1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.cpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,350 @@
1.4 +/*
1.5 + * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +# include "incls/_precompiled.incl"
1.29 +# include "incls/_concurrentMarkSweepThread.cpp.incl"
1.30 +
1.31 +// ======= Concurrent Mark Sweep Thread ========
1.32 +
1.33 +// The CMS thread is created when Concurrent Mark Sweep is used in the
1.34 +// older of two generations in a generational memory system.
1.35 +
1.36 +ConcurrentMarkSweepThread*
1.37 + ConcurrentMarkSweepThread::_cmst = NULL;
1.38 +CMSCollector* ConcurrentMarkSweepThread::_collector = NULL;
1.39 +bool ConcurrentMarkSweepThread::_should_terminate = false;
1.40 +int ConcurrentMarkSweepThread::_CMS_flag = CMS_nil;
1.41 +
1.42 +volatile jint ConcurrentMarkSweepThread::_pending_yields = 0;
1.43 +volatile jint ConcurrentMarkSweepThread::_pending_decrements = 0;
1.44 +
1.45 +volatile bool ConcurrentMarkSweepThread::_icms_enabled = false;
1.46 +volatile bool ConcurrentMarkSweepThread::_should_run = false;
1.47 +// When icms is enabled, the icms thread is stopped until explicitly
1.48 +// started.
1.49 +volatile bool ConcurrentMarkSweepThread::_should_stop = true;
1.50 +
1.51 +SurrogateLockerThread*
1.52 + ConcurrentMarkSweepThread::_slt = NULL;
1.53 +SurrogateLockerThread::SLT_msg_type
1.54 + ConcurrentMarkSweepThread::_sltBuffer = SurrogateLockerThread::empty;
1.55 +Monitor*
1.56 + ConcurrentMarkSweepThread::_sltMonitor = NULL;
1.57 +
1.58 +ConcurrentMarkSweepThread::ConcurrentMarkSweepThread(CMSCollector* collector)
1.59 + : ConcurrentGCThread() {
1.60 + assert(UseConcMarkSweepGC, "UseConcMarkSweepGC should be set");
1.61 + assert(_cmst == NULL, "CMS thread already created");
1.62 + _cmst = this;
1.63 + assert(_collector == NULL, "Collector already set");
1.64 + _collector = collector;
1.65 +
1.66 + set_name("Concurrent Mark-Sweep GC Thread");
1.67 +
1.68 + if (os::create_thread(this, os::cgc_thread)) {
1.69 + // XXX: need to set this to low priority
1.70 + // unless "agressive mode" set; priority
1.71 + // should be just less than that of VMThread.
1.72 + os::set_priority(this, NearMaxPriority);
1.73 + if (!DisableStartThread) {
1.74 + os::start_thread(this);
1.75 + }
1.76 + }
1.77 + _sltMonitor = SLT_lock;
1.78 + set_icms_enabled(CMSIncrementalMode);
1.79 +}
1.80 +
1.81 +void ConcurrentMarkSweepThread::run() {
1.82 + assert(this == cmst(), "just checking");
1.83 +
1.84 + this->record_stack_base_and_size();
1.85 + this->initialize_thread_local_storage();
1.86 + this->set_active_handles(JNIHandleBlock::allocate_block());
1.87 + // From this time Thread::current() should be working.
1.88 + assert(this == Thread::current(), "just checking");
1.89 + if (BindCMSThreadToCPU && !os::bind_to_processor(CPUForCMSThread)) {
1.90 + warning("Couldn't bind CMS thread to processor %u", CPUForCMSThread);
1.91 + }
1.92 + // Wait until Universe::is_fully_initialized()
1.93 + {
1.94 + CMSLoopCountWarn loopX("CMS::run", "waiting for "
1.95 + "Universe::is_fully_initialized()", 2);
1.96 + MutexLockerEx x(CGC_lock, true);
1.97 + set_CMS_flag(CMS_cms_wants_token);
1.98 + // Wait until Universe is initialized and all initialization is completed.
1.99 + while (!is_init_completed() && !Universe::is_fully_initialized() &&
1.100 + !_should_terminate) {
1.101 + CGC_lock->wait(true, 200);
1.102 + loopX.tick();
1.103 + }
1.104 + // Wait until the surrogate locker thread that will do
1.105 + // pending list locking on our behalf has been created.
1.106 + // We cannot start the SLT thread ourselves since we need
1.107 + // to be a JavaThread to do so.
1.108 + CMSLoopCountWarn loopY("CMS::run", "waiting for SLT installation", 2);
1.109 + while (_slt == NULL && !_should_terminate) {
1.110 + CGC_lock->wait(true, 200);
1.111 + loopY.tick();
1.112 + }
1.113 + clear_CMS_flag(CMS_cms_wants_token);
1.114 + }
1.115 +
1.116 + while (!_should_terminate) {
1.117 + sleepBeforeNextCycle();
1.118 + if (_should_terminate) break;
1.119 + _collector->collect_in_background(false); // !clear_all_soft_refs
1.120 + }
1.121 + assert(_should_terminate, "just checking");
1.122 + // Check that the state of any protocol for synchronization
1.123 + // between background (CMS) and foreground collector is "clean"
1.124 + // (i.e. will not potentially block the foreground collector,
1.125 + // requiring action by us).
1.126 + verify_ok_to_terminate();
1.127 + // Signal that it is terminated
1.128 + {
1.129 + MutexLockerEx mu(Terminator_lock,
1.130 + Mutex::_no_safepoint_check_flag);
1.131 + assert(_cmst == this, "Weird!");
1.132 + _cmst = NULL;
1.133 + Terminator_lock->notify();
1.134 + }
1.135 +
1.136 + // Thread destructor usually does this..
1.137 + ThreadLocalStorage::set_thread(NULL);
1.138 +}
1.139 +
1.140 +#ifndef PRODUCT
1.141 +void ConcurrentMarkSweepThread::verify_ok_to_terminate() const {
1.142 + assert(!(CGC_lock->owned_by_self() || cms_thread_has_cms_token() ||
1.143 + cms_thread_wants_cms_token()),
1.144 + "Must renounce all worldly possessions and desires for nirvana");
1.145 + _collector->verify_ok_to_terminate();
1.146 +}
1.147 +#endif
1.148 +
1.149 +// create and start a new ConcurrentMarkSweep Thread for given CMS generation
1.150 +ConcurrentMarkSweepThread* ConcurrentMarkSweepThread::start(CMSCollector* collector) {
1.151 + if (!_should_terminate) {
1.152 + assert(cmst() == NULL, "start() called twice?");
1.153 + ConcurrentMarkSweepThread* th = new ConcurrentMarkSweepThread(collector);
1.154 + assert(cmst() == th, "Where did the just-created CMS thread go?");
1.155 + return th;
1.156 + }
1.157 + return NULL;
1.158 +}
1.159 +
1.160 +void ConcurrentMarkSweepThread::stop() {
1.161 + if (CMSIncrementalMode) {
1.162 + // Disable incremental mode and wake up the thread so it notices the change.
1.163 + disable_icms();
1.164 + start_icms();
1.165 + }
1.166 + // it is ok to take late safepoints here, if needed
1.167 + {
1.168 + MutexLockerEx x(Terminator_lock);
1.169 + _should_terminate = true;
1.170 + }
1.171 + { // Now post a notify on CGC_lock so as to nudge
1.172 + // CMS thread(s) that might be slumbering in
1.173 + // sleepBeforeNextCycle.
1.174 + MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
1.175 + CGC_lock->notify_all();
1.176 + }
1.177 + { // Now wait until (all) CMS thread(s) have exited
1.178 + MutexLockerEx x(Terminator_lock);
1.179 + while(cmst() != NULL) {
1.180 + Terminator_lock->wait();
1.181 + }
1.182 + }
1.183 +}
1.184 +
1.185 +void ConcurrentMarkSweepThread::threads_do(ThreadClosure* tc) {
1.186 + assert(tc != NULL, "Null ThreadClosure");
1.187 + if (_cmst != NULL) {
1.188 + tc->do_thread(_cmst);
1.189 + }
1.190 + assert(Universe::is_fully_initialized(),
1.191 + "Called too early, make sure heap is fully initialized");
1.192 + if (_collector != NULL) {
1.193 + AbstractWorkGang* gang = _collector->conc_workers();
1.194 + if (gang != NULL) {
1.195 + gang->threads_do(tc);
1.196 + }
1.197 + }
1.198 +}
1.199 +
1.200 +void ConcurrentMarkSweepThread::print_on(outputStream* st) const {
1.201 + st->print("\"%s\" ", name());
1.202 + Thread::print_on(st);
1.203 + st->cr();
1.204 +}
1.205 +
1.206 +void ConcurrentMarkSweepThread::print_all_on(outputStream* st) {
1.207 + if (_cmst != NULL) {
1.208 + _cmst->print_on(st);
1.209 + }
1.210 + if (_collector != NULL) {
1.211 + AbstractWorkGang* gang = _collector->conc_workers();
1.212 + if (gang != NULL) {
1.213 + gang->print_worker_threads_on(st);
1.214 + }
1.215 + }
1.216 +}
1.217 +
1.218 +void ConcurrentMarkSweepThread::synchronize(bool is_cms_thread) {
1.219 + assert(UseConcMarkSweepGC, "just checking");
1.220 +
1.221 + MutexLockerEx x(CGC_lock,
1.222 + Mutex::_no_safepoint_check_flag);
1.223 + if (!is_cms_thread) {
1.224 + assert(Thread::current()->is_VM_thread(), "Not a VM thread");
1.225 + CMSSynchronousYieldRequest yr;
1.226 + while (CMS_flag_is_set(CMS_cms_has_token)) {
1.227 + // indicate that we want to get the token
1.228 + set_CMS_flag(CMS_vm_wants_token);
1.229 + CGC_lock->wait(true);
1.230 + }
1.231 + // claim the token and proceed
1.232 + clear_CMS_flag(CMS_vm_wants_token);
1.233 + set_CMS_flag(CMS_vm_has_token);
1.234 + } else {
1.235 + assert(Thread::current()->is_ConcurrentGC_thread(),
1.236 + "Not a CMS thread");
1.237 + // The following barrier assumes there's only one CMS thread.
1.238 + // This will need to be modified is there are more CMS threads than one.
1.239 + while (CMS_flag_is_set(CMS_vm_has_token | CMS_vm_wants_token)) {
1.240 + set_CMS_flag(CMS_cms_wants_token);
1.241 + CGC_lock->wait(true);
1.242 + }
1.243 + // claim the token
1.244 + clear_CMS_flag(CMS_cms_wants_token);
1.245 + set_CMS_flag(CMS_cms_has_token);
1.246 + }
1.247 +}
1.248 +
1.249 +void ConcurrentMarkSweepThread::desynchronize(bool is_cms_thread) {
1.250 + assert(UseConcMarkSweepGC, "just checking");
1.251 +
1.252 + MutexLockerEx x(CGC_lock,
1.253 + Mutex::_no_safepoint_check_flag);
1.254 + if (!is_cms_thread) {
1.255 + assert(Thread::current()->is_VM_thread(), "Not a VM thread");
1.256 + assert(CMS_flag_is_set(CMS_vm_has_token), "just checking");
1.257 + clear_CMS_flag(CMS_vm_has_token);
1.258 + if (CMS_flag_is_set(CMS_cms_wants_token)) {
1.259 + // wake-up a waiting CMS thread
1.260 + CGC_lock->notify();
1.261 + }
1.262 + assert(!CMS_flag_is_set(CMS_vm_has_token | CMS_vm_wants_token),
1.263 + "Should have been cleared");
1.264 + } else {
1.265 + assert(Thread::current()->is_ConcurrentGC_thread(),
1.266 + "Not a CMS thread");
1.267 + assert(CMS_flag_is_set(CMS_cms_has_token), "just checking");
1.268 + clear_CMS_flag(CMS_cms_has_token);
1.269 + if (CMS_flag_is_set(CMS_vm_wants_token)) {
1.270 + // wake-up a waiting VM thread
1.271 + CGC_lock->notify();
1.272 + }
1.273 + assert(!CMS_flag_is_set(CMS_cms_has_token | CMS_cms_wants_token),
1.274 + "Should have been cleared");
1.275 + }
1.276 +}
1.277 +
1.278 +// Wait until the next synchronous GC or a timeout, whichever is earlier.
1.279 +void ConcurrentMarkSweepThread::wait_on_cms_lock(long t) {
1.280 + MutexLockerEx x(CGC_lock,
1.281 + Mutex::_no_safepoint_check_flag);
1.282 + set_CMS_flag(CMS_cms_wants_token); // to provoke notifies
1.283 + CGC_lock->wait(Mutex::_no_safepoint_check_flag, t);
1.284 + clear_CMS_flag(CMS_cms_wants_token);
1.285 + assert(!CMS_flag_is_set(CMS_cms_has_token | CMS_cms_wants_token),
1.286 + "Should not be set");
1.287 +}
1.288 +
1.289 +void ConcurrentMarkSweepThread::sleepBeforeNextCycle() {
1.290 + while (!_should_terminate) {
1.291 + if (CMSIncrementalMode) {
1.292 + icms_wait();
1.293 + return;
1.294 + } else {
1.295 + // Wait until the next synchronous GC or a timeout, whichever is earlier
1.296 + wait_on_cms_lock(CMSWaitDuration);
1.297 + }
1.298 + // Check if we should start a CMS collection cycle
1.299 + if (_collector->shouldConcurrentCollect()) {
1.300 + return;
1.301 + }
1.302 + // .. collection criterion not yet met, let's go back
1.303 + // and wait some more
1.304 + }
1.305 +}
1.306 +
1.307 +// Incremental CMS
1.308 +void ConcurrentMarkSweepThread::start_icms() {
1.309 + assert(UseConcMarkSweepGC && CMSIncrementalMode, "just checking");
1.310 + MutexLockerEx x(iCMS_lock, Mutex::_no_safepoint_check_flag);
1.311 + trace_state("start_icms");
1.312 + _should_run = true;
1.313 + iCMS_lock->notify_all();
1.314 +}
1.315 +
1.316 +void ConcurrentMarkSweepThread::stop_icms() {
1.317 + assert(UseConcMarkSweepGC && CMSIncrementalMode, "just checking");
1.318 + MutexLockerEx x(iCMS_lock, Mutex::_no_safepoint_check_flag);
1.319 + if (!_should_stop) {
1.320 + trace_state("stop_icms");
1.321 + _should_stop = true;
1.322 + _should_run = false;
1.323 + asynchronous_yield_request();
1.324 + iCMS_lock->notify_all();
1.325 + }
1.326 +}
1.327 +
1.328 +void ConcurrentMarkSweepThread::icms_wait() {
1.329 + assert(UseConcMarkSweepGC && CMSIncrementalMode, "just checking");
1.330 + if (_should_stop && icms_enabled()) {
1.331 + MutexLockerEx x(iCMS_lock, Mutex::_no_safepoint_check_flag);
1.332 + trace_state("pause_icms");
1.333 + _collector->stats().stop_cms_timer();
1.334 + while(!_should_run && icms_enabled()) {
1.335 + iCMS_lock->wait(Mutex::_no_safepoint_check_flag);
1.336 + }
1.337 + _collector->stats().start_cms_timer();
1.338 + _should_stop = false;
1.339 + trace_state("pause_icms end");
1.340 + }
1.341 +}
1.342 +
1.343 +// Note: this method, although exported by the ConcurrentMarkSweepThread,
1.344 +// which is a non-JavaThread, can only be called by a JavaThread.
1.345 +// Currently this is done at vm creation time (post-vm-init) by the
1.346 +// main/Primordial (Java)Thread.
1.347 +// XXX Consider changing this in the future to allow the CMS thread
1.348 +// itself to create this thread?
1.349 +void ConcurrentMarkSweepThread::makeSurrogateLockerThread(TRAPS) {
1.350 + assert(UseConcMarkSweepGC, "SLT thread needed only for CMS GC");
1.351 + assert(_slt == NULL, "SLT already created");
1.352 + _slt = SurrogateLockerThread::make(THREAD);
1.353 +}
