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/classUnloadingContext.hpp"
34 #include "gc/shared/suspendibleThreadSet.hpp"
35 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
36 #include "gc/shenandoah/shenandoahLock.hpp"
37 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
38 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
39 #include "gc/shenandoah/shenandoahUnload.hpp"
40 #include "gc/shenandoah/shenandoahVerifier.hpp"
41 #include "memory/iterator.hpp"
42 #include "memory/metaspaceUtils.hpp"
43 #include "memory/resourceArea.hpp"
44 #include "oops/access.inline.hpp"
45
46 class ShenandoahIsUnloadingOopClosure : public OopClosure {
47 private:
48 ShenandoahMarkingContext* const _marking_context;
49 bool _is_unloading;
50
51 public:
52 ShenandoahIsUnloadingOopClosure() :
53 _marking_context(ShenandoahHeap::heap()->global_generation()->complete_marking_context()),
54 _is_unloading(false) {
55 }
56
57 virtual void do_oop(oop* p) {
58 if (_is_unloading) {
59 return;
60 }
61
62 const oop o = RawAccess<>::oop_load(p);
63 if (!CompressedOops::is_null(o) &&
64 !_marking_context->is_marked(o)) {
65 _is_unloading = true;
66 }
67 }
68
69 virtual void do_oop(narrowOop* p) {
70 ShouldNotReachHere();
71 }
72
73 bool is_unloading() const {
74 return _is_unloading;
75 }
76 };
77
78 class ShenandoahIsUnloadingBehaviour : public IsUnloadingBehaviour {
79 public:
80 virtual bool has_dead_oop(CompiledMethod* method) const {
81 nmethod* const nm = method->as_nmethod();
82 assert(ShenandoahHeap::heap()->is_concurrent_weak_root_in_progress(), "Only for this phase");
83 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
84 ShenandoahReentrantLocker locker(data->lock());
85 ShenandoahIsUnloadingOopClosure cl;
86 data->oops_do(&cl);
87 return cl.is_unloading();
88 }
89 };
90
91 class ShenandoahCompiledICProtectionBehaviour : public CompiledICProtectionBehaviour {
92 public:
93 virtual bool lock(CompiledMethod* method) {
94 nmethod* const nm = method->as_nmethod();
95 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
96 assert(lock != nullptr, "Not yet registered?");
97 lock->lock();
98 return true;
99 }
100
101 virtual void unlock(CompiledMethod* method) {
102 nmethod* const nm = method->as_nmethod();
103 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
104 assert(lock != nullptr, "Not yet registered?");
105 lock->unlock();
106 }
107
108 virtual bool is_safe(CompiledMethod* method) {
109 if (SafepointSynchronize::is_at_safepoint()) {
110 return true;
111 }
112
113 nmethod* const nm = method->as_nmethod();
114 ShenandoahReentrantLock* const lock = ShenandoahNMethod::lock_for_nmethod(nm);
115 assert(lock != nullptr, "Not yet registered?");
116 return lock->owned_by_self();
117 }
118 };
119
120 ShenandoahUnload::ShenandoahUnload() {
121 if (ClassUnloading) {
122 static ShenandoahIsUnloadingBehaviour is_unloading_behaviour;
123 IsUnloadingBehaviour::set_current(&is_unloading_behaviour);
124
125 static ShenandoahCompiledICProtectionBehaviour ic_protection_behaviour;
126 CompiledICProtectionBehaviour::set_current(&ic_protection_behaviour);
127 }
128 }
129
130 void ShenandoahUnload::prepare() {
131 assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
132 assert(ClassUnloading, "Sanity");
133 CodeCache::increment_unloading_cycle();
134 DependencyContext::cleaning_start();
135 }
136
137 void ShenandoahUnload::unload() {
138 ShenandoahHeap* heap = ShenandoahHeap::heap();
139 assert(ClassUnloading, "Filtered by caller");
140 assert(heap->is_concurrent_weak_root_in_progress(), "Filtered by caller");
141
142 ClassUnloadingContext ctx(heap->workers()->active_workers(),
143 true /* unregister_nmethods_during_purge */,
144 true /* lock_codeblob_free_separately */);
145
146 // Unlink stale metadata and nmethods
147 {
148 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink);
149
150 SuspendibleThreadSetJoiner sts;
151 bool unloadingOccurred;
152 {
153 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_sd);
154 MutexLocker cldgMl(ClassLoaderDataGraph_lock);
155 unloadingOccurred = SystemDictionary::do_unloading(heap->gc_timer());
156 }
157
158 {
159 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_weak_klass);
160 Klass::clean_weak_klass_links(unloadingOccurred);
161 }
162
163 {
164 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_code_roots);
165 ShenandoahCodeRoots::unlink(heap->workers(), unloadingOccurred);
166 }
167
168 DependencyContext::cleaning_end();
169 }
170
171 // Make sure stale metadata and nmethods are no longer observable
172 {
173 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_rendezvous);
174 heap->rendezvous_threads("Shenandoah Class Unloading");
175 }
176
177 // Purge stale metadata and nmethods that were unlinked
178 {
179 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge);
180
181 {
182 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_coderoots);
183 SuspendibleThreadSetJoiner sts;
184 ShenandoahCodeRoots::purge();
185 }
186
187 {
188 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_cldg);
189 ClassLoaderDataGraph::purge(false /* at_safepoint */);
190 }
191
192 {
193 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_ec);
194 CodeCache::purge_exception_caches();
195 }
196 }
197 }
198
199 void ShenandoahUnload::finish() {
200 MetaspaceGC::compute_new_size();
201 DEBUG_ONLY(MetaspaceUtils::verify();)
202 }