn't dequeue from empty list");
244 // Look down to the next barrier for a task with this affinity.
245 GCTask* result = NULL;
246 for (GCTask* element = remove_end();
247 element != NULL;
248 element = element->newer()) {
249 if (element->is_barrier_task()) {
250 // Don't consider barrier tasks, nor past them.
251 result = NULL;
252 break;
253 }
254 if (element->affinity() == affinity) {
255 result = remove(element);
256 break;
257 }
258 }
259 // If we didn't find anything with affinity, just take the next task.
260 if (result == NULL) {
261 result = remove();
262 }
263 if (TraceGCTaskQueue) {
264 tty->print_cr(" return: " INTPTR_FORMAT, result);
265 print("after:");
266 }
267 return result;
268 }
269
270 GCTask* GCTaskQueue::remove() {
271 // Dequeue from remove end.
272 GCTask* result = remove_end();
273 assert(result != NULL, "shouldn't have null task");
274 assert(result->older() == NULL, "not the remove_end");
275 set_remove_end(result->newer());
276 if (remove_end() == NULL) {
277 assert(insert_end() == result, "not a singleton");
278 set_insert_end(NULL);
279 } else {
280 remove_end()->set_older(NULL);
281 }
282 result->set_newer(NULL);
283 decrement_length();
284 assert(result->newer() == NULL, "shouldn't be on queue");
285 assert(result->older() == NULL, "shouldn't be on queue");
286 return result;
287 }
288
289 GCTask* GCTaskQueue::remove(GCTask* task) {
290 // This is slightly more work, and has slightly fewer asserts
291 // than removing from the remove end.
292 assert(task != NULL, "shouldn't have null task");
293 GCTask* result = task;
294 if (result->newer() != NULL) {
295 result->newer()->set_older(result->older());
296 } else {
297 assert(insert_end() == result, "not youngest");
298 set_insert_end(result->older());
299 }
300 if (result->older() != NULL) {
301 result->older()->set_newer(result->newer());
302 } else {
303 assert(remove_end() == result, "not oldest");
304 set_remove_end(result->newer());
305 }
306 result->set_newer(NULL);
307 result->set_older(NULL);
308 decrement_length();
309 return result;
310 }
311
312 NOT_PRODUCT(
313 void GCTaskQueue::print(const char* message) const {
314 tty->print_cr("[" INTPTR_FORMAT "] GCTaskQueue:"
315 " insert_end: " INTPTR_FORMAT
316 " remove_end: " INTPTR_FORMAT
317 " %s",
318 this, insert_end(), remove_end(), message);
319 for (GCTask* element = insert_end();
320 element != NULL;
321 element = element->older()) {
322 element->print(" ");
323 tty->cr();
324 }
325 }
326 )
327
328 //
329 // SynchronizedGCTaskQueue
330 //
331
332 SynchronizedGCTaskQueue::SynchronizedGCTaskQueue(GCTaskQueue* queue_arg,
333 Monitor * lock_arg) :
334 _unsynchronized_queue(queue_arg),
335 _lock(lock_arg) {
336 assert(unsynchronized_queue() != NULL, "null queue");
337 assert(lock() != NULL, "null lock");
338 }
339
340 SynchronizedGCTaskQueue::~SynchronizedGCTaskQueue() {
341 // Nothing to do.
342 }
343
344 //
345 // GCTaskManager
346 //
347 GCTaskManager::GCTaskManager(uint workers) :
348 _workers(workers),
349 _ndc(NULL) {
350 initialize();
351 }
352
353 GCTaskManager::GCTaskManager(uint workers, NotifyDoneClosure* ndc) :
354 _workers(workers),
355 _ndc(ndc) {
356 initialize();
357 }
358
359 void GCTaskManager::initialize() {
360 if (TraceGCTaskManager) {
361 tty->print_cr("GCTaskManager::initialize: workers: %u", workers());
362 }
363 assert(workers() != 0, "no workers");
364 _monitor = new Monitor(Mutex::barrier, // rank
365 "GCTaskManager monitor", // name
366 Mutex::_allow_vm_block_flag); // allow_vm_block
367 // The queue for the GCTaskManager must be a CHeapObj.
368 GCTaskQueue* unsynchronized_queue = GCTaskQueue::create_on_c_heap();
369 _queue = SynchronizedGCTaskQueue::create(unsynchronized_queue, lock());
370 _noop_task = NoopGCTask::create_on_c_heap();
371 _resource_flag = NEW_C_HEAP_ARRAY(bool, workers());
372 {
373 // Set up worker threads.
374 // Distribute the workers among the available processors,
375 // unless we were told not to, or if the os doesn't want to.
376 uint* processor_assignment = NEW_C_HEAP_ARRAY(uint, workers());
377 if (!BindGCTaskThreadsToCPUs ||
378 !os::distribute_processes(workers(), processor_assignment)) {
379 for (uint a = 0; a < workers(); a += 1) {
380 processor_assignment[a] = sentinel_worker();
381 }
382 }
383 _thread = NEW_C_HEAP_ARRAY(GCTaskThread*, workers());
384 for (uint t = 0; t < workers(); t += 1) {
385 set_thread(t, GCTaskThread::create(this, t, processor_assignment[t]));
386 }
387 if (TraceGCTaskThread) {
388 tty->print("GCTaskManager::initialize: distribution:");
389 for (uint t = 0; t < workers(); t += 1) {
390 tty->print(" %u", processor_assignment[t]);
391 }
392 tty->cr();
393 }
394 FREE_C_HEAP_ARRAY(uint, processor_assignment);
395 }
396 reset_busy_workers();
397 set_unblocked();
398 for (uint w = 0; w < workers(); w += 1) {
399 set_resource_flag(w, false);
400 }
401 reset_delivered_tasks();
402 reset_completed_tasks();
403 reset_noop_tasks();
404 reset_barriers();
405 reset_emptied_queue();
406 for (uint s = 0; s < workers(); s += 1) {
407 thread(s)->start();
408 }
409 }
410
411 GCTaskManager::~GCTaskManager() {
412 assert(busy_workers() == 0, "still have busy workers");
413 assert(queue()->is_empty(), "still have queued work");
414 NoopGCTask::destroy(_noop_task);
415 _noop_task = NULL;
416 if (_thread != NULL) {
417 for (uint i = 0; i < workers(); i += 1) {
418 GCTaskThread::destroy(thread(i));
419 set_thread(i, NULL);
420 }
421 FREE_C_HEAP_ARRAY(GCTaskThread*, _thread);
422 _thread = NULL;
423 }
424 if (_resource_flag != NULL) {
425 FREE_C_HEAP_ARRAY(bool, _resource_flag);
426 _resource_flag = NULL;
427 }
428 if (queue() != NULL) {
429 GCTaskQueue* unsynchronized_queue = queue()->unsynchronized_queue();
430 GCTaskQueue::destroy(unsynchronized_queue);
431 SynchronizedGCTaskQueue::destroy(queue());
432 _queue = NULL;
433 }
434 if (monitor() != NULL) {
435 delete monitor();
436 _monitor = NULL;
437 }
438 }
439
440 void GCTaskManager::print_task_time_stamps() {
441 for(uint i=0; i<ParallelGCThreads; i++) {
442 GCTaskThread* t = thread(i);
443 t->print_task_time_stamps();
444 }
445 }
446
447 void GCTaskManager::print_threads_on(outputStream* st) {
448 uint num_thr = workers();
449 for (uint i = 0; i < num_thr; i++) {
450 thread(i)->print_on(st);
451 st->cr();
452 }
453 }
454
455 void GCTaskManager::threads_do(ThreadClosure* tc) {
456 assert(tc != NULL, "Null ThreadClosure");
457 uint num_thr = workers();
458 for (uint i = 0; i < num_thr; i++) {
459 tc->do_thread(thread(i));
460 }
461 }
462
463 GCTaskThread* GCTaskManager::thread(uint which) {
464 assert(which < workers(), "index out of bounds");
465 assert(_thread[which] != NULL, "shouldn't have null thread");
466 return _thread[which];
467 }
468
469 void GCTaskManager::set_thread(uint which, GCTaskThread* value) {
470 assert(which < workers(), "index out of bounds");
471 assert(value != NULL, "shouldn't have null thread");
472 _thread[which] = value;
473 }
474
475 void GCTaskManager::add_task(GCTask* task) {
476 assert(task != NULL, "shouldn't have null task");
477 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
478 if (TraceGCTaskManager) {
479 tty->print_cr("GCTaskManager::add_task(" INTPTR_FORMAT " [%s])",
480 task, GCTask::Kind::to_string(task->kind()));
481 }
482 queue()->enqueue(task);
483 // Notify with the lock held to avoid missed notifies.
484 if (TraceGCTaskManager) {
485 tty->print_cr(" GCTaskManager::add_task (%s)->notify_all",
486 monitor()->name());
487 }
488 (void) monitor()->notify_all();
489 // Release monitor().
490 }
491
492 void GCTaskManager::add_list(GCTaskQueue* list) {
493 assert(list != NULL, "shouldn't have null task");
494 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
495 if (TraceGCTaskManager) {
496 tty->print_cr("GCTaskManager::add_list(%u)", list->length());
497 }
498 queue()->enqueue(list);
499 // Notify with the lock held to avoid missed notifies.
500 if (TraceGCTaskManager) {
501 tty->print_cr(" GCTaskManager::add_list (%s)->notify_all",
502 monitor()->name());
503 }
504 (void) monitor()->notify_all();
505 // Release monitor().
506 }
507
508 GCTask* GCTaskManager::get_task(uint which) {
509 GCTask* result = NULL;
510 // Grab the queue lock.
511 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
512 // Wait while the queue is block or
513 // there is nothing to do, except maybe release resources.
514 while (is_blocked() ||
515 (queue()->is_empty() && !should_release_resources(which))) {
516 if (TraceGCTaskManager) {
517 tty->print_cr("GCTaskManager::get_task(%u)"
518 " blocked: %s"
519 " empty: %s"
520 " release: %s",
521 which,
522 is_blocked() ? "true" : "false",
523 queue()->is_empty() ? "true" : "false",
524 should_release_resources(which) ? "true" : "false");
525 tty->print_cr(" => (%s)->wait()",
526 monitor()->name());
527 }
528 monitor()->wait(Mutex::_no_safepoint_check_flag, 0);
529 }
530 // We've reacquired the queue lock here.
531 // Figure out which condition caused us to exit the loop above.
532 if (!queue()->is_empty()) {
533 if (UseGCTaskAffinity) {
534 result = queue()->dequeue(which);
535 } else {
536 result = queue()->dequeue();
537 }
538 if (result->is_barrier_task()) {
539 assert(which != sentinel_worker(),
540 "blocker shouldn't be bogus");
541 set_blocking_worker(which);
542 }
543 } else {
544 // The queue is empty, but we were woken up.
545 // Just hand back a Noop task,
546 // in case someone wanted us to release resources, or whatever.
547 result = noop_task();
548 increment_noop_tasks();
549 }
550 assert(result != NULL, "shouldn't have null task");
551 if (TraceGCTaskManager) {
552 tty->print_cr("GCTaskManager::get_task(%u) => " INTPTR_FORMAT " [%s]",
553 which, result, GCTask::Kind::to_string(result->kind()));
554 tty->print_cr(" %s", result->name());
555 }
556 increment_busy_workers();
557 increment_delivered_tasks();
558 return result;
559 // Release monitor().
560 }
561
562 void GCTaskManager::note_completion(uint which) {
563 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
564 if (TraceGCTaskManager) {
565 tty->print_cr("GCTaskManager::note_completion(%u)", which);
566 }
567 // If we are blocked, check if the completing thread is the blocker.
568 if (blocking_worker() == which) {
569 assert(blocking_worker() != sentinel_worker(),
570 "blocker shouldn't be bogus");
571 increment_barriers();
572 set_unblocked();
573 }
574 increment_completed_tasks();
575 uint active = decrement_busy_workers();
576 if ((active == 0) && (queue()->is_empty())) {
577 increment_emptied_queue();
578 if (TraceGCTaskManager) {
579 tty->print_cr(" GCTaskManager::note_completion(%u) done", which);
580 }
581 // Notify client that we are done.
582 NotifyDoneClosure* ndc = notify_done_closure();
583 if (ndc != NULL) {
584 ndc->notify(this);
585 }
586 }
587 if (TraceGCTaskManager) {
588 tty->print_cr(" GCTaskManager::note_completion(%u) (%s)->notify_all",
589 which, monitor()->name());
590 tty->print_cr(" "
591 " blocked: %s"
592 " empty: %s"
593 " release: %s",
594 is_blocked() ? "true" : "false",
595 queue()->is_empty() ? "true" : "false",
596 should_release_resources(which) ? "true" : "false");
597 tty->print_cr(" "
598 " delivered: %u"
599 " completed: %u"
600 " barriers: %u"
601 " emptied: %u",
602 delivered_tasks(),
603 completed_tasks(),
604 barriers(),
605 emptied_queue());
606 }
607 // Tell everyone that a task has completed.
608 (void) monitor()->notify_all();
609 // Release monitor().
610 }
611
612 uint GCTaskManager::increment_busy_workers() {
613 assert(queue()->own_lock(), "don't own the lock");
614 _busy_workers += 1;
615 return _busy_workers;
616 }
617
618 uint GCTaskManager::decrement_busy_workers() {
619 assert(queue()->own_lock(), "don't own the lock");
620 _busy_workers -= 1;
621 return _busy_workers;
622 }
623
624 void GCTaskManager::release_all_resources() {
625 // If you want this to be done atomically, do it in a BarrierGCTask.
626 for (uint i = 0; i < workers(); i += 1) {
627 set_resource_flag(i, true);
628 }
629 }
630
631 bool GCTaskManager::should_release_resources(uint which) {
632 // This can be done without a lock because each thread reads one element.
633 return resource_flag(which);
634 }
635
636 void GCTaskManager::note_release(uint which) {
637 // This can be done without a lock because each thread writes one element.
638 set_resource_flag(which, false);
639 }
640
641 void GCTaskManager::execute_and_wait(GCTaskQueue* list) {
642 WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
643 list->enqueue(fin);
644 add_list(list);
645 fin->wait_for();
646 // We have to release the barrier tasks!
647 WaitForBarrierGCTask::destroy(fin);
648 }
649
650 bool GCTaskManager::resource_flag(uint which) {
651 assert(which < workers(), "index out of bounds");
652 return _resource_flag[which];
653 }
654
655 void GCTaskManager::set_resource_flag(uint which, bool value) {
656 assert(which < workers(), "index out of bounds");
657 _resource_flag[which] = value;
658 }
659
660 //
661 // NoopGCTask
662 //
663
664 NoopGCTask* NoopGCTask::create() {
665 NoopGCTask* result = new NoopGCTask(false);
666 return result;
667 }
668
669 NoopGCTask* NoopGCTask::create_on_c_heap() {
670 NoopGCTask* result = new(ResourceObj::C_HEAP) NoopGCTask(true);
671 return result;
672 }
673
674 void NoopGCTask::destroy(NoopGCTask* that) {
675 if (that != NULL) {
676 that->destruct();
677 if (that->is_c_heap_obj()) {
678 FreeHeap(that);
679 }
680 }
681 }
682
683 void NoopGCTask::destruct() {
684 // This has to know it's superclass structure, just like the constructor.
685 this->GCTask::destruct();
686 // Nothing else to do.
687 }
688
689 //
690 // BarrierGCTask
691 //
692
693 void BarrierGCTask::do_it(GCTaskManager* manager, uint which) {
694 // Wait for this to be the only busy worker.
695 // ??? I thought of having a StackObj class
696 // whose constructor would grab the lock and come to the barrier,
697 // and whose destructor would release the lock,
698 // but that seems like too much mechanism for two lines of code.
699 MutexLockerEx ml(manager->lock(), Mutex::_no_safepoint_check_flag);
700 do_it_internal(manager, which);
701 // Release manager->lock().
702 }
703
704 void BarrierGCTask::do_it_internal(GCTaskManager* manager, uint which) {
705 // Wait for this to be the only busy worker.
706 assert(manager->monitor()->owned_by_self(), "don't own the lock");
707 assert(manager->is_blocked(), "manager isn't blocked");
708 while (manager->busy_workers() > 1) {
709 if (TraceGCTaskManager) {
710 tty->print_cr("BarrierGCTask::do_it(%u) waiting on %u workers",
711 which, manager->busy_workers());
712 }
713 manager->monitor()->wait(Mutex::_no_safepoint_check_flag, 0);
714 }
715 }
716
717 void BarrierGCTask::destruct() {
718 this->GCTask::destruct();
719 // Nothing else to do.
720 }
721
722 //
723 // ReleasingBarrierGCTask
724 //
725
726 void ReleasingBarrierGCTask::do_it(GCTaskManager* manager, uint which) {
727 MutexLockerEx ml(manager->lock(), Mutex::_no_safepoint_check_flag);
728 do_it_internal(manager, which);
729 manager->release_all_resources();
730 // Release manager->lock().
731 }
732
733 void ReleasingBarrierGCTask::destruct() {
734 this->BarrierGCTask::destruct();
735 // Nothing else to do.
736 }
737
738 //
739 // NotifyingBarrierGCTask
740 //
741
742 void NotifyingBarrierGCTask::do_it(GCTaskManager* manager, uint which) {
743 MutexLockerEx ml(manager->lock(), Mutex::_no_safepoint_check_flag);
744 do_it_internal(manager, which);
745 NotifyDoneClosure* ndc = notify_done_closure();
746 if (ndc != NULL) {
747 ndc->notify(manager);
748 }
749 // Release manager->lock().
750 }
751
752 void NotifyingBarrierGCTask::destruct() {
753 this->BarrierGCTask::destruct();
754 // Nothing else to do.
755 }
756
757 //
758 // WaitForBarrierGCTask
759 //
760 WaitForBarrierGCTask* WaitForBarrierGCTask::create() {
761 WaitForBarrierGCTask* result = new WaitForBarrierGCTask(false);
762 return result;
763 }
764
765 WaitForBarrierGCTask* WaitForBarrierGCTask::create_on_c_heap() {
766 WaitForBarrierGCTask* result = new WaitForBarrierGCTask(true);
767 return result;
768 }
769
770 WaitForBarrierGCTask::WaitForBarrierGCTask(bool on_c_heap) :
771 _is_c_heap_obj(on_c_heap) {
772 _monitor = MonitorSupply::reserve();
773 set_should_wait(true);
774 if (TraceGCTaskManager) {
775 tty->print_cr("[" INTPTR_FORMAT "]"
776 " WaitForBarrierGCTask::WaitForBarrierGCTask()"
777 " monitor: " INTPTR_FORMAT,
778 this, monitor());
779 }
780 }
781
782 void WaitForBarrierGCTask::destroy(WaitForBarrierGCTask* that) {
783 if (that != NULL) {
784 if (TraceGCTaskManager) {
785 tty->print_cr("[" INTPTR_FORMAT "]"
786 " WaitForBarrierGCTask::destroy()"
787 " is_c_heap_obj: %s"
788 " monitor: " INTPTR_FORMAT,
789 that,
790 that->is_c_heap_obj() ? "true" : "false",
791 that->monitor());
792 }
793 that->destruct();
794 if (that->is_c_heap_obj()) {
795 FreeHeap(that);
796 }
797 }
798 }
799
800 void WaitForBarrierGCTask::destruct() {
801 assert(monitor() != NULL, "monitor should not be NULL");
802 if (TraceGCTaskManager) {
803 tty->print_cr("[" INTPTR_FORMAT "]"
804 " WaitForBarrierGCTask::destruct()"
805 " monitor: " INTPTR_FORMAT,
806 this, monitor());
807 }
808 this->BarrierGCTask::destruct();
809 // Clean up that should be in the destructor,
810 // except that ResourceMarks don't call destructors.
811 if (monitor() != NULL) {
812 MonitorSupply::release(monitor());
813 }
814 _monitor = (Monitor*) 0xDEAD000F;
815 }
816
817 void WaitForBarrierGCTask::do_it(GCTaskManager* manager, uint which) {
818 if (TraceGCTaskManager) {
819 tty->print_cr("[" INTPTR_FORMAT "]"
820 " WaitForBarrierGCTask::do_it() waiting for idle"
821 " monitor: " INTPTR_FORMAT,
822 this, monitor());
823 }
824 {
825 // First, wait for the barrier to arrive.
826 MutexLockerEx ml(manager->lock(), Mutex::_no_safepoint_check_flag);
827 do_it_internal(manager, which);
828 // Release manager->lock().
829 }
830 {
831 // Then notify the waiter.
832 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
833 set_should_wait(false);
834 // Waiter doesn't miss the notify in the wait_for method
835 // since it checks the flag after grabbing the monitor.
836 if (TraceGCTaskManager) {
837 tty->print_cr("[" INTPTR_FORMAT "]"
838 " WaitForBarrierGCTask::do_it()"
839 " [" INTPTR_FORMAT "] (%s)->notify_all()",
840 this, monitor(), monitor()->name());
841 }
842 monitor()->notify_all();
843 // Release monitor().
844 }
845 }
846
847 void WaitForBarrierGCTask::wait_for() {
848 if (TraceGCTaskManager) {
849 tty->print_cr("[" INTPTR_FORMAT "]"
850 " WaitForBarrierGCTask::wait_for()"
851 " should_wait: %s",
852 this, should_wait() ? "true" : "false");
853 }
854 {
855 // Grab the lock and check again.
856 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
857 while (should_wait()) {
858 if (TraceGCTaskManager) {
859 tty->print_cr("[" INTPTR_FORMAT "]"
860 " WaitForBarrierGCTask::wait_for()"
861 " [" INTPTR_FORMAT "] (%s)->wait()",
862 this, monitor(), monitor()->name());
863 }
864 monitor()->wait(Mutex::_no_safepoint_check_flag, 0);
865 }
866 // Reset the flag in case someone reuses this task.
867 set_should_wait(true);
868 if (TraceGCTaskManager) {
869 tty->print_cr("[" INTPTR_FORMAT "]"
870 " WaitForBarrierGCTask::wait_for() returns"
871 " should_wait: %s",
872 this, should_wait() ? "true" : "false");
873 }
874 // Release monitor().
875 }
876 }
877
878 Mutex* MonitorSupply::_lock = NULL;
879 GrowableArray<Monitor*>* MonitorSupply::_freelist = NULL;
880
881 Monitor* MonitorSupply::reserve() {
882 Monitor* result = NULL;
883 // Lazy initialization: possible race.
884 if (lock() == NULL) {
885 _lock = new Mutex(Mutex::barrier, // rank
886 "MonitorSupply mutex", // name
887 Mutex::_allow_vm_block_flag); // allow_vm_block
888 }
889 {
890 MutexLockerEx ml(lock());
891 // Lazy initialization.
892 if (freelist() == NULL) {
893 _freelist =
894 new(ResourceObj::C_HEAP) GrowableArray<Monitor*>(ParallelGCThreads,
895 true);
896 }
897 if (! freelist()->is_empty()) {
898 result = freelist()->pop();
899 } else {
900 result = new Monitor(Mutex::barrier, // rank
901 "MonitorSupply monitor", // name
902 Mutex::_allow_vm_block_flag); // allow_vm_block
903 }
904 guarantee(result != NULL, "shouldn't return NULL");
905 assert(!result->is_locked(), "shouldn't be locked");
906 // release lock().
907 }
908 return result;
909 }
910
911 void MonitorSupply::release(Monitor* instance) {
912 assert(instance != NULL, "shouldn't release NULL");
913 assert(!instance->is_locked(), "shouldn't be locked");
914 {
915 MutexLockerEx ml(lock());
916 freelist()->push(instance);
917 // release lock().
918 }
919 }