--- a/src/hotspot/share/gc/cms/concurrentMarkSweepThread.cpp Fri Nov 08 14:54:17 2019 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,311 +0,0 @@
-/*
- * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- *
- */
-
-#include "precompiled.hpp"
-#include "classfile/systemDictionary.hpp"
-#include "gc/cms/cmsHeap.hpp"
-#include "gc/cms/concurrentMarkSweepGeneration.inline.hpp"
-#include "gc/cms/concurrentMarkSweepThread.hpp"
-#include "gc/shared/gcId.hpp"
-#include "memory/universe.hpp"
-#include "oops/oop.inline.hpp"
-#include "runtime/init.hpp"
-#include "runtime/java.hpp"
-#include "runtime/javaCalls.hpp"
-#include "runtime/mutexLocker.hpp"
-#include "runtime/os.hpp"
-#include "runtime/vmThread.hpp"
-
-// ======= Concurrent Mark Sweep Thread ========
-
-ConcurrentMarkSweepThread* ConcurrentMarkSweepThread::_cmst = NULL;
-CMSCollector* ConcurrentMarkSweepThread::_collector = NULL;
-int ConcurrentMarkSweepThread::_CMS_flag = CMS_nil;
-
-volatile jint ConcurrentMarkSweepThread::_pending_yields = 0;
-
-ConcurrentMarkSweepThread::ConcurrentMarkSweepThread(CMSCollector* collector)
- : ConcurrentGCThread() {
- assert(UseConcMarkSweepGC, "UseConcMarkSweepGC should be set");
- assert(_cmst == NULL, "CMS thread already created");
- _cmst = this;
- assert(_collector == NULL, "Collector already set");
- _collector = collector;
-
- set_name("CMS Main Thread");
-
- // An old comment here said: "Priority should be just less
- // than that of VMThread". Since the VMThread runs at
- // NearMaxPriority, the old comment was inaccurate, but
- // changing the default priority to NearMaxPriority-1
- // could change current behavior, so the default of
- // NearMaxPriority stays in place.
- //
- // Note that there's a possibility of the VMThread
- // starving if UseCriticalCMSThreadPriority is on.
- // That won't happen on Solaris for various reasons,
- // but may well happen on non-Solaris platforms.
- create_and_start(UseCriticalCMSThreadPriority ? CriticalPriority : NearMaxPriority);
-}
-
-void ConcurrentMarkSweepThread::run_service() {
- assert(this == cmst(), "just checking");
-
- if (BindCMSThreadToCPU && !os::bind_to_processor(CPUForCMSThread)) {
- log_warning(gc)("Couldn't bind CMS thread to processor " UINTX_FORMAT, CPUForCMSThread);
- }
-
- while (!should_terminate()) {
- sleepBeforeNextCycle();
- if (should_terminate()) break;
- GCIdMark gc_id_mark;
- GCCause::Cause cause = _collector->_full_gc_requested ?
- _collector->_full_gc_cause : GCCause::_cms_concurrent_mark;
- _collector->collect_in_background(cause);
- }
-
- // Check that the state of any protocol for synchronization
- // between background (CMS) and foreground collector is "clean"
- // (i.e. will not potentially block the foreground collector,
- // requiring action by us).
- verify_ok_to_terminate();
-}
-
-#ifndef PRODUCT
-void ConcurrentMarkSweepThread::verify_ok_to_terminate() const {
- assert(!(CGC_lock->owned_by_self() || cms_thread_has_cms_token() ||
- cms_thread_wants_cms_token()),
- "Must renounce all worldly possessions and desires for nirvana");
- _collector->verify_ok_to_terminate();
-}
-#endif
-
-// create and start a new ConcurrentMarkSweep Thread for given CMS generation
-ConcurrentMarkSweepThread* ConcurrentMarkSweepThread::start(CMSCollector* collector) {
- guarantee(_cmst == NULL, "start() called twice!");
- ConcurrentMarkSweepThread* th = new ConcurrentMarkSweepThread(collector);
- assert(_cmst == th, "Where did the just-created CMS thread go?");
- return th;
-}
-
-void ConcurrentMarkSweepThread::stop_service() {
- // Now post a notify on CGC_lock so as to nudge
- // CMS thread(s) that might be slumbering in
- // sleepBeforeNextCycle.
- MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
- CGC_lock->notify_all();
-}
-
-void ConcurrentMarkSweepThread::threads_do(ThreadClosure* tc) {
- assert(tc != NULL, "Null ThreadClosure");
- if (cmst() != NULL && !cmst()->has_terminated()) {
- tc->do_thread(cmst());
- }
- assert(Universe::is_fully_initialized(),
- "Called too early, make sure heap is fully initialized");
- if (_collector != NULL) {
- AbstractWorkGang* gang = _collector->conc_workers();
- if (gang != NULL) {
- gang->threads_do(tc);
- }
- }
-}
-
-void ConcurrentMarkSweepThread::print_all_on(outputStream* st) {
- if (cmst() != NULL && !cmst()->has_terminated()) {
- cmst()->print_on(st);
- st->cr();
- }
- if (_collector != NULL) {
- AbstractWorkGang* gang = _collector->conc_workers();
- if (gang != NULL) {
- gang->print_worker_threads_on(st);
- }
- }
-}
-
-void ConcurrentMarkSweepThread::synchronize(bool is_cms_thread) {
- assert(UseConcMarkSweepGC, "just checking");
-
- MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
- if (!is_cms_thread) {
- assert(Thread::current()->is_VM_thread(), "Not a VM thread");
- CMSSynchronousYieldRequest yr;
- while (CMS_flag_is_set(CMS_cms_has_token)) {
- // indicate that we want to get the token
- set_CMS_flag(CMS_vm_wants_token);
- CGC_lock->wait_without_safepoint_check();
- }
- // claim the token and proceed
- clear_CMS_flag(CMS_vm_wants_token);
- set_CMS_flag(CMS_vm_has_token);
- } else {
- assert(Thread::current()->is_ConcurrentGC_thread(),
- "Not a CMS thread");
- // The following barrier assumes there's only one CMS thread.
- // This will need to be modified is there are more CMS threads than one.
- while (CMS_flag_is_set(CMS_vm_has_token | CMS_vm_wants_token)) {
- set_CMS_flag(CMS_cms_wants_token);
- CGC_lock->wait_without_safepoint_check();
- }
- // claim the token
- clear_CMS_flag(CMS_cms_wants_token);
- set_CMS_flag(CMS_cms_has_token);
- }
-}
-
-void ConcurrentMarkSweepThread::desynchronize(bool is_cms_thread) {
- assert(UseConcMarkSweepGC, "just checking");
-
- MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
- if (!is_cms_thread) {
- assert(Thread::current()->is_VM_thread(), "Not a VM thread");
- assert(CMS_flag_is_set(CMS_vm_has_token), "just checking");
- clear_CMS_flag(CMS_vm_has_token);
- if (CMS_flag_is_set(CMS_cms_wants_token)) {
- // wake-up a waiting CMS thread
- CGC_lock->notify();
- }
- assert(!CMS_flag_is_set(CMS_vm_has_token | CMS_vm_wants_token),
- "Should have been cleared");
- } else {
- assert(Thread::current()->is_ConcurrentGC_thread(),
- "Not a CMS thread");
- assert(CMS_flag_is_set(CMS_cms_has_token), "just checking");
- clear_CMS_flag(CMS_cms_has_token);
- if (CMS_flag_is_set(CMS_vm_wants_token)) {
- // wake-up a waiting VM thread
- CGC_lock->notify();
- }
- assert(!CMS_flag_is_set(CMS_cms_has_token | CMS_cms_wants_token),
- "Should have been cleared");
- }
-}
-
-// Wait until any cms_lock event
-void ConcurrentMarkSweepThread::wait_on_cms_lock(long t_millis) {
- MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
- if (should_terminate() || _collector->_full_gc_requested) {
- return;
- }
- set_CMS_flag(CMS_cms_wants_token); // to provoke notifies
- CGC_lock->wait_without_safepoint_check(t_millis);
- clear_CMS_flag(CMS_cms_wants_token);
- assert(!CMS_flag_is_set(CMS_cms_has_token | CMS_cms_wants_token),
- "Should not be set");
-}
-
-// Wait until the next synchronous GC, a concurrent full gc request,
-// or a timeout, whichever is earlier.
-void ConcurrentMarkSweepThread::wait_on_cms_lock_for_scavenge(long t_millis) {
- // Wait time in millis or 0 value representing infinite wait for a scavenge
- assert(t_millis >= 0, "Wait time for scavenge should be 0 or positive");
-
- CMSHeap* heap = CMSHeap::heap();
- double start_time_secs = os::elapsedTime();
- double end_time_secs = start_time_secs + (t_millis / ((double) MILLIUNITS));
-
- // Total collections count before waiting loop
- unsigned int before_count;
- {
- MutexLocker hl(Heap_lock, Mutex::_no_safepoint_check_flag);
- before_count = heap->total_collections();
- }
-
- unsigned int loop_count = 0;
-
- while(!should_terminate()) {
- double now_time = os::elapsedTime();
- long wait_time_millis;
-
- if(t_millis != 0) {
- // New wait limit
- wait_time_millis = (long) ((end_time_secs - now_time) * MILLIUNITS);
- if(wait_time_millis <= 0) {
- // Wait time is over
- break;
- }
- } else {
- // No wait limit, wait if necessary forever
- wait_time_millis = 0;
- }
-
- // Wait until the next event or the remaining timeout
- {
- MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
-
- if (should_terminate() || _collector->_full_gc_requested) {
- return;
- }
- set_CMS_flag(CMS_cms_wants_token); // to provoke notifies
- assert(t_millis == 0 || wait_time_millis > 0, "Sanity");
- CGC_lock->wait_without_safepoint_check(wait_time_millis);
- clear_CMS_flag(CMS_cms_wants_token);
- assert(!CMS_flag_is_set(CMS_cms_has_token | CMS_cms_wants_token),
- "Should not be set");
- }
-
- // Extra wait time check before entering the heap lock to get the collection count
- if(t_millis != 0 && os::elapsedTime() >= end_time_secs) {
- // Wait time is over
- break;
- }
-
- // Total collections count after the event
- unsigned int after_count;
- {
- MutexLocker hl(Heap_lock, Mutex::_no_safepoint_check_flag);
- after_count = heap->total_collections();
- }
-
- if(before_count != after_count) {
- // There was a collection - success
- break;
- }
-
- // Too many loops warning
- if(++loop_count == 0) {
- log_warning(gc)("wait_on_cms_lock_for_scavenge() has looped %u times", loop_count - 1);
- }
- }
-}
-
-void ConcurrentMarkSweepThread::sleepBeforeNextCycle() {
- while (!should_terminate()) {
- if(CMSWaitDuration >= 0) {
- // Wait until the next synchronous GC, a concurrent full gc
- // request or a timeout, whichever is earlier.
- wait_on_cms_lock_for_scavenge(CMSWaitDuration);
- } else {
- // Wait until any cms_lock event or check interval not to call shouldConcurrentCollect permanently
- wait_on_cms_lock(CMSCheckInterval);
- }
- // Check if we should start a CMS collection cycle
- if (_collector->shouldConcurrentCollect()) {
- return;
- }
- // .. collection criterion not yet met, let's go back
- // and wait some more
- }
-}