1 /* 2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "memory/allocation.hpp" 27 #include "memory/allocation.inline.hpp" 28 #include "runtime/os.hpp" 29 #include "utilities/workgroup.hpp" 30 31 // Definitions of WorkGang methods. 32 33 AbstractWorkGang::AbstractWorkGang(const char* name, 34 bool are_GC_task_threads, 35 bool are_ConcurrentGC_threads) : 36 _name(name), 37 _are_GC_task_threads(are_GC_task_threads), 38 _are_ConcurrentGC_threads(are_ConcurrentGC_threads) { 39 40 assert(!(are_GC_task_threads && are_ConcurrentGC_threads), 41 "They cannot both be STW GC and Concurrent threads" ); 42 43 // Other initialization. 44 _monitor = new Monitor(/* priority */ Mutex::leaf, 45 /* name */ "WorkGroup monitor", 46 /* allow_vm_block */ are_GC_task_threads); 47 assert(monitor() != NULL, "Failed to allocate monitor"); 48 _terminate = false; 49 _task = NULL; 50 _sequence_number = 0; 51 _started_workers = 0; 52 _finished_workers = 0; 53 } 54 55 WorkGang::WorkGang(const char* name, 56 int workers, 57 bool are_GC_task_threads, 58 bool are_ConcurrentGC_threads) : 59 AbstractWorkGang(name, are_GC_task_threads, are_ConcurrentGC_threads) { 60 // Save arguments. 61 _total_workers = workers; 62 } 63 64 GangWorker* WorkGang::allocate_worker(int which) { 65 GangWorker* new_worker = new GangWorker(this, which); 66 return new_worker; 67 } 68 69 // The current implementation will exit if the allocation 70 // of any worker fails. Still, return a boolean so that 71 // a future implementation can possibly do a partial 72 // initialization of the workers and report such to the 73 // caller. 74 bool WorkGang::initialize_workers() { 75 76 if (TraceWorkGang) { 77 tty->print_cr("Constructing work gang %s with %d threads", 78 name(), 79 total_workers()); 80 } 81 _gang_workers = NEW_C_HEAP_ARRAY(GangWorker*, total_workers()); 82 if (gang_workers() == NULL) { 83 vm_exit_out_of_memory(0, "Cannot create GangWorker array."); 84 return false; 85 } 86 os::ThreadType worker_type; 87 if (are_ConcurrentGC_threads()) { 88 worker_type = os::cgc_thread; 89 } else { 90 worker_type = os::pgc_thread; 91 } 92 for (int worker = 0; worker < total_workers(); worker += 1) { 93 GangWorker* new_worker = allocate_worker(worker); 94 assert(new_worker != NULL, "Failed to allocate GangWorker"); 95 _gang_workers[worker] = new_worker; 96 if (new_worker == NULL || !os::create_thread(new_worker, worker_type)) { 97 vm_exit_out_of_memory(0, "Cannot create worker GC thread. Out of system resources."); 98 return false; 99 } 100 if (!DisableStartThread) { 101 os::start_thread(new_worker); 102 } 103 } 104 return true; 105 } 106 107 AbstractWorkGang::~AbstractWorkGang() { 108 if (TraceWorkGang) { 109 tty->print_cr("Destructing work gang %s", name()); 110 } 111 stop(); // stop all the workers 112 for (int worker = 0; worker < total_workers(); worker += 1) { 113 delete gang_worker(worker); 114 } 115 delete gang_workers(); 116 delete monitor(); 117 } 118 119 GangWorker* AbstractWorkGang::gang_worker(int i) const { 120 // Array index bounds checking. 121 GangWorker* result = NULL; 122 assert(gang_workers() != NULL, "No workers for indexing"); 123 assert(((i >= 0) && (i < total_workers())), "Worker index out of bounds"); 124 result = _gang_workers[i]; 125 assert(result != NULL, "Indexing to null worker"); 126 return result; 127 } 128 129 void WorkGang::run_task(AbstractGangTask* task) { 130 // This thread is executed by the VM thread which does not block 131 // on ordinary MutexLocker's. 132 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag); 133 if (TraceWorkGang) { 134 tty->print_cr("Running work gang %s task %s", name(), task->name()); 135 } 136 // Tell all the workers to run a task. 137 assert(task != NULL, "Running a null task"); 138 // Initialize. 139 _task = task; 140 _sequence_number += 1; 141 _started_workers = 0; 142 _finished_workers = 0; 143 // Tell the workers to get to work. 144 monitor()->notify_all(); 145 // Wait for them to be finished 146 while (finished_workers() < total_workers()) { 147 if (TraceWorkGang) { 148 tty->print_cr("Waiting in work gang %s: %d/%d finished sequence %d", 149 name(), finished_workers(), total_workers(), 150 _sequence_number); 151 } 152 monitor()->wait(/* no_safepoint_check */ true); 153 } 154 _task = NULL; 155 if (TraceWorkGang) { 156 tty->print_cr("/nFinished work gang %s: %d/%d sequence %d", 157 name(), finished_workers(), total_workers(), 158 _sequence_number); 159 } 160 } 161 162 void AbstractWorkGang::stop() { 163 // Tell all workers to terminate, then wait for them to become inactive. 164 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag); 165 if (TraceWorkGang) { 166 tty->print_cr("Stopping work gang %s task %s", name(), task()->name()); 167 } 168 _task = NULL; 169 _terminate = true; 170 monitor()->notify_all(); 171 while (finished_workers() < total_workers()) { 172 if (TraceWorkGang) { 173 tty->print_cr("Waiting in work gang %s: %d/%d finished", 174 name(), finished_workers(), total_workers()); 175 } 176 monitor()->wait(/* no_safepoint_check */ true); 177 } 178 } 179 180 void AbstractWorkGang::internal_worker_poll(WorkData* data) const { 181 assert(monitor()->owned_by_self(), "worker_poll is an internal method"); 182 assert(data != NULL, "worker data is null"); 183 data->set_terminate(terminate()); 184 data->set_task(task()); 185 data->set_sequence_number(sequence_number()); 186 } 187 188 void AbstractWorkGang::internal_note_start() { 189 assert(monitor()->owned_by_self(), "note_finish is an internal method"); 190 _started_workers += 1; 191 } 192 193 void AbstractWorkGang::internal_note_finish() { 194 assert(monitor()->owned_by_self(), "note_finish is an internal method"); 195 _finished_workers += 1; 196 } 197 198 void AbstractWorkGang::print_worker_threads_on(outputStream* st) const { 199 uint num_thr = total_workers(); 200 for (uint i = 0; i < num_thr; i++) { 201 gang_worker(i)->print_on(st); 202 st->cr(); 203 } 204 } 205 206 void AbstractWorkGang::threads_do(ThreadClosure* tc) const { 207 assert(tc != NULL, "Null ThreadClosure"); 208 uint num_thr = total_workers(); 209 for (uint i = 0; i < num_thr; i++) { 210 tc->do_thread(gang_worker(i)); 211 } 212 } 213 214 // GangWorker methods. 215 216 GangWorker::GangWorker(AbstractWorkGang* gang, uint id) { 217 _gang = gang; 218 set_id(id); 219 set_name("Gang worker#%d (%s)", id, gang->name()); 220 } 221 222 void GangWorker::run() { 223 initialize(); 224 loop(); 225 } 226 227 void GangWorker::initialize() { 228 this->initialize_thread_local_storage(); 229 assert(_gang != NULL, "No gang to run in"); 230 os::set_priority(this, NearMaxPriority); 231 if (TraceWorkGang) { 232 tty->print_cr("Running gang worker for gang %s id %d", 233 gang()->name(), id()); 234 } 235 // The VM thread should not execute here because MutexLocker's are used 236 // as (opposed to MutexLockerEx's). 237 assert(!Thread::current()->is_VM_thread(), "VM thread should not be part" 238 " of a work gang"); 239 } 240 241 void GangWorker::loop() { 242 int previous_sequence_number = 0; 243 Monitor* gang_monitor = gang()->monitor(); 244 for ( ; /* !terminate() */; ) { 245 WorkData data; 246 int part; // Initialized below. 247 { 248 // Grab the gang mutex. 249 MutexLocker ml(gang_monitor); 250 // Wait for something to do. 251 // Polling outside the while { wait } avoids missed notifies 252 // in the outer loop. 253 gang()->internal_worker_poll(&data); 254 if (TraceWorkGang) { 255 tty->print("Polled outside for work in gang %s worker %d", 256 gang()->name(), id()); 257 tty->print(" terminate: %s", 258 data.terminate() ? "true" : "false"); 259 tty->print(" sequence: %d (prev: %d)", 260 data.sequence_number(), previous_sequence_number); 261 if (data.task() != NULL) { 262 tty->print(" task: %s", data.task()->name()); 263 } else { 264 tty->print(" task: NULL"); 265 } 266 tty->cr(); 267 } 268 for ( ; /* break or return */; ) { 269 // Terminate if requested. 270 if (data.terminate()) { 271 gang()->internal_note_finish(); 272 gang_monitor->notify_all(); 273 return; 274 } 275 // Check for new work. 276 if ((data.task() != NULL) && 277 (data.sequence_number() != previous_sequence_number)) { 278 gang()->internal_note_start(); 279 gang_monitor->notify_all(); 280 part = gang()->started_workers() - 1; 281 break; 282 } 283 // Nothing to do. 284 gang_monitor->wait(/* no_safepoint_check */ true); 285 gang()->internal_worker_poll(&data); 286 if (TraceWorkGang) { 287 tty->print("Polled inside for work in gang %s worker %d", 288 gang()->name(), id()); 289 tty->print(" terminate: %s", 290 data.terminate() ? "true" : "false"); 291 tty->print(" sequence: %d (prev: %d)", 292 data.sequence_number(), previous_sequence_number); 293 if (data.task() != NULL) { 294 tty->print(" task: %s", data.task()->name()); 295 } else { 296 tty->print(" task: NULL"); 297 } 298 tty->cr(); 299 } 300 } 301 // Drop gang mutex. 302 } 303 if (TraceWorkGang) { 304 tty->print("Work for work gang %s id %d task %s part %d", 305 gang()->name(), id(), data.task()->name(), part); 306 } 307 assert(data.task() != NULL, "Got null task"); 308 data.task()->work(part); 309 { 310 if (TraceWorkGang) { 311 tty->print("Finish for work gang %s id %d task %s part %d", 312 gang()->name(), id(), data.task()->name(), part); 313 } 314 // Grab the gang mutex. 315 MutexLocker ml(gang_monitor); 316 gang()->internal_note_finish(); 317 // Tell the gang you are done. 318 gang_monitor->notify_all(); 319 // Drop the gang mutex. 320 } 321 previous_sequence_number = data.sequence_number(); 322 } 323 } 324 325 bool GangWorker::is_GC_task_thread() const { 326 return gang()->are_GC_task_threads(); 327 } 328 329 bool GangWorker::is_ConcurrentGC_thread() const { 330 return gang()->are_ConcurrentGC_threads(); 331 } 332 333 void GangWorker::print_on(outputStream* st) const { 334 st->print("\"%s\" ", name()); 335 Thread::print_on(st); 336 st->cr(); 337 } 338 339 // Printing methods 340 341 const char* AbstractWorkGang::name() const { 342 return _name; 343 } 344 345 #ifndef PRODUCT 346 347 const char* AbstractGangTask::name() const { 348 return _name; 349 } 350 351 #endif /* PRODUCT */ 352 353 // *** WorkGangBarrierSync 354 355 WorkGangBarrierSync::WorkGangBarrierSync() 356 : _monitor(Mutex::safepoint, "work gang barrier sync", true), 357 _n_workers(0), _n_completed(0), _should_reset(false) { 358 } 359 360 WorkGangBarrierSync::WorkGangBarrierSync(int n_workers, const char* name) 361 : _monitor(Mutex::safepoint, name, true), 362 _n_workers(n_workers), _n_completed(0), _should_reset(false) { 363 } 364 365 void WorkGangBarrierSync::set_n_workers(int n_workers) { 366 _n_workers = n_workers; 367 _n_completed = 0; 368 _should_reset = false; 369 } 370 371 void WorkGangBarrierSync::enter() { 372 MutexLockerEx x(monitor(), Mutex::_no_safepoint_check_flag); 373 if (should_reset()) { 374 // The should_reset() was set and we are the first worker to enter 375 // the sync barrier. We will zero the n_completed() count which 376 // effectively resets the barrier. 377 zero_completed(); 378 set_should_reset(false); 379 } 380 inc_completed(); 381 if (n_completed() == n_workers()) { 382 // At this point we would like to reset the barrier to be ready in 383 // case it is used again. However, we cannot set n_completed() to 384 // 0, even after the notify_all(), given that some other workers 385 // might still be waiting for n_completed() to become == 386 // n_workers(). So, if we set n_completed() to 0, those workers 387 // will get stuck (as they will wake up, see that n_completed() != 388 // n_workers() and go back to sleep). Instead, we raise the 389 // should_reset() flag and the barrier will be reset the first 390 // time a worker enters it again. 391 set_should_reset(true); 392 monitor()->notify_all(); 393 } else { 394 while (n_completed() != n_workers()) { 395 monitor()->wait(/* no_safepoint_check */ true); 396 } 397 } 398 } 399 400 // SubTasksDone functions. 401 402 SubTasksDone::SubTasksDone(int n) : 403 _n_tasks(n), _n_threads(1), _tasks(NULL) { 404 _tasks = NEW_C_HEAP_ARRAY(jint, n); 405 guarantee(_tasks != NULL, "alloc failure"); 406 clear(); 407 } 408 409 bool SubTasksDone::valid() { 410 return _tasks != NULL; 411 } 412 413 void SubTasksDone::set_n_threads(int t) { 414 #ifdef ASSERT 415 assert(_claimed == 0 || _threads_completed == _n_threads, 416 "should not be called while tasks are being processed!"); 417 #endif 418 _n_threads = (t == 0 ? 1 : t); 419 } 420 421 void SubTasksDone::clear() { 422 for (int i = 0; i < _n_tasks; i++) { 423 _tasks[i] = 0; 424 } 425 _threads_completed = 0; 426 #ifdef ASSERT 427 _claimed = 0; 428 #endif 429 } 430 431 bool SubTasksDone::is_task_claimed(int t) { 432 assert(0 <= t && t < _n_tasks, "bad task id."); 433 jint old = _tasks[t]; 434 if (old == 0) { 435 old = Atomic::cmpxchg(1, &_tasks[t], 0); 436 } 437 assert(_tasks[t] == 1, "What else?"); 438 bool res = old != 0; 439 #ifdef ASSERT 440 if (!res) { 441 assert(_claimed < _n_tasks, "Too many tasks claimed; missing clear?"); 442 Atomic::inc(&_claimed); 443 } 444 #endif 445 return res; 446 } 447 448 void SubTasksDone::all_tasks_completed() { 449 jint observed = _threads_completed; 450 jint old; 451 do { 452 old = observed; 453 observed = Atomic::cmpxchg(old+1, &_threads_completed, old); 454 } while (observed != old); 455 // If this was the last thread checking in, clear the tasks. 456 if (observed+1 == _n_threads) clear(); 457 } 458 459 460 SubTasksDone::~SubTasksDone() { 461 if (_tasks != NULL) FREE_C_HEAP_ARRAY(jint, _tasks); 462 } 463 464 // *** SequentialSubTasksDone 465 466 void SequentialSubTasksDone::clear() { 467 _n_tasks = _n_claimed = 0; 468 _n_threads = _n_completed = 0; 469 } 470 471 bool SequentialSubTasksDone::valid() { 472 return _n_threads > 0; 473 } 474 475 bool SequentialSubTasksDone::is_task_claimed(int& t) { 476 jint* n_claimed_ptr = &_n_claimed; 477 t = *n_claimed_ptr; 478 while (t < _n_tasks) { 479 jint res = Atomic::cmpxchg(t+1, n_claimed_ptr, t); 480 if (res == t) { 481 return false; 482 } 483 t = *n_claimed_ptr; 484 } 485 return true; 486 } 487 488 bool SequentialSubTasksDone::all_tasks_completed() { 489 jint* n_completed_ptr = &_n_completed; 490 jint complete = *n_completed_ptr; 491 while (true) { 492 jint res = Atomic::cmpxchg(complete+1, n_completed_ptr, complete); 493 if (res == complete) { 494 break; 495 } 496 complete = res; 497 } 498 if (complete+1 == _n_threads) { 499 clear(); 500 return true; 501 } 502 return false; 503 } 504 505 bool FreeIdSet::_stat_init = false; 506 FreeIdSet* FreeIdSet::_sets[NSets]; 507 bool FreeIdSet::_safepoint; 508 509 FreeIdSet::FreeIdSet(int sz, Monitor* mon) : 510 _sz(sz), _mon(mon), _hd(0), _waiters(0), _index(-1), _claimed(0) 511 { 512 _ids = new int[sz]; 513 for (int i = 0; i < sz; i++) _ids[i] = i+1; 514 _ids[sz-1] = end_of_list; // end of list. 515 if (_stat_init) { 516 for (int j = 0; j < NSets; j++) _sets[j] = NULL; 517 _stat_init = true; 518 } 519 // Add to sets. (This should happen while the system is still single-threaded.) 520 for (int j = 0; j < NSets; j++) { 521 if (_sets[j] == NULL) { 522 _sets[j] = this; 523 _index = j; 524 break; 525 } 526 } 527 guarantee(_index != -1, "Too many FreeIdSets in use!"); 528 } 529 530 FreeIdSet::~FreeIdSet() { 531 _sets[_index] = NULL; 532 } 533 534 void FreeIdSet::set_safepoint(bool b) { 535 _safepoint = b; 536 if (b) { 537 for (int j = 0; j < NSets; j++) { 538 if (_sets[j] != NULL && _sets[j]->_waiters > 0) { 539 Monitor* mon = _sets[j]->_mon; 540 mon->lock_without_safepoint_check(); 541 mon->notify_all(); 542 mon->unlock(); 543 } 544 } 545 } 546 } 547 548 #define FID_STATS 0 549 550 int FreeIdSet::claim_par_id() { 551 #if FID_STATS 552 thread_t tslf = thr_self(); 553 tty->print("claim_par_id[%d]: sz = %d, claimed = %d\n", tslf, _sz, _claimed); 554 #endif 555 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag); 556 while (!_safepoint && _hd == end_of_list) { 557 _waiters++; 558 #if FID_STATS 559 if (_waiters > 5) { 560 tty->print("claim_par_id waiting[%d]: %d waiters, %d claimed.\n", 561 tslf, _waiters, _claimed); 562 } 563 #endif 564 _mon->wait(Mutex::_no_safepoint_check_flag); 565 _waiters--; 566 } 567 if (_hd == end_of_list) { 568 #if FID_STATS 569 tty->print("claim_par_id[%d]: returning EOL.\n", tslf); 570 #endif 571 return -1; 572 } else { 573 int res = _hd; 574 _hd = _ids[res]; 575 _ids[res] = claimed; // For debugging. 576 _claimed++; 577 #if FID_STATS 578 tty->print("claim_par_id[%d]: returning %d, claimed = %d.\n", 579 tslf, res, _claimed); 580 #endif 581 return res; 582 } 583 } 584 585 bool FreeIdSet::claim_perm_id(int i) { 586 assert(0 <= i && i < _sz, "Out of range."); 587 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag); 588 int prev = end_of_list; 589 int cur = _hd; 590 while (cur != end_of_list) { 591 if (cur == i) { 592 if (prev == end_of_list) { 593 _hd = _ids[cur]; 594 } else { 595 _ids[prev] = _ids[cur]; 596 } 597 _ids[cur] = claimed; 598 _claimed++; 599 return true; 600 } else { 601 prev = cur; 602 cur = _ids[cur]; 603 } 604 } 605 return false; 606 607 } 608 609 void FreeIdSet::release_par_id(int id) { 610 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag); 611 assert(_ids[id] == claimed, "Precondition."); 612 _ids[id] = _hd; 613 _hd = id; 614 _claimed--; 615 #if FID_STATS 616 tty->print("[%d] release_par_id(%d), waiters =%d, claimed = %d.\n", 617 thr_self(), id, _waiters, _claimed); 618 #endif 619 if (_waiters > 0) 620 // Notify all would be safer, but this is OK, right? 621 _mon->notify_all(); 622 }