1 /*
2 * Copyright (c) 2012, 2019, 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
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/protectionDomainCache.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "memory/universe.hpp"
31 #include "runtime/handles.inline.hpp"
32 #include "runtime/interfaceSupport.inline.hpp"
33 #include "runtime/javaCalls.hpp"
34 #include "runtime/jniHandles.hpp"
35 #include "runtime/serviceThread.hpp"
36 #include "runtime/mutexLocker.hpp"
37 #include "runtime/os.hpp"
38 #include "prims/jvmtiImpl.hpp"
39 #include "prims/resolvedMethodTable.hpp"
40
41 ServiceThread* ServiceThread::_instance = NULL;
42
43 void ServiceThread::initialize() {
44 EXCEPTION_MARK;
45
46 const char* name = "Service Thread";
47 Handle string = java_lang_String::create_from_str(name, CHECK);
48
49 // Initialize thread_oop to put it into the system threadGroup
50 Handle thread_group (THREAD, Universe::system_thread_group());
51 Handle thread_oop = JavaCalls::construct_new_instance(
52 SystemDictionary::Thread_klass(),
53 vmSymbols::threadgroup_string_void_signature(),
54 thread_group,
55 string,
56 CHECK);
57
58 {
59 MutexLocker mu(Threads_lock);
60 ServiceThread* thread = new ServiceThread(&service_thread_entry);
61
62 // At this point it may be possible that no osthread was created for the
63 // JavaThread due to lack of memory. We would have to throw an exception
64 // in that case. However, since this must work and we do not allow
65 // exceptions anyway, check and abort if this fails.
66 if (thread == NULL || thread->osthread() == NULL) {
67 vm_exit_during_initialization("java.lang.OutOfMemoryError",
68 os::native_thread_creation_failed_msg());
69 }
70
71 java_lang_Thread::set_thread(thread_oop(), thread);
72 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
73 java_lang_Thread::set_daemon(thread_oop());
74 thread->set_threadObj(thread_oop());
75 _instance = thread;
76
77 Threads::add(thread);
78 Thread::start(thread);
79 }
80 }
81
82 static bool needs_oopstorage_cleanup(OopStorage* const* storages,
83 bool* needs_cleanup,
84 size_t size) {
85 bool any_needs_cleanup = false;
86 for (size_t i = 0; i < size; ++i) {
87 assert(!needs_cleanup[i], "precondition");
88 if (storages[i]->needs_delete_empty_blocks()) {
89 needs_cleanup[i] = true;
90 any_needs_cleanup = true;
91 }
92 }
93 return any_needs_cleanup;
94 }
95
96 static void cleanup_oopstorages(OopStorage* const* storages,
97 const bool* needs_cleanup,
98 size_t size) {
99 for (size_t i = 0; i < size; ++i) {
100 if (needs_cleanup[i]) {
101 storages[i]->delete_empty_blocks();
102 }
103 }
104 }
105
106 void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {
107 OopStorage* const oopstorages[] = {
108 JNIHandles::global_handles(),
109 JNIHandles::weak_global_handles(),
110 StringTable::weak_storage(),
111 SystemDictionary::vm_weak_oop_storage()
112 };
113 const size_t oopstorage_count = ARRAY_SIZE(oopstorages);
114
115 while (true) {
116 bool has_jvmti_events = false;
117 bool stringtable_work = false;
118 bool symboltable_work = false;
119 bool resolved_method_table_work = false;
120 bool protection_domain_table_work = false;
121 bool oopstorage_work = false;
122 bool oopstorages_cleanup[oopstorage_count] = {}; // Zero (false) initialize.
123 JvmtiDeferredEvent jvmti_event;
124 {
125 // Need state transition ThreadBlockInVM so that this thread
126 // will be handled by safepoint correctly when this thread is
127 // notified at a safepoint.
128
129 // This ThreadBlockInVM object is not also considered to be
130 // suspend-equivalent because ServiceThread is not visible to
131 // external suspension.
132
133 ThreadBlockInVM tbivm(jt);
134
135 MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
136 // Process all available work on each (outer) iteration, rather than
137 // only the first recognized bit of work, to avoid frequently true early
138 // tests from potentially starving later work. Hence the use of
139 // arithmetic-or to combine results; we don't want short-circuiting.
140 while (((has_jvmti_events = JvmtiDeferredEventQueue::has_events()) |
141 (stringtable_work = StringTable::has_work()) |
142 (symboltable_work = SymbolTable::has_work()) |
143 (resolved_method_table_work = ResolvedMethodTable::has_work()) |
144 (protection_domain_table_work = SystemDictionary::pd_cache_table()->has_work()) |
145 (oopstorage_work = needs_oopstorage_cleanup(oopstorages,
146 oopstorages_cleanup,
147 oopstorage_count)))
148
149 == 0) {
150 // Wait until notified that there is some work to do.
151 ml.wait();
152 }
153
154 if (has_jvmti_events) {
155 jvmti_event = JvmtiDeferredEventQueue::dequeue();
156 }
157 }
158
159 if (stringtable_work) {
160 StringTable::do_concurrent_work(jt);
161 }
162
163 if (symboltable_work) {
164 SymbolTable::do_concurrent_work(jt);
165 }
166
167 if (has_jvmti_events) {
168 jvmti_event.post();
169 }
170
171 if (resolved_method_table_work) {
172 ResolvedMethodTable::do_concurrent_work(jt);
173 }
174
175 if (protection_domain_table_work) {
176 SystemDictionary::pd_cache_table()->unlink();
177 }
178
179 if (oopstorage_work) {
180 cleanup_oopstorages(oopstorages, oopstorages_cleanup, oopstorage_count);
181 }
182 }
183 }
184
185 bool ServiceThread::is_service_thread(Thread* thread) {
186 return thread == _instance;
187 }