1 /*
2 * Copyright (c) 2001, 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/concurrentMarkThread.inline.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1Policy.hpp"
29 #include "gc/shared/gcId.hpp"
30 #include "gc/g1/vm_operations_g1.hpp"
31 #include "gc/shared/gcTimer.hpp"
32 #include "gc/shared/gcTraceTime.inline.hpp"
33 #include "gc/shared/isGCActiveMark.hpp"
34 #include "runtime/interfaceSupport.hpp"
35
36 VM_G1CollectForAllocation::VM_G1CollectForAllocation(uint gc_count_before,
37 size_t word_size)
38 : VM_G1OperationWithAllocRequest(gc_count_before, word_size,
39 GCCause::_allocation_failure) {
40 guarantee(word_size != 0, "An allocation should always be requested with this operation.");
41 }
42
43 void VM_G1CollectForAllocation::doit() {
44 G1CollectedHeap* g1h = G1CollectedHeap::heap();
45 GCCauseSetter x(g1h, _gc_cause);
46
47 _result = g1h->satisfy_failed_allocation(_word_size, allocation_context(), &_pause_succeeded);
48 assert(_result == NULL || _pause_succeeded,
49 "if we get back a result, the pause should have succeeded");
50 }
51
52 void VM_G1CollectFull::doit() {
53 G1CollectedHeap* g1h = G1CollectedHeap::heap();
54 GCCauseSetter x(g1h, _gc_cause);
55 g1h->do_full_collection(false /* clear_all_soft_refs */);
56 }
57
58 VM_G1IncCollectionPause::VM_G1IncCollectionPause(uint gc_count_before,
59 size_t word_size,
60 bool should_initiate_conc_mark,
61 double target_pause_time_ms,
62 GCCause::Cause gc_cause)
63 : VM_G1OperationWithAllocRequest(gc_count_before, word_size, gc_cause),
64 _should_initiate_conc_mark(should_initiate_conc_mark),
65 _target_pause_time_ms(target_pause_time_ms),
66 _should_retry_gc(false),
67 _old_marking_cycles_completed_before(0) {
68 guarantee(target_pause_time_ms > 0.0,
69 "target_pause_time_ms = %1.6lf should be positive",
70 target_pause_time_ms);
71 _gc_cause = gc_cause;
72 }
73
74 bool VM_G1IncCollectionPause::doit_prologue() {
75 bool res = VM_G1OperationWithAllocRequest::doit_prologue();
76 if (!res) {
77 if (_should_initiate_conc_mark) {
78 // The prologue can fail for a couple of reasons. The first is that another GC
79 // got scheduled and prevented the scheduling of the initial mark GC. The
80 // second is that the GC locker may be active and the heap can't be expanded.
81 // In both cases we want to retry the GC so that the initial mark pause is
82 // actually scheduled. In the second case, however, we should stall until
83 // until the GC locker is no longer active and then retry the initial mark GC.
84 _should_retry_gc = true;
85 }
86 }
87 return res;
88 }
89
90 void VM_G1IncCollectionPause::doit() {
91 G1CollectedHeap* g1h = G1CollectedHeap::heap();
92 assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause),
93 "only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle");
94
95 if (_word_size > 0) {
96 // An allocation has been requested. So, try to do that first.
97 _result = g1h->attempt_allocation_at_safepoint(_word_size,
98 allocation_context(),
99 false /* expect_null_cur_alloc_region */);
100 if (_result != NULL) {
101 // If we can successfully allocate before we actually do the
102 // pause then we will consider this pause successful.
103 _pause_succeeded = true;
104 return;
105 }
106 }
107
108 GCCauseSetter x(g1h, _gc_cause);
109 if (_should_initiate_conc_mark) {
110 // It's safer to read old_marking_cycles_completed() here, given
111 // that noone else will be updating it concurrently. Since we'll
112 // only need it if we're initiating a marking cycle, no point in
113 // setting it earlier.
114 _old_marking_cycles_completed_before = g1h->old_marking_cycles_completed();
115
116 // At this point we are supposed to start a concurrent cycle. We
117 // will do so if one is not already in progress.
118 bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
127 // doit_epilogue() until the marking cycle is complete.
128 //
129 // If this initial mark pause was requested as part of a humongous
130 // allocation then we know that the marking cycle must just have
131 // been started by another thread (possibly also allocating a humongous
132 // object) as there was no active marking cycle when the requesting
133 // thread checked before calling collect() in
134 // attempt_allocation_humongous(). Retrying the GC, in this case,
135 // will cause the requesting thread to spin inside collect() until the
136 // just started marking cycle is complete - which may be a while. So
137 // we do NOT retry the GC.
138 if (!res) {
139 assert(_word_size == 0, "Concurrent Full GC/Humongous Object IM shouldn't be allocating");
140 if (_gc_cause != GCCause::_g1_humongous_allocation) {
141 _should_retry_gc = true;
142 }
143 return;
144 }
145 }
146
147 _pause_succeeded =
148 g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
149 if (_pause_succeeded && _word_size > 0) {
150 // An allocation had been requested.
151 _result = g1h->attempt_allocation_at_safepoint(_word_size,
152 allocation_context(),
153 true /* expect_null_cur_alloc_region */);
154 } else {
155 assert(_result == NULL, "invariant");
156 if (!_pause_succeeded) {
157 // Another possible reason reason for the pause to not be successful
158 // is that, again, the GC locker is active (and has become active
159 // since the prologue was executed). In this case we should retry
160 // the pause after waiting for the GC locker to become inactive.
161 _should_retry_gc = true;
162 }
163 }
164 }
165
166 void VM_G1IncCollectionPause::doit_epilogue() {
167 VM_G1OperationWithAllocRequest::doit_epilogue();
168
169 // If the pause was initiated by a System.gc() and
170 // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
171 // that just started (or maybe one that was already in progress) to
172 // finish.
173 if (GCCause::is_user_requested_gc(_gc_cause) &&
174 _should_initiate_conc_mark) {
175 assert(ExplicitGCInvokesConcurrent,
176 "the only way to be here is if ExplicitGCInvokesConcurrent is set");
177
178 G1CollectedHeap* g1h = G1CollectedHeap::heap();
179
180 // In the doit() method we saved g1h->old_marking_cycles_completed()
181 // in the _old_marking_cycles_completed_before field. We have to
182 // wait until we observe that g1h->old_marking_cycles_completed()
183 // has increased by at least one. This can happen if a) we started
184 // a cycle and it completes, b) a cycle already in progress
185 // completes, or c) a Full GC happens.
186
187 // If the condition has already been reached, there's no point in
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1 /*
2 * Copyright (c) 2001, 2018, 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/concurrentMarkThread.inline.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1Policy.hpp"
29 #include "gc/shared/gcId.hpp"
30 #include "gc/g1/vm_operations_g1.hpp"
31 #include "gc/shared/gcTimer.hpp"
32 #include "gc/shared/gcTraceTime.inline.hpp"
33 #include "gc/shared/isGCActiveMark.hpp"
34 #include "runtime/interfaceSupport.hpp"
35
36 void VM_G1CollectFull::doit() {
37 G1CollectedHeap* g1h = G1CollectedHeap::heap();
38 GCCauseSetter x(g1h, _gc_cause);
39 g1h->do_full_collection(false /* clear_all_soft_refs */);
40 }
41
42 VM_G1CollectForAllocation::VM_G1CollectForAllocation(size_t word_size,
43 uint gc_count_before,
44 GCCause::Cause gc_cause,
45 bool should_initiate_conc_mark,
46 double target_pause_time_ms,
47 AllocationContext_t allocation_context)
48 : VM_CollectForAllocation(word_size, gc_count_before, gc_cause),
49 _pause_succeeded(false),
50 _allocation_context(allocation_context),
51 _should_initiate_conc_mark(should_initiate_conc_mark),
52 _target_pause_time_ms(target_pause_time_ms),
53 _should_retry_gc(false),
54 _old_marking_cycles_completed_before(0) {
55 guarantee(target_pause_time_ms > 0.0,
56 "target_pause_time_ms = %1.6lf should be positive",
57 target_pause_time_ms);
58 _gc_cause = gc_cause;
59 }
60
61 bool VM_G1CollectForAllocation::doit_prologue() {
62 bool res = VM_CollectForAllocation::doit_prologue();
63 if (!res) {
64 if (_should_initiate_conc_mark) {
65 // The prologue can fail for a couple of reasons. The first is that another GC
66 // got scheduled and prevented the scheduling of the initial mark GC. The
67 // second is that the GC locker may be active and the heap can't be expanded.
68 // In both cases we want to retry the GC so that the initial mark pause is
69 // actually scheduled. In the second case, however, we should stall until
70 // until the GC locker is no longer active and then retry the initial mark GC.
71 _should_retry_gc = true;
72 }
73 }
74 return res;
75 }
76
77 void VM_G1CollectForAllocation::doit() {
78 G1CollectedHeap* g1h = G1CollectedHeap::heap();
79 assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause),
80 "only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle");
81
82 if (_word_size > 0) {
83 // An allocation has been requested. So, try to do that first.
84 _result = g1h->attempt_allocation_at_safepoint(_word_size,
85 _allocation_context,
86 false /* expect_null_cur_alloc_region */);
87 if (_result != NULL) {
88 // If we can successfully allocate before we actually do the
89 // pause then we will consider this pause successful.
90 _pause_succeeded = true;
91 return;
92 }
93 }
94
95 GCCauseSetter x(g1h, _gc_cause);
96 if (_should_initiate_conc_mark) {
97 // It's safer to read old_marking_cycles_completed() here, given
98 // that noone else will be updating it concurrently. Since we'll
99 // only need it if we're initiating a marking cycle, no point in
100 // setting it earlier.
101 _old_marking_cycles_completed_before = g1h->old_marking_cycles_completed();
102
103 // At this point we are supposed to start a concurrent cycle. We
104 // will do so if one is not already in progress.
105 bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
114 // doit_epilogue() until the marking cycle is complete.
115 //
116 // If this initial mark pause was requested as part of a humongous
117 // allocation then we know that the marking cycle must just have
118 // been started by another thread (possibly also allocating a humongous
119 // object) as there was no active marking cycle when the requesting
120 // thread checked before calling collect() in
121 // attempt_allocation_humongous(). Retrying the GC, in this case,
122 // will cause the requesting thread to spin inside collect() until the
123 // just started marking cycle is complete - which may be a while. So
124 // we do NOT retry the GC.
125 if (!res) {
126 assert(_word_size == 0, "Concurrent Full GC/Humongous Object IM shouldn't be allocating");
127 if (_gc_cause != GCCause::_g1_humongous_allocation) {
128 _should_retry_gc = true;
129 }
130 return;
131 }
132 }
133
134 // Try a partial collection of some kind.
135 _pause_succeeded = g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
136
137 if (_pause_succeeded) {
138 if (_word_size > 0) {
139 // An allocation had been requested. Do it, eventually trying a stronger
140 // kind of GC.
141 _result = g1h->satisfy_failed_allocation(_word_size, _allocation_context, &_pause_succeeded);
142 } else if (!g1h->has_regions_left_for_allocation()) {
143 // There has been a request to perform a GC to free some space. We have no
144 // information on how much memory has been asked for. In case there are
145 // absolutely no regions left to allocate into, do a maximally compacting full GC.
146 log_info(gc, ergo)("Attempting maximally compacting collection");
147 _pause_succeeded = g1h->do_full_collection(false, /* explicit gc */
148 true /* clear_all_soft_refs */);
149 }
150 guarantee(_pause_succeeded, "Elevated collections during the safepoint must always succeed.");
151 } else {
152 assert(_result == NULL, "invariant");
153 // The only reason for the pause to not be successful is that, the GC locker is
154 // active (or has become active since the prologue was executed). In this case
155 // we should retry the pause after waiting for the GC locker to become inactive.
156 _should_retry_gc = true;
157 }
158 }
159
160 void VM_G1CollectForAllocation::doit_epilogue() {
161 VM_CollectForAllocation::doit_epilogue();
162
163 // If the pause was initiated by a System.gc() and
164 // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
165 // that just started (or maybe one that was already in progress) to
166 // finish.
167 if (GCCause::is_user_requested_gc(_gc_cause) &&
168 _should_initiate_conc_mark) {
169 assert(ExplicitGCInvokesConcurrent,
170 "the only way to be here is if ExplicitGCInvokesConcurrent is set");
171
172 G1CollectedHeap* g1h = G1CollectedHeap::heap();
173
174 // In the doit() method we saved g1h->old_marking_cycles_completed()
175 // in the _old_marking_cycles_completed_before field. We have to
176 // wait until we observe that g1h->old_marking_cycles_completed()
177 // has increased by at least one. This can happen if a) we started
178 // a cycle and it completes, b) a cycle already in progress
179 // completes, or c) a Full GC happens.
180
181 // If the condition has already been reached, there's no point in
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