56 g1h->do_full_collection(false /* clear_all_soft_refs */);
57 }
58
59 VM_G1IncCollectionPause::VM_G1IncCollectionPause(uint gc_count_before,
60 size_t word_size,
61 bool should_initiate_conc_mark,
62 double target_pause_time_ms,
63 GCCause::Cause gc_cause)
64 : VM_G1OperationWithAllocRequest(gc_count_before, word_size, gc_cause),
65 _should_initiate_conc_mark(should_initiate_conc_mark),
66 _target_pause_time_ms(target_pause_time_ms),
67 _should_retry_gc(false),
68 _old_marking_cycles_completed_before(0) {
69 guarantee(target_pause_time_ms > 0.0,
70 err_msg("target_pause_time_ms = %1.6lf should be positive",
71 target_pause_time_ms));
72 _gc_cause = gc_cause;
73 }
74
75 bool VM_G1IncCollectionPause::doit_prologue() {
76 bool res = VM_GC_Operation::doit_prologue();
77 if (!res) {
78 if (_should_initiate_conc_mark) {
79 // The prologue can fail for a couple of reasons. The first is that another GC
80 // got scheduled and prevented the scheduling of the initial mark GC. The
81 // second is that the GC locker may be active and the heap can't be expanded.
82 // In both cases we want to retry the GC so that the initial mark pause is
83 // actually scheduled. In the second case, however, we should stall until
84 // until the GC locker is no longer active and then retry the initial mark GC.
85 _should_retry_gc = true;
86 }
87 }
88 return res;
89 }
90
91 void VM_G1IncCollectionPause::doit() {
92 G1CollectedHeap* g1h = G1CollectedHeap::heap();
93 assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause),
94 "only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle");
95
96 if (_word_size > 0) {
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, allocation_context(),
152 true /* expect_null_cur_alloc_region */);
153 } else {
154 assert(_result == NULL, "invariant");
155 if (!_pause_succeeded) {
156 // Another possible reason reason for the pause to not be successful
157 // is that, again, the GC locker is active (and has become active
158 // since the prologue was executed). In this case we should retry
159 // the pause after waiting for the GC locker to become inactive.
160 _should_retry_gc = true;
161 }
162 }
163 }
164
165 void VM_G1IncCollectionPause::doit_epilogue() {
166 VM_GC_Operation::doit_epilogue();
167
168 // If the pause was initiated by a System.gc() and
169 // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
170 // that just started (or maybe one that was already in progress) to
171 // finish.
172 if (_gc_cause == GCCause::_java_lang_system_gc &&
173 _should_initiate_conc_mark) {
174 assert(ExplicitGCInvokesConcurrent,
175 "the only way to be here is if ExplicitGCInvokesConcurrent is set");
176
177 G1CollectedHeap* g1h = G1CollectedHeap::heap();
178
179 // In the doit() method we saved g1h->old_marking_cycles_completed()
180 // in the _old_marking_cycles_completed_before field. We have to
181 // wait until we observe that g1h->old_marking_cycles_completed()
182 // has increased by at least one. This can happen if a) we started
183 // a cycle and it completes, b) a cycle already in progress
184 // completes, or c) a Full GC happens.
185
186 // If the condition has already been reached, there's no point in
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56 g1h->do_full_collection(false /* clear_all_soft_refs */);
57 }
58
59 VM_G1IncCollectionPause::VM_G1IncCollectionPause(uint gc_count_before,
60 size_t word_size,
61 bool should_initiate_conc_mark,
62 double target_pause_time_ms,
63 GCCause::Cause gc_cause)
64 : VM_G1OperationWithAllocRequest(gc_count_before, word_size, gc_cause),
65 _should_initiate_conc_mark(should_initiate_conc_mark),
66 _target_pause_time_ms(target_pause_time_ms),
67 _should_retry_gc(false),
68 _old_marking_cycles_completed_before(0) {
69 guarantee(target_pause_time_ms > 0.0,
70 err_msg("target_pause_time_ms = %1.6lf should be positive",
71 target_pause_time_ms));
72 _gc_cause = gc_cause;
73 }
74
75 bool VM_G1IncCollectionPause::doit_prologue() {
76 bool res = VM_G1OperationWithAllocRequest::doit_prologue();
77 if (!res) {
78 if (_should_initiate_conc_mark) {
79 // The prologue can fail for a couple of reasons. The first is that another GC
80 // got scheduled and prevented the scheduling of the initial mark GC. The
81 // second is that the GC locker may be active and the heap can't be expanded.
82 // In both cases we want to retry the GC so that the initial mark pause is
83 // actually scheduled. In the second case, however, we should stall until
84 // until the GC locker is no longer active and then retry the initial mark GC.
85 _should_retry_gc = true;
86 }
87 }
88 return res;
89 }
90
91 void VM_G1IncCollectionPause::doit() {
92 G1CollectedHeap* g1h = G1CollectedHeap::heap();
93 assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause),
94 "only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle");
95
96 if (_word_size > 0) {
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, allocation_context(),
152 true /* expect_null_cur_alloc_region */);
153 } else {
154 assert(_result == NULL, "invariant");
155 if (!_pause_succeeded) {
156 // Another possible reason reason for the pause to not be successful
157 // is that, again, the GC locker is active (and has become active
158 // since the prologue was executed). In this case we should retry
159 // the pause after waiting for the GC locker to become inactive.
160 _should_retry_gc = true;
161 }
162 }
163 }
164
165 void VM_G1IncCollectionPause::doit_epilogue() {
166 VM_G1OperationWithAllocRequest::doit_epilogue();
167
168 // If the pause was initiated by a System.gc() and
169 // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
170 // that just started (or maybe one that was already in progress) to
171 // finish.
172 if (_gc_cause == GCCause::_java_lang_system_gc &&
173 _should_initiate_conc_mark) {
174 assert(ExplicitGCInvokesConcurrent,
175 "the only way to be here is if ExplicitGCInvokesConcurrent is set");
176
177 G1CollectedHeap* g1h = G1CollectedHeap::heap();
178
179 // In the doit() method we saved g1h->old_marking_cycles_completed()
180 // in the _old_marking_cycles_completed_before field. We have to
181 // wait until we observe that g1h->old_marking_cycles_completed()
182 // has increased by at least one. This can happen if a) we started
183 // a cycle and it completes, b) a cycle already in progress
184 // completes, or c) a Full GC happens.
185
186 // If the condition has already been reached, there's no point in
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