1 /* 2 * Copyright (c) 2001, 2014, 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_implementation/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->set_active_handles(JNIHandleBlock::allocate_block()); 60 // From this time Thread::current() should be working. 61 assert(this == Thread::current(), "just checking"); 62 } 63 64 void ConcurrentGCThread::wait_for_universe_init() { 65 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 66 while (!is_init_completed() && !_should_terminate) { 67 CGC_lock->wait(Mutex::_no_safepoint_check_flag, 200); 68 } 69 } 70 71 void ConcurrentGCThread::terminate() { 72 // Signal that it is terminated 73 { 74 MutexLockerEx mu(Terminator_lock, 75 Mutex::_no_safepoint_check_flag); 76 _has_terminated = true; 77 Terminator_lock->notify(); 78 } 79 80 // Thread destructor usually does this.. 81 ThreadLocalStorage::set_thread(NULL); 82 } 83 84 static void _sltLoop(JavaThread* thread, TRAPS) { 85 SurrogateLockerThread* slt = (SurrogateLockerThread*)thread; 86 slt->loop(); 87 } 88 89 SurrogateLockerThread::SurrogateLockerThread() : 90 JavaThread(&_sltLoop), 91 _monitor(Mutex::nonleaf, "SLTMonitor"), 92 _buffer(empty) 93 {} 94 95 SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) { 96 Klass* k = 97 SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), 98 true, CHECK_NULL); 99 instanceKlassHandle klass (THREAD, k); 100 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 101 102 const char thread_name[] = "Surrogate Locker Thread (Concurrent GC)"; 103 Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL); 104 105 // Initialize thread_oop to put it into the system threadGroup 106 Handle thread_group (THREAD, Universe::system_thread_group()); 107 JavaValue result(T_VOID); 108 JavaCalls::call_special(&result, thread_oop, 109 klass, 110 vmSymbols::object_initializer_name(), 111 vmSymbols::threadgroup_string_void_signature(), 112 thread_group, 113 string, 114 CHECK_NULL); 115 116 SurrogateLockerThread* res; 117 { 118 MutexLocker mu(Threads_lock); 119 res = new SurrogateLockerThread(); 120 121 // At this point it may be possible that no osthread was created for the 122 // JavaThread due to lack of memory. We would have to throw an exception 123 // in that case. However, since this must work and we do not allow 124 // exceptions anyway, check and abort if this fails. 125 if (res == NULL || res->osthread() == NULL) { 126 vm_exit_during_initialization("java.lang.OutOfMemoryError", 127 os::native_thread_creation_failed_msg()); 128 } 129 java_lang_Thread::set_thread(thread_oop(), res); 130 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority); 131 java_lang_Thread::set_daemon(thread_oop()); 132 133 res->set_threadObj(thread_oop()); 134 Threads::add(res); 135 Thread::start(res); 136 } 137 os::naked_yield(); // This seems to help with initial start-up of SLT 138 return res; 139 } 140 141 void SurrogateLockerThread::report_missing_slt() { 142 vm_exit_during_initialization( 143 "GC before GC support fully initialized: " 144 "SLT is needed but has not yet been created."); 145 ShouldNotReachHere(); 146 } 147 148 void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) { 149 MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag); 150 assert(_buffer == empty, "Should be empty"); 151 assert(msg != empty, "empty message"); 152 assert(!Heap_lock->owned_by_self(), "Heap_lock owned by requesting thread"); 153 154 _buffer = msg; 155 while (_buffer != empty) { 156 _monitor.notify(); 157 _monitor.wait(Mutex::_no_safepoint_check_flag); 158 } 159 } 160 161 // ======= Surrogate Locker Thread ============= 162 163 void SurrogateLockerThread::loop() { 164 BasicLock pll_basic_lock; 165 SLT_msg_type msg; 166 debug_only(unsigned int owned = 0;) 167 168 while (/* !isTerminated() */ 1) { 169 { 170 MutexLocker x(&_monitor); 171 // Since we are a JavaThread, we can't be here at a safepoint. 172 assert(!SafepointSynchronize::is_at_safepoint(), 173 "SLT is a JavaThread"); 174 // wait for msg buffer to become non-empty 175 while (_buffer == empty) { 176 _monitor.notify(); 177 _monitor.wait(); 178 } 179 msg = _buffer; 180 } 181 switch(msg) { 182 case acquirePLL: { 183 InstanceRefKlass::acquire_pending_list_lock(&pll_basic_lock); 184 debug_only(owned++;) 185 break; 186 } 187 case releaseAndNotifyPLL: { 188 assert(owned > 0, "Don't have PLL"); 189 InstanceRefKlass::release_and_notify_pending_list_lock(&pll_basic_lock); 190 debug_only(owned--;) 191 break; 192 } 193 case empty: 194 default: { 195 guarantee(false,"Unexpected message in _buffer"); 196 break; 197 } 198 } 199 { 200 MutexLocker x(&_monitor); 201 // Since we are a JavaThread, we can't be here at a safepoint. 202 assert(!SafepointSynchronize::is_at_safepoint(), 203 "SLT is a JavaThread"); 204 _buffer = empty; 205 _monitor.notify(); 206 } 207 } 208 assert(!_monitor.owned_by_self(), "Should unlock before exit."); 209 }