Mercurial > hg > truffle
annotate src/share/vm/runtime/vmThread.cpp @ 3989:b9390528617c
7095236: G1: _markedRegions never contains NULL regions
Summary: Removed the code for skipping over NULL regions in _markedRegions, replacing it with an assertion that a NULL region is never encountered; removed dead methods, remove() and remove_region(), and inlined a simplified addRegion() directly into fillCache().
Reviewed-by: brutisso, tonyp
author | ysr |
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date | Thu, 06 Oct 2011 18:56:47 -0700 |
parents | f08d439fab8c |
children | 436b4a3231bf |
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 |
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53 HS_DTRACE_PROBE_DECL3(hotspot, vmops__request, char *, uintptr_t, int); |
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54 HS_DTRACE_PROBE_DECL3(hotspot, vmops__begin, char *, uintptr_t, int); |
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55 HS_DTRACE_PROBE_DECL3(hotspot, vmops__end, char *, uintptr_t, int); |
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56 |
0 | 57 // Dummy VM operation to act as first element in our circular double-linked list |
58 class VM_Dummy: public VM_Operation { | |
59 VMOp_Type type() const { return VMOp_Dummy; } | |
60 void doit() {}; | |
61 }; | |
62 | |
63 VMOperationQueue::VMOperationQueue() { | |
64 // The queue is a circular doubled-linked list, which always contains | |
65 // one element (i.e., one element means empty). | |
66 for(int i = 0; i < nof_priorities; i++) { | |
67 _queue_length[i] = 0; | |
68 _queue_counter = 0; | |
69 _queue[i] = new VM_Dummy(); | |
70 _queue[i]->set_next(_queue[i]); | |
71 _queue[i]->set_prev(_queue[i]); | |
72 } | |
73 _drain_list = NULL; | |
74 } | |
75 | |
76 | |
77 bool VMOperationQueue::queue_empty(int prio) { | |
78 // It is empty if there is exactly one element | |
79 bool empty = (_queue[prio] == _queue[prio]->next()); | |
80 assert( (_queue_length[prio] == 0 && empty) || | |
81 (_queue_length[prio] > 0 && !empty), "sanity check"); | |
82 return _queue_length[prio] == 0; | |
83 } | |
84 | |
85 // Inserts an element to the right of the q element | |
86 void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) { | |
87 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); | |
88 n->set_prev(q); | |
89 n->set_next(q->next()); | |
90 q->next()->set_prev(n); | |
91 q->set_next(n); | |
92 } | |
93 | |
94 void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) { | |
95 _queue_length[prio]++; | |
96 insert(_queue[prio]->next(), op); | |
97 } | |
98 | |
99 void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) { | |
100 _queue_length[prio]++; | |
101 insert(_queue[prio]->prev(), op); | |
102 } | |
103 | |
104 | |
105 void VMOperationQueue::unlink(VM_Operation* q) { | |
106 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); | |
107 q->prev()->set_next(q->next()); | |
108 q->next()->set_prev(q->prev()); | |
109 } | |
110 | |
111 VM_Operation* VMOperationQueue::queue_remove_front(int prio) { | |
112 if (queue_empty(prio)) return NULL; | |
113 assert(_queue_length[prio] >= 0, "sanity check"); | |
114 _queue_length[prio]--; | |
115 VM_Operation* r = _queue[prio]->next(); | |
116 assert(r != _queue[prio], "cannot remove base element"); | |
117 unlink(r); | |
118 return r; | |
119 } | |
120 | |
121 VM_Operation* VMOperationQueue::queue_drain(int prio) { | |
122 if (queue_empty(prio)) return NULL; | |
123 DEBUG_ONLY(int length = _queue_length[prio];); | |
124 assert(length >= 0, "sanity check"); | |
125 _queue_length[prio] = 0; | |
126 VM_Operation* r = _queue[prio]->next(); | |
127 assert(r != _queue[prio], "cannot remove base element"); | |
128 // remove links to base element from head and tail | |
129 r->set_prev(NULL); | |
130 _queue[prio]->prev()->set_next(NULL); | |
131 // restore queue to empty state | |
132 _queue[prio]->set_next(_queue[prio]); | |
133 _queue[prio]->set_prev(_queue[prio]); | |
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134 assert(queue_empty(prio), "drain corrupted queue"); |
0 | 135 #ifdef DEBUG |
136 int len = 0; | |
137 VM_Operation* cur; | |
138 for(cur = r; cur != NULL; cur=cur->next()) len++; | |
139 assert(len == length, "drain lost some ops"); | |
140 #endif | |
141 return r; | |
142 } | |
143 | |
144 void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) { | |
145 VM_Operation* cur = _queue[queue]; | |
146 cur = cur->next(); | |
147 while (cur != _queue[queue]) { | |
148 cur->oops_do(f); | |
149 cur = cur->next(); | |
150 } | |
151 } | |
152 | |
153 void VMOperationQueue::drain_list_oops_do(OopClosure* f) { | |
154 VM_Operation* cur = _drain_list; | |
155 while (cur != NULL) { | |
156 cur->oops_do(f); | |
157 cur = cur->next(); | |
158 } | |
159 } | |
160 | |
161 //----------------------------------------------------------------- | |
162 // High-level interface | |
163 bool VMOperationQueue::add(VM_Operation *op) { | |
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164 |
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165 HS_DTRACE_PROBE3(hotspot, vmops__request, op->name(), strlen(op->name()), |
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166 op->evaluation_mode()); |
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167 |
0 | 168 // Encapsulates VM queue policy. Currently, that |
169 // only involves putting them on the right list | |
170 if (op->evaluate_at_safepoint()) { | |
171 queue_add_back(SafepointPriority, op); | |
172 return true; | |
173 } | |
174 | |
175 queue_add_back(MediumPriority, op); | |
176 return true; | |
177 } | |
178 | |
179 VM_Operation* VMOperationQueue::remove_next() { | |
180 // Assuming VMOperation queue is two-level priority queue. If there are | |
181 // more than two priorities, we need a different scheduling algorithm. | |
182 assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2, | |
183 "current algorithm does not work"); | |
184 | |
185 // simple counter based scheduling to prevent starvation of lower priority | |
186 // queue. -- see 4390175 | |
187 int high_prio, low_prio; | |
188 if (_queue_counter++ < 10) { | |
189 high_prio = SafepointPriority; | |
190 low_prio = MediumPriority; | |
191 } else { | |
192 _queue_counter = 0; | |
193 high_prio = MediumPriority; | |
194 low_prio = SafepointPriority; | |
195 } | |
196 | |
197 return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio); | |
198 } | |
199 | |
200 void VMOperationQueue::oops_do(OopClosure* f) { | |
201 for(int i = 0; i < nof_priorities; i++) { | |
202 queue_oops_do(i, f); | |
203 } | |
204 drain_list_oops_do(f); | |
205 } | |
206 | |
207 | |
208 //------------------------------------------------------------------------------------------------------------------ | |
209 // Implementation of VMThread stuff | |
210 | |
211 bool VMThread::_should_terminate = false; | |
212 bool VMThread::_terminated = false; | |
213 Monitor* VMThread::_terminate_lock = NULL; | |
214 VMThread* VMThread::_vm_thread = NULL; | |
215 VM_Operation* VMThread::_cur_vm_operation = NULL; | |
216 VMOperationQueue* VMThread::_vm_queue = NULL; | |
217 PerfCounter* VMThread::_perf_accumulated_vm_operation_time = NULL; | |
218 | |
219 | |
220 void VMThread::create() { | |
221 assert(vm_thread() == NULL, "we can only allocate one VMThread"); | |
222 _vm_thread = new VMThread(); | |
223 | |
224 // Create VM operation queue | |
225 _vm_queue = new VMOperationQueue(); | |
226 guarantee(_vm_queue != NULL, "just checking"); | |
227 | |
228 _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true); | |
229 | |
230 if (UsePerfData) { | |
231 // jvmstat performance counters | |
232 Thread* THREAD = Thread::current(); | |
233 _perf_accumulated_vm_operation_time = | |
234 PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime", | |
235 PerfData::U_Ticks, CHECK); | |
236 } | |
237 } | |
238 | |
239 | |
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240 VMThread::VMThread() : NamedThread() { |
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241 set_name("VM Thread"); |
0 | 242 } |
243 | |
244 void VMThread::destroy() { | |
245 if (_vm_thread != NULL) { | |
246 delete _vm_thread; | |
247 _vm_thread = NULL; // VM thread is gone | |
248 } | |
249 } | |
250 | |
251 void VMThread::run() { | |
252 assert(this == vm_thread(), "check"); | |
253 | |
254 this->initialize_thread_local_storage(); | |
255 this->record_stack_base_and_size(); | |
256 // Notify_lock wait checks on active_handles() to rewait in | |
257 // case of spurious wakeup, it should wait on the last | |
258 // value set prior to the notify | |
259 this->set_active_handles(JNIHandleBlock::allocate_block()); | |
260 | |
261 { | |
262 MutexLocker ml(Notify_lock); | |
263 Notify_lock->notify(); | |
264 } | |
265 // Notify_lock is destroyed by Threads::create_vm() | |
266 | |
267 int prio = (VMThreadPriority == -1) | |
268 ? os::java_to_os_priority[NearMaxPriority] | |
269 : VMThreadPriority; | |
270 // Note that I cannot call os::set_priority because it expects Java | |
271 // priorities and I am *explicitly* using OS priorities so that it's | |
272 // possible to set the VM thread priority higher than any Java thread. | |
273 os::set_native_priority( this, prio ); | |
274 | |
275 // Wait for VM_Operations until termination | |
276 this->loop(); | |
277 | |
278 // Note the intention to exit before safepointing. | |
279 // 6295565 This has the effect of waiting for any large tty | |
280 // outputs to finish. | |
281 if (xtty != NULL) { | |
282 ttyLocker ttyl; | |
283 xtty->begin_elem("destroy_vm"); | |
284 xtty->stamp(); | |
285 xtty->end_elem(); | |
286 assert(should_terminate(), "termination flag must be set"); | |
287 } | |
288 | |
289 // 4526887 let VM thread exit at Safepoint | |
290 SafepointSynchronize::begin(); | |
291 | |
292 if (VerifyBeforeExit) { | |
293 HandleMark hm(VMThread::vm_thread()); | |
294 // Among other things, this ensures that Eden top is correct. | |
295 Universe::heap()->prepare_for_verify(); | |
296 os::check_heap(); | |
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297 // Silent verification so as not to pollute normal output, |
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298 // unless we really asked for it. |
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299 Universe::verify(true, !(PrintGCDetails || Verbose)); |
0 | 300 } |
301 | |
302 CompileBroker::set_should_block(); | |
303 | |
304 // wait for threads (compiler threads or daemon threads) in the | |
305 // _thread_in_native state to block. | |
306 VM_Exit::wait_for_threads_in_native_to_block(); | |
307 | |
308 // signal other threads that VM process is gone | |
309 { | |
310 // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows | |
311 // VM thread to enter any lock at Safepoint as long as its _owner is NULL. | |
312 // If that happens after _terminate_lock->wait() has unset _owner | |
313 // but before it actually drops the lock and waits, the notification below | |
314 // may get lost and we will have a hang. To avoid this, we need to use | |
315 // Mutex::lock_without_safepoint_check(). | |
316 MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag); | |
317 _terminated = true; | |
318 _terminate_lock->notify(); | |
319 } | |
320 | |
321 // Deletion must be done synchronously by the JNI DestroyJavaVM thread | |
322 // so that the VMThread deletion completes before the main thread frees | |
323 // up the CodeHeap. | |
324 | |
325 } | |
326 | |
327 | |
328 // Notify the VMThread that the last non-daemon JavaThread has terminated, | |
329 // and wait until operation is performed. | |
330 void VMThread::wait_for_vm_thread_exit() { | |
331 { MutexLocker mu(VMOperationQueue_lock); | |
332 _should_terminate = true; | |
333 VMOperationQueue_lock->notify(); | |
334 } | |
335 | |
336 // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint | |
337 // because this thread has been removed from the threads list. But anything | |
338 // that could get blocked by Safepoint should not be used after this point, | |
339 // otherwise we will hang, since there is no one can end the safepoint. | |
340 | |
341 // Wait until VM thread is terminated | |
342 // Note: it should be OK to use Terminator_lock here. But this is called | |
343 // at a very delicate time (VM shutdown) and we are operating in non- VM | |
344 // thread at Safepoint. It's safer to not share lock with other threads. | |
345 { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag); | |
346 while(!VMThread::is_terminated()) { | |
347 _terminate_lock->wait(Mutex::_no_safepoint_check_flag); | |
348 } | |
349 } | |
350 } | |
351 | |
352 void VMThread::print_on(outputStream* st) const { | |
353 st->print("\"%s\" ", name()); | |
354 Thread::print_on(st); | |
355 st->cr(); | |
356 } | |
357 | |
358 void VMThread::evaluate_operation(VM_Operation* op) { | |
359 ResourceMark rm; | |
360 | |
361 { | |
362 PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time()); | |
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363 HS_DTRACE_PROBE3(hotspot, vmops__begin, op->name(), strlen(op->name()), |
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364 op->evaluation_mode()); |
0 | 365 op->evaluate(); |
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366 HS_DTRACE_PROBE3(hotspot, vmops__end, op->name(), strlen(op->name()), |
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367 op->evaluation_mode()); |
0 | 368 } |
369 | |
370 // Last access of info in _cur_vm_operation! | |
371 bool c_heap_allocated = op->is_cheap_allocated(); | |
372 | |
373 // Mark as completed | |
374 if (!op->evaluate_concurrently()) { | |
375 op->calling_thread()->increment_vm_operation_completed_count(); | |
376 } | |
377 // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call, | |
378 // since if it is stack allocated the calling thread might have deallocated | |
379 if (c_heap_allocated) { | |
380 delete _cur_vm_operation; | |
381 } | |
382 } | |
383 | |
384 | |
385 void VMThread::loop() { | |
386 assert(_cur_vm_operation == NULL, "no current one should be executing"); | |
387 | |
388 while(true) { | |
389 VM_Operation* safepoint_ops = NULL; | |
390 // | |
391 // Wait for VM operation | |
392 // | |
393 // use no_safepoint_check to get lock without attempting to "sneak" | |
394 { MutexLockerEx mu_queue(VMOperationQueue_lock, | |
395 Mutex::_no_safepoint_check_flag); | |
396 | |
397 // Look for new operation | |
398 assert(_cur_vm_operation == NULL, "no current one should be executing"); | |
399 _cur_vm_operation = _vm_queue->remove_next(); | |
400 | |
401 // Stall time tracking code | |
402 if (PrintVMQWaitTime && _cur_vm_operation != NULL && | |
403 !_cur_vm_operation->evaluate_concurrently()) { | |
404 long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp(); | |
405 if (stall > 0) | |
406 tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall); | |
407 } | |
408 | |
409 while (!should_terminate() && _cur_vm_operation == NULL) { | |
410 // wait with a timeout to guarantee safepoints at regular intervals | |
411 bool timedout = | |
412 VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag, | |
413 GuaranteedSafepointInterval); | |
414 | |
415 // Support for self destruction | |
416 if ((SelfDestructTimer != 0) && !is_error_reported() && | |
417 (os::elapsedTime() > SelfDestructTimer * 60)) { | |
418 tty->print_cr("VM self-destructed"); | |
419 exit(-1); | |
420 } | |
421 | |
422 if (timedout && (SafepointALot || | |
423 SafepointSynchronize::is_cleanup_needed())) { | |
424 MutexUnlockerEx mul(VMOperationQueue_lock, | |
425 Mutex::_no_safepoint_check_flag); | |
426 // Force a safepoint since we have not had one for at least | |
427 // 'GuaranteedSafepointInterval' milliseconds. This will run all | |
428 // the clean-up processing that needs to be done regularly at a | |
429 // safepoint | |
430 SafepointSynchronize::begin(); | |
431 #ifdef ASSERT | |
432 if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot(); | |
433 #endif | |
434 SafepointSynchronize::end(); | |
435 } | |
436 _cur_vm_operation = _vm_queue->remove_next(); | |
437 | |
438 // If we are at a safepoint we will evaluate all the operations that | |
439 // follow that also require a safepoint | |
440 if (_cur_vm_operation != NULL && | |
441 _cur_vm_operation->evaluate_at_safepoint()) { | |
442 safepoint_ops = _vm_queue->drain_at_safepoint_priority(); | |
443 } | |
444 } | |
445 | |
446 if (should_terminate()) break; | |
447 } // Release mu_queue_lock | |
448 | |
449 // | |
450 // Execute VM operation | |
451 // | |
452 { HandleMark hm(VMThread::vm_thread()); | |
453 | |
454 EventMark em("Executing VM operation: %s", vm_operation()->name()); | |
455 assert(_cur_vm_operation != NULL, "we should have found an operation to execute"); | |
456 | |
457 // Give the VM thread an extra quantum. Jobs tend to be bursty and this | |
458 // helps the VM thread to finish up the job. | |
459 // FIXME: When this is enabled and there are many threads, this can degrade | |
460 // performance significantly. | |
461 if( VMThreadHintNoPreempt ) | |
462 os::hint_no_preempt(); | |
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->evaluate_at_safepoint()) { | |
467 | |
468 _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned | |
469 | |
470 SafepointSynchronize::begin(); | |
471 evaluate_operation(_cur_vm_operation); | |
472 // now process all queued safepoint ops, iteratively draining | |
473 // the queue until there are none left | |
474 do { | |
475 _cur_vm_operation = safepoint_ops; | |
476 if (_cur_vm_operation != NULL) { | |
477 do { | |
478 // evaluate_operation deletes the op object so we have | |
479 // to grab the next op now | |
480 VM_Operation* next = _cur_vm_operation->next(); | |
481 _vm_queue->set_drain_list(next); | |
482 evaluate_operation(_cur_vm_operation); | |
483 _cur_vm_operation = next; | |
484 if (PrintSafepointStatistics) { | |
485 SafepointSynchronize::inc_vmop_coalesced_count(); | |
486 } | |
487 } while (_cur_vm_operation != NULL); | |
488 } | |
489 // There is a chance that a thread enqueued a safepoint op | |
490 // since we released the op-queue lock and initiated the safepoint. | |
491 // So we drain the queue again if there is anything there, as an | |
492 // optimization to try and reduce the number of safepoints. | |
493 // As the safepoint synchronizes us with JavaThreads we will see | |
494 // any enqueue made by a JavaThread, but the peek will not | |
495 // necessarily detect a concurrent enqueue by a GC thread, but | |
496 // that simply means the op will wait for the next major cycle of the | |
497 // VMThread - just as it would if the GC thread lost the race for | |
498 // the lock. | |
499 if (_vm_queue->peek_at_safepoint_priority()) { | |
500 // must hold lock while draining queue | |
501 MutexLockerEx mu_queue(VMOperationQueue_lock, | |
502 Mutex::_no_safepoint_check_flag); | |
503 safepoint_ops = _vm_queue->drain_at_safepoint_priority(); | |
504 } else { | |
505 safepoint_ops = NULL; | |
506 } | |
507 } while(safepoint_ops != NULL); | |
508 | |
509 _vm_queue->set_drain_list(NULL); | |
510 | |
511 // Complete safepoint synchronization | |
512 SafepointSynchronize::end(); | |
513 | |
514 } else { // not a safepoint operation | |
515 if (TraceLongCompiles) { | |
516 elapsedTimer t; | |
517 t.start(); | |
518 evaluate_operation(_cur_vm_operation); | |
519 t.stop(); | |
520 double secs = t.seconds(); | |
521 if (secs * 1e3 > LongCompileThreshold) { | |
522 // XXX - _cur_vm_operation should not be accessed after | |
523 // the completed count has been incremented; the waiting | |
524 // thread may have already freed this memory. | |
525 tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs); | |
526 } | |
527 } else { | |
528 evaluate_operation(_cur_vm_operation); | |
529 } | |
530 | |
531 _cur_vm_operation = NULL; | |
532 } | |
533 } | |
534 | |
535 // | |
536 // Notify (potential) waiting Java thread(s) - lock without safepoint | |
537 // check so that sneaking is not possible | |
538 { MutexLockerEx mu(VMOperationRequest_lock, | |
539 Mutex::_no_safepoint_check_flag); | |
540 VMOperationRequest_lock->notify_all(); | |
541 } | |
542 | |
543 // | |
544 // We want to make sure that we get to a safepoint regularly. | |
545 // | |
546 if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) { | |
547 long interval = SafepointSynchronize::last_non_safepoint_interval(); | |
548 bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval); | |
549 if (SafepointALot || max_time_exceeded) { | |
550 HandleMark hm(VMThread::vm_thread()); | |
551 SafepointSynchronize::begin(); | |
552 SafepointSynchronize::end(); | |
553 } | |
554 } | |
555 } | |
556 } | |
557 | |
558 void VMThread::execute(VM_Operation* op) { | |
559 Thread* t = Thread::current(); | |
560 | |
561 if (!t->is_VM_thread()) { | |
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562 SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot |
0 | 563 // JavaThread or WatcherThread |
564 t->check_for_valid_safepoint_state(true); | |
565 | |
566 // New request from Java thread, evaluate prologue | |
567 if (!op->doit_prologue()) { | |
568 return; // op was cancelled | |
569 } | |
570 | |
571 // Setup VM_operations for execution | |
572 op->set_calling_thread(t, Thread::get_priority(t)); | |
573 | |
574 // It does not make sense to execute the epilogue, if the VM operation object is getting | |
575 // deallocated by the VM thread. | |
576 bool concurrent = op->evaluate_concurrently(); | |
577 bool execute_epilog = !op->is_cheap_allocated(); | |
578 assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated"); | |
579 | |
580 // Get ticket number for non-concurrent VM operations | |
581 int ticket = 0; | |
582 if (!concurrent) { | |
583 ticket = t->vm_operation_ticket(); | |
584 } | |
585 | |
586 // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the | |
587 // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests | |
588 // to be queued up during a safepoint synchronization. | |
589 { | |
590 VMOperationQueue_lock->lock_without_safepoint_check(); | |
591 bool ok = _vm_queue->add(op); | |
592 op->set_timestamp(os::javaTimeMillis()); | |
593 VMOperationQueue_lock->notify(); | |
594 VMOperationQueue_lock->unlock(); | |
595 // VM_Operation got skipped | |
596 if (!ok) { | |
597 assert(concurrent, "can only skip concurrent tasks"); | |
598 if (op->is_cheap_allocated()) delete op; | |
599 return; | |
600 } | |
601 } | |
602 | |
603 if (!concurrent) { | |
604 // Wait for completion of request (non-concurrent) | |
605 // Note: only a JavaThread triggers the safepoint check when locking | |
606 MutexLocker mu(VMOperationRequest_lock); | |
607 while(t->vm_operation_completed_count() < ticket) { | |
608 VMOperationRequest_lock->wait(!t->is_Java_thread()); | |
609 } | |
610 } | |
611 | |
612 if (execute_epilog) { | |
613 op->doit_epilogue(); | |
614 } | |
615 } else { | |
616 // invoked by VM thread; usually nested VM operation | |
617 assert(t->is_VM_thread(), "must be a VM thread"); | |
618 VM_Operation* prev_vm_operation = vm_operation(); | |
619 if (prev_vm_operation != NULL) { | |
620 // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler | |
621 // does not allow nested scavenges or compiles. | |
622 if (!prev_vm_operation->allow_nested_vm_operations()) { | |
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623 fatal(err_msg("Nested VM operation %s requested by operation %s", |
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624 op->name(), vm_operation()->name())); |
0 | 625 } |
626 op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority()); | |
627 } | |
628 | |
629 EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name()); | |
630 | |
631 // Release all internal handles after operation is evaluated | |
632 HandleMark hm(t); | |
633 _cur_vm_operation = op; | |
634 | |
635 if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) { | |
636 SafepointSynchronize::begin(); | |
637 op->evaluate(); | |
638 SafepointSynchronize::end(); | |
639 } else { | |
640 op->evaluate(); | |
641 } | |
642 | |
643 // Free memory if needed | |
644 if (op->is_cheap_allocated()) delete op; | |
645 | |
646 _cur_vm_operation = prev_vm_operation; | |
647 } | |
648 } | |
649 | |
650 | |
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651 void VMThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { |
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652 Thread::oops_do(f, cf); |
0 | 653 _vm_queue->oops_do(f); |
654 } | |
655 | |
656 //------------------------------------------------------------------------------------------------------------------ | |
657 #ifndef PRODUCT | |
658 | |
659 void VMOperationQueue::verify_queue(int prio) { | |
660 // Check that list is correctly linked | |
661 int length = _queue_length[prio]; | |
662 VM_Operation *cur = _queue[prio]; | |
663 int i; | |
664 | |
665 // Check forward links | |
666 for(i = 0; i < length; i++) { | |
667 cur = cur->next(); | |
668 assert(cur != _queue[prio], "list to short (forward)"); | |
669 } | |
670 assert(cur->next() == _queue[prio], "list to long (forward)"); | |
671 | |
672 // Check backwards links | |
673 cur = _queue[prio]; | |
674 for(i = 0; i < length; i++) { | |
675 cur = cur->prev(); | |
676 assert(cur != _queue[prio], "list to short (backwards)"); | |
677 } | |
678 assert(cur->prev() == _queue[prio], "list to long (backwards)"); | |
679 } | |
680 | |
681 #endif | |
682 | |
683 void VMThread::verify() { | |
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684 oops_do(&VerifyOopClosure::verify_oop, NULL); |
0 | 685 } |