1 /* 2 * Copyright (c) 2013, 2018, Red Hat, Inc. All rights reserved. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. 7 * 8 * This code is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 * version 2 for more details (a copy is included in the LICENSE file that 12 * accompanied this code). 13 * 14 * You should have received a copy of the GNU General Public License version 15 * 2 along with this work; if not, write to the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 * 18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 * or visit www.oracle.com if you need additional information or have any 20 * questions. 21 * 22 */ 23 24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTTHREAD_HPP 25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTTHREAD_HPP 26 27 #include "gc_interface/gcCause.hpp" 28 #include "gc_implementation/shared/concurrentGCThread.hpp" 29 #include "gc_implementation/shenandoah/shenandoahHeap.hpp" 30 #include "gc_implementation/shenandoah/shenandoahSharedVariables.hpp" 31 #include "runtime/task.hpp" 32 #include "utilities/ostream.hpp" 33 34 class ShenandoahControlThread; 35 36 // Periodic task is useful for doing asynchronous things that do not require (heap) locks, 37 // or synchronization with other parts of collector. These could run even when ShenandoahConcurrentThread 38 // is busy driving the GC cycle. 39 class ShenandoahPeriodicTask : public PeriodicTask { 40 private: 41 ShenandoahControlThread* _thread; 42 public: 43 ShenandoahPeriodicTask(ShenandoahControlThread* thread) : 44 PeriodicTask(100), _thread(thread) {} 45 virtual void task(); 46 }; 47 48 // Periodic task to flush SATB buffers periodically. 49 class ShenandoahPeriodicSATBFlushTask : public PeriodicTask { 50 public: 51 ShenandoahPeriodicSATBFlushTask() : PeriodicTask(ShenandoahSATBBufferFlushInterval) {} 52 virtual void task(); 53 }; 54 55 class ShenandoahControlThread: public ConcurrentGCThread { 56 friend class VMStructs; 57 58 private: 59 typedef enum { 60 none, 61 concurrent_traversal, 62 concurrent_normal, 63 stw_degenerated, 64 stw_full 65 } GCMode; 66 67 // While we could have a single lock for these, it may risk unblocking 68 // GC waiters when alloc failure GC cycle finishes. We want instead 69 // to make complete explicit cycle for for demanding customers. 70 Monitor _alloc_failure_waiters_lock; 71 Monitor _gc_waiters_lock; 72 ShenandoahPeriodicTask _periodic_task; 73 ShenandoahPeriodicSATBFlushTask _periodic_satb_flush_task; 74 75 private: 76 static SurrogateLockerThread* _slt; 77 78 public: 79 void run(); 80 void stop(); 81 82 private: 83 ShenandoahSharedFlag _gc_requested; 84 ShenandoahSharedFlag _alloc_failure_gc; 85 ShenandoahSharedFlag _graceful_shutdown; 86 ShenandoahSharedFlag _heap_changed; 87 ShenandoahSharedFlag _do_counters_update; 88 ShenandoahSharedFlag _force_counters_update; 89 GCCause::Cause _requested_gc_cause; 90 ShenandoahHeap::ShenandoahDegenPoint _degen_point; 91 92 char _pad0[DEFAULT_CACHE_LINE_SIZE]; 93 volatile intptr_t _allocs_seen; 94 char _pad1[DEFAULT_CACHE_LINE_SIZE]; 95 96 bool check_cancellation_or_degen(ShenandoahHeap::ShenandoahDegenPoint point); 97 void service_concurrent_normal_cycle(GCCause::Cause cause); 98 void service_stw_full_cycle(GCCause::Cause cause); 99 void service_stw_degenerated_cycle(GCCause::Cause cause, ShenandoahHeap::ShenandoahDegenPoint point); 100 void service_concurrent_traversal_cycle(GCCause::Cause cause); 101 void service_uncommit(double shrink_before); 102 103 bool try_set_alloc_failure_gc(); 104 void notify_alloc_failure_waiters(); 105 bool is_alloc_failure_gc(); 106 107 void notify_gc_waiters(); 108 109 // Handle GC request. 110 // Blocks until GC is over. 111 void handle_requested_gc(GCCause::Cause cause); 112 113 bool is_explicit_gc(GCCause::Cause cause) const; 114 public: 115 // Constructor 116 ShenandoahControlThread(); 117 ~ShenandoahControlThread(); 118 119 static void makeSurrogateLockerThread(TRAPS); 120 static SurrogateLockerThread* slt() { return _slt; } 121 122 // Handle allocation failure from normal allocation. 123 // Blocks until memory is available. 124 void handle_alloc_failure(size_t words); 125 126 // Handle allocation failure from evacuation path. 127 // Optionally blocks while collector is handling the failure. 128 void handle_alloc_failure_evac(size_t words); 129 130 void request_gc(GCCause::Cause cause); 131 132 void handle_counters_update(); 133 void handle_force_counters_update(); 134 void set_forced_counters_update(bool value); 135 136 void notify_heap_changed(); 137 138 void pacing_notify_alloc(size_t words); 139 140 void start(); 141 void prepare_for_graceful_shutdown(); 142 bool in_graceful_shutdown(); 143 144 char* name() const { return (char*)"ShenandoahConcurrentThread";} 145 146 // Printing 147 void print_on(outputStream* st) const; 148 void print() const; 149 150 }; 151 152 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTTHREAD_HPP