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