1
2 /*
3 * Copyright (c) 2019, Oracle and/or its affiliates. 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 #include "runtime/interfaceSupport.inline.hpp"
28 #include "runtime/thread.hpp"
29 #include "runtime/threadSMR.hpp"
30 #include "runtime/timerTrace.hpp"
31 #include "services/threadIdTable.hpp"
32 #include "utilities/concurrentHashTable.inline.hpp"
33 #include "utilities/concurrentHashTableTasks.inline.hpp"
34
35
36 typedef ConcurrentHashTable<ThreadIdTableConfig, mtInternal> ThreadIdTableHash;
37
38 // 2^24 is max size
39 static const size_t END_SIZE = 24;
40 // Default initial size 256
41 static const size_t DEFAULT_TABLE_SIZE_LOG = 8;
42 // Prefer short chains of avg 2
43 static const double PREF_AVG_LIST_LEN = 2.0;
44 static ThreadIdTableHash* volatile _local_table = NULL;
45 static volatile size_t _current_size = 0;
46 static volatile size_t _items_count = 0;
47
48 volatile bool ThreadIdTable::_is_initialized = false;
49 volatile bool ThreadIdTable::_has_work = false;
50
51 class ThreadIdTableEntry : public CHeapObj<mtInternal> {
52 private:
53 jlong _tid;
54 JavaThread* _java_thread;
55 public:
56 ThreadIdTableEntry(jlong tid, JavaThread* java_thread) :
57 _tid(tid), _java_thread(java_thread) {}
58
59 jlong tid() const { return _tid; }
60 JavaThread* thread() const { return _java_thread; }
61 };
62
63 class ThreadIdTableConfig : public AllStatic {
64 public:
65 typedef ThreadIdTableEntry* Value;
66
67 static uintx get_hash(Value const& value, bool* is_dead) {
68 jlong tid = value->tid();
69 return primitive_hash(tid);
70 }
71 static void* allocate_node(size_t size, Value const& value) {
72 ThreadIdTable::item_added();
73 return AllocateHeap(size, mtInternal);
74 }
75 static void free_node(void* memory, Value const& value) {
76 delete value;
77 FreeHeap(memory);
78 ThreadIdTable::item_removed();
79 }
80 };
81
82 static size_t ceil_log2(size_t val) {
83 size_t ret;
84 for (ret = 1; ((size_t)1 << ret) < val; ++ret);
85 return ret;
86 }
87
88 // Lazily creates the table and populates it with the given
89 // thread list
90 void ThreadIdTable::lazy_initialize(const ThreadsList *threads) {
91 if (!_is_initialized) {
92 {
93 // There is no obvious benefits in allowing the thread table
94 // to be concurently populated during the initalization.
95 MutexLocker ml(ThreadIdTableCreate_lock);
96 if (_is_initialized) {
97 return;
98 }
99 create_table(threads->length());
100 _is_initialized = true;
101 }
102 for (uint i = 0; i < threads->length(); i++) {
103 JavaThread* thread = threads->thread_at(i);
104 oop tobj = thread->threadObj();
105 if (tobj != NULL) {
106 jlong java_tid = java_lang_Thread::thread_id(tobj);
107 MutexLocker ml(Threads_lock);
108 if (!thread->is_exiting()) {
109 // Must be inside the lock to ensure that we don't add a thread to the table
110 // that has just passed the removal point in ThreadsSMRSupport::remove_thread()
111 add_thread(java_tid, thread);
112 }
113 }
114 }
115 }
116 }
117
118 void ThreadIdTable::create_table(size_t size) {
119 assert(_local_table == NULL, "Thread table is already created");
120 size_t size_log = ceil_log2(size);
121 size_t start_size_log =
122 size_log > DEFAULT_TABLE_SIZE_LOG ? size_log : DEFAULT_TABLE_SIZE_LOG;
123 _current_size = (size_t)1 << start_size_log;
124 _local_table = new ThreadIdTableHash(start_size_log, END_SIZE);
125 }
126
127 void ThreadIdTable::item_added() {
128 Atomic::inc(&_items_count);
129 log_trace(thread, table) ("Thread entry added");
130 }
131
132 void ThreadIdTable::item_removed() {
133 Atomic::dec(&_items_count);
134 log_trace(thread, table) ("Thread entry removed");
135 }
136
137 double ThreadIdTable::get_load_factor() {
138 return ((double)_items_count) / _current_size;
139 }
140
141 size_t ThreadIdTable::table_size() {
142 return (size_t)1 << _local_table->get_size_log2(Thread::current());
143 }
144
145 void ThreadIdTable::check_concurrent_work() {
146 if (_has_work) {
147 return;
148 }
149
150 double load_factor = get_load_factor();
151 // Resize if we have more items than preferred load factor
152 if ( load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
153 log_debug(thread, table)("Concurrent work triggered, load factor: %g",
154 load_factor);
155 trigger_concurrent_work();
156 }
157 }
158
159 void ThreadIdTable::trigger_concurrent_work() {
160 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
161 _has_work = true;
162 Service_lock->notify_all();
163 }
164
165 void ThreadIdTable::grow(JavaThread* jt) {
166 ThreadIdTableHash::GrowTask gt(_local_table);
167 if (!gt.prepare(jt)) {
168 return;
169 }
170 log_trace(thread, table)("Started to grow");
171 TraceTime timer("Grow", TRACETIME_LOG(Debug, membername, table, perf));
172 while (gt.do_task(jt)) {
173 gt.pause(jt);
174 {
175 ThreadBlockInVM tbivm(jt);
176 }
177 gt.cont(jt);
178 }
179 gt.done(jt);
180 _current_size = table_size();
181 log_info(thread, table)("Grown to size:" SIZE_FORMAT, _current_size);
182 }
183
184 class ThreadIdTableLookup : public StackObj {
185 private:
186 jlong _tid;
187 uintx _hash;
188 public:
189 ThreadIdTableLookup(jlong tid)
190 : _tid(tid), _hash(primitive_hash(tid)) {}
191 uintx get_hash() const {
192 return _hash;
193 }
194 bool equals(ThreadIdTableEntry** value, bool* is_dead) {
195 bool equals = primitive_equals(_tid, (*value)->tid());
196 if (!equals) {
197 return false;
198 }
199 return true;
200 }
201 };
202
203 class ThreadGet : public StackObj {
204 private:
205 JavaThread* _return;
206 public:
207 ThreadGet(): _return(NULL) {}
208 void operator()(ThreadIdTableEntry** val) {
209 _return = (*val)->thread();
210 }
211 JavaThread* get_res_thread() {
212 return _return;
213 }
214 };
215
216 void ThreadIdTable::do_concurrent_work(JavaThread* jt) {
217 assert(_is_initialized, "Thread table is not initialized");
218 _has_work = false;
219 double load_factor = get_load_factor();
220 log_debug(thread, table)("Concurrent work, load factor: %g", load_factor);
221 if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
222 grow(jt);
223 }
224 }
225
226 JavaThread* ThreadIdTable::add_thread(jlong tid, JavaThread* java_thread) {
227 assert(_is_initialized, "Thread table is not initialized");
228 Thread* thread = Thread::current();
229 ThreadIdTableLookup lookup(tid);
230 ThreadGet tg;
231 while (true) {
232 if (_local_table->get(thread, lookup, tg)) {
233 return tg.get_res_thread();
234 }
235 ThreadIdTableEntry* entry = new ThreadIdTableEntry(tid, java_thread);
236 // The hash table takes ownership of the ThreadTableEntry,
237 // even if it's not inserted.
238 if (_local_table->insert(thread, lookup, entry)) {
239 check_concurrent_work();
240 return java_thread;
241 }
242 }
243 }
244
245 JavaThread* ThreadIdTable::find_thread_by_tid(jlong tid) {
246 assert(_is_initialized, "Thread table is not initialized");
247 Thread* thread = Thread::current();
248 ThreadIdTableLookup lookup(tid);
249 ThreadGet tg;
250 _local_table->get(thread, lookup, tg);
251 return tg.get_res_thread();
252 }
253
254 bool ThreadIdTable::remove_thread(jlong tid) {
255 assert(_is_initialized, "Thread table is not initialized");
256 Thread* thread = Thread::current();
257 ThreadIdTableLookup lookup(tid);
258 return _local_table->remove(thread, lookup);
259 }