Mercurial > hg > truffle
annotate src/share/vm/runtime/vmThread.cpp @ 14199:49a31fd8b93d
8025277: Add -XX: flag to print code cache sweeper statistics
Summary: New diagnostic flag prints statistics about the code cache sweeper
Reviewed-by: kvn
Contributed-by: tobi.hartmann@gmail.com
author | anoll |
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date | Thu, 19 Dec 2013 14:08:02 +0100 |
parents | f2110083203d |
children | e6195383bcaf be0ac0e8f6e7 21dd1c827123 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "compiler/compileBroker.hpp" | |
27 #include "gc_interface/collectedHeap.hpp" | |
28 #include "memory/resourceArea.hpp" | |
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29 #include "oops/method.hpp" |
1972 | 30 #include "oops/oop.inline.hpp" |
31 #include "runtime/interfaceSupport.hpp" | |
32 #include "runtime/mutexLocker.hpp" | |
33 #include "runtime/os.hpp" | |
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34 #include "runtime/thread.inline.hpp" |
1972 | 35 #include "runtime/vmThread.hpp" |
36 #include "runtime/vm_operations.hpp" | |
37 #include "services/runtimeService.hpp" | |
10405 | 38 #include "trace/tracing.hpp" |
1972 | 39 #include "utilities/dtrace.hpp" |
40 #include "utilities/events.hpp" | |
41 #include "utilities/xmlstream.hpp" | |
0 | 42 |
4006 | 43 #ifndef USDT2 |
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44 HS_DTRACE_PROBE_DECL3(hotspot, vmops__request, char *, uintptr_t, int); |
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45 HS_DTRACE_PROBE_DECL3(hotspot, vmops__begin, char *, uintptr_t, int); |
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46 HS_DTRACE_PROBE_DECL3(hotspot, vmops__end, char *, uintptr_t, int); |
4006 | 47 #endif /* !USDT2 */ |
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48 |
0 | 49 // Dummy VM operation to act as first element in our circular double-linked list |
50 class VM_Dummy: public VM_Operation { | |
51 VMOp_Type type() const { return VMOp_Dummy; } | |
52 void doit() {}; | |
53 }; | |
54 | |
55 VMOperationQueue::VMOperationQueue() { | |
56 // The queue is a circular doubled-linked list, which always contains | |
57 // one element (i.e., one element means empty). | |
58 for(int i = 0; i < nof_priorities; i++) { | |
59 _queue_length[i] = 0; | |
60 _queue_counter = 0; | |
61 _queue[i] = new VM_Dummy(); | |
62 _queue[i]->set_next(_queue[i]); | |
63 _queue[i]->set_prev(_queue[i]); | |
64 } | |
65 _drain_list = NULL; | |
66 } | |
67 | |
68 | |
69 bool VMOperationQueue::queue_empty(int prio) { | |
70 // It is empty if there is exactly one element | |
71 bool empty = (_queue[prio] == _queue[prio]->next()); | |
72 assert( (_queue_length[prio] == 0 && empty) || | |
73 (_queue_length[prio] > 0 && !empty), "sanity check"); | |
74 return _queue_length[prio] == 0; | |
75 } | |
76 | |
77 // Inserts an element to the right of the q element | |
78 void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) { | |
79 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); | |
80 n->set_prev(q); | |
81 n->set_next(q->next()); | |
82 q->next()->set_prev(n); | |
83 q->set_next(n); | |
84 } | |
85 | |
86 void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) { | |
87 _queue_length[prio]++; | |
88 insert(_queue[prio]->next(), op); | |
89 } | |
90 | |
91 void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) { | |
92 _queue_length[prio]++; | |
93 insert(_queue[prio]->prev(), op); | |
94 } | |
95 | |
96 | |
97 void VMOperationQueue::unlink(VM_Operation* q) { | |
98 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); | |
99 q->prev()->set_next(q->next()); | |
100 q->next()->set_prev(q->prev()); | |
101 } | |
102 | |
103 VM_Operation* VMOperationQueue::queue_remove_front(int prio) { | |
104 if (queue_empty(prio)) return NULL; | |
105 assert(_queue_length[prio] >= 0, "sanity check"); | |
106 _queue_length[prio]--; | |
107 VM_Operation* r = _queue[prio]->next(); | |
108 assert(r != _queue[prio], "cannot remove base element"); | |
109 unlink(r); | |
110 return r; | |
111 } | |
112 | |
113 VM_Operation* VMOperationQueue::queue_drain(int prio) { | |
114 if (queue_empty(prio)) return NULL; | |
115 DEBUG_ONLY(int length = _queue_length[prio];); | |
116 assert(length >= 0, "sanity check"); | |
117 _queue_length[prio] = 0; | |
118 VM_Operation* r = _queue[prio]->next(); | |
119 assert(r != _queue[prio], "cannot remove base element"); | |
120 // remove links to base element from head and tail | |
121 r->set_prev(NULL); | |
122 _queue[prio]->prev()->set_next(NULL); | |
123 // restore queue to empty state | |
124 _queue[prio]->set_next(_queue[prio]); | |
125 _queue[prio]->set_prev(_queue[prio]); | |
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126 assert(queue_empty(prio), "drain corrupted queue"); |
9152 | 127 #ifdef ASSERT |
0 | 128 int len = 0; |
129 VM_Operation* cur; | |
130 for(cur = r; cur != NULL; cur=cur->next()) len++; | |
131 assert(len == length, "drain lost some ops"); | |
132 #endif | |
133 return r; | |
134 } | |
135 | |
136 void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) { | |
137 VM_Operation* cur = _queue[queue]; | |
138 cur = cur->next(); | |
139 while (cur != _queue[queue]) { | |
140 cur->oops_do(f); | |
141 cur = cur->next(); | |
142 } | |
143 } | |
144 | |
145 void VMOperationQueue::drain_list_oops_do(OopClosure* f) { | |
146 VM_Operation* cur = _drain_list; | |
147 while (cur != NULL) { | |
148 cur->oops_do(f); | |
149 cur = cur->next(); | |
150 } | |
151 } | |
152 | |
153 //----------------------------------------------------------------- | |
154 // High-level interface | |
155 bool VMOperationQueue::add(VM_Operation *op) { | |
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156 |
4006 | 157 #ifndef USDT2 |
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158 HS_DTRACE_PROBE3(hotspot, vmops__request, op->name(), strlen(op->name()), |
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159 op->evaluation_mode()); |
4006 | 160 #else /* USDT2 */ |
161 HOTSPOT_VMOPS_REQUEST( | |
162 (char *) op->name(), strlen(op->name()), | |
163 op->evaluation_mode()); | |
164 #endif /* USDT2 */ | |
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165 |
0 | 166 // Encapsulates VM queue policy. Currently, that |
167 // only involves putting them on the right list | |
168 if (op->evaluate_at_safepoint()) { | |
169 queue_add_back(SafepointPriority, op); | |
170 return true; | |
171 } | |
172 | |
173 queue_add_back(MediumPriority, op); | |
174 return true; | |
175 } | |
176 | |
177 VM_Operation* VMOperationQueue::remove_next() { | |
178 // Assuming VMOperation queue is two-level priority queue. If there are | |
179 // more than two priorities, we need a different scheduling algorithm. | |
180 assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2, | |
181 "current algorithm does not work"); | |
182 | |
183 // simple counter based scheduling to prevent starvation of lower priority | |
184 // queue. -- see 4390175 | |
185 int high_prio, low_prio; | |
186 if (_queue_counter++ < 10) { | |
187 high_prio = SafepointPriority; | |
188 low_prio = MediumPriority; | |
189 } else { | |
190 _queue_counter = 0; | |
191 high_prio = MediumPriority; | |
192 low_prio = SafepointPriority; | |
193 } | |
194 | |
195 return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio); | |
196 } | |
197 | |
198 void VMOperationQueue::oops_do(OopClosure* f) { | |
199 for(int i = 0; i < nof_priorities; i++) { | |
200 queue_oops_do(i, f); | |
201 } | |
202 drain_list_oops_do(f); | |
203 } | |
204 | |
205 | |
206 //------------------------------------------------------------------------------------------------------------------ | |
207 // Implementation of VMThread stuff | |
208 | |
209 bool VMThread::_should_terminate = false; | |
210 bool VMThread::_terminated = false; | |
211 Monitor* VMThread::_terminate_lock = NULL; | |
212 VMThread* VMThread::_vm_thread = NULL; | |
213 VM_Operation* VMThread::_cur_vm_operation = NULL; | |
214 VMOperationQueue* VMThread::_vm_queue = NULL; | |
215 PerfCounter* VMThread::_perf_accumulated_vm_operation_time = NULL; | |
216 | |
217 | |
218 void VMThread::create() { | |
219 assert(vm_thread() == NULL, "we can only allocate one VMThread"); | |
220 _vm_thread = new VMThread(); | |
221 | |
222 // Create VM operation queue | |
223 _vm_queue = new VMOperationQueue(); | |
224 guarantee(_vm_queue != NULL, "just checking"); | |
225 | |
226 _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true); | |
227 | |
228 if (UsePerfData) { | |
229 // jvmstat performance counters | |
230 Thread* THREAD = Thread::current(); | |
231 _perf_accumulated_vm_operation_time = | |
232 PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime", | |
233 PerfData::U_Ticks, CHECK); | |
234 } | |
235 } | |
236 | |
237 | |
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238 VMThread::VMThread() : NamedThread() { |
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239 set_name("VM Thread"); |
0 | 240 } |
241 | |
242 void VMThread::destroy() { | |
243 if (_vm_thread != NULL) { | |
244 delete _vm_thread; | |
245 _vm_thread = NULL; // VM thread is gone | |
246 } | |
247 } | |
248 | |
249 void VMThread::run() { | |
250 assert(this == vm_thread(), "check"); | |
251 | |
252 this->initialize_thread_local_storage(); | |
253 this->record_stack_base_and_size(); | |
254 // Notify_lock wait checks on active_handles() to rewait in | |
255 // case of spurious wakeup, it should wait on the last | |
256 // value set prior to the notify | |
257 this->set_active_handles(JNIHandleBlock::allocate_block()); | |
258 | |
259 { | |
260 MutexLocker ml(Notify_lock); | |
261 Notify_lock->notify(); | |
262 } | |
263 // Notify_lock is destroyed by Threads::create_vm() | |
264 | |
265 int prio = (VMThreadPriority == -1) | |
266 ? os::java_to_os_priority[NearMaxPriority] | |
267 : VMThreadPriority; | |
268 // Note that I cannot call os::set_priority because it expects Java | |
269 // priorities and I am *explicitly* using OS priorities so that it's | |
270 // possible to set the VM thread priority higher than any Java thread. | |
271 os::set_native_priority( this, prio ); | |
272 | |
273 // Wait for VM_Operations until termination | |
274 this->loop(); | |
275 | |
276 // Note the intention to exit before safepointing. | |
277 // 6295565 This has the effect of waiting for any large tty | |
278 // outputs to finish. | |
279 if (xtty != NULL) { | |
280 ttyLocker ttyl; | |
281 xtty->begin_elem("destroy_vm"); | |
282 xtty->stamp(); | |
283 xtty->end_elem(); | |
284 assert(should_terminate(), "termination flag must be set"); | |
285 } | |
286 | |
287 // 4526887 let VM thread exit at Safepoint | |
288 SafepointSynchronize::begin(); | |
289 | |
290 if (VerifyBeforeExit) { | |
291 HandleMark hm(VMThread::vm_thread()); | |
292 // Among other things, this ensures that Eden top is correct. | |
293 Universe::heap()->prepare_for_verify(); | |
294 os::check_heap(); | |
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295 // Silent verification so as not to pollute normal output, |
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296 // unless we really asked for it. |
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297 Universe::verify(!(PrintGCDetails || Verbose) || VerifySilently); |
0 | 298 } |
299 | |
300 CompileBroker::set_should_block(); | |
301 | |
302 // wait for threads (compiler threads or daemon threads) in the | |
303 // _thread_in_native state to block. | |
304 VM_Exit::wait_for_threads_in_native_to_block(); | |
305 | |
306 // signal other threads that VM process is gone | |
307 { | |
308 // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows | |
309 // VM thread to enter any lock at Safepoint as long as its _owner is NULL. | |
310 // If that happens after _terminate_lock->wait() has unset _owner | |
311 // but before it actually drops the lock and waits, the notification below | |
312 // may get lost and we will have a hang. To avoid this, we need to use | |
313 // Mutex::lock_without_safepoint_check(). | |
314 MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag); | |
315 _terminated = true; | |
316 _terminate_lock->notify(); | |
317 } | |
318 | |
319 // Deletion must be done synchronously by the JNI DestroyJavaVM thread | |
320 // so that the VMThread deletion completes before the main thread frees | |
321 // up the CodeHeap. | |
322 | |
323 } | |
324 | |
325 | |
326 // Notify the VMThread that the last non-daemon JavaThread has terminated, | |
327 // and wait until operation is performed. | |
328 void VMThread::wait_for_vm_thread_exit() { | |
329 { MutexLocker mu(VMOperationQueue_lock); | |
330 _should_terminate = true; | |
331 VMOperationQueue_lock->notify(); | |
332 } | |
333 | |
334 // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint | |
335 // because this thread has been removed from the threads list. But anything | |
336 // that could get blocked by Safepoint should not be used after this point, | |
337 // otherwise we will hang, since there is no one can end the safepoint. | |
338 | |
339 // Wait until VM thread is terminated | |
340 // Note: it should be OK to use Terminator_lock here. But this is called | |
341 // at a very delicate time (VM shutdown) and we are operating in non- VM | |
342 // thread at Safepoint. It's safer to not share lock with other threads. | |
343 { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag); | |
344 while(!VMThread::is_terminated()) { | |
345 _terminate_lock->wait(Mutex::_no_safepoint_check_flag); | |
346 } | |
347 } | |
348 } | |
349 | |
350 void VMThread::print_on(outputStream* st) const { | |
351 st->print("\"%s\" ", name()); | |
352 Thread::print_on(st); | |
353 st->cr(); | |
354 } | |
355 | |
356 void VMThread::evaluate_operation(VM_Operation* op) { | |
357 ResourceMark rm; | |
358 | |
359 { | |
360 PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time()); | |
4006 | 361 #ifndef USDT2 |
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362 HS_DTRACE_PROBE3(hotspot, vmops__begin, op->name(), strlen(op->name()), |
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363 op->evaluation_mode()); |
4006 | 364 #else /* USDT2 */ |
365 HOTSPOT_VMOPS_BEGIN( | |
366 (char *) op->name(), strlen(op->name()), | |
367 op->evaluation_mode()); | |
368 #endif /* USDT2 */ | |
10405 | 369 |
370 EventExecuteVMOperation event; | |
371 | |
0 | 372 op->evaluate(); |
10405 | 373 |
374 if (event.should_commit()) { | |
375 bool is_concurrent = op->evaluate_concurrently(); | |
376 event.set_operation(op->type()); | |
377 event.set_safepoint(op->evaluate_at_safepoint()); | |
378 event.set_blocking(!is_concurrent); | |
379 // Only write caller thread information for non-concurrent vm operations. | |
380 // For concurrent vm operations, the thread id is set to 0 indicating thread is unknown. | |
381 // This is because the caller thread could have exited already. | |
382 event.set_caller(is_concurrent ? 0 : op->calling_thread()->osthread()->thread_id()); | |
383 event.commit(); | |
384 } | |
385 | |
4006 | 386 #ifndef USDT2 |
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387 HS_DTRACE_PROBE3(hotspot, vmops__end, op->name(), strlen(op->name()), |
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388 op->evaluation_mode()); |
4006 | 389 #else /* USDT2 */ |
390 HOTSPOT_VMOPS_END( | |
391 (char *) op->name(), strlen(op->name()), | |
392 op->evaluation_mode()); | |
393 #endif /* USDT2 */ | |
0 | 394 } |
395 | |
396 // Last access of info in _cur_vm_operation! | |
397 bool c_heap_allocated = op->is_cheap_allocated(); | |
398 | |
399 // Mark as completed | |
400 if (!op->evaluate_concurrently()) { | |
401 op->calling_thread()->increment_vm_operation_completed_count(); | |
402 } | |
403 // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call, | |
404 // since if it is stack allocated the calling thread might have deallocated | |
405 if (c_heap_allocated) { | |
406 delete _cur_vm_operation; | |
407 } | |
408 } | |
409 | |
410 | |
411 void VMThread::loop() { | |
412 assert(_cur_vm_operation == NULL, "no current one should be executing"); | |
413 | |
414 while(true) { | |
415 VM_Operation* safepoint_ops = NULL; | |
416 // | |
417 // Wait for VM operation | |
418 // | |
419 // use no_safepoint_check to get lock without attempting to "sneak" | |
420 { MutexLockerEx mu_queue(VMOperationQueue_lock, | |
421 Mutex::_no_safepoint_check_flag); | |
422 | |
423 // Look for new operation | |
424 assert(_cur_vm_operation == NULL, "no current one should be executing"); | |
425 _cur_vm_operation = _vm_queue->remove_next(); | |
426 | |
427 // Stall time tracking code | |
428 if (PrintVMQWaitTime && _cur_vm_operation != NULL && | |
429 !_cur_vm_operation->evaluate_concurrently()) { | |
430 long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp(); | |
431 if (stall > 0) | |
432 tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall); | |
433 } | |
434 | |
435 while (!should_terminate() && _cur_vm_operation == NULL) { | |
436 // wait with a timeout to guarantee safepoints at regular intervals | |
437 bool timedout = | |
438 VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag, | |
439 GuaranteedSafepointInterval); | |
440 | |
441 // Support for self destruction | |
442 if ((SelfDestructTimer != 0) && !is_error_reported() && | |
443 (os::elapsedTime() > SelfDestructTimer * 60)) { | |
444 tty->print_cr("VM self-destructed"); | |
445 exit(-1); | |
446 } | |
447 | |
448 if (timedout && (SafepointALot || | |
449 SafepointSynchronize::is_cleanup_needed())) { | |
450 MutexUnlockerEx mul(VMOperationQueue_lock, | |
451 Mutex::_no_safepoint_check_flag); | |
452 // Force a safepoint since we have not had one for at least | |
453 // 'GuaranteedSafepointInterval' milliseconds. This will run all | |
454 // the clean-up processing that needs to be done regularly at a | |
455 // safepoint | |
456 SafepointSynchronize::begin(); | |
457 #ifdef ASSERT | |
458 if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot(); | |
459 #endif | |
460 SafepointSynchronize::end(); | |
461 } | |
462 _cur_vm_operation = _vm_queue->remove_next(); | |
463 | |
464 // If we are at a safepoint we will evaluate all the operations that | |
465 // follow that also require a safepoint | |
466 if (_cur_vm_operation != NULL && | |
467 _cur_vm_operation->evaluate_at_safepoint()) { | |
468 safepoint_ops = _vm_queue->drain_at_safepoint_priority(); | |
469 } | |
470 } | |
471 | |
472 if (should_terminate()) break; | |
473 } // Release mu_queue_lock | |
474 | |
475 // | |
476 // Execute VM operation | |
477 // | |
478 { HandleMark hm(VMThread::vm_thread()); | |
479 | |
480 EventMark em("Executing VM operation: %s", vm_operation()->name()); | |
481 assert(_cur_vm_operation != NULL, "we should have found an operation to execute"); | |
482 | |
483 // Give the VM thread an extra quantum. Jobs tend to be bursty and this | |
484 // helps the VM thread to finish up the job. | |
485 // FIXME: When this is enabled and there are many threads, this can degrade | |
486 // performance significantly. | |
487 if( VMThreadHintNoPreempt ) | |
488 os::hint_no_preempt(); | |
489 | |
490 // If we are at a safepoint we will evaluate all the operations that | |
491 // follow that also require a safepoint | |
492 if (_cur_vm_operation->evaluate_at_safepoint()) { | |
493 | |
494 _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned | |
495 | |
496 SafepointSynchronize::begin(); | |
497 evaluate_operation(_cur_vm_operation); | |
498 // now process all queued safepoint ops, iteratively draining | |
499 // the queue until there are none left | |
500 do { | |
501 _cur_vm_operation = safepoint_ops; | |
502 if (_cur_vm_operation != NULL) { | |
503 do { | |
504 // evaluate_operation deletes the op object so we have | |
505 // to grab the next op now | |
506 VM_Operation* next = _cur_vm_operation->next(); | |
507 _vm_queue->set_drain_list(next); | |
508 evaluate_operation(_cur_vm_operation); | |
509 _cur_vm_operation = next; | |
510 if (PrintSafepointStatistics) { | |
511 SafepointSynchronize::inc_vmop_coalesced_count(); | |
512 } | |
513 } while (_cur_vm_operation != NULL); | |
514 } | |
515 // There is a chance that a thread enqueued a safepoint op | |
516 // since we released the op-queue lock and initiated the safepoint. | |
517 // So we drain the queue again if there is anything there, as an | |
518 // optimization to try and reduce the number of safepoints. | |
519 // As the safepoint synchronizes us with JavaThreads we will see | |
520 // any enqueue made by a JavaThread, but the peek will not | |
521 // necessarily detect a concurrent enqueue by a GC thread, but | |
522 // that simply means the op will wait for the next major cycle of the | |
523 // VMThread - just as it would if the GC thread lost the race for | |
524 // the lock. | |
525 if (_vm_queue->peek_at_safepoint_priority()) { | |
526 // must hold lock while draining queue | |
527 MutexLockerEx mu_queue(VMOperationQueue_lock, | |
528 Mutex::_no_safepoint_check_flag); | |
529 safepoint_ops = _vm_queue->drain_at_safepoint_priority(); | |
530 } else { | |
531 safepoint_ops = NULL; | |
532 } | |
533 } while(safepoint_ops != NULL); | |
534 | |
535 _vm_queue->set_drain_list(NULL); | |
536 | |
537 // Complete safepoint synchronization | |
538 SafepointSynchronize::end(); | |
539 | |
540 } else { // not a safepoint operation | |
541 if (TraceLongCompiles) { | |
542 elapsedTimer t; | |
543 t.start(); | |
544 evaluate_operation(_cur_vm_operation); | |
545 t.stop(); | |
546 double secs = t.seconds(); | |
547 if (secs * 1e3 > LongCompileThreshold) { | |
548 // XXX - _cur_vm_operation should not be accessed after | |
549 // the completed count has been incremented; the waiting | |
550 // thread may have already freed this memory. | |
551 tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs); | |
552 } | |
553 } else { | |
554 evaluate_operation(_cur_vm_operation); | |
555 } | |
556 | |
557 _cur_vm_operation = NULL; | |
558 } | |
559 } | |
560 | |
561 // | |
562 // Notify (potential) waiting Java thread(s) - lock without safepoint | |
563 // check so that sneaking is not possible | |
564 { MutexLockerEx mu(VMOperationRequest_lock, | |
565 Mutex::_no_safepoint_check_flag); | |
566 VMOperationRequest_lock->notify_all(); | |
567 } | |
568 | |
569 // | |
570 // We want to make sure that we get to a safepoint regularly. | |
571 // | |
572 if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) { | |
573 long interval = SafepointSynchronize::last_non_safepoint_interval(); | |
574 bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval); | |
575 if (SafepointALot || max_time_exceeded) { | |
576 HandleMark hm(VMThread::vm_thread()); | |
577 SafepointSynchronize::begin(); | |
578 SafepointSynchronize::end(); | |
579 } | |
580 } | |
581 } | |
582 } | |
583 | |
584 void VMThread::execute(VM_Operation* op) { | |
585 Thread* t = Thread::current(); | |
586 | |
587 if (!t->is_VM_thread()) { | |
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588 SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot |
0 | 589 // JavaThread or WatcherThread |
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590 bool concurrent = op->evaluate_concurrently(); |
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591 // only blocking VM operations need to verify the caller's safepoint state: |
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592 if (!concurrent) { |
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593 t->check_for_valid_safepoint_state(true); |
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594 } |
0 | 595 |
596 // New request from Java thread, evaluate prologue | |
597 if (!op->doit_prologue()) { | |
598 return; // op was cancelled | |
599 } | |
600 | |
601 // Setup VM_operations for execution | |
602 op->set_calling_thread(t, Thread::get_priority(t)); | |
603 | |
604 // It does not make sense to execute the epilogue, if the VM operation object is getting | |
605 // deallocated by the VM thread. | |
606 bool execute_epilog = !op->is_cheap_allocated(); | |
607 assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated"); | |
608 | |
609 // Get ticket number for non-concurrent VM operations | |
610 int ticket = 0; | |
611 if (!concurrent) { | |
612 ticket = t->vm_operation_ticket(); | |
613 } | |
614 | |
615 // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the | |
616 // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests | |
617 // to be queued up during a safepoint synchronization. | |
618 { | |
619 VMOperationQueue_lock->lock_without_safepoint_check(); | |
620 bool ok = _vm_queue->add(op); | |
10405 | 621 op->set_timestamp(os::javaTimeMillis()); |
0 | 622 VMOperationQueue_lock->notify(); |
623 VMOperationQueue_lock->unlock(); | |
624 // VM_Operation got skipped | |
625 if (!ok) { | |
626 assert(concurrent, "can only skip concurrent tasks"); | |
627 if (op->is_cheap_allocated()) delete op; | |
628 return; | |
629 } | |
630 } | |
631 | |
632 if (!concurrent) { | |
633 // Wait for completion of request (non-concurrent) | |
634 // Note: only a JavaThread triggers the safepoint check when locking | |
635 MutexLocker mu(VMOperationRequest_lock); | |
636 while(t->vm_operation_completed_count() < ticket) { | |
637 VMOperationRequest_lock->wait(!t->is_Java_thread()); | |
638 } | |
639 } | |
640 | |
641 if (execute_epilog) { | |
642 op->doit_epilogue(); | |
643 } | |
644 } else { | |
645 // invoked by VM thread; usually nested VM operation | |
646 assert(t->is_VM_thread(), "must be a VM thread"); | |
647 VM_Operation* prev_vm_operation = vm_operation(); | |
648 if (prev_vm_operation != NULL) { | |
649 // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler | |
650 // does not allow nested scavenges or compiles. | |
651 if (!prev_vm_operation->allow_nested_vm_operations()) { | |
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652 fatal(err_msg("Nested VM operation %s requested by operation %s", |
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653 op->name(), vm_operation()->name())); |
0 | 654 } |
655 op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority()); | |
656 } | |
657 | |
658 EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name()); | |
659 | |
660 // Release all internal handles after operation is evaluated | |
661 HandleMark hm(t); | |
662 _cur_vm_operation = op; | |
663 | |
664 if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) { | |
665 SafepointSynchronize::begin(); | |
666 op->evaluate(); | |
667 SafepointSynchronize::end(); | |
668 } else { | |
669 op->evaluate(); | |
670 } | |
671 | |
672 // Free memory if needed | |
673 if (op->is_cheap_allocated()) delete op; | |
674 | |
675 _cur_vm_operation = prev_vm_operation; | |
676 } | |
677 } | |
678 | |
679 | |
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680 void VMThread::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) { |
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681 Thread::oops_do(f, cld_f, cf); |
0 | 682 _vm_queue->oops_do(f); |
683 } | |
684 | |
685 //------------------------------------------------------------------------------------------------------------------ | |
686 #ifndef PRODUCT | |
687 | |
688 void VMOperationQueue::verify_queue(int prio) { | |
689 // Check that list is correctly linked | |
690 int length = _queue_length[prio]; | |
691 VM_Operation *cur = _queue[prio]; | |
692 int i; | |
693 | |
694 // Check forward links | |
695 for(i = 0; i < length; i++) { | |
696 cur = cur->next(); | |
697 assert(cur != _queue[prio], "list to short (forward)"); | |
698 } | |
699 assert(cur->next() == _queue[prio], "list to long (forward)"); | |
700 | |
701 // Check backwards links | |
702 cur = _queue[prio]; | |
703 for(i = 0; i < length; i++) { | |
704 cur = cur->prev(); | |
705 assert(cur != _queue[prio], "list to short (backwards)"); | |
706 } | |
707 assert(cur->prev() == _queue[prio], "list to long (backwards)"); | |
708 } | |
709 | |
710 #endif | |
711 | |
712 void VMThread::verify() { | |
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713 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL); |
0 | 714 } |