1 /* 2 * Copyright (c) 2015, 2016, 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/g1CollectedHeap.inline.hpp" 27 #include "gc/g1/g1CollectorPolicy.hpp" 28 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 29 #include "gc/g1/suspendibleThreadSet.hpp" 30 #include "runtime/mutexLocker.hpp" 31 32 void G1YoungRemSetSamplingThread::run() { 33 initialize_in_thread(); 34 wait_for_universe_init(); 35 36 run_service(); 37 38 terminate(); 39 } 40 41 void G1YoungRemSetSamplingThread::stop() { 42 // it is ok to take late safepoints here, if needed 43 { 44 MutexLockerEx mu(Terminator_lock); 45 _should_terminate = true; 46 } 47 48 stop_service(); 49 50 { 51 MutexLockerEx mu(Terminator_lock); 52 while (!_has_terminated) { 53 Terminator_lock->wait(); 54 } 55 } 56 } 57 58 G1YoungRemSetSamplingThread::G1YoungRemSetSamplingThread() : ConcurrentGCThread() { 59 _monitor = new Monitor(Mutex::nonleaf, 60 "G1YoungRemSetSamplingThread monitor", 61 true, 62 Monitor::_safepoint_check_never); 63 64 set_name("G1 Young RemSet Sampling"); 65 create_and_start(); 66 } 67 68 void G1YoungRemSetSamplingThread::sleep_before_next_cycle() { 69 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 70 if (!_should_terminate) { 71 intx waitms = G1ConcRefinementServiceIntervalMillis; // 300, really should be? 72 _monitor->wait(Mutex::_no_safepoint_check_flag, waitms); 73 } 74 } 75 76 void G1YoungRemSetSamplingThread::run_service() { 77 double vtime_start = os::elapsedVTime(); 78 79 while (!_should_terminate) { 80 sample_young_list_rs_lengths(); 81 82 if (os::supports_vtime()) { 83 _vtime_accum = (os::elapsedVTime() - vtime_start); 84 } else { 85 _vtime_accum = 0.0; 86 } 87 88 sleep_before_next_cycle(); 89 } 90 } 91 92 void G1YoungRemSetSamplingThread::stop_service() { 93 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 94 _monitor->notify(); 95 } 96 97 void G1YoungRemSetSamplingThread::sample_young_list_rs_lengths() { 98 SuspendibleThreadSetJoiner sts; 99 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 100 G1CollectorPolicy* g1p = g1h->g1_policy(); 101 if (g1p->adaptive_young_list_length()) { 102 int regions_visited = 0; 103 g1h->young_list()->rs_length_sampling_init(); 104 while (g1h->young_list()->rs_length_sampling_more()) { 105 g1h->young_list()->rs_length_sampling_next(); 106 ++regions_visited; 107 108 // we try to yield every time we visit 10 regions 109 if (regions_visited == 10) { 110 if (sts.should_yield()) { 111 sts.yield(); 112 // we just abandon the iteration 113 break; 114 } 115 regions_visited = 0; 116 } 117 } 118 119 g1p->revise_young_list_target_length_if_necessary(); 120 } 121 }