1 /*
2 * Copyright (c) 2013, 2021, Red Hat, Inc. 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 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHCONTROLTHREAD_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHCONTROLTHREAD_HPP
27
28 #include "gc/shared/gcCause.hpp"
29 #include "gc/shared/concurrentGCThread.hpp"
30 #include "gc/shenandoah/shenandoahGC.hpp"
31 #include "gc/shenandoah/shenandoahHeap.hpp"
32 #include "gc/shenandoah/shenandoahPadding.hpp"
33 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
34 #include "runtime/task.hpp"
35 #include "utilities/ostream.hpp"
36
37 // Periodic task is useful for doing asynchronous things that do not require (heap) locks,
38 // or synchronization with other parts of collector. These could run even when ShenandoahConcurrentThread
39 // is busy driving the GC cycle.
40 class ShenandoahPeriodicTask : public PeriodicTask {
41 private:
42 ShenandoahControlThread* _thread;
43 public:
44 ShenandoahPeriodicTask(ShenandoahControlThread* thread) :
45 PeriodicTask(100), _thread(thread) {}
46 virtual void task();
47 };
48
49 // Periodic task to notify blocked paced waiters.
50 class ShenandoahPeriodicPacerNotify : public PeriodicTask {
51 public:
52 ShenandoahPeriodicPacerNotify() : PeriodicTask(PeriodicTask::min_interval) {}
53 virtual void task();
54 };
55
56 class ShenandoahControlThread: public ConcurrentGCThread {
57 friend class VMStructs;
58
59 private:
60 typedef enum {
61 none,
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 ShenandoahPeriodicPacerNotify _periodic_pacer_notify_task;
74
75 public:
76 void run_service();
77 void stop_service();
78
79 private:
80 ShenandoahSharedFlag _gc_requested;
81 ShenandoahSharedFlag _alloc_failure_gc;
82 ShenandoahSharedFlag _graceful_shutdown;
83 ShenandoahSharedFlag _heap_changed;
84 ShenandoahSharedFlag _do_counters_update;
85 ShenandoahSharedFlag _force_counters_update;
86 GCCause::Cause _requested_gc_cause;
87 ShenandoahGC::ShenandoahDegenPoint _degen_point;
88
89 shenandoah_padding(0);
90 volatile size_t _allocs_seen;
91 shenandoah_padding(1);
92 volatile size_t _gc_id;
93 shenandoah_padding(2);
94
95 bool check_cancellation_or_degen(ShenandoahGC::ShenandoahDegenPoint point);
96 void service_concurrent_normal_cycle(GCCause::Cause cause);
97 void service_stw_full_cycle(GCCause::Cause cause);
98 void service_stw_degenerated_cycle(GCCause::Cause cause, ShenandoahGC::ShenandoahDegenPoint point);
99 void service_uncommit(double shrink_before, size_t shrink_until);
100
101 bool try_set_alloc_failure_gc();
102 void notify_alloc_failure_waiters();
103 bool is_alloc_failure_gc();
104
105 void reset_gc_id();
106 void update_gc_id();
107 size_t get_gc_id();
108
109 void notify_gc_waiters();
110
111 // Handle GC request.
112 // Blocks until GC is over.
113 void handle_requested_gc(GCCause::Cause cause);
114
115 bool is_explicit_gc(GCCause::Cause cause) const;
116
117 bool check_soft_max_changed() const;
118
119 public:
120 // Constructor
121 ShenandoahControlThread();
122 ~ShenandoahControlThread();
123
124 // Handle allocation failure from normal allocation.
125 // Blocks until memory is available.
126 void handle_alloc_failure(ShenandoahAllocRequest& req);
127
128 // Handle allocation failure from evacuation path.
129 // Optionally blocks while collector is handling the failure.
130 void handle_alloc_failure_evac(size_t words);
131
132 void request_gc(GCCause::Cause cause);
133
134 void handle_counters_update();
135 void handle_force_counters_update();
136 void set_forced_counters_update(bool value);
137
138 void notify_heap_changed();
139
140 void pacing_notify_alloc(size_t words);
141
142 void start();
143 void prepare_for_graceful_shutdown();
144 bool in_graceful_shutdown();
145 };
146
147 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHCONTROLTHREAD_HPP