src/share/vm/runtime/vmThread.cpp

Sun, 01 Jan 2012 11:17:59 -0500

author
phh
date
Sun, 01 Jan 2012 11:17:59 -0500
changeset 3378
7ab5f6318694
parent 3202
436b4a3231bf
child 3711
b632e80fc9dc
permissions
-rw-r--r--

7125934: Add a fast unordered timestamp capability to Hotspot on x86/x64
Summary: Add rdtsc detection and inline generation.
Reviewed-by: kamg, dholmes
Contributed-by: karen.kinnear@oracle.com

duke@435 1 /*
trims@1907 2 * Copyright (c) 1998, 2010, 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"
stefank@2314 29 #include "oops/methodOop.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@2314 34 #include "runtime/vmThread.hpp"
stefank@2314 35 #include "runtime/vm_operations.hpp"
stefank@2314 36 #include "services/runtimeService.hpp"
stefank@2314 37 #include "utilities/dtrace.hpp"
stefank@2314 38 #include "utilities/events.hpp"
stefank@2314 39 #include "utilities/xmlstream.hpp"
stefank@2314 40 #ifdef TARGET_OS_FAMILY_linux
stefank@2314 41 # include "thread_linux.inline.hpp"
stefank@2314 42 #endif
stefank@2314 43 #ifdef TARGET_OS_FAMILY_solaris
stefank@2314 44 # include "thread_solaris.inline.hpp"
stefank@2314 45 #endif
stefank@2314 46 #ifdef TARGET_OS_FAMILY_windows
stefank@2314 47 # include "thread_windows.inline.hpp"
stefank@2314 48 #endif
never@3156 49 #ifdef TARGET_OS_FAMILY_bsd
never@3156 50 # include "thread_bsd.inline.hpp"
never@3156 51 #endif
duke@435 52
dcubed@3202 53 #ifndef USDT2
fparain@1759 54 HS_DTRACE_PROBE_DECL3(hotspot, vmops__request, char *, uintptr_t, int);
fparain@1759 55 HS_DTRACE_PROBE_DECL3(hotspot, vmops__begin, char *, uintptr_t, int);
fparain@1759 56 HS_DTRACE_PROBE_DECL3(hotspot, vmops__end, char *, uintptr_t, int);
dcubed@3202 57 #endif /* !USDT2 */
fparain@1759 58
duke@435 59 // Dummy VM operation to act as first element in our circular double-linked list
duke@435 60 class VM_Dummy: public VM_Operation {
duke@435 61 VMOp_Type type() const { return VMOp_Dummy; }
duke@435 62 void doit() {};
duke@435 63 };
duke@435 64
duke@435 65 VMOperationQueue::VMOperationQueue() {
duke@435 66 // The queue is a circular doubled-linked list, which always contains
duke@435 67 // one element (i.e., one element means empty).
duke@435 68 for(int i = 0; i < nof_priorities; i++) {
duke@435 69 _queue_length[i] = 0;
duke@435 70 _queue_counter = 0;
duke@435 71 _queue[i] = new VM_Dummy();
duke@435 72 _queue[i]->set_next(_queue[i]);
duke@435 73 _queue[i]->set_prev(_queue[i]);
duke@435 74 }
duke@435 75 _drain_list = NULL;
duke@435 76 }
duke@435 77
duke@435 78
duke@435 79 bool VMOperationQueue::queue_empty(int prio) {
duke@435 80 // It is empty if there is exactly one element
duke@435 81 bool empty = (_queue[prio] == _queue[prio]->next());
duke@435 82 assert( (_queue_length[prio] == 0 && empty) ||
duke@435 83 (_queue_length[prio] > 0 && !empty), "sanity check");
duke@435 84 return _queue_length[prio] == 0;
duke@435 85 }
duke@435 86
duke@435 87 // Inserts an element to the right of the q element
duke@435 88 void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) {
duke@435 89 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
duke@435 90 n->set_prev(q);
duke@435 91 n->set_next(q->next());
duke@435 92 q->next()->set_prev(n);
duke@435 93 q->set_next(n);
duke@435 94 }
duke@435 95
duke@435 96 void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) {
duke@435 97 _queue_length[prio]++;
duke@435 98 insert(_queue[prio]->next(), op);
duke@435 99 }
duke@435 100
duke@435 101 void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) {
duke@435 102 _queue_length[prio]++;
duke@435 103 insert(_queue[prio]->prev(), op);
duke@435 104 }
duke@435 105
duke@435 106
duke@435 107 void VMOperationQueue::unlink(VM_Operation* q) {
duke@435 108 assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check");
duke@435 109 q->prev()->set_next(q->next());
duke@435 110 q->next()->set_prev(q->prev());
duke@435 111 }
duke@435 112
duke@435 113 VM_Operation* VMOperationQueue::queue_remove_front(int prio) {
duke@435 114 if (queue_empty(prio)) return NULL;
duke@435 115 assert(_queue_length[prio] >= 0, "sanity check");
duke@435 116 _queue_length[prio]--;
duke@435 117 VM_Operation* r = _queue[prio]->next();
duke@435 118 assert(r != _queue[prio], "cannot remove base element");
duke@435 119 unlink(r);
duke@435 120 return r;
duke@435 121 }
duke@435 122
duke@435 123 VM_Operation* VMOperationQueue::queue_drain(int prio) {
duke@435 124 if (queue_empty(prio)) return NULL;
duke@435 125 DEBUG_ONLY(int length = _queue_length[prio];);
duke@435 126 assert(length >= 0, "sanity check");
duke@435 127 _queue_length[prio] = 0;
duke@435 128 VM_Operation* r = _queue[prio]->next();
duke@435 129 assert(r != _queue[prio], "cannot remove base element");
duke@435 130 // remove links to base element from head and tail
duke@435 131 r->set_prev(NULL);
duke@435 132 _queue[prio]->prev()->set_next(NULL);
duke@435 133 // restore queue to empty state
duke@435 134 _queue[prio]->set_next(_queue[prio]);
duke@435 135 _queue[prio]->set_prev(_queue[prio]);
jcoomes@1844 136 assert(queue_empty(prio), "drain corrupted queue");
duke@435 137 #ifdef DEBUG
duke@435 138 int len = 0;
duke@435 139 VM_Operation* cur;
duke@435 140 for(cur = r; cur != NULL; cur=cur->next()) len++;
duke@435 141 assert(len == length, "drain lost some ops");
duke@435 142 #endif
duke@435 143 return r;
duke@435 144 }
duke@435 145
duke@435 146 void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) {
duke@435 147 VM_Operation* cur = _queue[queue];
duke@435 148 cur = cur->next();
duke@435 149 while (cur != _queue[queue]) {
duke@435 150 cur->oops_do(f);
duke@435 151 cur = cur->next();
duke@435 152 }
duke@435 153 }
duke@435 154
duke@435 155 void VMOperationQueue::drain_list_oops_do(OopClosure* f) {
duke@435 156 VM_Operation* cur = _drain_list;
duke@435 157 while (cur != NULL) {
duke@435 158 cur->oops_do(f);
duke@435 159 cur = cur->next();
duke@435 160 }
duke@435 161 }
duke@435 162
duke@435 163 //-----------------------------------------------------------------
duke@435 164 // High-level interface
duke@435 165 bool VMOperationQueue::add(VM_Operation *op) {
fparain@1759 166
dcubed@3202 167 #ifndef USDT2
fparain@1759 168 HS_DTRACE_PROBE3(hotspot, vmops__request, op->name(), strlen(op->name()),
fparain@1759 169 op->evaluation_mode());
dcubed@3202 170 #else /* USDT2 */
dcubed@3202 171 HOTSPOT_VMOPS_REQUEST(
dcubed@3202 172 (char *) op->name(), strlen(op->name()),
dcubed@3202 173 op->evaluation_mode());
dcubed@3202 174 #endif /* USDT2 */
fparain@1759 175
duke@435 176 // Encapsulates VM queue policy. Currently, that
duke@435 177 // only involves putting them on the right list
duke@435 178 if (op->evaluate_at_safepoint()) {
duke@435 179 queue_add_back(SafepointPriority, op);
duke@435 180 return true;
duke@435 181 }
duke@435 182
duke@435 183 queue_add_back(MediumPriority, op);
duke@435 184 return true;
duke@435 185 }
duke@435 186
duke@435 187 VM_Operation* VMOperationQueue::remove_next() {
duke@435 188 // Assuming VMOperation queue is two-level priority queue. If there are
duke@435 189 // more than two priorities, we need a different scheduling algorithm.
duke@435 190 assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2,
duke@435 191 "current algorithm does not work");
duke@435 192
duke@435 193 // simple counter based scheduling to prevent starvation of lower priority
duke@435 194 // queue. -- see 4390175
duke@435 195 int high_prio, low_prio;
duke@435 196 if (_queue_counter++ < 10) {
duke@435 197 high_prio = SafepointPriority;
duke@435 198 low_prio = MediumPriority;
duke@435 199 } else {
duke@435 200 _queue_counter = 0;
duke@435 201 high_prio = MediumPriority;
duke@435 202 low_prio = SafepointPriority;
duke@435 203 }
duke@435 204
duke@435 205 return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio);
duke@435 206 }
duke@435 207
duke@435 208 void VMOperationQueue::oops_do(OopClosure* f) {
duke@435 209 for(int i = 0; i < nof_priorities; i++) {
duke@435 210 queue_oops_do(i, f);
duke@435 211 }
duke@435 212 drain_list_oops_do(f);
duke@435 213 }
duke@435 214
duke@435 215
duke@435 216 //------------------------------------------------------------------------------------------------------------------
duke@435 217 // Implementation of VMThread stuff
duke@435 218
duke@435 219 bool VMThread::_should_terminate = false;
duke@435 220 bool VMThread::_terminated = false;
duke@435 221 Monitor* VMThread::_terminate_lock = NULL;
duke@435 222 VMThread* VMThread::_vm_thread = NULL;
duke@435 223 VM_Operation* VMThread::_cur_vm_operation = NULL;
duke@435 224 VMOperationQueue* VMThread::_vm_queue = NULL;
duke@435 225 PerfCounter* VMThread::_perf_accumulated_vm_operation_time = NULL;
duke@435 226
duke@435 227
duke@435 228 void VMThread::create() {
duke@435 229 assert(vm_thread() == NULL, "we can only allocate one VMThread");
duke@435 230 _vm_thread = new VMThread();
duke@435 231
duke@435 232 // Create VM operation queue
duke@435 233 _vm_queue = new VMOperationQueue();
duke@435 234 guarantee(_vm_queue != NULL, "just checking");
duke@435 235
duke@435 236 _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true);
duke@435 237
duke@435 238 if (UsePerfData) {
duke@435 239 // jvmstat performance counters
duke@435 240 Thread* THREAD = Thread::current();
duke@435 241 _perf_accumulated_vm_operation_time =
duke@435 242 PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime",
duke@435 243 PerfData::U_Ticks, CHECK);
duke@435 244 }
duke@435 245 }
duke@435 246
duke@435 247
minqi@1554 248 VMThread::VMThread() : NamedThread() {
minqi@1554 249 set_name("VM Thread");
duke@435 250 }
duke@435 251
duke@435 252 void VMThread::destroy() {
duke@435 253 if (_vm_thread != NULL) {
duke@435 254 delete _vm_thread;
duke@435 255 _vm_thread = NULL; // VM thread is gone
duke@435 256 }
duke@435 257 }
duke@435 258
duke@435 259 void VMThread::run() {
duke@435 260 assert(this == vm_thread(), "check");
duke@435 261
duke@435 262 this->initialize_thread_local_storage();
duke@435 263 this->record_stack_base_and_size();
duke@435 264 // Notify_lock wait checks on active_handles() to rewait in
duke@435 265 // case of spurious wakeup, it should wait on the last
duke@435 266 // value set prior to the notify
duke@435 267 this->set_active_handles(JNIHandleBlock::allocate_block());
duke@435 268
duke@435 269 {
duke@435 270 MutexLocker ml(Notify_lock);
duke@435 271 Notify_lock->notify();
duke@435 272 }
duke@435 273 // Notify_lock is destroyed by Threads::create_vm()
duke@435 274
duke@435 275 int prio = (VMThreadPriority == -1)
duke@435 276 ? os::java_to_os_priority[NearMaxPriority]
duke@435 277 : VMThreadPriority;
duke@435 278 // Note that I cannot call os::set_priority because it expects Java
duke@435 279 // priorities and I am *explicitly* using OS priorities so that it's
duke@435 280 // possible to set the VM thread priority higher than any Java thread.
duke@435 281 os::set_native_priority( this, prio );
duke@435 282
duke@435 283 // Wait for VM_Operations until termination
duke@435 284 this->loop();
duke@435 285
duke@435 286 // Note the intention to exit before safepointing.
duke@435 287 // 6295565 This has the effect of waiting for any large tty
duke@435 288 // outputs to finish.
duke@435 289 if (xtty != NULL) {
duke@435 290 ttyLocker ttyl;
duke@435 291 xtty->begin_elem("destroy_vm");
duke@435 292 xtty->stamp();
duke@435 293 xtty->end_elem();
duke@435 294 assert(should_terminate(), "termination flag must be set");
duke@435 295 }
duke@435 296
duke@435 297 // 4526887 let VM thread exit at Safepoint
duke@435 298 SafepointSynchronize::begin();
duke@435 299
duke@435 300 if (VerifyBeforeExit) {
duke@435 301 HandleMark hm(VMThread::vm_thread());
duke@435 302 // Among other things, this ensures that Eden top is correct.
duke@435 303 Universe::heap()->prepare_for_verify();
duke@435 304 os::check_heap();
ysr@2825 305 // Silent verification so as not to pollute normal output,
ysr@2825 306 // unless we really asked for it.
ysr@2825 307 Universe::verify(true, !(PrintGCDetails || Verbose));
duke@435 308 }
duke@435 309
duke@435 310 CompileBroker::set_should_block();
duke@435 311
duke@435 312 // wait for threads (compiler threads or daemon threads) in the
duke@435 313 // _thread_in_native state to block.
duke@435 314 VM_Exit::wait_for_threads_in_native_to_block();
duke@435 315
duke@435 316 // signal other threads that VM process is gone
duke@435 317 {
duke@435 318 // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows
duke@435 319 // VM thread to enter any lock at Safepoint as long as its _owner is NULL.
duke@435 320 // If that happens after _terminate_lock->wait() has unset _owner
duke@435 321 // but before it actually drops the lock and waits, the notification below
duke@435 322 // may get lost and we will have a hang. To avoid this, we need to use
duke@435 323 // Mutex::lock_without_safepoint_check().
duke@435 324 MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
duke@435 325 _terminated = true;
duke@435 326 _terminate_lock->notify();
duke@435 327 }
duke@435 328
duke@435 329 // Deletion must be done synchronously by the JNI DestroyJavaVM thread
duke@435 330 // so that the VMThread deletion completes before the main thread frees
duke@435 331 // up the CodeHeap.
duke@435 332
duke@435 333 }
duke@435 334
duke@435 335
duke@435 336 // Notify the VMThread that the last non-daemon JavaThread has terminated,
duke@435 337 // and wait until operation is performed.
duke@435 338 void VMThread::wait_for_vm_thread_exit() {
duke@435 339 { MutexLocker mu(VMOperationQueue_lock);
duke@435 340 _should_terminate = true;
duke@435 341 VMOperationQueue_lock->notify();
duke@435 342 }
duke@435 343
duke@435 344 // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint
duke@435 345 // because this thread has been removed from the threads list. But anything
duke@435 346 // that could get blocked by Safepoint should not be used after this point,
duke@435 347 // otherwise we will hang, since there is no one can end the safepoint.
duke@435 348
duke@435 349 // Wait until VM thread is terminated
duke@435 350 // Note: it should be OK to use Terminator_lock here. But this is called
duke@435 351 // at a very delicate time (VM shutdown) and we are operating in non- VM
duke@435 352 // thread at Safepoint. It's safer to not share lock with other threads.
duke@435 353 { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag);
duke@435 354 while(!VMThread::is_terminated()) {
duke@435 355 _terminate_lock->wait(Mutex::_no_safepoint_check_flag);
duke@435 356 }
duke@435 357 }
duke@435 358 }
duke@435 359
duke@435 360 void VMThread::print_on(outputStream* st) const {
duke@435 361 st->print("\"%s\" ", name());
duke@435 362 Thread::print_on(st);
duke@435 363 st->cr();
duke@435 364 }
duke@435 365
duke@435 366 void VMThread::evaluate_operation(VM_Operation* op) {
duke@435 367 ResourceMark rm;
duke@435 368
duke@435 369 {
duke@435 370 PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time());
dcubed@3202 371 #ifndef USDT2
fparain@1759 372 HS_DTRACE_PROBE3(hotspot, vmops__begin, op->name(), strlen(op->name()),
fparain@1759 373 op->evaluation_mode());
dcubed@3202 374 #else /* USDT2 */
dcubed@3202 375 HOTSPOT_VMOPS_BEGIN(
dcubed@3202 376 (char *) op->name(), strlen(op->name()),
dcubed@3202 377 op->evaluation_mode());
dcubed@3202 378 #endif /* USDT2 */
duke@435 379 op->evaluate();
dcubed@3202 380 #ifndef USDT2
fparain@1759 381 HS_DTRACE_PROBE3(hotspot, vmops__end, op->name(), strlen(op->name()),
fparain@1759 382 op->evaluation_mode());
dcubed@3202 383 #else /* USDT2 */
dcubed@3202 384 HOTSPOT_VMOPS_END(
dcubed@3202 385 (char *) op->name(), strlen(op->name()),
dcubed@3202 386 op->evaluation_mode());
dcubed@3202 387 #endif /* USDT2 */
duke@435 388 }
duke@435 389
duke@435 390 // Last access of info in _cur_vm_operation!
duke@435 391 bool c_heap_allocated = op->is_cheap_allocated();
duke@435 392
duke@435 393 // Mark as completed
duke@435 394 if (!op->evaluate_concurrently()) {
duke@435 395 op->calling_thread()->increment_vm_operation_completed_count();
duke@435 396 }
duke@435 397 // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call,
duke@435 398 // since if it is stack allocated the calling thread might have deallocated
duke@435 399 if (c_heap_allocated) {
duke@435 400 delete _cur_vm_operation;
duke@435 401 }
duke@435 402 }
duke@435 403
duke@435 404
duke@435 405 void VMThread::loop() {
duke@435 406 assert(_cur_vm_operation == NULL, "no current one should be executing");
duke@435 407
duke@435 408 while(true) {
duke@435 409 VM_Operation* safepoint_ops = NULL;
duke@435 410 //
duke@435 411 // Wait for VM operation
duke@435 412 //
duke@435 413 // use no_safepoint_check to get lock without attempting to "sneak"
duke@435 414 { MutexLockerEx mu_queue(VMOperationQueue_lock,
duke@435 415 Mutex::_no_safepoint_check_flag);
duke@435 416
duke@435 417 // Look for new operation
duke@435 418 assert(_cur_vm_operation == NULL, "no current one should be executing");
duke@435 419 _cur_vm_operation = _vm_queue->remove_next();
duke@435 420
duke@435 421 // Stall time tracking code
duke@435 422 if (PrintVMQWaitTime && _cur_vm_operation != NULL &&
duke@435 423 !_cur_vm_operation->evaluate_concurrently()) {
duke@435 424 long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp();
duke@435 425 if (stall > 0)
duke@435 426 tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall);
duke@435 427 }
duke@435 428
duke@435 429 while (!should_terminate() && _cur_vm_operation == NULL) {
duke@435 430 // wait with a timeout to guarantee safepoints at regular intervals
duke@435 431 bool timedout =
duke@435 432 VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag,
duke@435 433 GuaranteedSafepointInterval);
duke@435 434
duke@435 435 // Support for self destruction
duke@435 436 if ((SelfDestructTimer != 0) && !is_error_reported() &&
duke@435 437 (os::elapsedTime() > SelfDestructTimer * 60)) {
duke@435 438 tty->print_cr("VM self-destructed");
duke@435 439 exit(-1);
duke@435 440 }
duke@435 441
duke@435 442 if (timedout && (SafepointALot ||
duke@435 443 SafepointSynchronize::is_cleanup_needed())) {
duke@435 444 MutexUnlockerEx mul(VMOperationQueue_lock,
duke@435 445 Mutex::_no_safepoint_check_flag);
duke@435 446 // Force a safepoint since we have not had one for at least
duke@435 447 // 'GuaranteedSafepointInterval' milliseconds. This will run all
duke@435 448 // the clean-up processing that needs to be done regularly at a
duke@435 449 // safepoint
duke@435 450 SafepointSynchronize::begin();
duke@435 451 #ifdef ASSERT
duke@435 452 if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
duke@435 453 #endif
duke@435 454 SafepointSynchronize::end();
duke@435 455 }
duke@435 456 _cur_vm_operation = _vm_queue->remove_next();
duke@435 457
duke@435 458 // If we are at a safepoint we will evaluate all the operations that
duke@435 459 // follow that also require a safepoint
duke@435 460 if (_cur_vm_operation != NULL &&
duke@435 461 _cur_vm_operation->evaluate_at_safepoint()) {
duke@435 462 safepoint_ops = _vm_queue->drain_at_safepoint_priority();
duke@435 463 }
duke@435 464 }
duke@435 465
duke@435 466 if (should_terminate()) break;
duke@435 467 } // Release mu_queue_lock
duke@435 468
duke@435 469 //
duke@435 470 // Execute VM operation
duke@435 471 //
duke@435 472 { HandleMark hm(VMThread::vm_thread());
duke@435 473
duke@435 474 EventMark em("Executing VM operation: %s", vm_operation()->name());
duke@435 475 assert(_cur_vm_operation != NULL, "we should have found an operation to execute");
duke@435 476
duke@435 477 // Give the VM thread an extra quantum. Jobs tend to be bursty and this
duke@435 478 // helps the VM thread to finish up the job.
duke@435 479 // FIXME: When this is enabled and there are many threads, this can degrade
duke@435 480 // performance significantly.
duke@435 481 if( VMThreadHintNoPreempt )
duke@435 482 os::hint_no_preempt();
duke@435 483
duke@435 484 // If we are at a safepoint we will evaluate all the operations that
duke@435 485 // follow that also require a safepoint
duke@435 486 if (_cur_vm_operation->evaluate_at_safepoint()) {
duke@435 487
duke@435 488 _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned
duke@435 489
duke@435 490 SafepointSynchronize::begin();
duke@435 491 evaluate_operation(_cur_vm_operation);
duke@435 492 // now process all queued safepoint ops, iteratively draining
duke@435 493 // the queue until there are none left
duke@435 494 do {
duke@435 495 _cur_vm_operation = safepoint_ops;
duke@435 496 if (_cur_vm_operation != NULL) {
duke@435 497 do {
duke@435 498 // evaluate_operation deletes the op object so we have
duke@435 499 // to grab the next op now
duke@435 500 VM_Operation* next = _cur_vm_operation->next();
duke@435 501 _vm_queue->set_drain_list(next);
duke@435 502 evaluate_operation(_cur_vm_operation);
duke@435 503 _cur_vm_operation = next;
duke@435 504 if (PrintSafepointStatistics) {
duke@435 505 SafepointSynchronize::inc_vmop_coalesced_count();
duke@435 506 }
duke@435 507 } while (_cur_vm_operation != NULL);
duke@435 508 }
duke@435 509 // There is a chance that a thread enqueued a safepoint op
duke@435 510 // since we released the op-queue lock and initiated the safepoint.
duke@435 511 // So we drain the queue again if there is anything there, as an
duke@435 512 // optimization to try and reduce the number of safepoints.
duke@435 513 // As the safepoint synchronizes us with JavaThreads we will see
duke@435 514 // any enqueue made by a JavaThread, but the peek will not
duke@435 515 // necessarily detect a concurrent enqueue by a GC thread, but
duke@435 516 // that simply means the op will wait for the next major cycle of the
duke@435 517 // VMThread - just as it would if the GC thread lost the race for
duke@435 518 // the lock.
duke@435 519 if (_vm_queue->peek_at_safepoint_priority()) {
duke@435 520 // must hold lock while draining queue
duke@435 521 MutexLockerEx mu_queue(VMOperationQueue_lock,
duke@435 522 Mutex::_no_safepoint_check_flag);
duke@435 523 safepoint_ops = _vm_queue->drain_at_safepoint_priority();
duke@435 524 } else {
duke@435 525 safepoint_ops = NULL;
duke@435 526 }
duke@435 527 } while(safepoint_ops != NULL);
duke@435 528
duke@435 529 _vm_queue->set_drain_list(NULL);
duke@435 530
duke@435 531 // Complete safepoint synchronization
duke@435 532 SafepointSynchronize::end();
duke@435 533
duke@435 534 } else { // not a safepoint operation
duke@435 535 if (TraceLongCompiles) {
duke@435 536 elapsedTimer t;
duke@435 537 t.start();
duke@435 538 evaluate_operation(_cur_vm_operation);
duke@435 539 t.stop();
duke@435 540 double secs = t.seconds();
duke@435 541 if (secs * 1e3 > LongCompileThreshold) {
duke@435 542 // XXX - _cur_vm_operation should not be accessed after
duke@435 543 // the completed count has been incremented; the waiting
duke@435 544 // thread may have already freed this memory.
duke@435 545 tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs);
duke@435 546 }
duke@435 547 } else {
duke@435 548 evaluate_operation(_cur_vm_operation);
duke@435 549 }
duke@435 550
duke@435 551 _cur_vm_operation = NULL;
duke@435 552 }
duke@435 553 }
duke@435 554
duke@435 555 //
duke@435 556 // Notify (potential) waiting Java thread(s) - lock without safepoint
duke@435 557 // check so that sneaking is not possible
duke@435 558 { MutexLockerEx mu(VMOperationRequest_lock,
duke@435 559 Mutex::_no_safepoint_check_flag);
duke@435 560 VMOperationRequest_lock->notify_all();
duke@435 561 }
duke@435 562
duke@435 563 //
duke@435 564 // We want to make sure that we get to a safepoint regularly.
duke@435 565 //
duke@435 566 if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) {
duke@435 567 long interval = SafepointSynchronize::last_non_safepoint_interval();
duke@435 568 bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval);
duke@435 569 if (SafepointALot || max_time_exceeded) {
duke@435 570 HandleMark hm(VMThread::vm_thread());
duke@435 571 SafepointSynchronize::begin();
duke@435 572 SafepointSynchronize::end();
duke@435 573 }
duke@435 574 }
duke@435 575 }
duke@435 576 }
duke@435 577
duke@435 578 void VMThread::execute(VM_Operation* op) {
duke@435 579 Thread* t = Thread::current();
duke@435 580
duke@435 581 if (!t->is_VM_thread()) {
ysr@1241 582 SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot
duke@435 583 // JavaThread or WatcherThread
duke@435 584 t->check_for_valid_safepoint_state(true);
duke@435 585
duke@435 586 // New request from Java thread, evaluate prologue
duke@435 587 if (!op->doit_prologue()) {
duke@435 588 return; // op was cancelled
duke@435 589 }
duke@435 590
duke@435 591 // Setup VM_operations for execution
duke@435 592 op->set_calling_thread(t, Thread::get_priority(t));
duke@435 593
duke@435 594 // It does not make sense to execute the epilogue, if the VM operation object is getting
duke@435 595 // deallocated by the VM thread.
duke@435 596 bool concurrent = op->evaluate_concurrently();
duke@435 597 bool execute_epilog = !op->is_cheap_allocated();
duke@435 598 assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated");
duke@435 599
duke@435 600 // Get ticket number for non-concurrent VM operations
duke@435 601 int ticket = 0;
duke@435 602 if (!concurrent) {
duke@435 603 ticket = t->vm_operation_ticket();
duke@435 604 }
duke@435 605
duke@435 606 // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the
duke@435 607 // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests
duke@435 608 // to be queued up during a safepoint synchronization.
duke@435 609 {
duke@435 610 VMOperationQueue_lock->lock_without_safepoint_check();
duke@435 611 bool ok = _vm_queue->add(op);
duke@435 612 op->set_timestamp(os::javaTimeMillis());
duke@435 613 VMOperationQueue_lock->notify();
duke@435 614 VMOperationQueue_lock->unlock();
duke@435 615 // VM_Operation got skipped
duke@435 616 if (!ok) {
duke@435 617 assert(concurrent, "can only skip concurrent tasks");
duke@435 618 if (op->is_cheap_allocated()) delete op;
duke@435 619 return;
duke@435 620 }
duke@435 621 }
duke@435 622
duke@435 623 if (!concurrent) {
duke@435 624 // Wait for completion of request (non-concurrent)
duke@435 625 // Note: only a JavaThread triggers the safepoint check when locking
duke@435 626 MutexLocker mu(VMOperationRequest_lock);
duke@435 627 while(t->vm_operation_completed_count() < ticket) {
duke@435 628 VMOperationRequest_lock->wait(!t->is_Java_thread());
duke@435 629 }
duke@435 630 }
duke@435 631
duke@435 632 if (execute_epilog) {
duke@435 633 op->doit_epilogue();
duke@435 634 }
duke@435 635 } else {
duke@435 636 // invoked by VM thread; usually nested VM operation
duke@435 637 assert(t->is_VM_thread(), "must be a VM thread");
duke@435 638 VM_Operation* prev_vm_operation = vm_operation();
duke@435 639 if (prev_vm_operation != NULL) {
duke@435 640 // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler
duke@435 641 // does not allow nested scavenges or compiles.
duke@435 642 if (!prev_vm_operation->allow_nested_vm_operations()) {
jcoomes@1845 643 fatal(err_msg("Nested VM operation %s requested by operation %s",
jcoomes@1845 644 op->name(), vm_operation()->name()));
duke@435 645 }
duke@435 646 op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority());
duke@435 647 }
duke@435 648
duke@435 649 EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name());
duke@435 650
duke@435 651 // Release all internal handles after operation is evaluated
duke@435 652 HandleMark hm(t);
duke@435 653 _cur_vm_operation = op;
duke@435 654
duke@435 655 if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) {
duke@435 656 SafepointSynchronize::begin();
duke@435 657 op->evaluate();
duke@435 658 SafepointSynchronize::end();
duke@435 659 } else {
duke@435 660 op->evaluate();
duke@435 661 }
duke@435 662
duke@435 663 // Free memory if needed
duke@435 664 if (op->is_cheap_allocated()) delete op;
duke@435 665
duke@435 666 _cur_vm_operation = prev_vm_operation;
duke@435 667 }
duke@435 668 }
duke@435 669
duke@435 670
jrose@1424 671 void VMThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
jrose@1424 672 Thread::oops_do(f, cf);
duke@435 673 _vm_queue->oops_do(f);
duke@435 674 }
duke@435 675
duke@435 676 //------------------------------------------------------------------------------------------------------------------
duke@435 677 #ifndef PRODUCT
duke@435 678
duke@435 679 void VMOperationQueue::verify_queue(int prio) {
duke@435 680 // Check that list is correctly linked
duke@435 681 int length = _queue_length[prio];
duke@435 682 VM_Operation *cur = _queue[prio];
duke@435 683 int i;
duke@435 684
duke@435 685 // Check forward links
duke@435 686 for(i = 0; i < length; i++) {
duke@435 687 cur = cur->next();
duke@435 688 assert(cur != _queue[prio], "list to short (forward)");
duke@435 689 }
duke@435 690 assert(cur->next() == _queue[prio], "list to long (forward)");
duke@435 691
duke@435 692 // Check backwards links
duke@435 693 cur = _queue[prio];
duke@435 694 for(i = 0; i < length; i++) {
duke@435 695 cur = cur->prev();
duke@435 696 assert(cur != _queue[prio], "list to short (backwards)");
duke@435 697 }
duke@435 698 assert(cur->prev() == _queue[prio], "list to long (backwards)");
duke@435 699 }
duke@435 700
duke@435 701 #endif
duke@435 702
duke@435 703 void VMThread::verify() {
jrose@1424 704 oops_do(&VerifyOopClosure::verify_oop, NULL);
duke@435 705 }

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