Mon, 04 Jan 2010 14:51:26 -0800
6637203: Classunloading messages go to stdout rather than Xloggc file, causing hangs when stdout is closed
Summary: Decoupled TraceClassUnloading from verbose:gc, JVMTI_VERBOSE_GC and PrintGC[Details], making it settable in a manner identical to TraceClassLoading. Reverted an inadvertent change of TraceClassUnloading output in a previous changeset from gclog back to tty.
Reviewed-by: coleenp, dholmes, jmasa, poonam
duke@435 | 1 | /* |
xdono@1279 | 2 | * Copyright 1998-2009 Sun Microsystems, Inc. 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 | * |
duke@435 | 19 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
duke@435 | 20 | * CA 95054 USA or visit www.sun.com if you need additional information or |
duke@435 | 21 | * have any questions. |
duke@435 | 22 | * |
duke@435 | 23 | */ |
duke@435 | 24 | |
duke@435 | 25 | # include "incls/_precompiled.incl" |
duke@435 | 26 | # include "incls/_vmThread.cpp.incl" |
duke@435 | 27 | |
duke@435 | 28 | // Dummy VM operation to act as first element in our circular double-linked list |
duke@435 | 29 | class VM_Dummy: public VM_Operation { |
duke@435 | 30 | VMOp_Type type() const { return VMOp_Dummy; } |
duke@435 | 31 | void doit() {}; |
duke@435 | 32 | }; |
duke@435 | 33 | |
duke@435 | 34 | VMOperationQueue::VMOperationQueue() { |
duke@435 | 35 | // The queue is a circular doubled-linked list, which always contains |
duke@435 | 36 | // one element (i.e., one element means empty). |
duke@435 | 37 | for(int i = 0; i < nof_priorities; i++) { |
duke@435 | 38 | _queue_length[i] = 0; |
duke@435 | 39 | _queue_counter = 0; |
duke@435 | 40 | _queue[i] = new VM_Dummy(); |
duke@435 | 41 | _queue[i]->set_next(_queue[i]); |
duke@435 | 42 | _queue[i]->set_prev(_queue[i]); |
duke@435 | 43 | } |
duke@435 | 44 | _drain_list = NULL; |
duke@435 | 45 | } |
duke@435 | 46 | |
duke@435 | 47 | |
duke@435 | 48 | bool VMOperationQueue::queue_empty(int prio) { |
duke@435 | 49 | // It is empty if there is exactly one element |
duke@435 | 50 | bool empty = (_queue[prio] == _queue[prio]->next()); |
duke@435 | 51 | assert( (_queue_length[prio] == 0 && empty) || |
duke@435 | 52 | (_queue_length[prio] > 0 && !empty), "sanity check"); |
duke@435 | 53 | return _queue_length[prio] == 0; |
duke@435 | 54 | } |
duke@435 | 55 | |
duke@435 | 56 | // Inserts an element to the right of the q element |
duke@435 | 57 | void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) { |
duke@435 | 58 | assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); |
duke@435 | 59 | n->set_prev(q); |
duke@435 | 60 | n->set_next(q->next()); |
duke@435 | 61 | q->next()->set_prev(n); |
duke@435 | 62 | q->set_next(n); |
duke@435 | 63 | } |
duke@435 | 64 | |
duke@435 | 65 | void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) { |
duke@435 | 66 | _queue_length[prio]++; |
duke@435 | 67 | insert(_queue[prio]->next(), op); |
duke@435 | 68 | } |
duke@435 | 69 | |
duke@435 | 70 | void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) { |
duke@435 | 71 | _queue_length[prio]++; |
duke@435 | 72 | insert(_queue[prio]->prev(), op); |
duke@435 | 73 | } |
duke@435 | 74 | |
duke@435 | 75 | |
duke@435 | 76 | void VMOperationQueue::unlink(VM_Operation* q) { |
duke@435 | 77 | assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); |
duke@435 | 78 | q->prev()->set_next(q->next()); |
duke@435 | 79 | q->next()->set_prev(q->prev()); |
duke@435 | 80 | } |
duke@435 | 81 | |
duke@435 | 82 | VM_Operation* VMOperationQueue::queue_remove_front(int prio) { |
duke@435 | 83 | if (queue_empty(prio)) return NULL; |
duke@435 | 84 | assert(_queue_length[prio] >= 0, "sanity check"); |
duke@435 | 85 | _queue_length[prio]--; |
duke@435 | 86 | VM_Operation* r = _queue[prio]->next(); |
duke@435 | 87 | assert(r != _queue[prio], "cannot remove base element"); |
duke@435 | 88 | unlink(r); |
duke@435 | 89 | return r; |
duke@435 | 90 | } |
duke@435 | 91 | |
duke@435 | 92 | VM_Operation* VMOperationQueue::queue_drain(int prio) { |
duke@435 | 93 | if (queue_empty(prio)) return NULL; |
duke@435 | 94 | DEBUG_ONLY(int length = _queue_length[prio];); |
duke@435 | 95 | assert(length >= 0, "sanity check"); |
duke@435 | 96 | _queue_length[prio] = 0; |
duke@435 | 97 | VM_Operation* r = _queue[prio]->next(); |
duke@435 | 98 | assert(r != _queue[prio], "cannot remove base element"); |
duke@435 | 99 | // remove links to base element from head and tail |
duke@435 | 100 | r->set_prev(NULL); |
duke@435 | 101 | _queue[prio]->prev()->set_next(NULL); |
duke@435 | 102 | // restore queue to empty state |
duke@435 | 103 | _queue[prio]->set_next(_queue[prio]); |
duke@435 | 104 | _queue[prio]->set_prev(_queue[prio]); |
duke@435 | 105 | assert(queue_empty(prio), "drain corrupted queue") |
duke@435 | 106 | #ifdef DEBUG |
duke@435 | 107 | int len = 0; |
duke@435 | 108 | VM_Operation* cur; |
duke@435 | 109 | for(cur = r; cur != NULL; cur=cur->next()) len++; |
duke@435 | 110 | assert(len == length, "drain lost some ops"); |
duke@435 | 111 | #endif |
duke@435 | 112 | return r; |
duke@435 | 113 | } |
duke@435 | 114 | |
duke@435 | 115 | void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) { |
duke@435 | 116 | VM_Operation* cur = _queue[queue]; |
duke@435 | 117 | cur = cur->next(); |
duke@435 | 118 | while (cur != _queue[queue]) { |
duke@435 | 119 | cur->oops_do(f); |
duke@435 | 120 | cur = cur->next(); |
duke@435 | 121 | } |
duke@435 | 122 | } |
duke@435 | 123 | |
duke@435 | 124 | void VMOperationQueue::drain_list_oops_do(OopClosure* f) { |
duke@435 | 125 | VM_Operation* cur = _drain_list; |
duke@435 | 126 | while (cur != NULL) { |
duke@435 | 127 | cur->oops_do(f); |
duke@435 | 128 | cur = cur->next(); |
duke@435 | 129 | } |
duke@435 | 130 | } |
duke@435 | 131 | |
duke@435 | 132 | //----------------------------------------------------------------- |
duke@435 | 133 | // High-level interface |
duke@435 | 134 | bool VMOperationQueue::add(VM_Operation *op) { |
duke@435 | 135 | // Encapsulates VM queue policy. Currently, that |
duke@435 | 136 | // only involves putting them on the right list |
duke@435 | 137 | if (op->evaluate_at_safepoint()) { |
duke@435 | 138 | queue_add_back(SafepointPriority, op); |
duke@435 | 139 | return true; |
duke@435 | 140 | } |
duke@435 | 141 | |
duke@435 | 142 | queue_add_back(MediumPriority, op); |
duke@435 | 143 | return true; |
duke@435 | 144 | } |
duke@435 | 145 | |
duke@435 | 146 | VM_Operation* VMOperationQueue::remove_next() { |
duke@435 | 147 | // Assuming VMOperation queue is two-level priority queue. If there are |
duke@435 | 148 | // more than two priorities, we need a different scheduling algorithm. |
duke@435 | 149 | assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2, |
duke@435 | 150 | "current algorithm does not work"); |
duke@435 | 151 | |
duke@435 | 152 | // simple counter based scheduling to prevent starvation of lower priority |
duke@435 | 153 | // queue. -- see 4390175 |
duke@435 | 154 | int high_prio, low_prio; |
duke@435 | 155 | if (_queue_counter++ < 10) { |
duke@435 | 156 | high_prio = SafepointPriority; |
duke@435 | 157 | low_prio = MediumPriority; |
duke@435 | 158 | } else { |
duke@435 | 159 | _queue_counter = 0; |
duke@435 | 160 | high_prio = MediumPriority; |
duke@435 | 161 | low_prio = SafepointPriority; |
duke@435 | 162 | } |
duke@435 | 163 | |
duke@435 | 164 | return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio); |
duke@435 | 165 | } |
duke@435 | 166 | |
duke@435 | 167 | void VMOperationQueue::oops_do(OopClosure* f) { |
duke@435 | 168 | for(int i = 0; i < nof_priorities; i++) { |
duke@435 | 169 | queue_oops_do(i, f); |
duke@435 | 170 | } |
duke@435 | 171 | drain_list_oops_do(f); |
duke@435 | 172 | } |
duke@435 | 173 | |
duke@435 | 174 | |
duke@435 | 175 | //------------------------------------------------------------------------------------------------------------------ |
duke@435 | 176 | // Implementation of VMThread stuff |
duke@435 | 177 | |
duke@435 | 178 | bool VMThread::_should_terminate = false; |
duke@435 | 179 | bool VMThread::_terminated = false; |
duke@435 | 180 | Monitor* VMThread::_terminate_lock = NULL; |
duke@435 | 181 | VMThread* VMThread::_vm_thread = NULL; |
duke@435 | 182 | VM_Operation* VMThread::_cur_vm_operation = NULL; |
duke@435 | 183 | VMOperationQueue* VMThread::_vm_queue = NULL; |
duke@435 | 184 | PerfCounter* VMThread::_perf_accumulated_vm_operation_time = NULL; |
duke@435 | 185 | |
duke@435 | 186 | |
duke@435 | 187 | void VMThread::create() { |
duke@435 | 188 | assert(vm_thread() == NULL, "we can only allocate one VMThread"); |
duke@435 | 189 | _vm_thread = new VMThread(); |
duke@435 | 190 | |
duke@435 | 191 | // Create VM operation queue |
duke@435 | 192 | _vm_queue = new VMOperationQueue(); |
duke@435 | 193 | guarantee(_vm_queue != NULL, "just checking"); |
duke@435 | 194 | |
duke@435 | 195 | _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true); |
duke@435 | 196 | |
duke@435 | 197 | if (UsePerfData) { |
duke@435 | 198 | // jvmstat performance counters |
duke@435 | 199 | Thread* THREAD = Thread::current(); |
duke@435 | 200 | _perf_accumulated_vm_operation_time = |
duke@435 | 201 | PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime", |
duke@435 | 202 | PerfData::U_Ticks, CHECK); |
duke@435 | 203 | } |
duke@435 | 204 | } |
duke@435 | 205 | |
duke@435 | 206 | |
minqi@1554 | 207 | VMThread::VMThread() : NamedThread() { |
minqi@1554 | 208 | set_name("VM Thread"); |
duke@435 | 209 | } |
duke@435 | 210 | |
duke@435 | 211 | void VMThread::destroy() { |
duke@435 | 212 | if (_vm_thread != NULL) { |
duke@435 | 213 | delete _vm_thread; |
duke@435 | 214 | _vm_thread = NULL; // VM thread is gone |
duke@435 | 215 | } |
duke@435 | 216 | } |
duke@435 | 217 | |
duke@435 | 218 | void VMThread::run() { |
duke@435 | 219 | assert(this == vm_thread(), "check"); |
duke@435 | 220 | |
duke@435 | 221 | this->initialize_thread_local_storage(); |
duke@435 | 222 | this->record_stack_base_and_size(); |
duke@435 | 223 | // Notify_lock wait checks on active_handles() to rewait in |
duke@435 | 224 | // case of spurious wakeup, it should wait on the last |
duke@435 | 225 | // value set prior to the notify |
duke@435 | 226 | this->set_active_handles(JNIHandleBlock::allocate_block()); |
duke@435 | 227 | |
duke@435 | 228 | { |
duke@435 | 229 | MutexLocker ml(Notify_lock); |
duke@435 | 230 | Notify_lock->notify(); |
duke@435 | 231 | } |
duke@435 | 232 | // Notify_lock is destroyed by Threads::create_vm() |
duke@435 | 233 | |
duke@435 | 234 | int prio = (VMThreadPriority == -1) |
duke@435 | 235 | ? os::java_to_os_priority[NearMaxPriority] |
duke@435 | 236 | : VMThreadPriority; |
duke@435 | 237 | // Note that I cannot call os::set_priority because it expects Java |
duke@435 | 238 | // priorities and I am *explicitly* using OS priorities so that it's |
duke@435 | 239 | // possible to set the VM thread priority higher than any Java thread. |
duke@435 | 240 | os::set_native_priority( this, prio ); |
duke@435 | 241 | |
duke@435 | 242 | // Wait for VM_Operations until termination |
duke@435 | 243 | this->loop(); |
duke@435 | 244 | |
duke@435 | 245 | // Note the intention to exit before safepointing. |
duke@435 | 246 | // 6295565 This has the effect of waiting for any large tty |
duke@435 | 247 | // outputs to finish. |
duke@435 | 248 | if (xtty != NULL) { |
duke@435 | 249 | ttyLocker ttyl; |
duke@435 | 250 | xtty->begin_elem("destroy_vm"); |
duke@435 | 251 | xtty->stamp(); |
duke@435 | 252 | xtty->end_elem(); |
duke@435 | 253 | assert(should_terminate(), "termination flag must be set"); |
duke@435 | 254 | } |
duke@435 | 255 | |
duke@435 | 256 | // 4526887 let VM thread exit at Safepoint |
duke@435 | 257 | SafepointSynchronize::begin(); |
duke@435 | 258 | |
duke@435 | 259 | if (VerifyBeforeExit) { |
duke@435 | 260 | HandleMark hm(VMThread::vm_thread()); |
duke@435 | 261 | // Among other things, this ensures that Eden top is correct. |
duke@435 | 262 | Universe::heap()->prepare_for_verify(); |
duke@435 | 263 | os::check_heap(); |
duke@435 | 264 | Universe::verify(true, true); // Silent verification to not polute normal output |
duke@435 | 265 | } |
duke@435 | 266 | |
duke@435 | 267 | CompileBroker::set_should_block(); |
duke@435 | 268 | |
duke@435 | 269 | // wait for threads (compiler threads or daemon threads) in the |
duke@435 | 270 | // _thread_in_native state to block. |
duke@435 | 271 | VM_Exit::wait_for_threads_in_native_to_block(); |
duke@435 | 272 | |
duke@435 | 273 | // signal other threads that VM process is gone |
duke@435 | 274 | { |
duke@435 | 275 | // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows |
duke@435 | 276 | // VM thread to enter any lock at Safepoint as long as its _owner is NULL. |
duke@435 | 277 | // If that happens after _terminate_lock->wait() has unset _owner |
duke@435 | 278 | // but before it actually drops the lock and waits, the notification below |
duke@435 | 279 | // may get lost and we will have a hang. To avoid this, we need to use |
duke@435 | 280 | // Mutex::lock_without_safepoint_check(). |
duke@435 | 281 | MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag); |
duke@435 | 282 | _terminated = true; |
duke@435 | 283 | _terminate_lock->notify(); |
duke@435 | 284 | } |
duke@435 | 285 | |
duke@435 | 286 | // Deletion must be done synchronously by the JNI DestroyJavaVM thread |
duke@435 | 287 | // so that the VMThread deletion completes before the main thread frees |
duke@435 | 288 | // up the CodeHeap. |
duke@435 | 289 | |
duke@435 | 290 | } |
duke@435 | 291 | |
duke@435 | 292 | |
duke@435 | 293 | // Notify the VMThread that the last non-daemon JavaThread has terminated, |
duke@435 | 294 | // and wait until operation is performed. |
duke@435 | 295 | void VMThread::wait_for_vm_thread_exit() { |
duke@435 | 296 | { MutexLocker mu(VMOperationQueue_lock); |
duke@435 | 297 | _should_terminate = true; |
duke@435 | 298 | VMOperationQueue_lock->notify(); |
duke@435 | 299 | } |
duke@435 | 300 | |
duke@435 | 301 | // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint |
duke@435 | 302 | // because this thread has been removed from the threads list. But anything |
duke@435 | 303 | // that could get blocked by Safepoint should not be used after this point, |
duke@435 | 304 | // otherwise we will hang, since there is no one can end the safepoint. |
duke@435 | 305 | |
duke@435 | 306 | // Wait until VM thread is terminated |
duke@435 | 307 | // Note: it should be OK to use Terminator_lock here. But this is called |
duke@435 | 308 | // at a very delicate time (VM shutdown) and we are operating in non- VM |
duke@435 | 309 | // thread at Safepoint. It's safer to not share lock with other threads. |
duke@435 | 310 | { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag); |
duke@435 | 311 | while(!VMThread::is_terminated()) { |
duke@435 | 312 | _terminate_lock->wait(Mutex::_no_safepoint_check_flag); |
duke@435 | 313 | } |
duke@435 | 314 | } |
duke@435 | 315 | } |
duke@435 | 316 | |
duke@435 | 317 | void VMThread::print_on(outputStream* st) const { |
duke@435 | 318 | st->print("\"%s\" ", name()); |
duke@435 | 319 | Thread::print_on(st); |
duke@435 | 320 | st->cr(); |
duke@435 | 321 | } |
duke@435 | 322 | |
duke@435 | 323 | void VMThread::evaluate_operation(VM_Operation* op) { |
duke@435 | 324 | ResourceMark rm; |
duke@435 | 325 | |
duke@435 | 326 | { |
duke@435 | 327 | PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time()); |
duke@435 | 328 | op->evaluate(); |
duke@435 | 329 | } |
duke@435 | 330 | |
duke@435 | 331 | // Last access of info in _cur_vm_operation! |
duke@435 | 332 | bool c_heap_allocated = op->is_cheap_allocated(); |
duke@435 | 333 | |
duke@435 | 334 | // Mark as completed |
duke@435 | 335 | if (!op->evaluate_concurrently()) { |
duke@435 | 336 | op->calling_thread()->increment_vm_operation_completed_count(); |
duke@435 | 337 | } |
duke@435 | 338 | // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call, |
duke@435 | 339 | // since if it is stack allocated the calling thread might have deallocated |
duke@435 | 340 | if (c_heap_allocated) { |
duke@435 | 341 | delete _cur_vm_operation; |
duke@435 | 342 | } |
duke@435 | 343 | } |
duke@435 | 344 | |
duke@435 | 345 | |
duke@435 | 346 | void VMThread::loop() { |
duke@435 | 347 | assert(_cur_vm_operation == NULL, "no current one should be executing"); |
duke@435 | 348 | |
duke@435 | 349 | while(true) { |
duke@435 | 350 | VM_Operation* safepoint_ops = NULL; |
duke@435 | 351 | // |
duke@435 | 352 | // Wait for VM operation |
duke@435 | 353 | // |
duke@435 | 354 | // use no_safepoint_check to get lock without attempting to "sneak" |
duke@435 | 355 | { MutexLockerEx mu_queue(VMOperationQueue_lock, |
duke@435 | 356 | Mutex::_no_safepoint_check_flag); |
duke@435 | 357 | |
duke@435 | 358 | // Look for new operation |
duke@435 | 359 | assert(_cur_vm_operation == NULL, "no current one should be executing"); |
duke@435 | 360 | _cur_vm_operation = _vm_queue->remove_next(); |
duke@435 | 361 | |
duke@435 | 362 | // Stall time tracking code |
duke@435 | 363 | if (PrintVMQWaitTime && _cur_vm_operation != NULL && |
duke@435 | 364 | !_cur_vm_operation->evaluate_concurrently()) { |
duke@435 | 365 | long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp(); |
duke@435 | 366 | if (stall > 0) |
duke@435 | 367 | tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall); |
duke@435 | 368 | } |
duke@435 | 369 | |
duke@435 | 370 | while (!should_terminate() && _cur_vm_operation == NULL) { |
duke@435 | 371 | // wait with a timeout to guarantee safepoints at regular intervals |
duke@435 | 372 | bool timedout = |
duke@435 | 373 | VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag, |
duke@435 | 374 | GuaranteedSafepointInterval); |
duke@435 | 375 | |
duke@435 | 376 | // Support for self destruction |
duke@435 | 377 | if ((SelfDestructTimer != 0) && !is_error_reported() && |
duke@435 | 378 | (os::elapsedTime() > SelfDestructTimer * 60)) { |
duke@435 | 379 | tty->print_cr("VM self-destructed"); |
duke@435 | 380 | exit(-1); |
duke@435 | 381 | } |
duke@435 | 382 | |
duke@435 | 383 | if (timedout && (SafepointALot || |
duke@435 | 384 | SafepointSynchronize::is_cleanup_needed())) { |
duke@435 | 385 | MutexUnlockerEx mul(VMOperationQueue_lock, |
duke@435 | 386 | Mutex::_no_safepoint_check_flag); |
duke@435 | 387 | // Force a safepoint since we have not had one for at least |
duke@435 | 388 | // 'GuaranteedSafepointInterval' milliseconds. This will run all |
duke@435 | 389 | // the clean-up processing that needs to be done regularly at a |
duke@435 | 390 | // safepoint |
duke@435 | 391 | SafepointSynchronize::begin(); |
duke@435 | 392 | #ifdef ASSERT |
duke@435 | 393 | if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot(); |
duke@435 | 394 | #endif |
duke@435 | 395 | SafepointSynchronize::end(); |
duke@435 | 396 | } |
duke@435 | 397 | _cur_vm_operation = _vm_queue->remove_next(); |
duke@435 | 398 | |
duke@435 | 399 | // If we are at a safepoint we will evaluate all the operations that |
duke@435 | 400 | // follow that also require a safepoint |
duke@435 | 401 | if (_cur_vm_operation != NULL && |
duke@435 | 402 | _cur_vm_operation->evaluate_at_safepoint()) { |
duke@435 | 403 | safepoint_ops = _vm_queue->drain_at_safepoint_priority(); |
duke@435 | 404 | } |
duke@435 | 405 | } |
duke@435 | 406 | |
duke@435 | 407 | if (should_terminate()) break; |
duke@435 | 408 | } // Release mu_queue_lock |
duke@435 | 409 | |
duke@435 | 410 | // |
duke@435 | 411 | // Execute VM operation |
duke@435 | 412 | // |
duke@435 | 413 | { HandleMark hm(VMThread::vm_thread()); |
duke@435 | 414 | |
duke@435 | 415 | EventMark em("Executing VM operation: %s", vm_operation()->name()); |
duke@435 | 416 | assert(_cur_vm_operation != NULL, "we should have found an operation to execute"); |
duke@435 | 417 | |
duke@435 | 418 | // Give the VM thread an extra quantum. Jobs tend to be bursty and this |
duke@435 | 419 | // helps the VM thread to finish up the job. |
duke@435 | 420 | // FIXME: When this is enabled and there are many threads, this can degrade |
duke@435 | 421 | // performance significantly. |
duke@435 | 422 | if( VMThreadHintNoPreempt ) |
duke@435 | 423 | os::hint_no_preempt(); |
duke@435 | 424 | |
duke@435 | 425 | // If we are at a safepoint we will evaluate all the operations that |
duke@435 | 426 | // follow that also require a safepoint |
duke@435 | 427 | if (_cur_vm_operation->evaluate_at_safepoint()) { |
duke@435 | 428 | |
duke@435 | 429 | if (PrintGCApplicationConcurrentTime) { |
duke@435 | 430 | gclog_or_tty->print_cr("Application time: %3.7f seconds", |
duke@435 | 431 | RuntimeService::last_application_time_sec()); |
duke@435 | 432 | } |
duke@435 | 433 | |
duke@435 | 434 | _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned |
duke@435 | 435 | |
duke@435 | 436 | SafepointSynchronize::begin(); |
duke@435 | 437 | evaluate_operation(_cur_vm_operation); |
duke@435 | 438 | // now process all queued safepoint ops, iteratively draining |
duke@435 | 439 | // the queue until there are none left |
duke@435 | 440 | do { |
duke@435 | 441 | _cur_vm_operation = safepoint_ops; |
duke@435 | 442 | if (_cur_vm_operation != NULL) { |
duke@435 | 443 | do { |
duke@435 | 444 | // evaluate_operation deletes the op object so we have |
duke@435 | 445 | // to grab the next op now |
duke@435 | 446 | VM_Operation* next = _cur_vm_operation->next(); |
duke@435 | 447 | _vm_queue->set_drain_list(next); |
duke@435 | 448 | evaluate_operation(_cur_vm_operation); |
duke@435 | 449 | _cur_vm_operation = next; |
duke@435 | 450 | if (PrintSafepointStatistics) { |
duke@435 | 451 | SafepointSynchronize::inc_vmop_coalesced_count(); |
duke@435 | 452 | } |
duke@435 | 453 | } while (_cur_vm_operation != NULL); |
duke@435 | 454 | } |
duke@435 | 455 | // There is a chance that a thread enqueued a safepoint op |
duke@435 | 456 | // since we released the op-queue lock and initiated the safepoint. |
duke@435 | 457 | // So we drain the queue again if there is anything there, as an |
duke@435 | 458 | // optimization to try and reduce the number of safepoints. |
duke@435 | 459 | // As the safepoint synchronizes us with JavaThreads we will see |
duke@435 | 460 | // any enqueue made by a JavaThread, but the peek will not |
duke@435 | 461 | // necessarily detect a concurrent enqueue by a GC thread, but |
duke@435 | 462 | // that simply means the op will wait for the next major cycle of the |
duke@435 | 463 | // VMThread - just as it would if the GC thread lost the race for |
duke@435 | 464 | // the lock. |
duke@435 | 465 | if (_vm_queue->peek_at_safepoint_priority()) { |
duke@435 | 466 | // must hold lock while draining queue |
duke@435 | 467 | MutexLockerEx mu_queue(VMOperationQueue_lock, |
duke@435 | 468 | Mutex::_no_safepoint_check_flag); |
duke@435 | 469 | safepoint_ops = _vm_queue->drain_at_safepoint_priority(); |
duke@435 | 470 | } else { |
duke@435 | 471 | safepoint_ops = NULL; |
duke@435 | 472 | } |
duke@435 | 473 | } while(safepoint_ops != NULL); |
duke@435 | 474 | |
duke@435 | 475 | _vm_queue->set_drain_list(NULL); |
duke@435 | 476 | |
duke@435 | 477 | // Complete safepoint synchronization |
duke@435 | 478 | SafepointSynchronize::end(); |
duke@435 | 479 | |
duke@435 | 480 | if (PrintGCApplicationStoppedTime) { |
duke@435 | 481 | gclog_or_tty->print_cr("Total time for which application threads " |
duke@435 | 482 | "were stopped: %3.7f seconds", |
duke@435 | 483 | RuntimeService::last_safepoint_time_sec()); |
duke@435 | 484 | } |
duke@435 | 485 | |
duke@435 | 486 | } else { // not a safepoint operation |
duke@435 | 487 | if (TraceLongCompiles) { |
duke@435 | 488 | elapsedTimer t; |
duke@435 | 489 | t.start(); |
duke@435 | 490 | evaluate_operation(_cur_vm_operation); |
duke@435 | 491 | t.stop(); |
duke@435 | 492 | double secs = t.seconds(); |
duke@435 | 493 | if (secs * 1e3 > LongCompileThreshold) { |
duke@435 | 494 | // XXX - _cur_vm_operation should not be accessed after |
duke@435 | 495 | // the completed count has been incremented; the waiting |
duke@435 | 496 | // thread may have already freed this memory. |
duke@435 | 497 | tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs); |
duke@435 | 498 | } |
duke@435 | 499 | } else { |
duke@435 | 500 | evaluate_operation(_cur_vm_operation); |
duke@435 | 501 | } |
duke@435 | 502 | |
duke@435 | 503 | _cur_vm_operation = NULL; |
duke@435 | 504 | } |
duke@435 | 505 | } |
duke@435 | 506 | |
duke@435 | 507 | // |
duke@435 | 508 | // Notify (potential) waiting Java thread(s) - lock without safepoint |
duke@435 | 509 | // check so that sneaking is not possible |
duke@435 | 510 | { MutexLockerEx mu(VMOperationRequest_lock, |
duke@435 | 511 | Mutex::_no_safepoint_check_flag); |
duke@435 | 512 | VMOperationRequest_lock->notify_all(); |
duke@435 | 513 | } |
duke@435 | 514 | |
duke@435 | 515 | // |
duke@435 | 516 | // We want to make sure that we get to a safepoint regularly. |
duke@435 | 517 | // |
duke@435 | 518 | if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) { |
duke@435 | 519 | long interval = SafepointSynchronize::last_non_safepoint_interval(); |
duke@435 | 520 | bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval); |
duke@435 | 521 | if (SafepointALot || max_time_exceeded) { |
duke@435 | 522 | HandleMark hm(VMThread::vm_thread()); |
duke@435 | 523 | SafepointSynchronize::begin(); |
duke@435 | 524 | SafepointSynchronize::end(); |
duke@435 | 525 | } |
duke@435 | 526 | } |
duke@435 | 527 | } |
duke@435 | 528 | } |
duke@435 | 529 | |
duke@435 | 530 | void VMThread::execute(VM_Operation* op) { |
duke@435 | 531 | Thread* t = Thread::current(); |
duke@435 | 532 | |
duke@435 | 533 | if (!t->is_VM_thread()) { |
ysr@1241 | 534 | SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot |
duke@435 | 535 | // JavaThread or WatcherThread |
duke@435 | 536 | t->check_for_valid_safepoint_state(true); |
duke@435 | 537 | |
duke@435 | 538 | // New request from Java thread, evaluate prologue |
duke@435 | 539 | if (!op->doit_prologue()) { |
duke@435 | 540 | return; // op was cancelled |
duke@435 | 541 | } |
duke@435 | 542 | |
duke@435 | 543 | // Setup VM_operations for execution |
duke@435 | 544 | op->set_calling_thread(t, Thread::get_priority(t)); |
duke@435 | 545 | |
duke@435 | 546 | // It does not make sense to execute the epilogue, if the VM operation object is getting |
duke@435 | 547 | // deallocated by the VM thread. |
duke@435 | 548 | bool concurrent = op->evaluate_concurrently(); |
duke@435 | 549 | bool execute_epilog = !op->is_cheap_allocated(); |
duke@435 | 550 | assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated"); |
duke@435 | 551 | |
duke@435 | 552 | // Get ticket number for non-concurrent VM operations |
duke@435 | 553 | int ticket = 0; |
duke@435 | 554 | if (!concurrent) { |
duke@435 | 555 | ticket = t->vm_operation_ticket(); |
duke@435 | 556 | } |
duke@435 | 557 | |
duke@435 | 558 | // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the |
duke@435 | 559 | // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests |
duke@435 | 560 | // to be queued up during a safepoint synchronization. |
duke@435 | 561 | { |
duke@435 | 562 | VMOperationQueue_lock->lock_without_safepoint_check(); |
duke@435 | 563 | bool ok = _vm_queue->add(op); |
duke@435 | 564 | op->set_timestamp(os::javaTimeMillis()); |
duke@435 | 565 | VMOperationQueue_lock->notify(); |
duke@435 | 566 | VMOperationQueue_lock->unlock(); |
duke@435 | 567 | // VM_Operation got skipped |
duke@435 | 568 | if (!ok) { |
duke@435 | 569 | assert(concurrent, "can only skip concurrent tasks"); |
duke@435 | 570 | if (op->is_cheap_allocated()) delete op; |
duke@435 | 571 | return; |
duke@435 | 572 | } |
duke@435 | 573 | } |
duke@435 | 574 | |
duke@435 | 575 | if (!concurrent) { |
duke@435 | 576 | // Wait for completion of request (non-concurrent) |
duke@435 | 577 | // Note: only a JavaThread triggers the safepoint check when locking |
duke@435 | 578 | MutexLocker mu(VMOperationRequest_lock); |
duke@435 | 579 | while(t->vm_operation_completed_count() < ticket) { |
duke@435 | 580 | VMOperationRequest_lock->wait(!t->is_Java_thread()); |
duke@435 | 581 | } |
duke@435 | 582 | } |
duke@435 | 583 | |
duke@435 | 584 | if (execute_epilog) { |
duke@435 | 585 | op->doit_epilogue(); |
duke@435 | 586 | } |
duke@435 | 587 | } else { |
duke@435 | 588 | // invoked by VM thread; usually nested VM operation |
duke@435 | 589 | assert(t->is_VM_thread(), "must be a VM thread"); |
duke@435 | 590 | VM_Operation* prev_vm_operation = vm_operation(); |
duke@435 | 591 | if (prev_vm_operation != NULL) { |
duke@435 | 592 | // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler |
duke@435 | 593 | // does not allow nested scavenges or compiles. |
duke@435 | 594 | if (!prev_vm_operation->allow_nested_vm_operations()) { |
duke@435 | 595 | fatal2("Nested VM operation %s requested by operation %s", op->name(), vm_operation()->name()); |
duke@435 | 596 | } |
duke@435 | 597 | op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority()); |
duke@435 | 598 | } |
duke@435 | 599 | |
duke@435 | 600 | EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name()); |
duke@435 | 601 | |
duke@435 | 602 | // Release all internal handles after operation is evaluated |
duke@435 | 603 | HandleMark hm(t); |
duke@435 | 604 | _cur_vm_operation = op; |
duke@435 | 605 | |
duke@435 | 606 | if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) { |
duke@435 | 607 | SafepointSynchronize::begin(); |
duke@435 | 608 | op->evaluate(); |
duke@435 | 609 | SafepointSynchronize::end(); |
duke@435 | 610 | } else { |
duke@435 | 611 | op->evaluate(); |
duke@435 | 612 | } |
duke@435 | 613 | |
duke@435 | 614 | // Free memory if needed |
duke@435 | 615 | if (op->is_cheap_allocated()) delete op; |
duke@435 | 616 | |
duke@435 | 617 | _cur_vm_operation = prev_vm_operation; |
duke@435 | 618 | } |
duke@435 | 619 | } |
duke@435 | 620 | |
duke@435 | 621 | |
jrose@1424 | 622 | void VMThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { |
jrose@1424 | 623 | Thread::oops_do(f, cf); |
duke@435 | 624 | _vm_queue->oops_do(f); |
duke@435 | 625 | } |
duke@435 | 626 | |
duke@435 | 627 | //------------------------------------------------------------------------------------------------------------------ |
duke@435 | 628 | #ifndef PRODUCT |
duke@435 | 629 | |
duke@435 | 630 | void VMOperationQueue::verify_queue(int prio) { |
duke@435 | 631 | // Check that list is correctly linked |
duke@435 | 632 | int length = _queue_length[prio]; |
duke@435 | 633 | VM_Operation *cur = _queue[prio]; |
duke@435 | 634 | int i; |
duke@435 | 635 | |
duke@435 | 636 | // Check forward links |
duke@435 | 637 | for(i = 0; i < length; i++) { |
duke@435 | 638 | cur = cur->next(); |
duke@435 | 639 | assert(cur != _queue[prio], "list to short (forward)"); |
duke@435 | 640 | } |
duke@435 | 641 | assert(cur->next() == _queue[prio], "list to long (forward)"); |
duke@435 | 642 | |
duke@435 | 643 | // Check backwards links |
duke@435 | 644 | cur = _queue[prio]; |
duke@435 | 645 | for(i = 0; i < length; i++) { |
duke@435 | 646 | cur = cur->prev(); |
duke@435 | 647 | assert(cur != _queue[prio], "list to short (backwards)"); |
duke@435 | 648 | } |
duke@435 | 649 | assert(cur->prev() == _queue[prio], "list to long (backwards)"); |
duke@435 | 650 | } |
duke@435 | 651 | |
duke@435 | 652 | #endif |
duke@435 | 653 | |
duke@435 | 654 | void VMThread::verify() { |
jrose@1424 | 655 | oops_do(&VerifyOopClosure::verify_oop, NULL); |
duke@435 | 656 | } |