1 /*
2 * Copyright (c) 2005, 2013, 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 "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 #include "utilities/macros.hpp"
40 #if INCLUDE_ALL_GCS
41 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
42 #endif // INCLUDE_ALL_GCS
43
44 #ifndef USDT2
45 HS_DTRACE_PROBE_DECL1(hotspot, gc__begin, bool);
46 HS_DTRACE_PROBE_DECL(hotspot, gc__end);
47 #endif /* !USDT2 */
48
49 // The same dtrace probe can't be inserted in two different files, so we
50 // have to call it here, so it's only in one file. Can't create new probes
51 // for the other file anymore. The dtrace probes have to remain stable.
52 void VM_GC_Operation::notify_gc_begin(bool full) {
53 #ifndef USDT2
54 HS_DTRACE_PROBE1(hotspot, gc__begin, full);
55 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
56 #else /* USDT2 */
57 HOTSPOT_GC_BEGIN(
58 full);
59 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
60 #endif /* USDT2 */
61 }
62
63 void VM_GC_Operation::notify_gc_end() {
64 #ifndef USDT2
65 HS_DTRACE_PROBE(hotspot, gc__end);
66 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
67 #else /* USDT2 */
68 HOTSPOT_GC_END();
69 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
70 #endif /* USDT2 */
71 }
72
73 void VM_GC_Operation::acquire_pending_list_lock() {
74 // we may enter this with pending exception set
75 InstanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);
76 }
77
78
79 void VM_GC_Operation::release_and_notify_pending_list_lock() {
80
81 InstanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);
82 }
83
84 // Allocations may fail in several threads at about the same time,
85 // resulting in multiple gc requests. We only want to do one of them.
86 // In case a GC locker is active and the need for a GC is already signaled,
87 // we want to skip this GC attempt altogether, without doing a futile
88 // safepoint operation.
89 bool VM_GC_Operation::skip_operation() const {
90 bool skip = (_gc_count_before != Universe::heap()->total_collections());
91 if (_full && skip) {
92 skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
93 }
94 if (!skip && GC_locker::is_active_and_needs_gc()) {
95 skip = Universe::heap()->is_maximal_no_gc();
96 assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
97 "GC_locker cannot be active when initiating GC");
98 }
99 return skip;
100 }
101
102 bool VM_GC_Operation::doit_prologue() {
103 assert(Thread::current()->is_Java_thread(), "just checking");
104 assert(((_gc_cause != GCCause::_no_gc) &&
105 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause");
106
107 // To be able to handle a GC the VM initialization needs to be completed.
108 if (!is_init_completed()) {
109 vm_exit_during_initialization(
110 err_msg("GC triggered before VM initialization completed. Try increasing "
111 "NewSize, current value " UINTX_FORMAT "K.", NewSize / K));
112 }
113
114 acquire_pending_list_lock();
115 // If the GC count has changed someone beat us to the collection
116 // Get the Heap_lock after the pending_list_lock.
117 Heap_lock->lock();
118
119 // Check invocations
120 if (skip_operation()) {
121 // skip collection
122 Heap_lock->unlock();
123 release_and_notify_pending_list_lock();
124 _prologue_succeeded = false;
125 } else {
126 _prologue_succeeded = true;
127 SharedHeap* sh = SharedHeap::heap();
128 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true;
129 }
130 return _prologue_succeeded;
131 }
132
133
134 void VM_GC_Operation::doit_epilogue() {
135 assert(Thread::current()->is_Java_thread(), "just checking");
136 // Release the Heap_lock first.
137 SharedHeap* sh = SharedHeap::heap();
138 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false;
139 Heap_lock->unlock();
140 release_and_notify_pending_list_lock();
141 }
142
143 bool VM_GC_HeapInspection::doit_prologue() {
144 if (Universe::heap()->supports_heap_inspection()) {
145 return VM_GC_Operation::doit_prologue();
146 } else {
147 return false;
148 }
149 }
150
151 bool VM_GC_HeapInspection::skip_operation() const {
152 assert(Universe::heap()->supports_heap_inspection(), "huh?");
153 return false;
154 }
155
156 bool VM_GC_HeapInspection::collect() {
157 if (GC_locker::is_active()) {
158 return false;
159 }
160 Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection);
161 return true;
162 }
163
164 void VM_GC_HeapInspection::doit() {
165 HandleMark hm;
166 Universe::heap()->ensure_parsability(false); // must happen, even if collection does
167 // not happen (e.g. due to GC_locker)
168 // or _full_gc being false
169 if (_full_gc) {
170 if (!collect()) {
171 // The collection attempt was skipped because the gc locker is held.
172 // The following dump may then be a tad misleading to someone expecting
173 // only live objects to show up in the dump (see CR 6944195). Just issue
174 // a suitable warning in that case and do not attempt to do a collection.
175 // The latter is a subtle point, because even a failed attempt
176 // to GC will, in fact, induce one in the future, which we
177 // probably want to avoid in this case because the GC that we may
178 // be about to attempt holds value for us only
179 // if it happens now and not if it happens in the eventual
180 // future.
181 warning("GC locker is held; pre-dump GC was skipped");
182 }
183 }
184 HeapInspection inspect(_csv_format, _print_help, _print_class_stats,
185 _columns);
186 inspect.heap_inspection(_out);
187 }
188
189
190 void VM_GenCollectForAllocation::doit() {
191 SvcGCMarker sgcm(SvcGCMarker::MINOR);
192
193 GenCollectedHeap* gch = GenCollectedHeap::heap();
194 GCCauseSetter gccs(gch, _gc_cause);
195 _res = gch->satisfy_failed_allocation(_size, _tlab);
196 assert(gch->is_in_reserved_or_null(_res), "result not in heap");
197
198 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
199 set_gc_locked();
200 }
201 }
202
203 void VM_GenCollectFull::doit() {
204 SvcGCMarker sgcm(SvcGCMarker::FULL);
205
206 GenCollectedHeap* gch = GenCollectedHeap::heap();
207 GCCauseSetter gccs(gch, _gc_cause);
208 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);
209 }
210
211 void VM_CollectForMetadataAllocation::doit() {
212 SvcGCMarker sgcm(SvcGCMarker::FULL);
213
214 CollectedHeap* heap = Universe::heap();
215 GCCauseSetter gccs(heap, _gc_cause);
216
217 // Check again if the space is available. Another thread
218 // may have similarly failed a metadata allocation and induced
219 // a GC that freed space for the allocation.
220 if (!MetadataAllocationFailALot) {
221 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
222 }
223
224 if (_result == NULL) {
225 if (UseConcMarkSweepGC) {
226 if (CMSClassUnloadingEnabled) {
227 MetaspaceGC::set_should_concurrent_collect(true);
228 }
229 // For CMS expand since the collection is going to be concurrent.
230 _result =
231 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
232 }
233 if (_result == NULL) {
234 // Don't clear the soft refs yet.
235 if (Verbose && PrintGCDetails && UseConcMarkSweepGC) {
236 gclog_or_tty->print_cr("\nCMS full GC for Metaspace");
237 }
238 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold);
239 // After a GC try to allocate without expanding. Could fail
240 // and expansion will be tried below.
241 _result =
242 _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
243 }
244 if (_result == NULL) {
245 // If still failing, allow the Metaspace to expand.
246 // See delta_capacity_until_GC() for explanation of the
247 // amount of the expansion.
248 // This should work unless there really is no more space
249 // or a MaxMetaspaceSize has been specified on the command line.
250 _result =
251 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
252 if (_result == NULL) {
253 // If expansion failed, do a last-ditch collection and try allocating
254 // again. A last-ditch collection will clear softrefs. This
255 // behavior is similar to the last-ditch collection done for perm
256 // gen when it was full and a collection for failed allocation
257 // did not free perm gen space.
258 heap->collect_as_vm_thread(GCCause::_last_ditch_collection);
259 _result =
260 _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
261 }
262 }
263 if (Verbose && PrintGCDetails && _result == NULL) {
264 gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size "
265 SIZE_FORMAT, _size);
266 }
267 }
268
269 if (_result == NULL && GC_locker::is_active_and_needs_gc()) {
270 set_gc_locked();
271 }
272 }