1 /* 2 * Copyright (c) 2017, 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/cms/concurrentMarkSweepThread.hpp" 27 #include "gc/cms/cmsHeap.hpp" 28 #include "gc/cms/vmCMSOperations.hpp" 29 #include "gc/shared/genOopClosures.inline.hpp" 30 #include "gc/shared/strongRootsScope.hpp" 31 #include "gc/shared/workgroup.hpp" 32 #include "oops/oop.inline.hpp" 33 #include "runtime/vmThread.hpp" 34 #include "utilities/stack.inline.hpp" 35 36 CMSHeap::CMSHeap(GenCollectorPolicy *policy) : GenCollectedHeap(policy) { 37 _workers = new WorkGang("GC Thread", ParallelGCThreads, 38 /* are_GC_task_threads */true, 39 /* are_ConcurrentGC_threads */false); 40 _workers->initialize_workers(); 41 } 42 43 jint CMSHeap::initialize() { 44 jint status = GenCollectedHeap::initialize(); 45 if (status != JNI_OK) return status; 46 47 // If we are running CMS, create the collector responsible 48 // for collecting the CMS generations. 49 assert(collector_policy()->is_concurrent_mark_sweep_policy(), "must be CMS policy"); 50 if (!create_cms_collector()) { 51 return JNI_ENOMEM; 52 } 53 54 return JNI_OK; 55 } 56 57 void CMSHeap::check_gen_kinds() { 58 assert(young_gen()->kind() == Generation::ParNew, 59 "Wrong youngest generation type"); 60 assert(old_gen()->kind() == Generation::ConcurrentMarkSweep, 61 "Wrong generation kind"); 62 } 63 64 CMSHeap* CMSHeap::heap() { 65 CollectedHeap* heap = Universe::heap(); 66 assert(heap != NULL, "Uninitialized access to CMSHeap::heap()"); 67 assert(heap->kind() == CollectedHeap::CMSHeap, "Not a CMSHeap"); 68 return (CMSHeap*) heap; 69 } 70 71 void CMSHeap::gc_threads_do(ThreadClosure* tc) const { 72 assert(workers() != NULL, "should have workers here"); 73 workers()->threads_do(tc); 74 ConcurrentMarkSweepThread::threads_do(tc); 75 } 76 77 void CMSHeap::print_gc_threads_on(outputStream* st) const { 78 assert(workers() != NULL, "should have workers here"); 79 workers()->print_worker_threads_on(st); 80 ConcurrentMarkSweepThread::print_all_on(st); 81 } 82 83 void CMSHeap::print_on_error(outputStream* st) const { 84 GenCollectedHeap::print_on_error(st); 85 st->cr(); 86 CMSCollector::print_on_error(st); 87 } 88 89 bool CMSHeap::create_cms_collector() { 90 assert(old_gen()->kind() == Generation::ConcurrentMarkSweep, 91 "Unexpected generation kinds"); 92 assert(gen_policy()->is_concurrent_mark_sweep_policy(), "Unexpected policy type"); 93 CMSCollector* collector = 94 new CMSCollector((ConcurrentMarkSweepGeneration*) old_gen(), 95 rem_set(), 96 gen_policy()->as_concurrent_mark_sweep_policy()); 97 98 if (collector == NULL || !collector->completed_initialization()) { 99 if (collector) { 100 delete collector; // Be nice in embedded situation 101 } 102 vm_shutdown_during_initialization("Could not create CMS collector"); 103 return false; 104 } 105 return true; // success 106 } 107 108 void CMSHeap::collect(GCCause::Cause cause) { 109 if (should_do_concurrent_full_gc(cause)) { 110 // Mostly concurrent full collection. 111 collect_mostly_concurrent(cause); 112 } else { 113 GenCollectedHeap::collect(cause); 114 } 115 } 116 117 bool CMSHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 118 switch (cause) { 119 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 120 case GCCause::_java_lang_system_gc: 121 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 122 default: return false; 123 } 124 } 125 126 void CMSHeap::collect_mostly_concurrent(GCCause::Cause cause) { 127 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 128 129 MutexLocker ml(Heap_lock); 130 // Read the GC counts while holding the Heap_lock 131 unsigned int full_gc_count_before = total_full_collections(); 132 unsigned int gc_count_before = total_collections(); 133 { 134 MutexUnlocker mu(Heap_lock); 135 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 136 VMThread::execute(&op); 137 } 138 } 139 140 void CMSHeap::stop() { 141 ConcurrentMarkSweepThread::cmst()->stop(); 142 } 143 144 void CMSHeap::safepoint_synchronize_begin() { 145 ConcurrentMarkSweepThread::synchronize(false); 146 } 147 148 void CMSHeap::safepoint_synchronize_end() { 149 ConcurrentMarkSweepThread::desynchronize(false); 150 } 151 152 void CMSHeap::cms_process_roots(StrongRootsScope* scope, 153 bool young_gen_as_roots, 154 ScanningOption so, 155 bool only_strong_roots, 156 OopsInGenClosure* root_closure, 157 CLDClosure* cld_closure) { 158 MarkingCodeBlobClosure mark_code_closure(root_closure, !CodeBlobToOopClosure::FixRelocations); 159 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure; 160 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 161 162 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure); 163 if (!only_strong_roots) { 164 process_string_table_roots(scope, root_closure); 165 } 166 167 if (young_gen_as_roots && 168 !_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 169 root_closure->set_generation(young_gen()); 170 young_gen()->oop_iterate(root_closure); 171 root_closure->reset_generation(); 172 } 173 174 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 175 } 176 177 void CMSHeap::gc_prologue(bool full) { 178 always_do_update_barrier = false; 179 GenCollectedHeap::gc_prologue(full); 180 }; 181 182 void CMSHeap::gc_epilogue(bool full) { 183 GenCollectedHeap::gc_epilogue(full); 184 always_do_update_barrier = true; 185 };