src/share/vm/runtime/vmThread.cpp

Tue, 05 Nov 2013 17:38:04 -0800

author
kvn
date
Tue, 05 Nov 2013 17:38:04 -0800
changeset 6472
2b8e28fdf503
parent 5237
f2110083203d
child 6553
21dd1c827123
permissions
-rw-r--r--

Merge

duke@435 1 /*
dcubed@4472 2 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
duke@435 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435 4 *
duke@435 5 * This code is free software; you can redistribute it and/or modify it
duke@435 6 * under the terms of the GNU General Public License version 2 only, as
duke@435 7 * published by the Free Software Foundation.
duke@435 8 *
duke@435 9 * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435 12 * version 2 for more details (a copy is included in the LICENSE file that
duke@435 13 * accompanied this code).
duke@435 14 *
duke@435 15 * You should have received a copy of the GNU General Public License version
duke@435 16 * 2 along with this work; if not, write to the Free Software Foundation,
duke@435 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435 18 *
trims@1907 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907 20 * or visit www.oracle.com if you need additional information or have any
trims@1907 21 * questions.
duke@435 22 *
duke@435 23 */
duke@435 24
stefank@2314 25 #include "precompiled.hpp"
stefank@2314 26 #include "compiler/compileBroker.hpp"
stefank@2314 27 #include "gc_interface/collectedHeap.hpp"
stefank@2314 28 #include "memory/resourceArea.hpp"
coleenp@4037 29 #include "oops/method.hpp"
stefank@2314 30 #include "oops/oop.inline.hpp"
stefank@2314 31 #include "runtime/interfaceSupport.hpp"
stefank@2314 32 #include "runtime/mutexLocker.hpp"
stefank@2314 33 #include "runtime/os.hpp"
stefank@4299 34 #include "runtime/thread.inline.hpp"
stefank@2314 35 #include "runtime/vmThread.hpp"
stefank@2314 36 #include "runtime/vm_operations.hpp"
stefank@2314 37 #include "services/runtimeService.hpp"
sla@5237 38 #include "trace/tracing.hpp"
stefank@2314 39 #include "utilities/dtrace.hpp"
stefank@2314 40 #include "utilities/events.hpp"
stefank@2314 41 #include "utilities/xmlstream.hpp"
duke@435 42
dcubed@3202 43 #ifndef USDT2
fparain@1759 44 HS_DTRACE_PROBE_DECL3(hotspot, vmops__request, char *, uintptr_t, int);
fparain@1759 45 HS_DTRACE_PROBE_DECL3(hotspot, vmops__begin, char *, uintptr_t, int);
fparain@1759 46 HS_DTRACE_PROBE_DECL3(hotspot, vmops__end, char *, uintptr_t, int);
dcubed@3202 47 #endif /* !USDT2 */
fparain@1759 48
duke@435 49 // Dummy VM operation to act as first element in our circular double-linked list
duke@435 50 class VM_Dummy: public VM_Operation {
duke@435 51 VMOp_Type type() const { return VMOp_Dummy; }
duke@435 52 void doit() {};
duke@435 53 };
duke@435 54
duke@435 55 VMOperationQueue::VMOperationQueue() {
duke@435 56 // The queue is a circular doubled-linked list, which always contains
duke@435 57 // one element (i.e., one element means empty).
duke@435 58 for(int i = 0; i < nof_priorities; i++) {
duke@435 59 _queue_length[i] = 0;
duke@435 60 _queue_counter = 0;
duke@435 61 _queue[i] = new VM_Dummy();
duke@435 62 _queue[i]->set_next(_queue[i]);
duke@435 63 _queue[i]->set_prev(_queue[i]);
duke@435 64 }
duke@435 65 _drain_list = NULL;
duke@435 66 }
duke@435 67
duke@435 68
duke@435 69 bool VMOperationQueue::queue_empty(int prio) {
duke@435 70 // It is empty if there is exactly one element
duke@435 71 bool empty = (_queue[prio] == _queue[prio]->next());
duke@435 72 assert( (_queue_length[prio] == 0 && empty) ||
duke@435 73 (_queue_length[prio] > 0 && !empty), "sanity check");
duke@435 74 return _queue_length[prio] == 0;
duke@435 75 }
duke@435 76
duke@435 77 // Inserts an element to the right of the q element
duke@435 78 void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) {
duke@435 79 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
duke@435 80 n->set_prev(q);
duke@435 81 n->set_next(q->next());
duke@435 82 q->next()->set_prev(n);
duke@435 83 q->set_next(n);
duke@435 84 }
duke@435 85
duke@435 86 void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) {
duke@435 87 _queue_length[prio]++;
duke@435 88 insert(_queue[prio]->next(), op);
duke@435 89 }
duke@435 90
duke@435 91 void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) {
duke@435 92 _queue_length[prio]++;
duke@435 93 insert(_queue[prio]->prev(), op);
duke@435 94 }
duke@435 95
duke@435 96
duke@435 97 void VMOperationQueue::unlink(VM_Operation* q) {
duke@435 98 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
duke@435 99 q->prev()->set_next(q->next());
duke@435 100 q->next()->set_prev(q->prev());
duke@435 101 }
duke@435 102
duke@435 103 VM_Operation* VMOperationQueue::queue_remove_front(int prio) {
duke@435 104 if (queue_empty(prio)) return NULL;
duke@435 105 assert(_queue_length[prio] >= 0, "sanity check");
duke@435 106 _queue_length[prio]--;
duke@435 107 VM_Operation* r = _queue[prio]->next();
duke@435 108 assert(r != _queue[prio], "cannot remove base element");
duke@435 109 unlink(r);
duke@435 110 return r;
duke@435 111 }
duke@435 112
duke@435 113 VM_Operation* VMOperationQueue::queue_drain(int prio) {
duke@435 114 if (queue_empty(prio)) return NULL;
duke@435 115 DEBUG_ONLY(int length = _queue_length[prio];);
duke@435 116 assert(length >= 0, "sanity check");
duke@435 117 _queue_length[prio] = 0;
duke@435 118 VM_Operation* r = _queue[prio]->next();
duke@435 119 assert(r != _queue[prio], "cannot remove base element");
duke@435 120 // remove links to base element from head and tail
duke@435 121 r->set_prev(NULL);
duke@435 122 _queue[prio]->prev()->set_next(NULL);
duke@435 123 // restore queue to empty state
duke@435 124 _queue[prio]->set_next(_queue[prio]);
duke@435 125 _queue[prio]->set_prev(_queue[prio]);
jcoomes@1844 126 assert(queue_empty(prio), "drain corrupted queue");
drchase@4942 127 #ifdef ASSERT
duke@435 128 int len = 0;
duke@435 129 VM_Operation* cur;
duke@435 130 for(cur = r; cur != NULL; cur=cur->next()) len++;
duke@435 131 assert(len == length, "drain lost some ops");
duke@435 132 #endif
duke@435 133 return r;
duke@435 134 }
duke@435 135
duke@435 136 void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) {
duke@435 137 VM_Operation* cur = _queue[queue];
duke@435 138 cur = cur->next();
duke@435 139 while (cur != _queue[queue]) {
duke@435 140 cur->oops_do(f);
duke@435 141 cur = cur->next();
duke@435 142 }
duke@435 143 }
duke@435 144
duke@435 145 void VMOperationQueue::drain_list_oops_do(OopClosure* f) {
duke@435 146 VM_Operation* cur = _drain_list;
duke@435 147 while (cur != NULL) {
duke@435 148 cur->oops_do(f);
duke@435 149 cur = cur->next();
duke@435 150 }
duke@435 151 }
duke@435 152
duke@435 153 //-----------------------------------------------------------------
duke@435 154 // High-level interface
duke@435 155 bool VMOperationQueue::add(VM_Operation *op) {
fparain@1759 156
dcubed@3202 157 #ifndef USDT2
fparain@1759 158 HS_DTRACE_PROBE3(hotspot, vmops__request, op->name(), strlen(op->name()),
fparain@1759 159 op->evaluation_mode());
dcubed@3202 160 #else /* USDT2 */
dcubed@3202 161 HOTSPOT_VMOPS_REQUEST(
dcubed@3202 162 (char *) op->name(), strlen(op->name()),
dcubed@3202 163 op->evaluation_mode());
dcubed@3202 164 #endif /* USDT2 */
fparain@1759 165
duke@435 166 // Encapsulates VM queue policy. Currently, that
duke@435 167 // only involves putting them on the right list
duke@435 168 if (op->evaluate_at_safepoint()) {
duke@435 169 queue_add_back(SafepointPriority, op);
duke@435 170 return true;
duke@435 171 }
duke@435 172
duke@435 173 queue_add_back(MediumPriority, op);
duke@435 174 return true;
duke@435 175 }
duke@435 176
duke@435 177 VM_Operation* VMOperationQueue::remove_next() {
duke@435 178 // Assuming VMOperation queue is two-level priority queue. If there are
duke@435 179 // more than two priorities, we need a different scheduling algorithm.
duke@435 180 assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2,
duke@435 181 "current algorithm does not work");
duke@435 182
duke@435 183 // simple counter based scheduling to prevent starvation of lower priority
duke@435 184 // queue. -- see 4390175
duke@435 185 int high_prio, low_prio;
duke@435 186 if (_queue_counter++ < 10) {
duke@435 187 high_prio = SafepointPriority;
duke@435 188 low_prio = MediumPriority;
duke@435 189 } else {
duke@435 190 _queue_counter = 0;
duke@435 191 high_prio = MediumPriority;
duke@435 192 low_prio = SafepointPriority;
duke@435 193 }
duke@435 194
duke@435 195 return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio);
duke@435 196 }
duke@435 197
duke@435 198 void VMOperationQueue::oops_do(OopClosure* f) {
duke@435 199 for(int i = 0; i < nof_priorities; i++) {
duke@435 200 queue_oops_do(i, f);
duke@435 201 }
duke@435 202 drain_list_oops_do(f);
duke@435 203 }
duke@435 204
duke@435 205
duke@435 206 //------------------------------------------------------------------------------------------------------------------
duke@435 207 // Implementation of VMThread stuff
duke@435 208
duke@435 209 bool VMThread::_should_terminate = false;
duke@435 210 bool VMThread::_terminated = false;
duke@435 211 Monitor* VMThread::_terminate_lock = NULL;
duke@435 212 VMThread* VMThread::_vm_thread = NULL;
duke@435 213 VM_Operation* VMThread::_cur_vm_operation = NULL;
duke@435 214 VMOperationQueue* VMThread::_vm_queue = NULL;
duke@435 215 PerfCounter* VMThread::_perf_accumulated_vm_operation_time = NULL;
duke@435 216
duke@435 217
duke@435 218 void VMThread::create() {
duke@435 219 assert(vm_thread() == NULL, "we can only allocate one VMThread");
duke@435 220 _vm_thread = new VMThread();
duke@435 221
duke@435 222 // Create VM operation queue
duke@435 223 _vm_queue = new VMOperationQueue();
duke@435 224 guarantee(_vm_queue != NULL, "just checking");
duke@435 225
duke@435 226 _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true);
duke@435 227
duke@435 228 if (UsePerfData) {
duke@435 229 // jvmstat performance counters
duke@435 230 Thread* THREAD = Thread::current();
duke@435 231 _perf_accumulated_vm_operation_time =
duke@435 232 PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime",
duke@435 233 PerfData::U_Ticks, CHECK);
duke@435 234 }
duke@435 235 }
duke@435 236
duke@435 237
minqi@1554 238 VMThread::VMThread() : NamedThread() {
minqi@1554 239 set_name("VM Thread");
duke@435 240 }
duke@435 241
duke@435 242 void VMThread::destroy() {
duke@435 243 if (_vm_thread != NULL) {
duke@435 244 delete _vm_thread;
duke@435 245 _vm_thread = NULL; // VM thread is gone
duke@435 246 }
duke@435 247 }
duke@435 248
duke@435 249 void VMThread::run() {
duke@435 250 assert(this == vm_thread(), "check");
duke@435 251
duke@435 252 this->initialize_thread_local_storage();
duke@435 253 this->record_stack_base_and_size();
duke@435 254 // Notify_lock wait checks on active_handles() to rewait in
duke@435 255 // case of spurious wakeup, it should wait on the last
duke@435 256 // value set prior to the notify
duke@435 257 this->set_active_handles(JNIHandleBlock::allocate_block());
duke@435 258
duke@435 259 {
duke@435 260 MutexLocker ml(Notify_lock);
duke@435 261 Notify_lock->notify();
duke@435 262 }
duke@435 263 // Notify_lock is destroyed by Threads::create_vm()
duke@435 264
duke@435 265 int prio = (VMThreadPriority == -1)
duke@435 266 ? os::java_to_os_priority[NearMaxPriority]
duke@435 267 : VMThreadPriority;
duke@435 268 // Note that I cannot call os::set_priority because it expects Java
duke@435 269 // priorities and I am *explicitly* using OS priorities so that it's
duke@435 270 // possible to set the VM thread priority higher than any Java thread.
duke@435 271 os::set_native_priority( this, prio );
duke@435 272
duke@435 273 // Wait for VM_Operations until termination
duke@435 274 this->loop();
duke@435 275
duke@435 276 // Note the intention to exit before safepointing.
duke@435 277 // 6295565 This has the effect of waiting for any large tty
duke@435 278 // outputs to finish.
duke@435 279 if (xtty != NULL) {
duke@435 280 ttyLocker ttyl;
duke@435 281 xtty->begin_elem("destroy_vm");
duke@435 282 xtty->stamp();
duke@435 283 xtty->end_elem();
duke@435 284 assert(should_terminate(), "termination flag must be set");
duke@435 285 }
duke@435 286
duke@435 287 // 4526887 let VM thread exit at Safepoint
duke@435 288 SafepointSynchronize::begin();
duke@435 289
duke@435 290 if (VerifyBeforeExit) {
duke@435 291 HandleMark hm(VMThread::vm_thread());
duke@435 292 // Among other things, this ensures that Eden top is correct.
duke@435 293 Universe::heap()->prepare_for_verify();
duke@435 294 os::check_heap();
ysr@2825 295 // Silent verification so as not to pollute normal output,
ysr@2825 296 // unless we really asked for it.
stefank@5018 297 Universe::verify(!(PrintGCDetails || Verbose) || VerifySilently);
duke@435 298 }
duke@435 299
duke@435 300 CompileBroker::set_should_block();
duke@435 301
duke@435 302 // wait for threads (compiler threads or daemon threads) in the
duke@435 303 // _thread_in_native state to block.
duke@435 304 VM_Exit::wait_for_threads_in_native_to_block();
duke@435 305
duke@435 306 // signal other threads that VM process is gone
duke@435 307 {
duke@435 308 // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows
duke@435 309 // VM thread to enter any lock at Safepoint as long as its _owner is NULL.
duke@435 310 // If that happens after _terminate_lock->wait() has unset _owner
duke@435 311 // but before it actually drops the lock and waits, the notification below
duke@435 312 // may get lost and we will have a hang. To avoid this, we need to use
duke@435 313 // Mutex::lock_without_safepoint_check().
duke@435 314 MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
duke@435 315 _terminated = true;
duke@435 316 _terminate_lock->notify();
duke@435 317 }
duke@435 318
duke@435 319 // Deletion must be done synchronously by the JNI DestroyJavaVM thread
duke@435 320 // so that the VMThread deletion completes before the main thread frees
duke@435 321 // up the CodeHeap.
duke@435 322
duke@435 323 }
duke@435 324
duke@435 325
duke@435 326 // Notify the VMThread that the last non-daemon JavaThread has terminated,
duke@435 327 // and wait until operation is performed.
duke@435 328 void VMThread::wait_for_vm_thread_exit() {
duke@435 329 { MutexLocker mu(VMOperationQueue_lock);
duke@435 330 _should_terminate = true;
duke@435 331 VMOperationQueue_lock->notify();
duke@435 332 }
duke@435 333
duke@435 334 // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint
duke@435 335 // because this thread has been removed from the threads list. But anything
duke@435 336 // that could get blocked by Safepoint should not be used after this point,
duke@435 337 // otherwise we will hang, since there is no one can end the safepoint.
duke@435 338
duke@435 339 // Wait until VM thread is terminated
duke@435 340 // Note: it should be OK to use Terminator_lock here. But this is called
duke@435 341 // at a very delicate time (VM shutdown) and we are operating in non- VM
duke@435 342 // thread at Safepoint. It's safer to not share lock with other threads.
duke@435 343 { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
duke@435 344 while(!VMThread::is_terminated()) {
duke@435 345 _terminate_lock->wait(Mutex::_no_safepoint_check_flag);
duke@435 346 }
duke@435 347 }
duke@435 348 }
duke@435 349
duke@435 350 void VMThread::print_on(outputStream* st) const {
duke@435 351 st->print("\"%s\" ", name());
duke@435 352 Thread::print_on(st);
duke@435 353 st->cr();
duke@435 354 }
duke@435 355
duke@435 356 void VMThread::evaluate_operation(VM_Operation* op) {
duke@435 357 ResourceMark rm;
duke@435 358
duke@435 359 {
duke@435 360 PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time());
dcubed@3202 361 #ifndef USDT2
fparain@1759 362 HS_DTRACE_PROBE3(hotspot, vmops__begin, op->name(), strlen(op->name()),
fparain@1759 363 op->evaluation_mode());
dcubed@3202 364 #else /* USDT2 */
dcubed@3202 365 HOTSPOT_VMOPS_BEGIN(
dcubed@3202 366 (char *) op->name(), strlen(op->name()),
dcubed@3202 367 op->evaluation_mode());
dcubed@3202 368 #endif /* USDT2 */
sla@5237 369
sla@5237 370 EventExecuteVMOperation event;
sla@5237 371
duke@435 372 op->evaluate();
sla@5237 373
sla@5237 374 if (event.should_commit()) {
sla@5237 375 bool is_concurrent = op->evaluate_concurrently();
sla@5237 376 event.set_operation(op->type());
sla@5237 377 event.set_safepoint(op->evaluate_at_safepoint());
sla@5237 378 event.set_blocking(!is_concurrent);
sla@5237 379 // Only write caller thread information for non-concurrent vm operations.
sla@5237 380 // For concurrent vm operations, the thread id is set to 0 indicating thread is unknown.
sla@5237 381 // This is because the caller thread could have exited already.
sla@5237 382 event.set_caller(is_concurrent ? 0 : op->calling_thread()->osthread()->thread_id());
sla@5237 383 event.commit();
sla@5237 384 }
sla@5237 385
dcubed@3202 386 #ifndef USDT2
fparain@1759 387 HS_DTRACE_PROBE3(hotspot, vmops__end, op->name(), strlen(op->name()),
fparain@1759 388 op->evaluation_mode());
dcubed@3202 389 #else /* USDT2 */
dcubed@3202 390 HOTSPOT_VMOPS_END(
dcubed@3202 391 (char *) op->name(), strlen(op->name()),
dcubed@3202 392 op->evaluation_mode());
dcubed@3202 393 #endif /* USDT2 */
duke@435 394 }
duke@435 395
duke@435 396 // Last access of info in _cur_vm_operation!
duke@435 397 bool c_heap_allocated = op->is_cheap_allocated();
duke@435 398
duke@435 399 // Mark as completed
duke@435 400 if (!op->evaluate_concurrently()) {
duke@435 401 op->calling_thread()->increment_vm_operation_completed_count();
duke@435 402 }
duke@435 403 // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call,
duke@435 404 // since if it is stack allocated the calling thread might have deallocated
duke@435 405 if (c_heap_allocated) {
duke@435 406 delete _cur_vm_operation;
duke@435 407 }
duke@435 408 }
duke@435 409
duke@435 410
duke@435 411 void VMThread::loop() {
duke@435 412 assert(_cur_vm_operation == NULL, "no current one should be executing");
duke@435 413
duke@435 414 while(true) {
duke@435 415 VM_Operation* safepoint_ops = NULL;
duke@435 416 //
duke@435 417 // Wait for VM operation
duke@435 418 //
duke@435 419 // use no_safepoint_check to get lock without attempting to "sneak"
duke@435 420 { MutexLockerEx mu_queue(VMOperationQueue_lock,
duke@435 421 Mutex::_no_safepoint_check_flag);
duke@435 422
duke@435 423 // Look for new operation
duke@435 424 assert(_cur_vm_operation == NULL, "no current one should be executing");
duke@435 425 _cur_vm_operation = _vm_queue->remove_next();
duke@435 426
duke@435 427 // Stall time tracking code
duke@435 428 if (PrintVMQWaitTime && _cur_vm_operation != NULL &&
duke@435 429 !_cur_vm_operation->evaluate_concurrently()) {
duke@435 430 long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp();
duke@435 431 if (stall > 0)
duke@435 432 tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall);
duke@435 433 }
duke@435 434
duke@435 435 while (!should_terminate() && _cur_vm_operation == NULL) {
duke@435 436 // wait with a timeout to guarantee safepoints at regular intervals
duke@435 437 bool timedout =
duke@435 438 VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag,
duke@435 439 GuaranteedSafepointInterval);
duke@435 440
duke@435 441 // Support for self destruction
duke@435 442 if ((SelfDestructTimer != 0) && !is_error_reported() &&
duke@435 443 (os::elapsedTime() > SelfDestructTimer * 60)) {
duke@435 444 tty->print_cr("VM self-destructed");
duke@435 445 exit(-1);
duke@435 446 }
duke@435 447
duke@435 448 if (timedout && (SafepointALot ||
duke@435 449 SafepointSynchronize::is_cleanup_needed())) {
duke@435 450 MutexUnlockerEx mul(VMOperationQueue_lock,
duke@435 451 Mutex::_no_safepoint_check_flag);
duke@435 452 // Force a safepoint since we have not had one for at least
duke@435 453 // 'GuaranteedSafepointInterval' milliseconds. This will run all
duke@435 454 // the clean-up processing that needs to be done regularly at a
duke@435 455 // safepoint
duke@435 456 SafepointSynchronize::begin();
duke@435 457 #ifdef ASSERT
duke@435 458 if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
duke@435 459 #endif
duke@435 460 SafepointSynchronize::end();
duke@435 461 }
duke@435 462 _cur_vm_operation = _vm_queue->remove_next();
duke@435 463
duke@435 464 // If we are at a safepoint we will evaluate all the operations that
duke@435 465 // follow that also require a safepoint
duke@435 466 if (_cur_vm_operation != NULL &&
duke@435 467 _cur_vm_operation->evaluate_at_safepoint()) {
duke@435 468 safepoint_ops = _vm_queue->drain_at_safepoint_priority();
duke@435 469 }
duke@435 470 }
duke@435 471
duke@435 472 if (should_terminate()) break;
duke@435 473 } // Release mu_queue_lock
duke@435 474
duke@435 475 //
duke@435 476 // Execute VM operation
duke@435 477 //
duke@435 478 { HandleMark hm(VMThread::vm_thread());
duke@435 479
duke@435 480 EventMark em("Executing VM operation: %s", vm_operation()->name());
duke@435 481 assert(_cur_vm_operation != NULL, "we should have found an operation to execute");
duke@435 482
duke@435 483 // Give the VM thread an extra quantum. Jobs tend to be bursty and this
duke@435 484 // helps the VM thread to finish up the job.
duke@435 485 // FIXME: When this is enabled and there are many threads, this can degrade
duke@435 486 // performance significantly.
duke@435 487 if( VMThreadHintNoPreempt )
duke@435 488 os::hint_no_preempt();
duke@435 489
duke@435 490 // If we are at a safepoint we will evaluate all the operations that
duke@435 491 // follow that also require a safepoint
duke@435 492 if (_cur_vm_operation->evaluate_at_safepoint()) {
duke@435 493
duke@435 494 _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned
duke@435 495
duke@435 496 SafepointSynchronize::begin();
duke@435 497 evaluate_operation(_cur_vm_operation);
duke@435 498 // now process all queued safepoint ops, iteratively draining
duke@435 499 // the queue until there are none left
duke@435 500 do {
duke@435 501 _cur_vm_operation = safepoint_ops;
duke@435 502 if (_cur_vm_operation != NULL) {
duke@435 503 do {
duke@435 504 // evaluate_operation deletes the op object so we have
duke@435 505 // to grab the next op now
duke@435 506 VM_Operation* next = _cur_vm_operation->next();
duke@435 507 _vm_queue->set_drain_list(next);
duke@435 508 evaluate_operation(_cur_vm_operation);
duke@435 509 _cur_vm_operation = next;
duke@435 510 if (PrintSafepointStatistics) {
duke@435 511 SafepointSynchronize::inc_vmop_coalesced_count();
duke@435 512 }
duke@435 513 } while (_cur_vm_operation != NULL);
duke@435 514 }
duke@435 515 // There is a chance that a thread enqueued a safepoint op
duke@435 516 // since we released the op-queue lock and initiated the safepoint.
duke@435 517 // So we drain the queue again if there is anything there, as an
duke@435 518 // optimization to try and reduce the number of safepoints.
duke@435 519 // As the safepoint synchronizes us with JavaThreads we will see
duke@435 520 // any enqueue made by a JavaThread, but the peek will not
duke@435 521 // necessarily detect a concurrent enqueue by a GC thread, but
duke@435 522 // that simply means the op will wait for the next major cycle of the
duke@435 523 // VMThread - just as it would if the GC thread lost the race for
duke@435 524 // the lock.
duke@435 525 if (_vm_queue->peek_at_safepoint_priority()) {
duke@435 526 // must hold lock while draining queue
duke@435 527 MutexLockerEx mu_queue(VMOperationQueue_lock,
duke@435 528 Mutex::_no_safepoint_check_flag);
duke@435 529 safepoint_ops = _vm_queue->drain_at_safepoint_priority();
duke@435 530 } else {
duke@435 531 safepoint_ops = NULL;
duke@435 532 }
duke@435 533 } while(safepoint_ops != NULL);
duke@435 534
duke@435 535 _vm_queue->set_drain_list(NULL);
duke@435 536
duke@435 537 // Complete safepoint synchronization
duke@435 538 SafepointSynchronize::end();
duke@435 539
duke@435 540 } else { // not a safepoint operation
duke@435 541 if (TraceLongCompiles) {
duke@435 542 elapsedTimer t;
duke@435 543 t.start();
duke@435 544 evaluate_operation(_cur_vm_operation);
duke@435 545 t.stop();
duke@435 546 double secs = t.seconds();
duke@435 547 if (secs * 1e3 > LongCompileThreshold) {
duke@435 548 // XXX - _cur_vm_operation should not be accessed after
duke@435 549 // the completed count has been incremented; the waiting
duke@435 550 // thread may have already freed this memory.
duke@435 551 tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs);
duke@435 552 }
duke@435 553 } else {
duke@435 554 evaluate_operation(_cur_vm_operation);
duke@435 555 }
duke@435 556
duke@435 557 _cur_vm_operation = NULL;
duke@435 558 }
duke@435 559 }
duke@435 560
duke@435 561 //
duke@435 562 // Notify (potential) waiting Java thread(s) - lock without safepoint
duke@435 563 // check so that sneaking is not possible
duke@435 564 { MutexLockerEx mu(VMOperationRequest_lock,
duke@435 565 Mutex::_no_safepoint_check_flag);
duke@435 566 VMOperationRequest_lock->notify_all();
duke@435 567 }
duke@435 568
duke@435 569 //
duke@435 570 // We want to make sure that we get to a safepoint regularly.
duke@435 571 //
duke@435 572 if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) {
duke@435 573 long interval = SafepointSynchronize::last_non_safepoint_interval();
duke@435 574 bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval);
duke@435 575 if (SafepointALot || max_time_exceeded) {
duke@435 576 HandleMark hm(VMThread::vm_thread());
duke@435 577 SafepointSynchronize::begin();
duke@435 578 SafepointSynchronize::end();
duke@435 579 }
duke@435 580 }
duke@435 581 }
duke@435 582 }
duke@435 583
duke@435 584 void VMThread::execute(VM_Operation* op) {
duke@435 585 Thread* t = Thread::current();
duke@435 586
duke@435 587 if (!t->is_VM_thread()) {
ysr@1241 588 SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot
duke@435 589 // JavaThread or WatcherThread
dcubed@4472 590 bool concurrent = op->evaluate_concurrently();
dcubed@4472 591 // only blocking VM operations need to verify the caller's safepoint state:
dcubed@4472 592 if (!concurrent) {
dcubed@4472 593 t->check_for_valid_safepoint_state(true);
dcubed@4472 594 }
duke@435 595
duke@435 596 // New request from Java thread, evaluate prologue
duke@435 597 if (!op->doit_prologue()) {
duke@435 598 return; // op was cancelled
duke@435 599 }
duke@435 600
duke@435 601 // Setup VM_operations for execution
duke@435 602 op->set_calling_thread(t, Thread::get_priority(t));
duke@435 603
duke@435 604 // It does not make sense to execute the epilogue, if the VM operation object is getting
duke@435 605 // deallocated by the VM thread.
duke@435 606 bool execute_epilog = !op->is_cheap_allocated();
duke@435 607 assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated");
duke@435 608
duke@435 609 // Get ticket number for non-concurrent VM operations
duke@435 610 int ticket = 0;
duke@435 611 if (!concurrent) {
duke@435 612 ticket = t->vm_operation_ticket();
duke@435 613 }
duke@435 614
duke@435 615 // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the
duke@435 616 // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests
duke@435 617 // to be queued up during a safepoint synchronization.
duke@435 618 {
duke@435 619 VMOperationQueue_lock->lock_without_safepoint_check();
duke@435 620 bool ok = _vm_queue->add(op);
sla@5237 621 op->set_timestamp(os::javaTimeMillis());
duke@435 622 VMOperationQueue_lock->notify();
duke@435 623 VMOperationQueue_lock->unlock();
duke@435 624 // VM_Operation got skipped
duke@435 625 if (!ok) {
duke@435 626 assert(concurrent, "can only skip concurrent tasks");
duke@435 627 if (op->is_cheap_allocated()) delete op;
duke@435 628 return;
duke@435 629 }
duke@435 630 }
duke@435 631
duke@435 632 if (!concurrent) {
duke@435 633 // Wait for completion of request (non-concurrent)
duke@435 634 // Note: only a JavaThread triggers the safepoint check when locking
duke@435 635 MutexLocker mu(VMOperationRequest_lock);
duke@435 636 while(t->vm_operation_completed_count() < ticket) {
duke@435 637 VMOperationRequest_lock->wait(!t->is_Java_thread());
duke@435 638 }
duke@435 639 }
duke@435 640
duke@435 641 if (execute_epilog) {
duke@435 642 op->doit_epilogue();
duke@435 643 }
duke@435 644 } else {
duke@435 645 // invoked by VM thread; usually nested VM operation
duke@435 646 assert(t->is_VM_thread(), "must be a VM thread");
duke@435 647 VM_Operation* prev_vm_operation = vm_operation();
duke@435 648 if (prev_vm_operation != NULL) {
duke@435 649 // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler
duke@435 650 // does not allow nested scavenges or compiles.
duke@435 651 if (!prev_vm_operation->allow_nested_vm_operations()) {
jcoomes@1845 652 fatal(err_msg("Nested VM operation %s requested by operation %s",
jcoomes@1845 653 op->name(), vm_operation()->name()));
duke@435 654 }
duke@435 655 op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority());
duke@435 656 }
duke@435 657
duke@435 658 EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name());
duke@435 659
duke@435 660 // Release all internal handles after operation is evaluated
duke@435 661 HandleMark hm(t);
duke@435 662 _cur_vm_operation = op;
duke@435 663
duke@435 664 if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) {
duke@435 665 SafepointSynchronize::begin();
duke@435 666 op->evaluate();
duke@435 667 SafepointSynchronize::end();
duke@435 668 } else {
duke@435 669 op->evaluate();
duke@435 670 }
duke@435 671
duke@435 672 // Free memory if needed
duke@435 673 if (op->is_cheap_allocated()) delete op;
duke@435 674
duke@435 675 _cur_vm_operation = prev_vm_operation;
duke@435 676 }
duke@435 677 }
duke@435 678
duke@435 679
stefank@4298 680 void VMThread::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
stefank@4298 681 Thread::oops_do(f, cld_f, cf);
duke@435 682 _vm_queue->oops_do(f);
duke@435 683 }
duke@435 684
duke@435 685 //------------------------------------------------------------------------------------------------------------------
duke@435 686 #ifndef PRODUCT
duke@435 687
duke@435 688 void VMOperationQueue::verify_queue(int prio) {
duke@435 689 // Check that list is correctly linked
duke@435 690 int length = _queue_length[prio];
duke@435 691 VM_Operation *cur = _queue[prio];
duke@435 692 int i;
duke@435 693
duke@435 694 // Check forward links
duke@435 695 for(i = 0; i < length; i++) {
duke@435 696 cur = cur->next();
duke@435 697 assert(cur != _queue[prio], "list to short (forward)");
duke@435 698 }
duke@435 699 assert(cur->next() == _queue[prio], "list to long (forward)");
duke@435 700
duke@435 701 // Check backwards links
duke@435 702 cur = _queue[prio];
duke@435 703 for(i = 0; i < length; i++) {
duke@435 704 cur = cur->prev();
duke@435 705 assert(cur != _queue[prio], "list to short (backwards)");
duke@435 706 }
duke@435 707 assert(cur->prev() == _queue[prio], "list to long (backwards)");
duke@435 708 }
duke@435 709
duke@435 710 #endif
duke@435 711
duke@435 712 void VMThread::verify() {
stefank@4298 713 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
duke@435 714 }

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