1 /* 2 * Copyright (c) 2012, 2018, 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/stringTable.hpp" 27 #include "classfile/symbolTable.hpp" 28 #include "runtime/interfaceSupport.inline.hpp" 29 #include "runtime/javaCalls.hpp" 30 #include "runtime/serviceThread.hpp" 31 #include "runtime/mutexLocker.hpp" 32 #include "runtime/os.hpp" 33 #include "prims/jvmtiImpl.hpp" 34 #include "services/diagnosticArgument.hpp" 35 #include "services/diagnosticFramework.hpp" 36 #include "services/gcNotifier.hpp" 37 #include "services/lowMemoryDetector.hpp" 38 39 ServiceThread* ServiceThread::_instance = NULL; 40 41 void ServiceThread::initialize() { 42 EXCEPTION_MARK; 43 44 const char* name = "Service Thread"; 45 Handle string = java_lang_String::create_from_str(name, CHECK); 46 47 // Initialize thread_oop to put it into the system threadGroup 48 Handle thread_group (THREAD, Universe::system_thread_group()); 49 Handle thread_oop = JavaCalls::construct_new_instance( 50 SystemDictionary::Thread_klass(), 51 vmSymbols::threadgroup_string_void_signature(), 52 thread_group, 53 string, 54 CHECK); 55 56 { 57 MutexLocker mu(Threads_lock); 58 ServiceThread* thread = new ServiceThread(&service_thread_entry); 59 60 // At this point it may be possible that no osthread was created for the 61 // JavaThread due to lack of memory. We would have to throw an exception 62 // in that case. However, since this must work and we do not allow 63 // exceptions anyway, check and abort if this fails. 64 if (thread == NULL || thread->osthread() == NULL) { 65 vm_exit_during_initialization("java.lang.OutOfMemoryError", 66 os::native_thread_creation_failed_msg()); 67 } 68 69 java_lang_Thread::set_thread(thread_oop(), thread); 70 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority); 71 java_lang_Thread::set_daemon(thread_oop()); 72 thread->set_threadObj(thread_oop()); 73 _instance = thread; 74 75 Threads::add(thread); 76 Thread::start(thread); 77 } 78 } 79 80 void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) { 81 while (true) { 82 bool sensors_changed = false; 83 bool has_jvmti_events = false; 84 bool has_gc_notification_event = false; 85 bool has_dcmd_notification_event = false; 86 bool acs_notify = false; 87 bool stringtable_work = false; 88 bool symboltable_work = false; 89 JvmtiDeferredEvent jvmti_event; 90 { 91 // Need state transition ThreadBlockInVM so that this thread 92 // will be handled by safepoint correctly when this thread is 93 // notified at a safepoint. 94 95 // This ThreadBlockInVM object is not also considered to be 96 // suspend-equivalent because ServiceThread is not visible to 97 // external suspension. 98 99 ThreadBlockInVM tbivm(jt); 100 101 MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag); 102 while (!(sensors_changed = LowMemoryDetector::has_pending_requests()) && 103 !(has_jvmti_events = JvmtiDeferredEventQueue::has_events()) && 104 !(has_gc_notification_event = GCNotifier::has_event()) && 105 !(has_dcmd_notification_event = DCmdFactory::has_pending_jmx_notification()) && 106 !(stringtable_work = StringTable::has_work()) && 107 !(symboltable_work = SymbolTable::has_work())) { 108 // wait until one of the sensors has pending requests, or there is a 109 // pending JVMTI event or JMX GC notification to post 110 Service_lock->wait(Mutex::_no_safepoint_check_flag); 111 } 112 113 if (has_jvmti_events) { 114 jvmti_event = JvmtiDeferredEventQueue::dequeue(); 115 } 116 } 117 118 if (stringtable_work) { 119 StringTable::do_concurrent_work(jt); 120 } 121 122 if (symboltable_work) { 123 SymbolTable::do_concurrent_work(jt); 124 } 125 126 if (has_jvmti_events) { 127 jvmti_event.post(); 128 } 129 130 if (sensors_changed) { 131 LowMemoryDetector::process_sensor_changes(jt); 132 } 133 134 if(has_gc_notification_event) { 135 GCNotifier::sendNotification(CHECK); 136 } 137 138 if(has_dcmd_notification_event) { 139 DCmdFactory::send_notification(CHECK); 140 } 141 } 142 } 143 144 bool ServiceThread::is_service_thread(Thread* thread) { 145 return thread == _instance; 146 }