1 /*
2 * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2019, 2021, Red Hat, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27
28 #include "classfile/classLoaderDataGraph.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "code/codeBehaviours.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/dependencyContext.hpp"
33 #include "gc/shared/gcBehaviours.hpp"
34 #include "gc/shared/classUnloadingContext.hpp"
35 #include "gc/shared/suspendibleThreadSet.hpp"
36 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
37 #include "gc/shenandoah/shenandoahLock.hpp"
38 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
39 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
40 #include "gc/shenandoah/shenandoahUnload.hpp"
41 #include "gc/shenandoah/shenandoahVerifier.hpp"
42 #include "memory/iterator.hpp"
43 #include "memory/metaspaceUtils.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "oops/access.inline.hpp"
46
47 class ShenandoahIsUnloadingOopClosure : public OopClosure {
48 private:
49 ShenandoahMarkingContext* const _marking_context;
50 bool _is_unloading;
51
52 public:
53 ShenandoahIsUnloadingOopClosure() :
54 // TODO: In non-generational mode, this should still be complete_marking_context()
55 _marking_context(ShenandoahHeap::heap()->marking_context()),
56 _is_unloading(false) {
57 }
58
59 virtual void do_oop(oop* p) {
60 if (_is_unloading) {
61 return;
62 }
63
64 const oop o = RawAccess<>::oop_load(p);
65 if (!CompressedOops::is_null(o) &&
66 !_marking_context->is_marked(o)) {
67 _is_unloading = true;
68 }
69 }
70
71 virtual void do_oop(narrowOop* p) {
72 ShouldNotReachHere();
73 }
74
75 bool is_unloading() const {
76 return _is_unloading;
77 }
78 };
79
80 class ShenandoahIsUnloadingBehaviour : public IsUnloadingBehaviour {
81 public:
82 virtual bool has_dead_oop(nmethod* nm) const {
83 assert(ShenandoahHeap::heap()->is_concurrent_weak_root_in_progress(), "Only for this phase");
84 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
85 ShenandoahReentrantLocker locker(data->lock());
86 ShenandoahIsUnloadingOopClosure cl;
87 data->oops_do(&cl);
88 return cl.is_unloading();
89 }
90 };
91
92 class ShenandoahCompiledICProtectionBehaviour : public CompiledICProtectionBehaviour {
93 public:
94 virtual bool lock(nmethod* nm) {
95 ShenandoahReentrantLock* const lock = ShenandoahNMethod::ic_lock_for_nmethod(nm);
96 assert(lock != nullptr, "Not yet registered?");
97 lock->lock();
98 return true;
99 }
100
101 virtual void unlock(nmethod* nm) {
102 ShenandoahReentrantLock* const lock = ShenandoahNMethod::ic_lock_for_nmethod(nm);
103 assert(lock != nullptr, "Not yet registered?");
104 lock->unlock();
105 }
106
107 virtual bool is_safe(nmethod* nm) {
108 if (SafepointSynchronize::is_at_safepoint() || nm->is_unloading()) {
109 return true;
110 }
111
112 ShenandoahReentrantLock* const lock = ShenandoahNMethod::ic_lock_for_nmethod(nm);
113 assert(lock != nullptr, "Not yet registered?");
114 return lock->owned_by_self();
115 }
116 };
117
118 ShenandoahUnload::ShenandoahUnload() {
119 if (ClassUnloading) {
120 static ShenandoahIsUnloadingBehaviour is_unloading_behaviour;
121 IsUnloadingBehaviour::set_current(&is_unloading_behaviour);
122
123 static ShenandoahCompiledICProtectionBehaviour ic_protection_behaviour;
124 CompiledICProtectionBehaviour::set_current(&ic_protection_behaviour);
125 }
126 }
127
128 void ShenandoahUnload::prepare() {
129 assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
130 assert(ClassUnloading, "Sanity");
131 CodeCache::increment_unloading_cycle();
132 DependencyContext::cleaning_start();
133 }
134
135 void ShenandoahUnload::unload() {
136 ShenandoahHeap* heap = ShenandoahHeap::heap();
137 assert(ClassUnloading, "Filtered by caller");
138 assert(heap->is_concurrent_weak_root_in_progress(), "Filtered by caller");
139
140 ClassUnloadingContext ctx(heap->workers()->active_workers(),
141 true /* unregister_nmethods_during_purge */,
142 true /* lock_nmethod_free_separately */);
143
144 // Unlink stale metadata and nmethods
145 {
146 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink);
147
148 SuspendibleThreadSetJoiner sts;
149 bool unloadingOccurred;
150 {
151 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_sd);
152 MutexLocker cldgMl(ClassLoaderDataGraph_lock);
153 unloadingOccurred = SystemDictionary::do_unloading(heap->gc_timer());
154 }
155
156 {
157 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_weak_klass);
158 Klass::clean_weak_klass_links(unloadingOccurred);
159 }
160
161 {
162 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_code_roots);
163 ShenandoahCodeRoots::unlink(heap->workers(), unloadingOccurred);
164 }
165
166 DependencyContext::cleaning_end();
167 }
168
169 // Make sure stale metadata and nmethods are no longer observable
170 {
171 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_rendezvous);
172 heap->rendezvous_threads();
173 }
174
175 // Purge stale metadata and nmethods that were unlinked
176 {
177 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge);
178
179 {
180 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_coderoots);
181 SuspendibleThreadSetJoiner sts;
182 ShenandoahCodeRoots::purge();
183 }
184
185 {
186 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_cldg);
187 ClassLoaderDataGraph::purge(false /* at_safepoint */);
188 }
189
190 {
191 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_ec);
192 CodeCache::purge_exception_caches();
193 }
194 }
195 }
196
197 void ShenandoahUnload::finish() {
198 MetaspaceGC::compute_new_size();
199 DEBUG_ONLY(MetaspaceUtils::verify();)
200 }
--- EOF ---