1 /*
2 * Copyright (c) 1998, 2014, 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 "precompiled.hpp"
26 #include "compiler/compileBroker.hpp"
27 #include "gc_interface/collectedHeap.hpp"
28 #include "memory/resourceArea.hpp"
29 #include "oops/method.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "runtime/interfaceSupport.hpp"
32 #include "runtime/mutexLocker.hpp"
33 #include "runtime/os.hpp"
34 #include "runtime/thread.inline.hpp"
35 #include "runtime/vmThread.hpp"
36 #include "runtime/vm_operations.hpp"
37 #include "services/runtimeService.hpp"
38 #include "trace/tracing.hpp"
39 #include "utilities/dtrace.hpp"
40 #include "utilities/events.hpp"
41 #include "utilities/xmlstream.hpp"
42
43 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
44
45 // Dummy VM operation to act as first element in our circular double-linked list
46 class VM_Dummy: public VM_Operation {
47 VMOp_Type type() const { return VMOp_Dummy; }
48 void doit() {};
49 };
50
51 VMOperationQueue::VMOperationQueue() {
52 // The queue is a circular doubled-linked list, which always contains
53 // one element (i.e., one element means empty).
54 for(int i = 0; i < nof_priorities; i++) {
55 _queue_length[i] = 0;
56 _queue_counter = 0;
57 _queue[i] = new VM_Dummy();
58 _queue[i]->set_next(_queue[i]);
59 _queue[i]->set_prev(_queue[i]);
60 }
61 _drain_list = NULL;
62 }
63
64
65 bool VMOperationQueue::queue_empty(int prio) {
66 // It is empty if there is exactly one element
67 bool empty = (_queue[prio] == _queue[prio]->next());
68 assert( (_queue_length[prio] == 0 && empty) ||
69 (_queue_length[prio] > 0 && !empty), "sanity check");
70 return _queue_length[prio] == 0;
71 }
72
73 // Inserts an element to the right of the q element
74 void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) {
75 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
76 n->set_prev(q);
77 n->set_next(q->next());
78 q->next()->set_prev(n);
79 q->set_next(n);
80 }
81
82 void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) {
83 _queue_length[prio]++;
84 insert(_queue[prio]->next(), op);
85 }
86
87 void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) {
88 _queue_length[prio]++;
89 insert(_queue[prio]->prev(), op);
90 }
91
92
93 void VMOperationQueue::unlink(VM_Operation* q) {
94 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
95 q->prev()->set_next(q->next());
96 q->next()->set_prev(q->prev());
97 }
98
99 VM_Operation* VMOperationQueue::queue_remove_front(int prio) {
100 if (queue_empty(prio)) return NULL;
101 assert(_queue_length[prio] >= 0, "sanity check");
102 _queue_length[prio]--;
103 VM_Operation* r = _queue[prio]->next();
104 assert(r != _queue[prio], "cannot remove base element");
105 unlink(r);
106 return r;
107 }
108
109 VM_Operation* VMOperationQueue::queue_drain(int prio) {
110 if (queue_empty(prio)) return NULL;
111 DEBUG_ONLY(int length = _queue_length[prio];);
112 assert(length >= 0, "sanity check");
113 _queue_length[prio] = 0;
114 VM_Operation* r = _queue[prio]->next();
115 assert(r != _queue[prio], "cannot remove base element");
116 // remove links to base element from head and tail
117 r->set_prev(NULL);
118 _queue[prio]->prev()->set_next(NULL);
119 // restore queue to empty state
120 _queue[prio]->set_next(_queue[prio]);
121 _queue[prio]->set_prev(_queue[prio]);
122 assert(queue_empty(prio), "drain corrupted queue");
123 #ifdef ASSERT
124 int len = 0;
125 VM_Operation* cur;
126 for(cur = r; cur != NULL; cur=cur->next()) len++;
127 assert(len == length, "drain lost some ops");
128 #endif
129 return r;
130 }
131
132 void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) {
133 VM_Operation* cur = _queue[queue];
134 cur = cur->next();
135 while (cur != _queue[queue]) {
136 cur->oops_do(f);
137 cur = cur->next();
138 }
139 }
140
141 void VMOperationQueue::drain_list_oops_do(OopClosure* f) {
142 VM_Operation* cur = _drain_list;
143 while (cur != NULL) {
144 cur->oops_do(f);
145 cur = cur->next();
146 }
147 }
148
149 //-----------------------------------------------------------------
150 // High-level interface
151 bool VMOperationQueue::add(VM_Operation *op) {
152
153 HOTSPOT_VMOPS_REQUEST(
154 (char *) op->name(), strlen(op->name()),
155 op->evaluation_mode());
156
157 // Encapsulates VM queue policy. Currently, that
158 // only involves putting them on the right list
159 if (op->evaluate_at_safepoint()) {
160 queue_add_back(SafepointPriority, op);
161 return true;
162 }
163
164 queue_add_back(MediumPriority, op);
165 return true;
166 }
167
168 VM_Operation* VMOperationQueue::remove_next() {
169 // Assuming VMOperation queue is two-level priority queue. If there are
170 // more than two priorities, we need a different scheduling algorithm.
171 assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2,
172 "current algorithm does not work");
173
174 // simple counter based scheduling to prevent starvation of lower priority
175 // queue. -- see 4390175
176 int high_prio, low_prio;
177 if (_queue_counter++ < 10) {
178 high_prio = SafepointPriority;
179 low_prio = MediumPriority;
180 } else {
181 _queue_counter = 0;
182 high_prio = MediumPriority;
183 low_prio = SafepointPriority;
184 }
185
186 return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio);
187 }
188
189 void VMOperationQueue::oops_do(OopClosure* f) {
190 for(int i = 0; i < nof_priorities; i++) {
191 queue_oops_do(i, f);
192 }
193 drain_list_oops_do(f);
194 }
195
196
197 //------------------------------------------------------------------------------------------------------------------
198 // Implementation of VMThread stuff
199
200 bool VMThread::_should_terminate = false;
201 bool VMThread::_terminated = false;
202 Monitor* VMThread::_terminate_lock = NULL;
203 VMThread* VMThread::_vm_thread = NULL;
204 VM_Operation* VMThread::_cur_vm_operation = NULL;
205 VMOperationQueue* VMThread::_vm_queue = NULL;
206 PerfCounter* VMThread::_perf_accumulated_vm_operation_time = NULL;
207
208
209 void VMThread::create() {
210 assert(vm_thread() == NULL, "we can only allocate one VMThread");
211 _vm_thread = new VMThread();
212
213 // Create VM operation queue
214 _vm_queue = new VMOperationQueue();
215 guarantee(_vm_queue != NULL, "just checking");
216
217 _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true,
218 Monitor::_safepoint_check_never);
219
220 if (UsePerfData) {
221 // jvmstat performance counters
222 Thread* THREAD = Thread::current();
223 _perf_accumulated_vm_operation_time =
224 PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime",
225 PerfData::U_Ticks, CHECK);
226 }
227 }
228
229
230 VMThread::VMThread() : NamedThread() {
231 set_name("VM Thread");
232 }
233
234 void VMThread::destroy() {
235 if (_vm_thread != NULL) {
236 delete _vm_thread;
237 _vm_thread = NULL; // VM thread is gone
238 }
239 }
240
241 void VMThread::run() {
242 assert(this == vm_thread(), "check");
243
244 this->initialize_thread_local_storage();
245 this->set_native_thread_name(this->name());
246 this->record_stack_base_and_size();
247 // Notify_lock wait checks on active_handles() to rewait in
248 // case of spurious wakeup, it should wait on the last
249 // value set prior to the notify
250 this->set_active_handles(JNIHandleBlock::allocate_block());
251
252 {
253 MutexLocker ml(Notify_lock);
254 Notify_lock->notify();
255 }
256 // Notify_lock is destroyed by Threads::create_vm()
257
258 int prio = (VMThreadPriority == -1)
259 ? os::java_to_os_priority[NearMaxPriority]
260 : VMThreadPriority;
261 // Note that I cannot call os::set_priority because it expects Java
262 // priorities and I am *explicitly* using OS priorities so that it's
263 // possible to set the VM thread priority higher than any Java thread.
264 os::set_native_priority( this, prio );
265
266 // Wait for VM_Operations until termination
267 this->loop();
268
269 // Note the intention to exit before safepointing.
270 // 6295565 This has the effect of waiting for any large tty
271 // outputs to finish.
272 if (xtty != NULL) {
273 ttyLocker ttyl;
274 xtty->begin_elem("destroy_vm");
275 xtty->stamp();
276 xtty->end_elem();
277 assert(should_terminate(), "termination flag must be set");
278 }
279
280 // 4526887 let VM thread exit at Safepoint
281 SafepointSynchronize::begin();
282
283 if (VerifyBeforeExit) {
284 HandleMark hm(VMThread::vm_thread());
285 // Among other things, this ensures that Eden top is correct.
286 Universe::heap()->prepare_for_verify();
287 os::check_heap();
288 // Silent verification so as not to pollute normal output,
289 // unless we really asked for it.
290 Universe::verify(!(PrintGCDetails || Verbose) || VerifySilently);
291 }
292
293 CompileBroker::set_should_block();
294
295 // wait for threads (compiler threads or daemon threads) in the
296 // _thread_in_native state to block.
297 VM_Exit::wait_for_threads_in_native_to_block();
298
299 // signal other threads that VM process is gone
300 {
301 // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows
302 // VM thread to enter any lock at Safepoint as long as its _owner is NULL.
303 // If that happens after _terminate_lock->wait() has unset _owner
304 // but before it actually drops the lock and waits, the notification below
305 // may get lost and we will have a hang. To avoid this, we need to use
306 // Mutex::lock_without_safepoint_check().
307 MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
308 _terminated = true;
309 _terminate_lock->notify();
310 }
311
312 // Thread destructor usually does this.
313 ThreadLocalStorage::set_thread(NULL);
314
315 // Deletion must be done synchronously by the JNI DestroyJavaVM thread
316 // so that the VMThread deletion completes before the main thread frees
317 // up the CodeHeap.
318
319 }
320
321
322 // Notify the VMThread that the last non-daemon JavaThread has terminated,
323 // and wait until operation is performed.
324 void VMThread::wait_for_vm_thread_exit() {
325 { MutexLocker mu(VMOperationQueue_lock);
326 _should_terminate = true;
327 VMOperationQueue_lock->notify();
328 }
329
330 // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint
331 // because this thread has been removed from the threads list. But anything
332 // that could get blocked by Safepoint should not be used after this point,
333 // otherwise we will hang, since there is no one can end the safepoint.
334
335 // Wait until VM thread is terminated
336 // Note: it should be OK to use Terminator_lock here. But this is called
337 // at a very delicate time (VM shutdown) and we are operating in non- VM
338 // thread at Safepoint. It's safer to not share lock with other threads.
339 { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
340 while(!VMThread::is_terminated()) {
341 _terminate_lock->wait(Mutex::_no_safepoint_check_flag);
342 }
343 }
344 }
345
346 void VMThread::evaluate_operation(VM_Operation* op) {
347 ResourceMark rm;
348
349 {
350 PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time());
351 HOTSPOT_VMOPS_BEGIN(
352 (char *) op->name(), strlen(op->name()),
353 op->evaluation_mode());
354
355 EventExecuteVMOperation event;
356
357 op->evaluate();
358
359 if (event.should_commit()) {
360 bool is_concurrent = op->evaluate_concurrently();
361 event.set_operation(op->type());
362 event.set_safepoint(op->evaluate_at_safepoint());
363 event.set_blocking(!is_concurrent);
364 // Only write caller thread information for non-concurrent vm operations.
365 // For concurrent vm operations, the thread id is set to 0 indicating thread is unknown.
366 // This is because the caller thread could have exited already.
367 event.set_caller(is_concurrent ? 0 : op->calling_thread()->osthread()->thread_id());
368 event.commit();
369 }
370
371 HOTSPOT_VMOPS_END(
372 (char *) op->name(), strlen(op->name()),
373 op->evaluation_mode());
374 }
375
376 // Last access of info in _cur_vm_operation!
377 bool c_heap_allocated = op->is_cheap_allocated();
378
379 // Mark as completed
380 if (!op->evaluate_concurrently()) {
381 op->calling_thread()->increment_vm_operation_completed_count();
382 }
383 // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call,
384 // since if it is stack allocated the calling thread might have deallocated
385 if (c_heap_allocated) {
386 delete _cur_vm_operation;
387 }
388 }
389
390
391 void VMThread::loop() {
392 assert(_cur_vm_operation == NULL, "no current one should be executing");
393
394 while(true) {
395 VM_Operation* safepoint_ops = NULL;
396 //
397 // Wait for VM operation
398 //
399 // use no_safepoint_check to get lock without attempting to "sneak"
400 { MutexLockerEx mu_queue(VMOperationQueue_lock,
401 Mutex::_no_safepoint_check_flag);
402
403 // Look for new operation
404 assert(_cur_vm_operation == NULL, "no current one should be executing");
405 _cur_vm_operation = _vm_queue->remove_next();
406
407 // Stall time tracking code
408 if (PrintVMQWaitTime && _cur_vm_operation != NULL &&
409 !_cur_vm_operation->evaluate_concurrently()) {
410 long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp();
411 if (stall > 0)
412 tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall);
413 }
414
415 while (!should_terminate() && _cur_vm_operation == NULL) {
416 // wait with a timeout to guarantee safepoints at regular intervals
417 bool timedout =
418 VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag,
419 GuaranteedSafepointInterval);
420
421 // Support for self destruction
422 if ((SelfDestructTimer != 0) && !is_error_reported() &&
423 (os::elapsedTime() > SelfDestructTimer * 60)) {
424 tty->print_cr("VM self-destructed");
425 exit(-1);
426 }
427
428 if (timedout && (SafepointALot ||
429 SafepointSynchronize::is_cleanup_needed())) {
430 MutexUnlockerEx mul(VMOperationQueue_lock,
431 Mutex::_no_safepoint_check_flag);
432 // Force a safepoint since we have not had one for at least
433 // 'GuaranteedSafepointInterval' milliseconds. This will run all
434 // the clean-up processing that needs to be done regularly at a
435 // safepoint
436 SafepointSynchronize::begin();
437 #ifdef ASSERT
438 if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
439 #endif
440 SafepointSynchronize::end();
441 }
442 _cur_vm_operation = _vm_queue->remove_next();
443
444 // If we are at a safepoint we will evaluate all the operations that
445 // follow that also require a safepoint
446 if (_cur_vm_operation != NULL &&
447 _cur_vm_operation->evaluate_at_safepoint()) {
448 safepoint_ops = _vm_queue->drain_at_safepoint_priority();
449 }
450 }
451
452 if (should_terminate()) break;
453 } // Release mu_queue_lock
454
455 //
456 // Execute VM operation
457 //
458 { HandleMark hm(VMThread::vm_thread());
459
460 EventMark em("Executing VM operation: %s", vm_operation()->name());
461 assert(_cur_vm_operation != NULL, "we should have found an operation to execute");
462
463 // Give the VM thread an extra quantum. Jobs tend to be bursty and this
464 // helps the VM thread to finish up the job.
465 // FIXME: When this is enabled and there are many threads, this can degrade
466 // performance significantly.
467 if( VMThreadHintNoPreempt )
468 os::hint_no_preempt();
469
470 // If we are at a safepoint we will evaluate all the operations that
471 // follow that also require a safepoint
472 if (_cur_vm_operation->evaluate_at_safepoint()) {
473
474 _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned
475
476 SafepointSynchronize::begin();
477 evaluate_operation(_cur_vm_operation);
478 // now process all queued safepoint ops, iteratively draining
479 // the queue until there are none left
480 do {
481 _cur_vm_operation = safepoint_ops;
482 if (_cur_vm_operation != NULL) {
483 do {
484 // evaluate_operation deletes the op object so we have
485 // to grab the next op now
486 VM_Operation* next = _cur_vm_operation->next();
487 _vm_queue->set_drain_list(next);
488 evaluate_operation(_cur_vm_operation);
489 _cur_vm_operation = next;
490 if (PrintSafepointStatistics) {
491 SafepointSynchronize::inc_vmop_coalesced_count();
492 }
493 } while (_cur_vm_operation != NULL);
494 }
495 // There is a chance that a thread enqueued a safepoint op
496 // since we released the op-queue lock and initiated the safepoint.
497 // So we drain the queue again if there is anything there, as an
498 // optimization to try and reduce the number of safepoints.
499 // As the safepoint synchronizes us with JavaThreads we will see
500 // any enqueue made by a JavaThread, but the peek will not
501 // necessarily detect a concurrent enqueue by a GC thread, but
502 // that simply means the op will wait for the next major cycle of the
503 // VMThread - just as it would if the GC thread lost the race for
504 // the lock.
505 if (_vm_queue->peek_at_safepoint_priority()) {
506 // must hold lock while draining queue
507 MutexLockerEx mu_queue(VMOperationQueue_lock,
508 Mutex::_no_safepoint_check_flag);
509 safepoint_ops = _vm_queue->drain_at_safepoint_priority();
510 } else {
511 safepoint_ops = NULL;
512 }
513 } while(safepoint_ops != NULL);
514
515 _vm_queue->set_drain_list(NULL);
516
517 // Complete safepoint synchronization
518 SafepointSynchronize::end();
519
520 } else { // not a safepoint operation
521 if (TraceLongCompiles) {
522 elapsedTimer t;
523 t.start();
524 evaluate_operation(_cur_vm_operation);
525 t.stop();
526 double secs = t.seconds();
527 if (secs * 1e3 > LongCompileThreshold) {
528 // XXX - _cur_vm_operation should not be accessed after
529 // the completed count has been incremented; the waiting
530 // thread may have already freed this memory.
531 tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs);
532 }
533 } else {
534 evaluate_operation(_cur_vm_operation);
535 }
536
537 _cur_vm_operation = NULL;
538 }
539 }
540
541 //
542 // Notify (potential) waiting Java thread(s) - lock without safepoint
543 // check so that sneaking is not possible
544 { MutexLockerEx mu(VMOperationRequest_lock,
545 Mutex::_no_safepoint_check_flag);
546 VMOperationRequest_lock->notify_all();
547 }
548
549 //
550 // We want to make sure that we get to a safepoint regularly.
551 //
552 if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) {
553 long interval = SafepointSynchronize::last_non_safepoint_interval();
554 bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval);
555 if (SafepointALot || max_time_exceeded) {
556 HandleMark hm(VMThread::vm_thread());
557 SafepointSynchronize::begin();
558 SafepointSynchronize::end();
559 }
560 }
561 }
562 }
563
564 void VMThread::execute(VM_Operation* op) {
565 Thread* t = Thread::current();
566
567 if (!t->is_VM_thread()) {
568 SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot
569 // JavaThread or WatcherThread
570 bool concurrent = op->evaluate_concurrently();
571 // only blocking VM operations need to verify the caller's safepoint state:
572 if (!concurrent) {
573 t->check_for_valid_safepoint_state(true);
574 }
575
576 // New request from Java thread, evaluate prologue
577 if (!op->doit_prologue()) {
578 return; // op was cancelled
579 }
580
581 // Setup VM_operations for execution
582 op->set_calling_thread(t, Thread::get_priority(t));
583
584 // It does not make sense to execute the epilogue, if the VM operation object is getting
585 // deallocated by the VM thread.
586 bool execute_epilog = !op->is_cheap_allocated();
587 assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated");
588
589 // Get ticket number for non-concurrent VM operations
590 int ticket = 0;
591 if (!concurrent) {
592 ticket = t->vm_operation_ticket();
593 }
594
595 // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the
596 // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests
597 // to be queued up during a safepoint synchronization.
598 {
599 VMOperationQueue_lock->lock_without_safepoint_check();
600 bool ok = _vm_queue->add(op);
601 op->set_timestamp(os::javaTimeMillis());
602 VMOperationQueue_lock->notify();
603 VMOperationQueue_lock->unlock();
604 // VM_Operation got skipped
605 if (!ok) {
606 assert(concurrent, "can only skip concurrent tasks");
607 if (op->is_cheap_allocated()) delete op;
608 return;
609 }
610 }
611
612 if (!concurrent) {
613 // Wait for completion of request (non-concurrent)
614 // Note: only a JavaThread triggers the safepoint check when locking
615 MutexLocker mu(VMOperationRequest_lock);
616 while(t->vm_operation_completed_count() < ticket) {
617 VMOperationRequest_lock->wait(!t->is_Java_thread());
618 }
619 }
620
621 if (execute_epilog) {
622 op->doit_epilogue();
623 }
624 } else {
625 // invoked by VM thread; usually nested VM operation
626 assert(t->is_VM_thread(), "must be a VM thread");
627 VM_Operation* prev_vm_operation = vm_operation();
628 if (prev_vm_operation != NULL) {
629 // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler
630 // does not allow nested scavenges or compiles.
631 if (!prev_vm_operation->allow_nested_vm_operations()) {
632 fatal(err_msg("Nested VM operation %s requested by operation %s",
633 op->name(), vm_operation()->name()));
634 }
635 op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority());
636 }
637
638 EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name());
639
640 // Release all internal handles after operation is evaluated
641 HandleMark hm(t);
642 _cur_vm_operation = op;
643
644 if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) {
645 SafepointSynchronize::begin();
646 op->evaluate();
647 SafepointSynchronize::end();
648 } else {
649 op->evaluate();
650 }
651
652 // Free memory if needed
653 if (op->is_cheap_allocated()) delete op;
654
655 _cur_vm_operation = prev_vm_operation;
656 }
657 }
658
659
660 void VMThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
661 Thread::oops_do(f, cld_f, cf);
662 _vm_queue->oops_do(f);
663 }
664
665 //------------------------------------------------------------------------------------------------------------------
666 #ifndef PRODUCT
667
668 void VMOperationQueue::verify_queue(int prio) {
669 // Check that list is correctly linked
670 int length = _queue_length[prio];
671 VM_Operation *cur = _queue[prio];
672 int i;
673
674 // Check forward links
675 for(i = 0; i < length; i++) {
676 cur = cur->next();
677 assert(cur != _queue[prio], "list to short (forward)");
678 }
679 assert(cur->next() == _queue[prio], "list to long (forward)");
680
681 // Check backwards links
682 cur = _queue[prio];
683 for(i = 0; i < length; i++) {
684 cur = cur->prev();
685 assert(cur != _queue[prio], "list to short (backwards)");
686 }
687 assert(cur->prev() == _queue[prio], "list to long (backwards)");
688 }
689
690 #endif
691
692 void VMThread::verify() {
693 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
694 }