1 /* 2 * Copyright (c) 2001, 2015, 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/systemDictionary.hpp" 27 #include "gc/shared/concurrentGCThread.hpp" 28 #include "oops/instanceRefKlass.hpp" 29 #include "oops/oop.inline.hpp" 30 #include "runtime/init.hpp" 31 #include "runtime/interfaceSupport.hpp" 32 #include "runtime/java.hpp" 33 #include "runtime/javaCalls.hpp" 34 #include "runtime/os.hpp" 35 36 // CopyrightVersion 1.2 37 38 int ConcurrentGCThread::_CGC_flag = CGC_nil; 39 40 ConcurrentGCThread::ConcurrentGCThread() : 41 _should_terminate(false), _has_terminated(false) { 42 }; 43 44 void ConcurrentGCThread::create_and_start() { 45 if (os::create_thread(this, os::cgc_thread)) { 46 // XXX: need to set this to low priority 47 // unless "aggressive mode" set; priority 48 // should be just less than that of VMThread. 49 os::set_priority(this, NearMaxPriority); 50 if (!_should_terminate && !DisableStartThread) { 51 os::start_thread(this); 52 } 53 } 54 } 55 56 void ConcurrentGCThread::initialize_in_thread() { 57 this->record_stack_base_and_size(); 58 this->initialize_thread_local_storage(); 59 this->initialize_named_thread(); 60 this->set_active_handles(JNIHandleBlock::allocate_block()); 61 // From this time Thread::current() should be working. 62 assert(this == Thread::current(), "just checking"); 63 } 64 65 void ConcurrentGCThread::wait_for_universe_init() { 66 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 67 while (!is_init_completed() && !_should_terminate) { 68 CGC_lock->wait(Mutex::_no_safepoint_check_flag, 200); 69 } 70 } 71 72 void ConcurrentGCThread::terminate() { 73 // Signal that it is terminated 74 { 75 MutexLockerEx mu(Terminator_lock, 76 Mutex::_no_safepoint_check_flag); 77 _has_terminated = true; 78 Terminator_lock->notify(); 79 } 80 81 // Thread destructor usually does this.. 82 ThreadLocalStorage::set_thread(NULL); 83 } 84 85 static void _sltLoop(JavaThread* thread, TRAPS) { 86 SurrogateLockerThread* slt = (SurrogateLockerThread*)thread; 87 slt->loop(); 88 } 89 90 SurrogateLockerThread::SurrogateLockerThread() : 91 JavaThread(&_sltLoop), 92 _monitor(Mutex::nonleaf, "SLTMonitor", false, 93 Monitor::_safepoint_check_sometimes), 94 _buffer(empty) 95 {} 96 97 SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) { 98 Klass* k = 99 SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), 100 true, CHECK_NULL); 101 instanceKlassHandle klass (THREAD, k); 102 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 103 104 const char thread_name[] = "Surrogate Locker Thread (Concurrent GC)"; 105 Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL); 106 107 // Initialize thread_oop to put it into the system threadGroup 108 Handle thread_group (THREAD, Universe::system_thread_group()); 109 JavaValue result(T_VOID); 110 JavaCalls::call_special(&result, thread_oop, 111 klass, 112 vmSymbols::object_initializer_name(), 113 vmSymbols::threadgroup_string_void_signature(), 114 thread_group, 115 string, 116 CHECK_NULL); 117 118 SurrogateLockerThread* res; 119 { 120 MutexLocker mu(Threads_lock); 121 res = new SurrogateLockerThread(); 122 123 // At this point it may be possible that no osthread was created for the 124 // JavaThread due to lack of memory. We would have to throw an exception 125 // in that case. However, since this must work and we do not allow 126 // exceptions anyway, check and abort if this fails. 127 if (res == NULL || res->osthread() == NULL) { 128 vm_exit_during_initialization("java.lang.OutOfMemoryError", 129 os::native_thread_creation_failed_msg()); 130 } 131 java_lang_Thread::set_thread(thread_oop(), res); 132 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority); 133 java_lang_Thread::set_daemon(thread_oop()); 134 135 res->set_threadObj(thread_oop()); 136 Threads::add(res); 137 Thread::start(res); 138 } 139 os::naked_yield(); // This seems to help with initial start-up of SLT 140 return res; 141 } 142 143 void SurrogateLockerThread::report_missing_slt() { 144 vm_exit_during_initialization( 145 "GC before GC support fully initialized: " 146 "SLT is needed but has not yet been created."); 147 ShouldNotReachHere(); 148 } 149 150 void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) { 151 MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag); 152 assert(_buffer == empty, "Should be empty"); 153 assert(msg != empty, "empty message"); 154 assert(!Heap_lock->owned_by_self(), "Heap_lock owned by requesting thread"); 155 156 _buffer = msg; 157 while (_buffer != empty) { 158 _monitor.notify(); 159 _monitor.wait(Mutex::_no_safepoint_check_flag); 160 } 161 } 162 163 // ======= Surrogate Locker Thread ============= 164 165 void SurrogateLockerThread::loop() { 166 BasicLock pll_basic_lock; 167 SLT_msg_type msg; 168 debug_only(unsigned int owned = 0;) 169 170 while (/* !isTerminated() */ 1) { 171 { 172 MutexLocker x(&_monitor); 173 // Since we are a JavaThread, we can't be here at a safepoint. 174 assert(!SafepointSynchronize::is_at_safepoint(), 175 "SLT is a JavaThread"); 176 // wait for msg buffer to become non-empty 177 while (_buffer == empty) { 178 _monitor.notify(); 179 _monitor.wait(); 180 } 181 msg = _buffer; 182 } 183 switch(msg) { 184 case acquirePLL: { 185 InstanceRefKlass::acquire_pending_list_lock(&pll_basic_lock); 186 debug_only(owned++;) 187 break; 188 } 189 case releaseAndNotifyPLL: { 190 assert(owned > 0, "Don't have PLL"); 191 InstanceRefKlass::release_and_notify_pending_list_lock(&pll_basic_lock); 192 debug_only(owned--;) 193 break; 194 } 195 case empty: 196 default: { 197 guarantee(false,"Unexpected message in _buffer"); 198 break; 199 } 200 } 201 { 202 MutexLocker x(&_monitor); 203 // Since we are a JavaThread, we can't be here at a safepoint. 204 assert(!SafepointSynchronize::is_at_safepoint(), 205 "SLT is a JavaThread"); 206 _buffer = empty; 207 _monitor.notify(); 208 } 209 } 210 assert(!_monitor.owned_by_self(), "Should unlock before exit."); 211 }