1 /* 2 * Copyright (c) 2014, 2015, 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 "gc/g1/suspendibleThreadSet.hpp" 27 #include "runtime/mutexLocker.hpp" 28 #include "runtime/thread.inline.hpp" 29 30 uint SuspendibleThreadSet::_nthreads = 0; 31 uint SuspendibleThreadSet::_nthreads_stopped = 0; 32 bool SuspendibleThreadSet::_suspend_all = false; 33 double SuspendibleThreadSet::_suspend_all_start = 0.0; 34 35 void SuspendibleThreadSet::join() { 36 assert(!Thread::current()->is_suspendible_thread(), "Thread already joined"); 37 MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag); 38 while (_suspend_all) { 39 ml.wait(Mutex::_no_safepoint_check_flag); 40 } 41 _nthreads++; 42 DEBUG_ONLY(Thread::current()->set_suspendible_thread();) 43 } 44 45 void SuspendibleThreadSet::leave() { 46 assert(Thread::current()->is_suspendible_thread(), "Thread not joined"); 47 MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag); 48 assert(_nthreads > 0, "Invalid"); 49 DEBUG_ONLY(Thread::current()->clear_suspendible_thread();) 50 _nthreads--; 51 if (_suspend_all) { 52 ml.notify_all(); 53 } 54 } 55 56 void SuspendibleThreadSet::yield() { 57 assert(Thread::current()->is_suspendible_thread(), "Must have joined"); 58 if (_suspend_all) { 59 MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag); 60 if (_suspend_all) { 61 _nthreads_stopped++; 62 if (_nthreads_stopped == _nthreads) { 63 if (ConcGCYieldTimeout > 0) { 64 double now = os::elapsedTime(); 65 guarantee((now - _suspend_all_start) * 1000.0 < (double)ConcGCYieldTimeout, "Long delay"); 66 } 67 } 68 ml.notify_all(); 69 while (_suspend_all) { 70 ml.wait(Mutex::_no_safepoint_check_flag); 71 } 72 assert(_nthreads_stopped > 0, "Invalid"); 73 _nthreads_stopped--; 74 ml.notify_all(); 75 } 76 } 77 } 78 79 void SuspendibleThreadSet::synchronize() { 80 assert(Thread::current()->is_VM_thread(), "Must be the VM thread"); 81 if (ConcGCYieldTimeout > 0) { 82 _suspend_all_start = os::elapsedTime(); 83 } 84 MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag); 85 assert(!_suspend_all, "Only one at a time"); 86 _suspend_all = true; 87 while (_nthreads_stopped < _nthreads) { 88 ml.wait(Mutex::_no_safepoint_check_flag); 89 } 90 } 91 92 void SuspendibleThreadSet::desynchronize() { 93 assert(Thread::current()->is_VM_thread(), "Must be the VM thread"); 94 MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag); 95 assert(_nthreads_stopped == _nthreads, "Invalid"); 96 _suspend_all = false; 97 ml.notify_all(); 98 }