Tue, 18 Mar 2014 19:07:22 +0100
8029075: String deduplication in G1
Summary: Implementation of JEP 192, http://openjdk.java.net/jeps/192
Reviewed-by: brutisso, tschatzl, coleenp
1 /*
2 * Copyright (c) 1997, 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
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23 */
25 #include "precompiled.hpp"
26 #include "compiler/compileBroker.hpp"
27 #include "gc_implementation/shared/gcTimer.hpp"
28 #include "gc_implementation/shared/gcTrace.hpp"
29 #include "gc_implementation/shared/markSweep.inline.hpp"
30 #include "gc_interface/collectedHeap.inline.hpp"
31 #include "oops/methodData.hpp"
32 #include "oops/objArrayKlass.inline.hpp"
33 #include "oops/oop.inline.hpp"
35 uint MarkSweep::_total_invocations = 0;
37 Stack<oop, mtGC> MarkSweep::_marking_stack;
38 Stack<ObjArrayTask, mtGC> MarkSweep::_objarray_stack;
40 Stack<oop, mtGC> MarkSweep::_preserved_oop_stack;
41 Stack<markOop, mtGC> MarkSweep::_preserved_mark_stack;
42 size_t MarkSweep::_preserved_count = 0;
43 size_t MarkSweep::_preserved_count_max = 0;
44 PreservedMark* MarkSweep::_preserved_marks = NULL;
45 ReferenceProcessor* MarkSweep::_ref_processor = NULL;
46 STWGCTimer* MarkSweep::_gc_timer = NULL;
47 SerialOldTracer* MarkSweep::_gc_tracer = NULL;
49 MarkSweep::FollowRootClosure MarkSweep::follow_root_closure;
50 CodeBlobToOopClosure MarkSweep::follow_code_root_closure(&MarkSweep::follow_root_closure, /*do_marking=*/ true);
52 void MarkSweep::FollowRootClosure::do_oop(oop* p) { follow_root(p); }
53 void MarkSweep::FollowRootClosure::do_oop(narrowOop* p) { follow_root(p); }
55 MarkSweep::MarkAndPushClosure MarkSweep::mark_and_push_closure;
56 MarkSweep::FollowKlassClosure MarkSweep::follow_klass_closure;
57 MarkSweep::AdjustKlassClosure MarkSweep::adjust_klass_closure;
59 void MarkSweep::MarkAndPushClosure::do_oop(oop* p) { mark_and_push(p); }
60 void MarkSweep::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(p); }
62 void MarkSweep::FollowKlassClosure::do_klass(Klass* klass) {
63 klass->oops_do(&MarkSweep::mark_and_push_closure);
64 }
65 void MarkSweep::AdjustKlassClosure::do_klass(Klass* klass) {
66 klass->oops_do(&MarkSweep::adjust_pointer_closure);
67 }
69 void MarkSweep::follow_class_loader(ClassLoaderData* cld) {
70 cld->oops_do(&MarkSweep::mark_and_push_closure, &MarkSweep::follow_klass_closure, true);
71 }
73 void MarkSweep::follow_stack() {
74 do {
75 while (!_marking_stack.is_empty()) {
76 oop obj = _marking_stack.pop();
77 assert (obj->is_gc_marked(), "p must be marked");
78 obj->follow_contents();
79 }
80 // Process ObjArrays one at a time to avoid marking stack bloat.
81 if (!_objarray_stack.is_empty()) {
82 ObjArrayTask task = _objarray_stack.pop();
83 ObjArrayKlass* k = (ObjArrayKlass*)task.obj()->klass();
84 k->oop_follow_contents(task.obj(), task.index());
85 }
86 } while (!_marking_stack.is_empty() || !_objarray_stack.is_empty());
87 }
89 MarkSweep::FollowStackClosure MarkSweep::follow_stack_closure;
91 void MarkSweep::FollowStackClosure::do_void() { follow_stack(); }
93 // We preserve the mark which should be replaced at the end and the location
94 // that it will go. Note that the object that this markOop belongs to isn't
95 // currently at that address but it will be after phase4
96 void MarkSweep::preserve_mark(oop obj, markOop mark) {
97 // We try to store preserved marks in the to space of the new generation since
98 // this is storage which should be available. Most of the time this should be
99 // sufficient space for the marks we need to preserve but if it isn't we fall
100 // back to using Stacks to keep track of the overflow.
101 if (_preserved_count < _preserved_count_max) {
102 _preserved_marks[_preserved_count++].init(obj, mark);
103 } else {
104 _preserved_mark_stack.push(mark);
105 _preserved_oop_stack.push(obj);
106 }
107 }
109 MarkSweep::AdjustPointerClosure MarkSweep::adjust_pointer_closure;
111 void MarkSweep::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p); }
112 void MarkSweep::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p); }
114 void MarkSweep::adjust_marks() {
115 assert( _preserved_oop_stack.size() == _preserved_mark_stack.size(),
116 "inconsistent preserved oop stacks");
118 // adjust the oops we saved earlier
119 for (size_t i = 0; i < _preserved_count; i++) {
120 _preserved_marks[i].adjust_pointer();
121 }
123 // deal with the overflow stack
124 StackIterator<oop, mtGC> iter(_preserved_oop_stack);
125 while (!iter.is_empty()) {
126 oop* p = iter.next_addr();
127 adjust_pointer(p);
128 }
129 }
131 void MarkSweep::restore_marks() {
132 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(),
133 "inconsistent preserved oop stacks");
134 if (PrintGC && Verbose) {
135 gclog_or_tty->print_cr("Restoring %d marks",
136 _preserved_count + _preserved_oop_stack.size());
137 }
139 // restore the marks we saved earlier
140 for (size_t i = 0; i < _preserved_count; i++) {
141 _preserved_marks[i].restore();
142 }
144 // deal with the overflow
145 while (!_preserved_oop_stack.is_empty()) {
146 oop obj = _preserved_oop_stack.pop();
147 markOop mark = _preserved_mark_stack.pop();
148 obj->set_mark(mark);
149 }
150 }
152 MarkSweep::IsAliveClosure MarkSweep::is_alive;
154 bool MarkSweep::IsAliveClosure::do_object_b(oop p) { return p->is_gc_marked(); }
156 MarkSweep::KeepAliveClosure MarkSweep::keep_alive;
158 void MarkSweep::KeepAliveClosure::do_oop(oop* p) { MarkSweep::KeepAliveClosure::do_oop_work(p); }
159 void MarkSweep::KeepAliveClosure::do_oop(narrowOop* p) { MarkSweep::KeepAliveClosure::do_oop_work(p); }
161 void marksweep_init() {
162 MarkSweep::_gc_timer = new (ResourceObj::C_HEAP, mtGC) STWGCTimer();
163 MarkSweep::_gc_tracer = new (ResourceObj::C_HEAP, mtGC) SerialOldTracer();
164 }
166 #ifndef PRODUCT
168 void MarkSweep::trace(const char* msg) {
169 if (TraceMarkSweep)
170 gclog_or_tty->print("%s", msg);
171 }
173 #endif