1 /* 2 * Copyright (c) 2019, 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 "memory/universe.hpp" 27 #include "runtime/interfaceSupport.inline.hpp" 28 #include "runtime/javaCalls.hpp" 29 #include "runtime/notificationThread.hpp" 30 #include "services/diagnosticArgument.hpp" 31 #include "services/diagnosticFramework.hpp" 32 #include "services/gcNotifier.hpp" 33 #include "services/lowMemoryDetector.hpp" 34 35 NotificationThread* NotificationThread::_instance = NULL; 36 37 void NotificationThread::initialize() { 38 EXCEPTION_MARK; 39 40 const char* name = "Notification Thread"; 41 Handle string = java_lang_String::create_from_str(name, CHECK); 42 43 // Initialize thread_oop to put it into the system threadGroup 44 Handle thread_group (THREAD, Universe::system_thread_group()); 45 Handle thread_oop = JavaCalls::construct_new_instance( 46 SystemDictionary::Thread_klass(), 47 vmSymbols::threadgroup_string_void_signature(), 48 thread_group, 49 string, 50 CHECK); 51 52 Klass* group = SystemDictionary::ThreadGroup_klass(); 53 JavaValue result(T_VOID); 54 JavaCalls::call_special(&result, 55 thread_group, 56 group, 57 vmSymbols::add_method_name(), 58 vmSymbols::thread_void_signature(), 59 thread_oop, 60 THREAD); 61 { 62 MutexLocker mu(Threads_lock); 63 NotificationThread* thread = new NotificationThread(¬ification_thread_entry); 64 65 // At this point it may be possible that no osthread was created for the 66 // JavaThread due to lack of memory. We would have to throw an exception 67 // in that case. However, since this must work and we do not allow 68 // exceptions anyway, check and abort if this fails. 69 if (thread == NULL || thread->osthread() == NULL) { 70 vm_exit_during_initialization("java.lang.OutOfMemoryError", 71 os::native_thread_creation_failed_msg()); 72 } 73 74 java_lang_Thread::set_thread(thread_oop(), thread); 75 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority); 76 java_lang_Thread::set_daemon(thread_oop()); 77 thread->set_threadObj(thread_oop()); 78 _instance = thread; 79 80 Threads::add(thread); 81 Thread::start(thread); 82 } 83 } 84 85 86 87 void NotificationThread::notification_thread_entry(JavaThread* jt, TRAPS) { 88 while (true) { 89 bool sensors_changed = false; 90 bool has_dcmd_notification_event = false; 91 bool has_gc_notification_event = false; 92 { 93 // Need state transition ThreadBlockInVM so that this thread 94 // will be handled by safepoint correctly when this thread is 95 // notified at a safepoint. 96 97 ThreadBlockInVM tbivm(jt); 98 99 MonitorLocker ml(Notification_lock, Mutex::_no_safepoint_check_flag); 100 // Process all available work on each (outer) iteration, rather than 101 // only the first recognized bit of work, to avoid frequently true early 102 // tests from potentially starving later work. Hence the use of 103 // arithmetic-or to combine results; we don't want short-circuiting. 104 while (((sensors_changed = LowMemoryDetector::has_pending_requests()) | 105 (has_dcmd_notification_event = DCmdFactory::has_pending_jmx_notification()) | 106 (has_gc_notification_event = GCNotifier::has_event())) 107 == 0) { 108 // Wait until notified that there is some work to do. 109 ml.wait(); 110 } 111 112 } 113 114 if (sensors_changed) { 115 LowMemoryDetector::process_sensor_changes(jt); 116 } 117 118 if(has_gc_notification_event) { 119 GCNotifier::sendNotification(CHECK); 120 } 121 122 if(has_dcmd_notification_event) { 123 DCmdFactory::send_notification(CHECK); 124 } 125 126 } 127 } 128