Mon, 07 Jul 2014 10:12:40 +0200
8049421: G1 Class Unloading after completing a concurrent mark cycle
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
Contributed-by: stefan.karlsson@oracle.com, mikael.gerdin@oracle.com
1 /*
2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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23 */
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "code/codeCache.hpp"
28 #include "compiler/compileBroker.hpp"
29 #include "oops/metadata.hpp"
30 #include "prims/jvmtiImpl.hpp"
31 #include "runtime/synchronizer.hpp"
32 #include "runtime/thread.hpp"
33 #include "services/threadService.hpp"
34 #include "utilities/growableArray.hpp"
37 // Keep track of marked on-stack metadata so it can be cleared.
38 GrowableArray<Metadata*>* _marked_objects = NULL;
39 NOT_PRODUCT(bool MetadataOnStackMark::_is_active = false;)
41 // Walk metadata on the stack and mark it so that redefinition doesn't delete
42 // it. Class unloading also walks the previous versions and might try to
43 // delete it, so this class is used by class unloading also.
44 MetadataOnStackMark::MetadataOnStackMark() {
45 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
46 NOT_PRODUCT(_is_active = true;)
47 if (_marked_objects == NULL) {
48 _marked_objects = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(1000, true);
49 }
51 Threads::metadata_do(Metadata::mark_on_stack);
52 if (JvmtiExport::has_redefined_a_class()) {
53 CodeCache::alive_nmethods_do(nmethod::mark_on_stack);
54 }
55 CompileBroker::mark_on_stack();
56 JvmtiCurrentBreakpoints::metadata_do(Metadata::mark_on_stack);
57 ThreadService::metadata_do(Metadata::mark_on_stack);
58 }
60 MetadataOnStackMark::~MetadataOnStackMark() {
61 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
62 // Unmark everything that was marked. Can't do the same walk because
63 // redefine classes messes up the code cache so the set of methods
64 // might not be the same.
65 for (int i = 0; i< _marked_objects->length(); i++) {
66 _marked_objects->at(i)->set_on_stack(false);
67 }
68 _marked_objects->clear(); // reuse growable array for next time.
69 NOT_PRODUCT(_is_active = false;)
70 }
72 // Record which objects are marked so we can unmark the same objects.
73 void MetadataOnStackMark::record(Metadata* m) {
74 assert(_is_active, "metadata on stack marking is active");
75 _marked_objects->push(m);
76 }