Wed, 17 Aug 2011 10:32:53 -0700
6791672: enable 1G and larger pages on solaris
Reviewed-by: ysr, iveresov, johnc
1 /*
2 * Copyright (c) 1998, 2010, 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 */
25 #include "precompiled.hpp"
26 #include "compiler/compileBroker.hpp"
27 #include "gc_interface/collectedHeap.hpp"
28 #include "memory/resourceArea.hpp"
29 #include "oops/methodOop.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/vmThread.hpp"
35 #include "runtime/vm_operations.hpp"
36 #include "services/runtimeService.hpp"
37 #include "utilities/dtrace.hpp"
38 #include "utilities/events.hpp"
39 #include "utilities/xmlstream.hpp"
40 #ifdef TARGET_OS_FAMILY_linux
41 # include "thread_linux.inline.hpp"
42 #endif
43 #ifdef TARGET_OS_FAMILY_solaris
44 # include "thread_solaris.inline.hpp"
45 #endif
46 #ifdef TARGET_OS_FAMILY_windows
47 # include "thread_windows.inline.hpp"
48 #endif
50 HS_DTRACE_PROBE_DECL3(hotspot, vmops__request, char *, uintptr_t, int);
51 HS_DTRACE_PROBE_DECL3(hotspot, vmops__begin, char *, uintptr_t, int);
52 HS_DTRACE_PROBE_DECL3(hotspot, vmops__end, char *, uintptr_t, int);
54 // Dummy VM operation to act as first element in our circular double-linked list
55 class VM_Dummy: public VM_Operation {
56 VMOp_Type type() const { return VMOp_Dummy; }
57 void doit() {};
58 };
60 VMOperationQueue::VMOperationQueue() {
61 // The queue is a circular doubled-linked list, which always contains
62 // one element (i.e., one element means empty).
63 for(int i = 0; i < nof_priorities; i++) {
64 _queue_length[i] = 0;
65 _queue_counter = 0;
66 _queue[i] = new VM_Dummy();
67 _queue[i]->set_next(_queue[i]);
68 _queue[i]->set_prev(_queue[i]);
69 }
70 _drain_list = NULL;
71 }
74 bool VMOperationQueue::queue_empty(int prio) {
75 // It is empty if there is exactly one element
76 bool empty = (_queue[prio] == _queue[prio]->next());
77 assert( (_queue_length[prio] == 0 && empty) ||
78 (_queue_length[prio] > 0 && !empty), "sanity check");
79 return _queue_length[prio] == 0;
80 }
82 // Inserts an element to the right of the q element
83 void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) {
84 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
85 n->set_prev(q);
86 n->set_next(q->next());
87 q->next()->set_prev(n);
88 q->set_next(n);
89 }
91 void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) {
92 _queue_length[prio]++;
93 insert(_queue[prio]->next(), op);
94 }
96 void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) {
97 _queue_length[prio]++;
98 insert(_queue[prio]->prev(), op);
99 }
102 void VMOperationQueue::unlink(VM_Operation* q) {
103 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
104 q->prev()->set_next(q->next());
105 q->next()->set_prev(q->prev());
106 }
108 VM_Operation* VMOperationQueue::queue_remove_front(int prio) {
109 if (queue_empty(prio)) return NULL;
110 assert(_queue_length[prio] >= 0, "sanity check");
111 _queue_length[prio]--;
112 VM_Operation* r = _queue[prio]->next();
113 assert(r != _queue[prio], "cannot remove base element");
114 unlink(r);
115 return r;
116 }
118 VM_Operation* VMOperationQueue::queue_drain(int prio) {
119 if (queue_empty(prio)) return NULL;
120 DEBUG_ONLY(int length = _queue_length[prio];);
121 assert(length >= 0, "sanity check");
122 _queue_length[prio] = 0;
123 VM_Operation* r = _queue[prio]->next();
124 assert(r != _queue[prio], "cannot remove base element");
125 // remove links to base element from head and tail
126 r->set_prev(NULL);
127 _queue[prio]->prev()->set_next(NULL);
128 // restore queue to empty state
129 _queue[prio]->set_next(_queue[prio]);
130 _queue[prio]->set_prev(_queue[prio]);
131 assert(queue_empty(prio), "drain corrupted queue");
132 #ifdef DEBUG
133 int len = 0;
134 VM_Operation* cur;
135 for(cur = r; cur != NULL; cur=cur->next()) len++;
136 assert(len == length, "drain lost some ops");
137 #endif
138 return r;
139 }
141 void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) {
142 VM_Operation* cur = _queue[queue];
143 cur = cur->next();
144 while (cur != _queue[queue]) {
145 cur->oops_do(f);
146 cur = cur->next();
147 }
148 }
150 void VMOperationQueue::drain_list_oops_do(OopClosure* f) {
151 VM_Operation* cur = _drain_list;
152 while (cur != NULL) {
153 cur->oops_do(f);
154 cur = cur->next();
155 }
156 }
158 //-----------------------------------------------------------------
159 // High-level interface
160 bool VMOperationQueue::add(VM_Operation *op) {
162 HS_DTRACE_PROBE3(hotspot, vmops__request, op->name(), strlen(op->name()),
163 op->evaluation_mode());
165 // Encapsulates VM queue policy. Currently, that
166 // only involves putting them on the right list
167 if (op->evaluate_at_safepoint()) {
168 queue_add_back(SafepointPriority, op);
169 return true;
170 }
172 queue_add_back(MediumPriority, op);
173 return true;
174 }
176 VM_Operation* VMOperationQueue::remove_next() {
177 // Assuming VMOperation queue is two-level priority queue. If there are
178 // more than two priorities, we need a different scheduling algorithm.
179 assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2,
180 "current algorithm does not work");
182 // simple counter based scheduling to prevent starvation of lower priority
183 // queue. -- see 4390175
184 int high_prio, low_prio;
185 if (_queue_counter++ < 10) {
186 high_prio = SafepointPriority;
187 low_prio = MediumPriority;
188 } else {
189 _queue_counter = 0;
190 high_prio = MediumPriority;
191 low_prio = SafepointPriority;
192 }
194 return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio);
195 }
197 void VMOperationQueue::oops_do(OopClosure* f) {
198 for(int i = 0; i < nof_priorities; i++) {
199 queue_oops_do(i, f);
200 }
201 drain_list_oops_do(f);
202 }
205 //------------------------------------------------------------------------------------------------------------------
206 // Implementation of VMThread stuff
208 bool VMThread::_should_terminate = false;
209 bool VMThread::_terminated = false;
210 Monitor* VMThread::_terminate_lock = NULL;
211 VMThread* VMThread::_vm_thread = NULL;
212 VM_Operation* VMThread::_cur_vm_operation = NULL;
213 VMOperationQueue* VMThread::_vm_queue = NULL;
214 PerfCounter* VMThread::_perf_accumulated_vm_operation_time = NULL;
217 void VMThread::create() {
218 assert(vm_thread() == NULL, "we can only allocate one VMThread");
219 _vm_thread = new VMThread();
221 // Create VM operation queue
222 _vm_queue = new VMOperationQueue();
223 guarantee(_vm_queue != NULL, "just checking");
225 _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true);
227 if (UsePerfData) {
228 // jvmstat performance counters
229 Thread* THREAD = Thread::current();
230 _perf_accumulated_vm_operation_time =
231 PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime",
232 PerfData::U_Ticks, CHECK);
233 }
234 }
237 VMThread::VMThread() : NamedThread() {
238 set_name("VM Thread");
239 }
241 void VMThread::destroy() {
242 if (_vm_thread != NULL) {
243 delete _vm_thread;
244 _vm_thread = NULL; // VM thread is gone
245 }
246 }
248 void VMThread::run() {
249 assert(this == vm_thread(), "check");
251 this->initialize_thread_local_storage();
252 this->record_stack_base_and_size();
253 // Notify_lock wait checks on active_handles() to rewait in
254 // case of spurious wakeup, it should wait on the last
255 // value set prior to the notify
256 this->set_active_handles(JNIHandleBlock::allocate_block());
258 {
259 MutexLocker ml(Notify_lock);
260 Notify_lock->notify();
261 }
262 // Notify_lock is destroyed by Threads::create_vm()
264 int prio = (VMThreadPriority == -1)
265 ? os::java_to_os_priority[NearMaxPriority]
266 : VMThreadPriority;
267 // Note that I cannot call os::set_priority because it expects Java
268 // priorities and I am *explicitly* using OS priorities so that it's
269 // possible to set the VM thread priority higher than any Java thread.
270 os::set_native_priority( this, prio );
272 // Wait for VM_Operations until termination
273 this->loop();
275 // Note the intention to exit before safepointing.
276 // 6295565 This has the effect of waiting for any large tty
277 // outputs to finish.
278 if (xtty != NULL) {
279 ttyLocker ttyl;
280 xtty->begin_elem("destroy_vm");
281 xtty->stamp();
282 xtty->end_elem();
283 assert(should_terminate(), "termination flag must be set");
284 }
286 // 4526887 let VM thread exit at Safepoint
287 SafepointSynchronize::begin();
289 if (VerifyBeforeExit) {
290 HandleMark hm(VMThread::vm_thread());
291 // Among other things, this ensures that Eden top is correct.
292 Universe::heap()->prepare_for_verify();
293 os::check_heap();
294 // Silent verification so as not to pollute normal output,
295 // unless we really asked for it.
296 Universe::verify(true, !(PrintGCDetails || Verbose));
297 }
299 CompileBroker::set_should_block();
301 // wait for threads (compiler threads or daemon threads) in the
302 // _thread_in_native state to block.
303 VM_Exit::wait_for_threads_in_native_to_block();
305 // signal other threads that VM process is gone
306 {
307 // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows
308 // VM thread to enter any lock at Safepoint as long as its _owner is NULL.
309 // If that happens after _terminate_lock->wait() has unset _owner
310 // but before it actually drops the lock and waits, the notification below
311 // may get lost and we will have a hang. To avoid this, we need to use
312 // Mutex::lock_without_safepoint_check().
313 MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
314 _terminated = true;
315 _terminate_lock->notify();
316 }
318 // Deletion must be done synchronously by the JNI DestroyJavaVM thread
319 // so that the VMThread deletion completes before the main thread frees
320 // up the CodeHeap.
322 }
325 // Notify the VMThread that the last non-daemon JavaThread has terminated,
326 // and wait until operation is performed.
327 void VMThread::wait_for_vm_thread_exit() {
328 { MutexLocker mu(VMOperationQueue_lock);
329 _should_terminate = true;
330 VMOperationQueue_lock->notify();
331 }
333 // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint
334 // because this thread has been removed from the threads list. But anything
335 // that could get blocked by Safepoint should not be used after this point,
336 // otherwise we will hang, since there is no one can end the safepoint.
338 // Wait until VM thread is terminated
339 // Note: it should be OK to use Terminator_lock here. But this is called
340 // at a very delicate time (VM shutdown) and we are operating in non- VM
341 // thread at Safepoint. It's safer to not share lock with other threads.
342 { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
343 while(!VMThread::is_terminated()) {
344 _terminate_lock->wait(Mutex::_no_safepoint_check_flag);
345 }
346 }
347 }
349 void VMThread::print_on(outputStream* st) const {
350 st->print("\"%s\" ", name());
351 Thread::print_on(st);
352 st->cr();
353 }
355 void VMThread::evaluate_operation(VM_Operation* op) {
356 ResourceMark rm;
358 {
359 PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time());
360 HS_DTRACE_PROBE3(hotspot, vmops__begin, op->name(), strlen(op->name()),
361 op->evaluation_mode());
362 op->evaluate();
363 HS_DTRACE_PROBE3(hotspot, vmops__end, op->name(), strlen(op->name()),
364 op->evaluation_mode());
365 }
367 // Last access of info in _cur_vm_operation!
368 bool c_heap_allocated = op->is_cheap_allocated();
370 // Mark as completed
371 if (!op->evaluate_concurrently()) {
372 op->calling_thread()->increment_vm_operation_completed_count();
373 }
374 // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call,
375 // since if it is stack allocated the calling thread might have deallocated
376 if (c_heap_allocated) {
377 delete _cur_vm_operation;
378 }
379 }
382 void VMThread::loop() {
383 assert(_cur_vm_operation == NULL, "no current one should be executing");
385 while(true) {
386 VM_Operation* safepoint_ops = NULL;
387 //
388 // Wait for VM operation
389 //
390 // use no_safepoint_check to get lock without attempting to "sneak"
391 { MutexLockerEx mu_queue(VMOperationQueue_lock,
392 Mutex::_no_safepoint_check_flag);
394 // Look for new operation
395 assert(_cur_vm_operation == NULL, "no current one should be executing");
396 _cur_vm_operation = _vm_queue->remove_next();
398 // Stall time tracking code
399 if (PrintVMQWaitTime && _cur_vm_operation != NULL &&
400 !_cur_vm_operation->evaluate_concurrently()) {
401 long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp();
402 if (stall > 0)
403 tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall);
404 }
406 while (!should_terminate() && _cur_vm_operation == NULL) {
407 // wait with a timeout to guarantee safepoints at regular intervals
408 bool timedout =
409 VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag,
410 GuaranteedSafepointInterval);
412 // Support for self destruction
413 if ((SelfDestructTimer != 0) && !is_error_reported() &&
414 (os::elapsedTime() > SelfDestructTimer * 60)) {
415 tty->print_cr("VM self-destructed");
416 exit(-1);
417 }
419 if (timedout && (SafepointALot ||
420 SafepointSynchronize::is_cleanup_needed())) {
421 MutexUnlockerEx mul(VMOperationQueue_lock,
422 Mutex::_no_safepoint_check_flag);
423 // Force a safepoint since we have not had one for at least
424 // 'GuaranteedSafepointInterval' milliseconds. This will run all
425 // the clean-up processing that needs to be done regularly at a
426 // safepoint
427 SafepointSynchronize::begin();
428 #ifdef ASSERT
429 if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
430 #endif
431 SafepointSynchronize::end();
432 }
433 _cur_vm_operation = _vm_queue->remove_next();
435 // If we are at a safepoint we will evaluate all the operations that
436 // follow that also require a safepoint
437 if (_cur_vm_operation != NULL &&
438 _cur_vm_operation->evaluate_at_safepoint()) {
439 safepoint_ops = _vm_queue->drain_at_safepoint_priority();
440 }
441 }
443 if (should_terminate()) break;
444 } // Release mu_queue_lock
446 //
447 // Execute VM operation
448 //
449 { HandleMark hm(VMThread::vm_thread());
451 EventMark em("Executing VM operation: %s", vm_operation()->name());
452 assert(_cur_vm_operation != NULL, "we should have found an operation to execute");
454 // Give the VM thread an extra quantum. Jobs tend to be bursty and this
455 // helps the VM thread to finish up the job.
456 // FIXME: When this is enabled and there are many threads, this can degrade
457 // performance significantly.
458 if( VMThreadHintNoPreempt )
459 os::hint_no_preempt();
461 // If we are at a safepoint we will evaluate all the operations that
462 // follow that also require a safepoint
463 if (_cur_vm_operation->evaluate_at_safepoint()) {
465 _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned
467 SafepointSynchronize::begin();
468 evaluate_operation(_cur_vm_operation);
469 // now process all queued safepoint ops, iteratively draining
470 // the queue until there are none left
471 do {
472 _cur_vm_operation = safepoint_ops;
473 if (_cur_vm_operation != NULL) {
474 do {
475 // evaluate_operation deletes the op object so we have
476 // to grab the next op now
477 VM_Operation* next = _cur_vm_operation->next();
478 _vm_queue->set_drain_list(next);
479 evaluate_operation(_cur_vm_operation);
480 _cur_vm_operation = next;
481 if (PrintSafepointStatistics) {
482 SafepointSynchronize::inc_vmop_coalesced_count();
483 }
484 } while (_cur_vm_operation != NULL);
485 }
486 // There is a chance that a thread enqueued a safepoint op
487 // since we released the op-queue lock and initiated the safepoint.
488 // So we drain the queue again if there is anything there, as an
489 // optimization to try and reduce the number of safepoints.
490 // As the safepoint synchronizes us with JavaThreads we will see
491 // any enqueue made by a JavaThread, but the peek will not
492 // necessarily detect a concurrent enqueue by a GC thread, but
493 // that simply means the op will wait for the next major cycle of the
494 // VMThread - just as it would if the GC thread lost the race for
495 // the lock.
496 if (_vm_queue->peek_at_safepoint_priority()) {
497 // must hold lock while draining queue
498 MutexLockerEx mu_queue(VMOperationQueue_lock,
499 Mutex::_no_safepoint_check_flag);
500 safepoint_ops = _vm_queue->drain_at_safepoint_priority();
501 } else {
502 safepoint_ops = NULL;
503 }
504 } while(safepoint_ops != NULL);
506 _vm_queue->set_drain_list(NULL);
508 // Complete safepoint synchronization
509 SafepointSynchronize::end();
511 } else { // not a safepoint operation
512 if (TraceLongCompiles) {
513 elapsedTimer t;
514 t.start();
515 evaluate_operation(_cur_vm_operation);
516 t.stop();
517 double secs = t.seconds();
518 if (secs * 1e3 > LongCompileThreshold) {
519 // XXX - _cur_vm_operation should not be accessed after
520 // the completed count has been incremented; the waiting
521 // thread may have already freed this memory.
522 tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs);
523 }
524 } else {
525 evaluate_operation(_cur_vm_operation);
526 }
528 _cur_vm_operation = NULL;
529 }
530 }
532 //
533 // Notify (potential) waiting Java thread(s) - lock without safepoint
534 // check so that sneaking is not possible
535 { MutexLockerEx mu(VMOperationRequest_lock,
536 Mutex::_no_safepoint_check_flag);
537 VMOperationRequest_lock->notify_all();
538 }
540 //
541 // We want to make sure that we get to a safepoint regularly.
542 //
543 if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) {
544 long interval = SafepointSynchronize::last_non_safepoint_interval();
545 bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval);
546 if (SafepointALot || max_time_exceeded) {
547 HandleMark hm(VMThread::vm_thread());
548 SafepointSynchronize::begin();
549 SafepointSynchronize::end();
550 }
551 }
552 }
553 }
555 void VMThread::execute(VM_Operation* op) {
556 Thread* t = Thread::current();
558 if (!t->is_VM_thread()) {
559 SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot
560 // JavaThread or WatcherThread
561 t->check_for_valid_safepoint_state(true);
563 // New request from Java thread, evaluate prologue
564 if (!op->doit_prologue()) {
565 return; // op was cancelled
566 }
568 // Setup VM_operations for execution
569 op->set_calling_thread(t, Thread::get_priority(t));
571 // It does not make sense to execute the epilogue, if the VM operation object is getting
572 // deallocated by the VM thread.
573 bool concurrent = op->evaluate_concurrently();
574 bool execute_epilog = !op->is_cheap_allocated();
575 assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated");
577 // Get ticket number for non-concurrent VM operations
578 int ticket = 0;
579 if (!concurrent) {
580 ticket = t->vm_operation_ticket();
581 }
583 // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the
584 // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests
585 // to be queued up during a safepoint synchronization.
586 {
587 VMOperationQueue_lock->lock_without_safepoint_check();
588 bool ok = _vm_queue->add(op);
589 op->set_timestamp(os::javaTimeMillis());
590 VMOperationQueue_lock->notify();
591 VMOperationQueue_lock->unlock();
592 // VM_Operation got skipped
593 if (!ok) {
594 assert(concurrent, "can only skip concurrent tasks");
595 if (op->is_cheap_allocated()) delete op;
596 return;
597 }
598 }
600 if (!concurrent) {
601 // Wait for completion of request (non-concurrent)
602 // Note: only a JavaThread triggers the safepoint check when locking
603 MutexLocker mu(VMOperationRequest_lock);
604 while(t->vm_operation_completed_count() < ticket) {
605 VMOperationRequest_lock->wait(!t->is_Java_thread());
606 }
607 }
609 if (execute_epilog) {
610 op->doit_epilogue();
611 }
612 } else {
613 // invoked by VM thread; usually nested VM operation
614 assert(t->is_VM_thread(), "must be a VM thread");
615 VM_Operation* prev_vm_operation = vm_operation();
616 if (prev_vm_operation != NULL) {
617 // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler
618 // does not allow nested scavenges or compiles.
619 if (!prev_vm_operation->allow_nested_vm_operations()) {
620 fatal(err_msg("Nested VM operation %s requested by operation %s",
621 op->name(), vm_operation()->name()));
622 }
623 op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority());
624 }
626 EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name());
628 // Release all internal handles after operation is evaluated
629 HandleMark hm(t);
630 _cur_vm_operation = op;
632 if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) {
633 SafepointSynchronize::begin();
634 op->evaluate();
635 SafepointSynchronize::end();
636 } else {
637 op->evaluate();
638 }
640 // Free memory if needed
641 if (op->is_cheap_allocated()) delete op;
643 _cur_vm_operation = prev_vm_operation;
644 }
645 }
648 void VMThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
649 Thread::oops_do(f, cf);
650 _vm_queue->oops_do(f);
651 }
653 //------------------------------------------------------------------------------------------------------------------
654 #ifndef PRODUCT
656 void VMOperationQueue::verify_queue(int prio) {
657 // Check that list is correctly linked
658 int length = _queue_length[prio];
659 VM_Operation *cur = _queue[prio];
660 int i;
662 // Check forward links
663 for(i = 0; i < length; i++) {
664 cur = cur->next();
665 assert(cur != _queue[prio], "list to short (forward)");
666 }
667 assert(cur->next() == _queue[prio], "list to long (forward)");
669 // Check backwards links
670 cur = _queue[prio];
671 for(i = 0; i < length; i++) {
672 cur = cur->prev();
673 assert(cur != _queue[prio], "list to short (backwards)");
674 }
675 assert(cur->prev() == _queue[prio], "list to long (backwards)");
676 }
678 #endif
680 void VMThread::verify() {
681 oops_do(&VerifyOopClosure::verify_oop, NULL);
682 }