1 /*
2 * Copyright (c) 2019, 2021, Red Hat, Inc. 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
27 #include "classfile/classLoaderDataGraph.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "code/codeBehaviours.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/dependencyContext.hpp"
32 #include "gc/shared/gcBehaviours.hpp"
33 #include "gc/shared/suspendibleThreadSet.hpp"
34 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
35 #include "gc/shenandoah/shenandoahLock.hpp"
36 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
37 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
38 #include "gc/shenandoah/shenandoahUnload.hpp"
39 #include "gc/shenandoah/shenandoahVerifier.hpp"
40 #include "memory/iterator.hpp"
41 #include "memory/metaspaceUtils.hpp"
42 #include "memory/resourceArea.hpp"
43 #include "oops/access.inline.hpp"
44
45 class ShenandoahIsUnloadingOopClosure : public OopClosure {
46 private:
47 ShenandoahMarkingContext* const _marking_context;
48 bool _is_unloading;
49
50 public:
51 ShenandoahIsUnloadingOopClosure() :
52 _marking_context(ShenandoahHeap::heap()->complete_marking_context()),
53 _is_unloading(false) {
54 }
55
56 virtual void do_oop(oop* p) {
57 if (_is_unloading) {
58 return;
59 }
60
61 const oop o = RawAccess<>::oop_load(p);
62 if (!CompressedOops::is_null(o) &&
63 !_marking_context->is_marked(o)) {
64 _is_unloading = true;
65 }
66 }
67
68 virtual void do_oop(narrowOop* p) {
69 ShouldNotReachHere();
70 }
71
72 bool is_unloading() const {
73 return _is_unloading;
74 }
75 };
76
77 class ShenandoahIsUnloadingBehaviour : public IsUnloadingBehaviour {
78 public:
79 virtual bool has_dead_oop(CompiledMethod* method) const {
80 nmethod* const nm = method->as_nmethod();
81 assert(ShenandoahHeap::heap()->is_concurrent_weak_root_in_progress(), "Only for this phase");
82 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
83 ShenandoahReentrantLocker locker(data->lock());
84 ShenandoahIsUnloadingOopClosure cl;
85 data->oops_do(&cl);
86 return cl.is_unloading();
87 }
88 };
89
90 class ShenandoahCompiledICProtectionBehaviour : public CompiledICProtectionBehaviour {
91 public:
92 virtual bool lock(CompiledMethod* method) {
93 nmethod* const nm = method->as_nmethod();
94 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
95 assert(lock != nullptr, "Not yet registered?");
96 lock->lock();
97 return true;
98 }
99
100 virtual void unlock(CompiledMethod* method) {
101 nmethod* const nm = method->as_nmethod();
102 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
103 assert(lock != nullptr, "Not yet registered?");
104 lock->unlock();
105 }
106
107 virtual bool is_safe(CompiledMethod* method) {
108 if (SafepointSynchronize::is_at_safepoint()) {
109 return true;
110 }
111
112 nmethod* const nm = method->as_nmethod();
113 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
114 assert(lock != nullptr, "Not yet registered?");
115 return lock->owned_by_self();
116 }
117 };
118
119 ShenandoahUnload::ShenandoahUnload() {
120 if (ClassUnloading) {
121 static ShenandoahIsUnloadingBehaviour is_unloading_behaviour;
122 IsUnloadingBehaviour::set_current(&is_unloading_behaviour);
123
124 static ShenandoahCompiledICProtectionBehaviour ic_protection_behaviour;
125 CompiledICProtectionBehaviour::set_current(&ic_protection_behaviour);
126 }
127 }
128
129 void ShenandoahUnload::prepare() {
130 assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
131 assert(ClassUnloading, "Sanity");
132 CodeCache::increment_unloading_cycle();
133 DependencyContext::cleaning_start();
134 }
135
136 void ShenandoahUnload::unload() {
137 ShenandoahHeap* heap = ShenandoahHeap::heap();
138 assert(ClassUnloading, "Filtered by caller");
139 assert(heap->is_concurrent_weak_root_in_progress(), "Filtered by caller");
140
141 // Unlink stale metadata and nmethods
142 {
143 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink);
144
145 SuspendibleThreadSetJoiner sts;
146 bool unloadingOccurred;
147 {
148 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_sd);
149 MutexLocker cldgMl(ClassLoaderDataGraph_lock);
150 unloadingOccurred = SystemDictionary::do_unloading(heap->gc_timer());
151 }
152
153 {
154 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_weak_klass);
155 Klass::clean_weak_klass_links(unloadingOccurred);
156 }
157
158 {
159 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_code_roots);
160 ShenandoahCodeRoots::unlink(heap->workers(), unloadingOccurred);
161 }
162
163 DependencyContext::cleaning_end();
164 }
165
166 // Make sure stale metadata and nmethods are no longer observable
167 {
168 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_rendezvous);
169 heap->rendezvous_threads();
170 }
171
172 // Purge stale metadata and nmethods that were unlinked
173 {
174 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge);
175
176 {
177 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_coderoots);
178 SuspendibleThreadSetJoiner sts;
179 ShenandoahCodeRoots::purge();
180 }
181
182 {
183 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_cldg);
184 ClassLoaderDataGraph::purge(/*at_safepoint*/false);
185 }
186
187 {
188 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_ec);
189 CodeCache::purge_exception_caches();
190 }
191 }
192 }
193
194 void ShenandoahUnload::finish() {
195 MetaspaceGC::compute_new_size();
196 DEBUG_ONLY(MetaspaceUtils::verify();)
197 }