Mercurial > hg > truffle
annotate src/share/vm/runtime/vmThread.cpp @ 4724:0841c0ec2ed6
7123810: new hotspot build - hs23-b10
Reviewed-by: jcoomes
author | amurillo |
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date | Fri, 23 Dec 2011 15:29:34 -0800 |
parents | 436b4a3231bf |
children | b632e80fc9dc |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1998, 2010, 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" | |
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 | |
3960 | 49 #ifdef TARGET_OS_FAMILY_bsd |
50 # include "thread_bsd.inline.hpp" | |
51 #endif | |
0 | 52 |
4006 | 53 #ifndef USDT2 |
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54 HS_DTRACE_PROBE_DECL3(hotspot, vmops__request, char *, uintptr_t, int); |
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55 HS_DTRACE_PROBE_DECL3(hotspot, vmops__begin, char *, uintptr_t, int); |
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56 HS_DTRACE_PROBE_DECL3(hotspot, vmops__end, char *, uintptr_t, int); |
4006 | 57 #endif /* !USDT2 */ |
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58 |
0 | 59 // Dummy VM operation to act as first element in our circular double-linked list |
60 class VM_Dummy: public VM_Operation { | |
61 VMOp_Type type() const { return VMOp_Dummy; } | |
62 void doit() {}; | |
63 }; | |
64 | |
65 VMOperationQueue::VMOperationQueue() { | |
66 // The queue is a circular doubled-linked list, which always contains | |
67 // one element (i.e., one element means empty). | |
68 for(int i = 0; i < nof_priorities; i++) { | |
69 _queue_length[i] = 0; | |
70 _queue_counter = 0; | |
71 _queue[i] = new VM_Dummy(); | |
72 _queue[i]->set_next(_queue[i]); | |
73 _queue[i]->set_prev(_queue[i]); | |
74 } | |
75 _drain_list = NULL; | |
76 } | |
77 | |
78 | |
79 bool VMOperationQueue::queue_empty(int prio) { | |
80 // It is empty if there is exactly one element | |
81 bool empty = (_queue[prio] == _queue[prio]->next()); | |
82 assert( (_queue_length[prio] == 0 && empty) || | |
83 (_queue_length[prio] > 0 && !empty), "sanity check"); | |
84 return _queue_length[prio] == 0; | |
85 } | |
86 | |
87 // Inserts an element to the right of the q element | |
88 void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) { | |
89 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); | |
90 n->set_prev(q); | |
91 n->set_next(q->next()); | |
92 q->next()->set_prev(n); | |
93 q->set_next(n); | |
94 } | |
95 | |
96 void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) { | |
97 _queue_length[prio]++; | |
98 insert(_queue[prio]->next(), op); | |
99 } | |
100 | |
101 void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) { | |
102 _queue_length[prio]++; | |
103 insert(_queue[prio]->prev(), op); | |
104 } | |
105 | |
106 | |
107 void VMOperationQueue::unlink(VM_Operation* q) { | |
108 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); | |
109 q->prev()->set_next(q->next()); | |
110 q->next()->set_prev(q->prev()); | |
111 } | |
112 | |
113 VM_Operation* VMOperationQueue::queue_remove_front(int prio) { | |
114 if (queue_empty(prio)) return NULL; | |
115 assert(_queue_length[prio] >= 0, "sanity check"); | |
116 _queue_length[prio]--; | |
117 VM_Operation* r = _queue[prio]->next(); | |
118 assert(r != _queue[prio], "cannot remove base element"); | |
119 unlink(r); | |
120 return r; | |
121 } | |
122 | |
123 VM_Operation* VMOperationQueue::queue_drain(int prio) { | |
124 if (queue_empty(prio)) return NULL; | |
125 DEBUG_ONLY(int length = _queue_length[prio];); | |
126 assert(length >= 0, "sanity check"); | |
127 _queue_length[prio] = 0; | |
128 VM_Operation* r = _queue[prio]->next(); | |
129 assert(r != _queue[prio], "cannot remove base element"); | |
130 // remove links to base element from head and tail | |
131 r->set_prev(NULL); | |
132 _queue[prio]->prev()->set_next(NULL); | |
133 // restore queue to empty state | |
134 _queue[prio]->set_next(_queue[prio]); | |
135 _queue[prio]->set_prev(_queue[prio]); | |
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136 assert(queue_empty(prio), "drain corrupted queue"); |
0 | 137 #ifdef DEBUG |
138 int len = 0; | |
139 VM_Operation* cur; | |
140 for(cur = r; cur != NULL; cur=cur->next()) len++; | |
141 assert(len == length, "drain lost some ops"); | |
142 #endif | |
143 return r; | |
144 } | |
145 | |
146 void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) { | |
147 VM_Operation* cur = _queue[queue]; | |
148 cur = cur->next(); | |
149 while (cur != _queue[queue]) { | |
150 cur->oops_do(f); | |
151 cur = cur->next(); | |
152 } | |
153 } | |
154 | |
155 void VMOperationQueue::drain_list_oops_do(OopClosure* f) { | |
156 VM_Operation* cur = _drain_list; | |
157 while (cur != NULL) { | |
158 cur->oops_do(f); | |
159 cur = cur->next(); | |
160 } | |
161 } | |
162 | |
163 //----------------------------------------------------------------- | |
164 // High-level interface | |
165 bool VMOperationQueue::add(VM_Operation *op) { | |
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166 |
4006 | 167 #ifndef USDT2 |
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168 HS_DTRACE_PROBE3(hotspot, vmops__request, op->name(), strlen(op->name()), |
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169 op->evaluation_mode()); |
4006 | 170 #else /* USDT2 */ |
171 HOTSPOT_VMOPS_REQUEST( | |
172 (char *) op->name(), strlen(op->name()), | |
173 op->evaluation_mode()); | |
174 #endif /* USDT2 */ | |
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175 |
0 | 176 // Encapsulates VM queue policy. Currently, that |
177 // only involves putting them on the right list | |
178 if (op->evaluate_at_safepoint()) { | |
179 queue_add_back(SafepointPriority, op); | |
180 return true; | |
181 } | |
182 | |
183 queue_add_back(MediumPriority, op); | |
184 return true; | |
185 } | |
186 | |
187 VM_Operation* VMOperationQueue::remove_next() { | |
188 // Assuming VMOperation queue is two-level priority queue. If there are | |
189 // more than two priorities, we need a different scheduling algorithm. | |
190 assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2, | |
191 "current algorithm does not work"); | |
192 | |
193 // simple counter based scheduling to prevent starvation of lower priority | |
194 // queue. -- see 4390175 | |
195 int high_prio, low_prio; | |
196 if (_queue_counter++ < 10) { | |
197 high_prio = SafepointPriority; | |
198 low_prio = MediumPriority; | |
199 } else { | |
200 _queue_counter = 0; | |
201 high_prio = MediumPriority; | |
202 low_prio = SafepointPriority; | |
203 } | |
204 | |
205 return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio); | |
206 } | |
207 | |
208 void VMOperationQueue::oops_do(OopClosure* f) { | |
209 for(int i = 0; i < nof_priorities; i++) { | |
210 queue_oops_do(i, f); | |
211 } | |
212 drain_list_oops_do(f); | |
213 } | |
214 | |
215 | |
216 //------------------------------------------------------------------------------------------------------------------ | |
217 // Implementation of VMThread stuff | |
218 | |
219 bool VMThread::_should_terminate = false; | |
220 bool VMThread::_terminated = false; | |
221 Monitor* VMThread::_terminate_lock = NULL; | |
222 VMThread* VMThread::_vm_thread = NULL; | |
223 VM_Operation* VMThread::_cur_vm_operation = NULL; | |
224 VMOperationQueue* VMThread::_vm_queue = NULL; | |
225 PerfCounter* VMThread::_perf_accumulated_vm_operation_time = NULL; | |
226 | |
227 | |
228 void VMThread::create() { | |
229 assert(vm_thread() == NULL, "we can only allocate one VMThread"); | |
230 _vm_thread = new VMThread(); | |
231 | |
232 // Create VM operation queue | |
233 _vm_queue = new VMOperationQueue(); | |
234 guarantee(_vm_queue != NULL, "just checking"); | |
235 | |
236 _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true); | |
237 | |
238 if (UsePerfData) { | |
239 // jvmstat performance counters | |
240 Thread* THREAD = Thread::current(); | |
241 _perf_accumulated_vm_operation_time = | |
242 PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime", | |
243 PerfData::U_Ticks, CHECK); | |
244 } | |
245 } | |
246 | |
247 | |
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248 VMThread::VMThread() : NamedThread() { |
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249 set_name("VM Thread"); |
0 | 250 } |
251 | |
252 void VMThread::destroy() { | |
253 if (_vm_thread != NULL) { | |
254 delete _vm_thread; | |
255 _vm_thread = NULL; // VM thread is gone | |
256 } | |
257 } | |
258 | |
259 void VMThread::run() { | |
260 assert(this == vm_thread(), "check"); | |
261 | |
262 this->initialize_thread_local_storage(); | |
263 this->record_stack_base_and_size(); | |
264 // Notify_lock wait checks on active_handles() to rewait in | |
265 // case of spurious wakeup, it should wait on the last | |
266 // value set prior to the notify | |
267 this->set_active_handles(JNIHandleBlock::allocate_block()); | |
268 | |
269 { | |
270 MutexLocker ml(Notify_lock); | |
271 Notify_lock->notify(); | |
272 } | |
273 // Notify_lock is destroyed by Threads::create_vm() | |
274 | |
275 int prio = (VMThreadPriority == -1) | |
276 ? os::java_to_os_priority[NearMaxPriority] | |
277 : VMThreadPriority; | |
278 // Note that I cannot call os::set_priority because it expects Java | |
279 // priorities and I am *explicitly* using OS priorities so that it's | |
280 // possible to set the VM thread priority higher than any Java thread. | |
281 os::set_native_priority( this, prio ); | |
282 | |
283 // Wait for VM_Operations until termination | |
284 this->loop(); | |
285 | |
286 // Note the intention to exit before safepointing. | |
287 // 6295565 This has the effect of waiting for any large tty | |
288 // outputs to finish. | |
289 if (xtty != NULL) { | |
290 ttyLocker ttyl; | |
291 xtty->begin_elem("destroy_vm"); | |
292 xtty->stamp(); | |
293 xtty->end_elem(); | |
294 assert(should_terminate(), "termination flag must be set"); | |
295 } | |
296 | |
297 // 4526887 let VM thread exit at Safepoint | |
298 SafepointSynchronize::begin(); | |
299 | |
300 if (VerifyBeforeExit) { | |
301 HandleMark hm(VMThread::vm_thread()); | |
302 // Among other things, this ensures that Eden top is correct. | |
303 Universe::heap()->prepare_for_verify(); | |
304 os::check_heap(); | |
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305 // Silent verification so as not to pollute normal output, |
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306 // unless we really asked for it. |
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307 Universe::verify(true, !(PrintGCDetails || Verbose)); |
0 | 308 } |
309 | |
310 CompileBroker::set_should_block(); | |
311 | |
312 // wait for threads (compiler threads or daemon threads) in the | |
313 // _thread_in_native state to block. | |
314 VM_Exit::wait_for_threads_in_native_to_block(); | |
315 | |
316 // signal other threads that VM process is gone | |
317 { | |
318 // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows | |
319 // VM thread to enter any lock at Safepoint as long as its _owner is NULL. | |
320 // If that happens after _terminate_lock->wait() has unset _owner | |
321 // but before it actually drops the lock and waits, the notification below | |
322 // may get lost and we will have a hang. To avoid this, we need to use | |
323 // Mutex::lock_without_safepoint_check(). | |
324 MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag); | |
325 _terminated = true; | |
326 _terminate_lock->notify(); | |
327 } | |
328 | |
329 // Deletion must be done synchronously by the JNI DestroyJavaVM thread | |
330 // so that the VMThread deletion completes before the main thread frees | |
331 // up the CodeHeap. | |
332 | |
333 } | |
334 | |
335 | |
336 // Notify the VMThread that the last non-daemon JavaThread has terminated, | |
337 // and wait until operation is performed. | |
338 void VMThread::wait_for_vm_thread_exit() { | |
339 { MutexLocker mu(VMOperationQueue_lock); | |
340 _should_terminate = true; | |
341 VMOperationQueue_lock->notify(); | |
342 } | |
343 | |
344 // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint | |
345 // because this thread has been removed from the threads list. But anything | |
346 // that could get blocked by Safepoint should not be used after this point, | |
347 // otherwise we will hang, since there is no one can end the safepoint. | |
348 | |
349 // Wait until VM thread is terminated | |
350 // Note: it should be OK to use Terminator_lock here. But this is called | |
351 // at a very delicate time (VM shutdown) and we are operating in non- VM | |
352 // thread at Safepoint. It's safer to not share lock with other threads. | |
353 { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag); | |
354 while(!VMThread::is_terminated()) { | |
355 _terminate_lock->wait(Mutex::_no_safepoint_check_flag); | |
356 } | |
357 } | |
358 } | |
359 | |
360 void VMThread::print_on(outputStream* st) const { | |
361 st->print("\"%s\" ", name()); | |
362 Thread::print_on(st); | |
363 st->cr(); | |
364 } | |
365 | |
366 void VMThread::evaluate_operation(VM_Operation* op) { | |
367 ResourceMark rm; | |
368 | |
369 { | |
370 PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time()); | |
4006 | 371 #ifndef USDT2 |
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372 HS_DTRACE_PROBE3(hotspot, vmops__begin, op->name(), strlen(op->name()), |
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373 op->evaluation_mode()); |
4006 | 374 #else /* USDT2 */ |
375 HOTSPOT_VMOPS_BEGIN( | |
376 (char *) op->name(), strlen(op->name()), | |
377 op->evaluation_mode()); | |
378 #endif /* USDT2 */ | |
0 | 379 op->evaluate(); |
4006 | 380 #ifndef USDT2 |
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381 HS_DTRACE_PROBE3(hotspot, vmops__end, op->name(), strlen(op->name()), |
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382 op->evaluation_mode()); |
4006 | 383 #else /* USDT2 */ |
384 HOTSPOT_VMOPS_END( | |
385 (char *) op->name(), strlen(op->name()), | |
386 op->evaluation_mode()); | |
387 #endif /* USDT2 */ | |
0 | 388 } |
389 | |
390 // Last access of info in _cur_vm_operation! | |
391 bool c_heap_allocated = op->is_cheap_allocated(); | |
392 | |
393 // Mark as completed | |
394 if (!op->evaluate_concurrently()) { | |
395 op->calling_thread()->increment_vm_operation_completed_count(); | |
396 } | |
397 // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call, | |
398 // since if it is stack allocated the calling thread might have deallocated | |
399 if (c_heap_allocated) { | |
400 delete _cur_vm_operation; | |
401 } | |
402 } | |
403 | |
404 | |
405 void VMThread::loop() { | |
406 assert(_cur_vm_operation == NULL, "no current one should be executing"); | |
407 | |
408 while(true) { | |
409 VM_Operation* safepoint_ops = NULL; | |
410 // | |
411 // Wait for VM operation | |
412 // | |
413 // use no_safepoint_check to get lock without attempting to "sneak" | |
414 { MutexLockerEx mu_queue(VMOperationQueue_lock, | |
415 Mutex::_no_safepoint_check_flag); | |
416 | |
417 // Look for new operation | |
418 assert(_cur_vm_operation == NULL, "no current one should be executing"); | |
419 _cur_vm_operation = _vm_queue->remove_next(); | |
420 | |
421 // Stall time tracking code | |
422 if (PrintVMQWaitTime && _cur_vm_operation != NULL && | |
423 !_cur_vm_operation->evaluate_concurrently()) { | |
424 long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp(); | |
425 if (stall > 0) | |
426 tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall); | |
427 } | |
428 | |
429 while (!should_terminate() && _cur_vm_operation == NULL) { | |
430 // wait with a timeout to guarantee safepoints at regular intervals | |
431 bool timedout = | |
432 VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag, | |
433 GuaranteedSafepointInterval); | |
434 | |
435 // Support for self destruction | |
436 if ((SelfDestructTimer != 0) && !is_error_reported() && | |
437 (os::elapsedTime() > SelfDestructTimer * 60)) { | |
438 tty->print_cr("VM self-destructed"); | |
439 exit(-1); | |
440 } | |
441 | |
442 if (timedout && (SafepointALot || | |
443 SafepointSynchronize::is_cleanup_needed())) { | |
444 MutexUnlockerEx mul(VMOperationQueue_lock, | |
445 Mutex::_no_safepoint_check_flag); | |
446 // Force a safepoint since we have not had one for at least | |
447 // 'GuaranteedSafepointInterval' milliseconds. This will run all | |
448 // the clean-up processing that needs to be done regularly at a | |
449 // safepoint | |
450 SafepointSynchronize::begin(); | |
451 #ifdef ASSERT | |
452 if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot(); | |
453 #endif | |
454 SafepointSynchronize::end(); | |
455 } | |
456 _cur_vm_operation = _vm_queue->remove_next(); | |
457 | |
458 // If we are at a safepoint we will evaluate all the operations that | |
459 // follow that also require a safepoint | |
460 if (_cur_vm_operation != NULL && | |
461 _cur_vm_operation->evaluate_at_safepoint()) { | |
462 safepoint_ops = _vm_queue->drain_at_safepoint_priority(); | |
463 } | |
464 } | |
465 | |
466 if (should_terminate()) break; | |
467 } // Release mu_queue_lock | |
468 | |
469 // | |
470 // Execute VM operation | |
471 // | |
472 { HandleMark hm(VMThread::vm_thread()); | |
473 | |
474 EventMark em("Executing VM operation: %s", vm_operation()->name()); | |
475 assert(_cur_vm_operation != NULL, "we should have found an operation to execute"); | |
476 | |
477 // Give the VM thread an extra quantum. Jobs tend to be bursty and this | |
478 // helps the VM thread to finish up the job. | |
479 // FIXME: When this is enabled and there are many threads, this can degrade | |
480 // performance significantly. | |
481 if( VMThreadHintNoPreempt ) | |
482 os::hint_no_preempt(); | |
483 | |
484 // If we are at a safepoint we will evaluate all the operations that | |
485 // follow that also require a safepoint | |
486 if (_cur_vm_operation->evaluate_at_safepoint()) { | |
487 | |
488 _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned | |
489 | |
490 SafepointSynchronize::begin(); | |
491 evaluate_operation(_cur_vm_operation); | |
492 // now process all queued safepoint ops, iteratively draining | |
493 // the queue until there are none left | |
494 do { | |
495 _cur_vm_operation = safepoint_ops; | |
496 if (_cur_vm_operation != NULL) { | |
497 do { | |
498 // evaluate_operation deletes the op object so we have | |
499 // to grab the next op now | |
500 VM_Operation* next = _cur_vm_operation->next(); | |
501 _vm_queue->set_drain_list(next); | |
502 evaluate_operation(_cur_vm_operation); | |
503 _cur_vm_operation = next; | |
504 if (PrintSafepointStatistics) { | |
505 SafepointSynchronize::inc_vmop_coalesced_count(); | |
506 } | |
507 } while (_cur_vm_operation != NULL); | |
508 } | |
509 // There is a chance that a thread enqueued a safepoint op | |
510 // since we released the op-queue lock and initiated the safepoint. | |
511 // So we drain the queue again if there is anything there, as an | |
512 // optimization to try and reduce the number of safepoints. | |
513 // As the safepoint synchronizes us with JavaThreads we will see | |
514 // any enqueue made by a JavaThread, but the peek will not | |
515 // necessarily detect a concurrent enqueue by a GC thread, but | |
516 // that simply means the op will wait for the next major cycle of the | |
517 // VMThread - just as it would if the GC thread lost the race for | |
518 // the lock. | |
519 if (_vm_queue->peek_at_safepoint_priority()) { | |
520 // must hold lock while draining queue | |
521 MutexLockerEx mu_queue(VMOperationQueue_lock, | |
522 Mutex::_no_safepoint_check_flag); | |
523 safepoint_ops = _vm_queue->drain_at_safepoint_priority(); | |
524 } else { | |
525 safepoint_ops = NULL; | |
526 } | |
527 } while(safepoint_ops != NULL); | |
528 | |
529 _vm_queue->set_drain_list(NULL); | |
530 | |
531 // Complete safepoint synchronization | |
532 SafepointSynchronize::end(); | |
533 | |
534 } else { // not a safepoint operation | |
535 if (TraceLongCompiles) { | |
536 elapsedTimer t; | |
537 t.start(); | |
538 evaluate_operation(_cur_vm_operation); | |
539 t.stop(); | |
540 double secs = t.seconds(); | |
541 if (secs * 1e3 > LongCompileThreshold) { | |
542 // XXX - _cur_vm_operation should not be accessed after | |
543 // the completed count has been incremented; the waiting | |
544 // thread may have already freed this memory. | |
545 tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs); | |
546 } | |
547 } else { | |
548 evaluate_operation(_cur_vm_operation); | |
549 } | |
550 | |
551 _cur_vm_operation = NULL; | |
552 } | |
553 } | |
554 | |
555 // | |
556 // Notify (potential) waiting Java thread(s) - lock without safepoint | |
557 // check so that sneaking is not possible | |
558 { MutexLockerEx mu(VMOperationRequest_lock, | |
559 Mutex::_no_safepoint_check_flag); | |
560 VMOperationRequest_lock->notify_all(); | |
561 } | |
562 | |
563 // | |
564 // We want to make sure that we get to a safepoint regularly. | |
565 // | |
566 if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) { | |
567 long interval = SafepointSynchronize::last_non_safepoint_interval(); | |
568 bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval); | |
569 if (SafepointALot || max_time_exceeded) { | |
570 HandleMark hm(VMThread::vm_thread()); | |
571 SafepointSynchronize::begin(); | |
572 SafepointSynchronize::end(); | |
573 } | |
574 } | |
575 } | |
576 } | |
577 | |
578 void VMThread::execute(VM_Operation* op) { | |
579 Thread* t = Thread::current(); | |
580 | |
581 if (!t->is_VM_thread()) { | |
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582 SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot |
0 | 583 // JavaThread or WatcherThread |
584 t->check_for_valid_safepoint_state(true); | |
585 | |
586 // New request from Java thread, evaluate prologue | |
587 if (!op->doit_prologue()) { | |
588 return; // op was cancelled | |
589 } | |
590 | |
591 // Setup VM_operations for execution | |
592 op->set_calling_thread(t, Thread::get_priority(t)); | |
593 | |
594 // It does not make sense to execute the epilogue, if the VM operation object is getting | |
595 // deallocated by the VM thread. | |
596 bool concurrent = op->evaluate_concurrently(); | |
597 bool execute_epilog = !op->is_cheap_allocated(); | |
598 assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated"); | |
599 | |
600 // Get ticket number for non-concurrent VM operations | |
601 int ticket = 0; | |
602 if (!concurrent) { | |
603 ticket = t->vm_operation_ticket(); | |
604 } | |
605 | |
606 // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the | |
607 // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests | |
608 // to be queued up during a safepoint synchronization. | |
609 { | |
610 VMOperationQueue_lock->lock_without_safepoint_check(); | |
611 bool ok = _vm_queue->add(op); | |
612 op->set_timestamp(os::javaTimeMillis()); | |
613 VMOperationQueue_lock->notify(); | |
614 VMOperationQueue_lock->unlock(); | |
615 // VM_Operation got skipped | |
616 if (!ok) { | |
617 assert(concurrent, "can only skip concurrent tasks"); | |
618 if (op->is_cheap_allocated()) delete op; | |
619 return; | |
620 } | |
621 } | |
622 | |
623 if (!concurrent) { | |
624 // Wait for completion of request (non-concurrent) | |
625 // Note: only a JavaThread triggers the safepoint check when locking | |
626 MutexLocker mu(VMOperationRequest_lock); | |
627 while(t->vm_operation_completed_count() < ticket) { | |
628 VMOperationRequest_lock->wait(!t->is_Java_thread()); | |
629 } | |
630 } | |
631 | |
632 if (execute_epilog) { | |
633 op->doit_epilogue(); | |
634 } | |
635 } else { | |
636 // invoked by VM thread; usually nested VM operation | |
637 assert(t->is_VM_thread(), "must be a VM thread"); | |
638 VM_Operation* prev_vm_operation = vm_operation(); | |
639 if (prev_vm_operation != NULL) { | |
640 // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler | |
641 // does not allow nested scavenges or compiles. | |
642 if (!prev_vm_operation->allow_nested_vm_operations()) { | |
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643 fatal(err_msg("Nested VM operation %s requested by operation %s", |
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644 op->name(), vm_operation()->name())); |
0 | 645 } |
646 op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority()); | |
647 } | |
648 | |
649 EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name()); | |
650 | |
651 // Release all internal handles after operation is evaluated | |
652 HandleMark hm(t); | |
653 _cur_vm_operation = op; | |
654 | |
655 if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) { | |
656 SafepointSynchronize::begin(); | |
657 op->evaluate(); | |
658 SafepointSynchronize::end(); | |
659 } else { | |
660 op->evaluate(); | |
661 } | |
662 | |
663 // Free memory if needed | |
664 if (op->is_cheap_allocated()) delete op; | |
665 | |
666 _cur_vm_operation = prev_vm_operation; | |
667 } | |
668 } | |
669 | |
670 | |
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671 void VMThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { |
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672 Thread::oops_do(f, cf); |
0 | 673 _vm_queue->oops_do(f); |
674 } | |
675 | |
676 //------------------------------------------------------------------------------------------------------------------ | |
677 #ifndef PRODUCT | |
678 | |
679 void VMOperationQueue::verify_queue(int prio) { | |
680 // Check that list is correctly linked | |
681 int length = _queue_length[prio]; | |
682 VM_Operation *cur = _queue[prio]; | |
683 int i; | |
684 | |
685 // Check forward links | |
686 for(i = 0; i < length; i++) { | |
687 cur = cur->next(); | |
688 assert(cur != _queue[prio], "list to short (forward)"); | |
689 } | |
690 assert(cur->next() == _queue[prio], "list to long (forward)"); | |
691 | |
692 // Check backwards links | |
693 cur = _queue[prio]; | |
694 for(i = 0; i < length; i++) { | |
695 cur = cur->prev(); | |
696 assert(cur != _queue[prio], "list to short (backwards)"); | |
697 } | |
698 assert(cur->prev() == _queue[prio], "list to long (backwards)"); | |
699 } | |
700 | |
701 #endif | |
702 | |
703 void VMThread::verify() { | |
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704 oops_do(&VerifyOopClosure::verify_oop, NULL); |
0 | 705 } |