Thu, 03 Feb 2011 20:49:09 -0800
7015169: GC Cause not always set
Summary: Sometimes the gc cause was not always set. This caused JStat to print the wrong information.
Reviewed-by: tonyp, ysr
Contributed-by: suenaga.yasumasa@oss.ntt.co.jp
1 /*
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23 */
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "gc_implementation/shared/vmGCOperations.hpp"
29 #include "memory/gcLocker.inline.hpp"
30 #include "memory/genCollectedHeap.hpp"
31 #include "memory/oopFactory.hpp"
32 #include "oops/instanceKlass.hpp"
33 #include "oops/instanceRefKlass.hpp"
34 #include "runtime/handles.inline.hpp"
35 #include "runtime/init.hpp"
36 #include "runtime/interfaceSupport.hpp"
37 #include "utilities/dtrace.hpp"
38 #include "utilities/preserveException.hpp"
39 #ifndef SERIALGC
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #endif
43 HS_DTRACE_PROBE_DECL1(hotspot, gc__begin, bool);
44 HS_DTRACE_PROBE_DECL(hotspot, gc__end);
46 // The same dtrace probe can't be inserted in two different files, so we
47 // have to call it here, so it's only in one file. Can't create new probes
48 // for the other file anymore. The dtrace probes have to remain stable.
49 void VM_GC_Operation::notify_gc_begin(bool full) {
50 HS_DTRACE_PROBE1(hotspot, gc__begin, full);
51 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
52 }
54 void VM_GC_Operation::notify_gc_end() {
55 HS_DTRACE_PROBE(hotspot, gc__end);
56 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
57 }
59 void VM_GC_Operation::acquire_pending_list_lock() {
60 // we may enter this with pending exception set
61 instanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);
62 }
65 void VM_GC_Operation::release_and_notify_pending_list_lock() {
67 instanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);
68 }
70 // Allocations may fail in several threads at about the same time,
71 // resulting in multiple gc requests. We only want to do one of them.
72 // In case a GC locker is active and the need for a GC is already signalled,
73 // we want to skip this GC attempt altogether, without doing a futile
74 // safepoint operation.
75 bool VM_GC_Operation::skip_operation() const {
76 bool skip = (_gc_count_before != Universe::heap()->total_collections());
77 if (_full && skip) {
78 skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
79 }
80 if (!skip && GC_locker::is_active_and_needs_gc()) {
81 skip = Universe::heap()->is_maximal_no_gc();
82 assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
83 "GC_locker cannot be active when initiating GC");
84 }
85 return skip;
86 }
88 bool VM_GC_Operation::doit_prologue() {
89 assert(Thread::current()->is_Java_thread(), "just checking");
90 assert(((_gc_cause != GCCause::_no_gc) &&
91 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause");
93 acquire_pending_list_lock();
94 // If the GC count has changed someone beat us to the collection
95 // Get the Heap_lock after the pending_list_lock.
96 Heap_lock->lock();
98 // Check invocations
99 if (skip_operation()) {
100 // skip collection
101 Heap_lock->unlock();
102 release_and_notify_pending_list_lock();
103 _prologue_succeeded = false;
104 } else {
105 _prologue_succeeded = true;
106 SharedHeap* sh = SharedHeap::heap();
107 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true;
108 }
109 return _prologue_succeeded;
110 }
113 void VM_GC_Operation::doit_epilogue() {
114 assert(Thread::current()->is_Java_thread(), "just checking");
115 // Release the Heap_lock first.
116 SharedHeap* sh = SharedHeap::heap();
117 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false;
118 Heap_lock->unlock();
119 release_and_notify_pending_list_lock();
120 }
122 bool VM_GC_HeapInspection::doit_prologue() {
123 if (Universe::heap()->supports_heap_inspection()) {
124 return VM_GC_Operation::doit_prologue();
125 } else {
126 return false;
127 }
128 }
130 bool VM_GC_HeapInspection::skip_operation() const {
131 assert(Universe::heap()->supports_heap_inspection(), "huh?");
132 return false;
133 }
135 void VM_GC_HeapInspection::doit() {
136 HandleMark hm;
137 CollectedHeap* ch = Universe::heap();
138 ch->ensure_parsability(false); // must happen, even if collection does
139 // not happen (e.g. due to GC_locker)
140 if (_full_gc) {
141 // The collection attempt below would be skipped anyway if
142 // the gc locker is held. The following dump may then be a tad
143 // misleading to someone expecting only live objects to show
144 // up in the dump (see CR 6944195). Just issue a suitable warning
145 // in that case and do not attempt to do a collection.
146 // The latter is a subtle point, because even a failed attempt
147 // to GC will, in fact, induce one in the future, which we
148 // probably want to avoid in this case because the GC that we may
149 // be about to attempt holds value for us only
150 // if it happens now and not if it happens in the eventual
151 // future.
152 if (GC_locker::is_active()) {
153 warning("GC locker is held; pre-dump GC was skipped");
154 } else {
155 ch->collect_as_vm_thread(GCCause::_heap_inspection);
156 }
157 }
158 HeapInspection::heap_inspection(_out, _need_prologue /* need_prologue */);
159 }
162 void VM_GenCollectForAllocation::doit() {
163 SvcGCMarker sgcm(SvcGCMarker::MINOR);
165 GenCollectedHeap* gch = GenCollectedHeap::heap();
166 GCCauseSetter gccs(gch, _gc_cause);
167 _res = gch->satisfy_failed_allocation(_size, _tlab);
168 assert(gch->is_in_reserved_or_null(_res), "result not in heap");
170 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
171 set_gc_locked();
172 }
173 }
175 void VM_GenCollectFull::doit() {
176 SvcGCMarker sgcm(SvcGCMarker::FULL);
178 GenCollectedHeap* gch = GenCollectedHeap::heap();
179 GCCauseSetter gccs(gch, _gc_cause);
180 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);
181 }
183 void VM_GenCollectForPermanentAllocation::doit() {
184 SvcGCMarker sgcm(SvcGCMarker::FULL);
186 SharedHeap* heap = (SharedHeap*)Universe::heap();
187 GCCauseSetter gccs(heap, _gc_cause);
188 switch (heap->kind()) {
189 case (CollectedHeap::GenCollectedHeap): {
190 GenCollectedHeap* gch = (GenCollectedHeap*)heap;
191 gch->do_full_collection(gch->must_clear_all_soft_refs(),
192 gch->n_gens() - 1);
193 break;
194 }
195 #ifndef SERIALGC
196 case (CollectedHeap::G1CollectedHeap): {
197 G1CollectedHeap* g1h = (G1CollectedHeap*)heap;
198 g1h->do_full_collection(_gc_cause == GCCause::_last_ditch_collection);
199 break;
200 }
201 #endif // SERIALGC
202 default:
203 ShouldNotReachHere();
204 }
205 _res = heap->perm_gen()->allocate(_size, false);
206 assert(heap->is_in_reserved_or_null(_res), "result not in heap");
207 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
208 set_gc_locked();
209 }
210 }