Mercurial > hg > truffle
annotate src/share/vm/runtime/vmThread.cpp @ 10278:6f3fd5150b67
6934604: enable parts of EliminateAutoBox by default
Summary: Resurrected autobox elimination code and enabled part of it by default.
Reviewed-by: roland, twisti
| author | kvn |
|---|---|
| date | Wed, 08 May 2013 15:08:01 -0700 |
| parents | b06ac540229e |
| children | f2110083203d |
| rev | line source |
|---|---|
| 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" | |
| 38 #include "utilities/dtrace.hpp" | |
| 39 #include "utilities/events.hpp" | |
| 40 #include "utilities/xmlstream.hpp" | |
| 0 | 41 |
| 4006 | 42 #ifndef USDT2 |
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43 HS_DTRACE_PROBE_DECL3(hotspot, vmops__request, char *, uintptr_t, int); |
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44 HS_DTRACE_PROBE_DECL3(hotspot, vmops__begin, char *, uintptr_t, int); |
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45 HS_DTRACE_PROBE_DECL3(hotspot, vmops__end, char *, uintptr_t, int); |
| 4006 | 46 #endif /* !USDT2 */ |
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47 |
| 0 | 48 // Dummy VM operation to act as first element in our circular double-linked list |
| 49 class VM_Dummy: public VM_Operation { | |
| 50 VMOp_Type type() const { return VMOp_Dummy; } | |
| 51 void doit() {}; | |
| 52 }; | |
| 53 | |
| 54 VMOperationQueue::VMOperationQueue() { | |
| 55 // The queue is a circular doubled-linked list, which always contains | |
| 56 // one element (i.e., one element means empty). | |
| 57 for(int i = 0; i < nof_priorities; i++) { | |
| 58 _queue_length[i] = 0; | |
| 59 _queue_counter = 0; | |
| 60 _queue[i] = new VM_Dummy(); | |
| 61 _queue[i]->set_next(_queue[i]); | |
| 62 _queue[i]->set_prev(_queue[i]); | |
| 63 } | |
| 64 _drain_list = NULL; | |
| 65 } | |
| 66 | |
| 67 | |
| 68 bool VMOperationQueue::queue_empty(int prio) { | |
| 69 // It is empty if there is exactly one element | |
| 70 bool empty = (_queue[prio] == _queue[prio]->next()); | |
| 71 assert( (_queue_length[prio] == 0 && empty) || | |
| 72 (_queue_length[prio] > 0 && !empty), "sanity check"); | |
| 73 return _queue_length[prio] == 0; | |
| 74 } | |
| 75 | |
| 76 // Inserts an element to the right of the q element | |
| 77 void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) { | |
| 78 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); | |
| 79 n->set_prev(q); | |
| 80 n->set_next(q->next()); | |
| 81 q->next()->set_prev(n); | |
| 82 q->set_next(n); | |
| 83 } | |
| 84 | |
| 85 void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) { | |
| 86 _queue_length[prio]++; | |
| 87 insert(_queue[prio]->next(), op); | |
| 88 } | |
| 89 | |
| 90 void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) { | |
| 91 _queue_length[prio]++; | |
| 92 insert(_queue[prio]->prev(), op); | |
| 93 } | |
| 94 | |
| 95 | |
| 96 void VMOperationQueue::unlink(VM_Operation* q) { | |
| 97 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); | |
| 98 q->prev()->set_next(q->next()); | |
| 99 q->next()->set_prev(q->prev()); | |
| 100 } | |
| 101 | |
| 102 VM_Operation* VMOperationQueue::queue_remove_front(int prio) { | |
| 103 if (queue_empty(prio)) return NULL; | |
| 104 assert(_queue_length[prio] >= 0, "sanity check"); | |
| 105 _queue_length[prio]--; | |
| 106 VM_Operation* r = _queue[prio]->next(); | |
| 107 assert(r != _queue[prio], "cannot remove base element"); | |
| 108 unlink(r); | |
| 109 return r; | |
| 110 } | |
| 111 | |
| 112 VM_Operation* VMOperationQueue::queue_drain(int prio) { | |
| 113 if (queue_empty(prio)) return NULL; | |
| 114 DEBUG_ONLY(int length = _queue_length[prio];); | |
| 115 assert(length >= 0, "sanity check"); | |
| 116 _queue_length[prio] = 0; | |
| 117 VM_Operation* r = _queue[prio]->next(); | |
| 118 assert(r != _queue[prio], "cannot remove base element"); | |
| 119 // remove links to base element from head and tail | |
| 120 r->set_prev(NULL); | |
| 121 _queue[prio]->prev()->set_next(NULL); | |
| 122 // restore queue to empty state | |
| 123 _queue[prio]->set_next(_queue[prio]); | |
| 124 _queue[prio]->set_prev(_queue[prio]); | |
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125 assert(queue_empty(prio), "drain corrupted queue"); |
| 9152 | 126 #ifdef ASSERT |
| 0 | 127 int len = 0; |
| 128 VM_Operation* cur; | |
| 129 for(cur = r; cur != NULL; cur=cur->next()) len++; | |
| 130 assert(len == length, "drain lost some ops"); | |
| 131 #endif | |
| 132 return r; | |
| 133 } | |
| 134 | |
| 135 void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) { | |
| 136 VM_Operation* cur = _queue[queue]; | |
| 137 cur = cur->next(); | |
| 138 while (cur != _queue[queue]) { | |
| 139 cur->oops_do(f); | |
| 140 cur = cur->next(); | |
| 141 } | |
| 142 } | |
| 143 | |
| 144 void VMOperationQueue::drain_list_oops_do(OopClosure* f) { | |
| 145 VM_Operation* cur = _drain_list; | |
| 146 while (cur != NULL) { | |
| 147 cur->oops_do(f); | |
| 148 cur = cur->next(); | |
| 149 } | |
| 150 } | |
| 151 | |
| 152 //----------------------------------------------------------------- | |
| 153 // High-level interface | |
| 154 bool VMOperationQueue::add(VM_Operation *op) { | |
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155 |
| 4006 | 156 #ifndef USDT2 |
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157 HS_DTRACE_PROBE3(hotspot, vmops__request, op->name(), strlen(op->name()), |
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158 op->evaluation_mode()); |
| 4006 | 159 #else /* USDT2 */ |
| 160 HOTSPOT_VMOPS_REQUEST( | |
| 161 (char *) op->name(), strlen(op->name()), | |
| 162 op->evaluation_mode()); | |
| 163 #endif /* USDT2 */ | |
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164 |
| 0 | 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 } | |
| 171 | |
| 172 queue_add_back(MediumPriority, op); | |
| 173 return true; | |
| 174 } | |
| 175 | |
| 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"); | |
| 181 | |
| 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 } | |
| 193 | |
| 194 return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio); | |
| 195 } | |
| 196 | |
| 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 } | |
| 203 | |
| 204 | |
| 205 //------------------------------------------------------------------------------------------------------------------ | |
| 206 // Implementation of VMThread stuff | |
| 207 | |
| 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; | |
| 215 | |
| 216 | |
| 217 void VMThread::create() { | |
| 218 assert(vm_thread() == NULL, "we can only allocate one VMThread"); | |
| 219 _vm_thread = new VMThread(); | |
| 220 | |
| 221 // Create VM operation queue | |
| 222 _vm_queue = new VMOperationQueue(); | |
| 223 guarantee(_vm_queue != NULL, "just checking"); | |
| 224 | |
| 225 _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true); | |
| 226 | |
| 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 } | |
| 235 | |
| 236 | |
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237 VMThread::VMThread() : NamedThread() { |
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238 set_name("VM Thread"); |
| 0 | 239 } |
| 240 | |
| 241 void VMThread::destroy() { | |
| 242 if (_vm_thread != NULL) { | |
| 243 delete _vm_thread; | |
| 244 _vm_thread = NULL; // VM thread is gone | |
| 245 } | |
| 246 } | |
| 247 | |
| 248 void VMThread::run() { | |
| 249 assert(this == vm_thread(), "check"); | |
| 250 | |
| 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()); | |
| 257 | |
| 258 { | |
| 259 MutexLocker ml(Notify_lock); | |
| 260 Notify_lock->notify(); | |
| 261 } | |
| 262 // Notify_lock is destroyed by Threads::create_vm() | |
| 263 | |
| 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 ); | |
| 271 | |
| 272 // Wait for VM_Operations until termination | |
| 273 this->loop(); | |
| 274 | |
| 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 } | |
| 285 | |
| 286 // 4526887 let VM thread exit at Safepoint | |
| 287 SafepointSynchronize::begin(); | |
| 288 | |
| 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(); | |
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294 // Silent verification so as not to pollute normal output, |
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295 // unless we really asked for it. |
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296 Universe::verify(!(PrintGCDetails || Verbose) || VerifySilently); |
| 0 | 297 } |
| 298 | |
| 299 CompileBroker::set_should_block(); | |
| 300 | |
| 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(); | |
| 304 | |
| 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 } | |
| 317 | |
| 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. | |
| 321 | |
| 322 } | |
| 323 | |
| 324 | |
| 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 } | |
| 332 | |
| 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. | |
| 337 | |
| 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 } | |
| 348 | |
| 349 void VMThread::print_on(outputStream* st) const { | |
| 350 st->print("\"%s\" ", name()); | |
| 351 Thread::print_on(st); | |
| 352 st->cr(); | |
| 353 } | |
| 354 | |
| 355 void VMThread::evaluate_operation(VM_Operation* op) { | |
| 356 ResourceMark rm; | |
| 357 | |
| 358 { | |
| 359 PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time()); | |
| 4006 | 360 #ifndef USDT2 |
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361 HS_DTRACE_PROBE3(hotspot, vmops__begin, op->name(), strlen(op->name()), |
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362 op->evaluation_mode()); |
| 4006 | 363 #else /* USDT2 */ |
| 364 HOTSPOT_VMOPS_BEGIN( | |
| 365 (char *) op->name(), strlen(op->name()), | |
| 366 op->evaluation_mode()); | |
| 367 #endif /* USDT2 */ | |
| 0 | 368 op->evaluate(); |
| 4006 | 369 #ifndef USDT2 |
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370 HS_DTRACE_PROBE3(hotspot, vmops__end, op->name(), strlen(op->name()), |
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371 op->evaluation_mode()); |
| 4006 | 372 #else /* USDT2 */ |
| 373 HOTSPOT_VMOPS_END( | |
| 374 (char *) op->name(), strlen(op->name()), | |
| 375 op->evaluation_mode()); | |
| 376 #endif /* USDT2 */ | |
| 0 | 377 } |
| 378 | |
| 379 // Last access of info in _cur_vm_operation! | |
| 380 bool c_heap_allocated = op->is_cheap_allocated(); | |
| 381 | |
| 382 // Mark as completed | |
| 383 if (!op->evaluate_concurrently()) { | |
| 384 op->calling_thread()->increment_vm_operation_completed_count(); | |
| 385 } | |
| 386 // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call, | |
| 387 // since if it is stack allocated the calling thread might have deallocated | |
| 388 if (c_heap_allocated) { | |
| 389 delete _cur_vm_operation; | |
| 390 } | |
| 391 } | |
| 392 | |
| 393 | |
| 394 void VMThread::loop() { | |
| 395 assert(_cur_vm_operation == NULL, "no current one should be executing"); | |
| 396 | |
| 397 while(true) { | |
| 398 VM_Operation* safepoint_ops = NULL; | |
| 399 // | |
| 400 // Wait for VM operation | |
| 401 // | |
| 402 // use no_safepoint_check to get lock without attempting to "sneak" | |
| 403 { MutexLockerEx mu_queue(VMOperationQueue_lock, | |
| 404 Mutex::_no_safepoint_check_flag); | |
| 405 | |
| 406 // Look for new operation | |
| 407 assert(_cur_vm_operation == NULL, "no current one should be executing"); | |
| 408 _cur_vm_operation = _vm_queue->remove_next(); | |
| 409 | |
| 410 // Stall time tracking code | |
| 411 if (PrintVMQWaitTime && _cur_vm_operation != NULL && | |
| 412 !_cur_vm_operation->evaluate_concurrently()) { | |
| 413 long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp(); | |
| 414 if (stall > 0) | |
| 415 tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall); | |
| 416 } | |
| 417 | |
| 418 while (!should_terminate() && _cur_vm_operation == NULL) { | |
| 419 // wait with a timeout to guarantee safepoints at regular intervals | |
| 420 bool timedout = | |
| 421 VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag, | |
| 422 GuaranteedSafepointInterval); | |
| 423 | |
| 424 // Support for self destruction | |
| 425 if ((SelfDestructTimer != 0) && !is_error_reported() && | |
| 426 (os::elapsedTime() > SelfDestructTimer * 60)) { | |
| 427 tty->print_cr("VM self-destructed"); | |
| 428 exit(-1); | |
| 429 } | |
| 430 | |
| 431 if (timedout && (SafepointALot || | |
| 432 SafepointSynchronize::is_cleanup_needed())) { | |
| 433 MutexUnlockerEx mul(VMOperationQueue_lock, | |
| 434 Mutex::_no_safepoint_check_flag); | |
| 435 // Force a safepoint since we have not had one for at least | |
| 436 // 'GuaranteedSafepointInterval' milliseconds. This will run all | |
| 437 // the clean-up processing that needs to be done regularly at a | |
| 438 // safepoint | |
| 439 SafepointSynchronize::begin(); | |
| 440 #ifdef ASSERT | |
| 441 if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot(); | |
| 442 #endif | |
| 443 SafepointSynchronize::end(); | |
| 444 } | |
| 445 _cur_vm_operation = _vm_queue->remove_next(); | |
| 446 | |
| 447 // If we are at a safepoint we will evaluate all the operations that | |
| 448 // follow that also require a safepoint | |
| 449 if (_cur_vm_operation != NULL && | |
| 450 _cur_vm_operation->evaluate_at_safepoint()) { | |
| 451 safepoint_ops = _vm_queue->drain_at_safepoint_priority(); | |
| 452 } | |
| 453 } | |
| 454 | |
| 455 if (should_terminate()) break; | |
| 456 } // Release mu_queue_lock | |
| 457 | |
| 458 // | |
| 459 // Execute VM operation | |
| 460 // | |
| 461 { HandleMark hm(VMThread::vm_thread()); | |
| 462 | |
| 463 EventMark em("Executing VM operation: %s", vm_operation()->name()); | |
| 464 assert(_cur_vm_operation != NULL, "we should have found an operation to execute"); | |
| 465 | |
| 466 // Give the VM thread an extra quantum. Jobs tend to be bursty and this | |
| 467 // helps the VM thread to finish up the job. | |
| 468 // FIXME: When this is enabled and there are many threads, this can degrade | |
| 469 // performance significantly. | |
| 470 if( VMThreadHintNoPreempt ) | |
| 471 os::hint_no_preempt(); | |
| 472 | |
| 473 // If we are at a safepoint we will evaluate all the operations that | |
| 474 // follow that also require a safepoint | |
| 475 if (_cur_vm_operation->evaluate_at_safepoint()) { | |
| 476 | |
| 477 _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned | |
| 478 | |
| 479 SafepointSynchronize::begin(); | |
| 480 evaluate_operation(_cur_vm_operation); | |
| 481 // now process all queued safepoint ops, iteratively draining | |
| 482 // the queue until there are none left | |
| 483 do { | |
| 484 _cur_vm_operation = safepoint_ops; | |
| 485 if (_cur_vm_operation != NULL) { | |
| 486 do { | |
| 487 // evaluate_operation deletes the op object so we have | |
| 488 // to grab the next op now | |
| 489 VM_Operation* next = _cur_vm_operation->next(); | |
| 490 _vm_queue->set_drain_list(next); | |
| 491 evaluate_operation(_cur_vm_operation); | |
| 492 _cur_vm_operation = next; | |
| 493 if (PrintSafepointStatistics) { | |
| 494 SafepointSynchronize::inc_vmop_coalesced_count(); | |
| 495 } | |
| 496 } while (_cur_vm_operation != NULL); | |
| 497 } | |
| 498 // There is a chance that a thread enqueued a safepoint op | |
| 499 // since we released the op-queue lock and initiated the safepoint. | |
| 500 // So we drain the queue again if there is anything there, as an | |
| 501 // optimization to try and reduce the number of safepoints. | |
| 502 // As the safepoint synchronizes us with JavaThreads we will see | |
| 503 // any enqueue made by a JavaThread, but the peek will not | |
| 504 // necessarily detect a concurrent enqueue by a GC thread, but | |
| 505 // that simply means the op will wait for the next major cycle of the | |
| 506 // VMThread - just as it would if the GC thread lost the race for | |
| 507 // the lock. | |
| 508 if (_vm_queue->peek_at_safepoint_priority()) { | |
| 509 // must hold lock while draining queue | |
| 510 MutexLockerEx mu_queue(VMOperationQueue_lock, | |
| 511 Mutex::_no_safepoint_check_flag); | |
| 512 safepoint_ops = _vm_queue->drain_at_safepoint_priority(); | |
| 513 } else { | |
| 514 safepoint_ops = NULL; | |
| 515 } | |
| 516 } while(safepoint_ops != NULL); | |
| 517 | |
| 518 _vm_queue->set_drain_list(NULL); | |
| 519 | |
| 520 // Complete safepoint synchronization | |
| 521 SafepointSynchronize::end(); | |
| 522 | |
| 523 } else { // not a safepoint operation | |
| 524 if (TraceLongCompiles) { | |
| 525 elapsedTimer t; | |
| 526 t.start(); | |
| 527 evaluate_operation(_cur_vm_operation); | |
| 528 t.stop(); | |
| 529 double secs = t.seconds(); | |
| 530 if (secs * 1e3 > LongCompileThreshold) { | |
| 531 // XXX - _cur_vm_operation should not be accessed after | |
| 532 // the completed count has been incremented; the waiting | |
| 533 // thread may have already freed this memory. | |
| 534 tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs); | |
| 535 } | |
| 536 } else { | |
| 537 evaluate_operation(_cur_vm_operation); | |
| 538 } | |
| 539 | |
| 540 _cur_vm_operation = NULL; | |
| 541 } | |
| 542 } | |
| 543 | |
| 544 // | |
| 545 // Notify (potential) waiting Java thread(s) - lock without safepoint | |
| 546 // check so that sneaking is not possible | |
| 547 { MutexLockerEx mu(VMOperationRequest_lock, | |
| 548 Mutex::_no_safepoint_check_flag); | |
| 549 VMOperationRequest_lock->notify_all(); | |
| 550 } | |
| 551 | |
| 552 // | |
| 553 // We want to make sure that we get to a safepoint regularly. | |
| 554 // | |
| 555 if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) { | |
| 556 long interval = SafepointSynchronize::last_non_safepoint_interval(); | |
| 557 bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval); | |
| 558 if (SafepointALot || max_time_exceeded) { | |
| 559 HandleMark hm(VMThread::vm_thread()); | |
| 560 SafepointSynchronize::begin(); | |
| 561 SafepointSynchronize::end(); | |
| 562 } | |
| 563 } | |
| 564 } | |
| 565 } | |
| 566 | |
| 567 void VMThread::execute(VM_Operation* op) { | |
| 568 Thread* t = Thread::current(); | |
| 569 | |
| 570 if (!t->is_VM_thread()) { | |
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571 SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot |
| 0 | 572 // JavaThread or WatcherThread |
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573 bool concurrent = op->evaluate_concurrently(); |
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574 // only blocking VM operations need to verify the caller's safepoint state: |
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575 if (!concurrent) { |
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576 t->check_for_valid_safepoint_state(true); |
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577 } |
| 0 | 578 |
| 579 // New request from Java thread, evaluate prologue | |
| 580 if (!op->doit_prologue()) { | |
| 581 return; // op was cancelled | |
| 582 } | |
| 583 | |
| 584 // Setup VM_operations for execution | |
| 585 op->set_calling_thread(t, Thread::get_priority(t)); | |
| 586 | |
| 587 // It does not make sense to execute the epilogue, if the VM operation object is getting | |
| 588 // deallocated by the VM thread. | |
| 589 bool execute_epilog = !op->is_cheap_allocated(); | |
| 590 assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated"); | |
| 591 | |
| 592 // Get ticket number for non-concurrent VM operations | |
| 593 int ticket = 0; | |
| 594 if (!concurrent) { | |
| 595 ticket = t->vm_operation_ticket(); | |
| 596 } | |
| 597 | |
| 598 // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the | |
| 599 // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests | |
| 600 // to be queued up during a safepoint synchronization. | |
| 601 { | |
| 602 VMOperationQueue_lock->lock_without_safepoint_check(); | |
| 603 bool ok = _vm_queue->add(op); | |
| 604 op->set_timestamp(os::javaTimeMillis()); | |
| 605 VMOperationQueue_lock->notify(); | |
| 606 VMOperationQueue_lock->unlock(); | |
| 607 // VM_Operation got skipped | |
| 608 if (!ok) { | |
| 609 assert(concurrent, "can only skip concurrent tasks"); | |
| 610 if (op->is_cheap_allocated()) delete op; | |
| 611 return; | |
| 612 } | |
| 613 } | |
| 614 | |
| 615 if (!concurrent) { | |
| 616 // Wait for completion of request (non-concurrent) | |
| 617 // Note: only a JavaThread triggers the safepoint check when locking | |
| 618 MutexLocker mu(VMOperationRequest_lock); | |
| 619 while(t->vm_operation_completed_count() < ticket) { | |
| 620 VMOperationRequest_lock->wait(!t->is_Java_thread()); | |
| 621 } | |
| 622 } | |
| 623 | |
| 624 if (execute_epilog) { | |
| 625 op->doit_epilogue(); | |
| 626 } | |
| 627 } else { | |
| 628 // invoked by VM thread; usually nested VM operation | |
| 629 assert(t->is_VM_thread(), "must be a VM thread"); | |
| 630 VM_Operation* prev_vm_operation = vm_operation(); | |
| 631 if (prev_vm_operation != NULL) { | |
| 632 // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler | |
| 633 // does not allow nested scavenges or compiles. | |
| 634 if (!prev_vm_operation->allow_nested_vm_operations()) { | |
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635 fatal(err_msg("Nested VM operation %s requested by operation %s", |
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636 op->name(), vm_operation()->name())); |
| 0 | 637 } |
| 638 op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority()); | |
| 639 } | |
| 640 | |
| 641 EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name()); | |
| 642 | |
| 643 // Release all internal handles after operation is evaluated | |
| 644 HandleMark hm(t); | |
| 645 _cur_vm_operation = op; | |
| 646 | |
| 647 if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) { | |
| 648 SafepointSynchronize::begin(); | |
| 649 op->evaluate(); | |
| 650 SafepointSynchronize::end(); | |
| 651 } else { | |
| 652 op->evaluate(); | |
| 653 } | |
| 654 | |
| 655 // Free memory if needed | |
| 656 if (op->is_cheap_allocated()) delete op; | |
| 657 | |
| 658 _cur_vm_operation = prev_vm_operation; | |
| 659 } | |
| 660 } | |
| 661 | |
| 662 | |
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663 void VMThread::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) { |
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664 Thread::oops_do(f, cld_f, cf); |
| 0 | 665 _vm_queue->oops_do(f); |
| 666 } | |
| 667 | |
| 668 //------------------------------------------------------------------------------------------------------------------ | |
| 669 #ifndef PRODUCT | |
| 670 | |
| 671 void VMOperationQueue::verify_queue(int prio) { | |
| 672 // Check that list is correctly linked | |
| 673 int length = _queue_length[prio]; | |
| 674 VM_Operation *cur = _queue[prio]; | |
| 675 int i; | |
| 676 | |
| 677 // Check forward links | |
| 678 for(i = 0; i < length; i++) { | |
| 679 cur = cur->next(); | |
| 680 assert(cur != _queue[prio], "list to short (forward)"); | |
| 681 } | |
| 682 assert(cur->next() == _queue[prio], "list to long (forward)"); | |
| 683 | |
| 684 // Check backwards links | |
| 685 cur = _queue[prio]; | |
| 686 for(i = 0; i < length; i++) { | |
| 687 cur = cur->prev(); | |
| 688 assert(cur != _queue[prio], "list to short (backwards)"); | |
| 689 } | |
| 690 assert(cur->prev() == _queue[prio], "list to long (backwards)"); | |
| 691 } | |
| 692 | |
| 693 #endif | |
| 694 | |
| 695 void VMThread::verify() { | |
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696 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL); |
| 0 | 697 } |