Java tutorial
//package com.java2s; /* * Copyright 2014 OW2 Chameleon * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.lang.management.*; import java.util.Map; public class Main { public static void threadDumps() { ThreadMXBean bean = ManagementFactory.getThreadMXBean(); long[] ids = bean.getAllThreadIds(); StringBuilder builder = new StringBuilder(); printTitle(builder); printDeadlockInfo(builder, bean); for (long id : ids) { ThreadInfo info = bean.getThreadInfo(id); printThreadInfo(info, builder); printThreadSeparator(builder); } System.out.println(builder.toString()); } private static void printTitle(StringBuilder builder) { builder.append("============ THREAD DUMP ============\n"); } private static void printDeadlockInfo(StringBuilder builder, ThreadMXBean bean) { long[] ids = bean.getAllThreadIds(); long[] dds = bean.findDeadlockedThreads(); if (dds != null) { ThreadInfo[] info = bean.getThreadInfo(ids, true, true); builder.append("The following threads are deadlocked:"); for (ThreadInfo ti : info) { builder.append("\t").append(ti); } } } public static void printThreadInfo(ThreadInfo info, StringBuilder builder) { builder.append("Thread ").append(info.getThreadName()).append("\" (").append(info.getThreadId()) .append(") -- "); formatState(builder, info); if (info.isSuspended()) { builder.append(" (suspended)"); } if (info.isInNative()) { builder.append(" (in native)"); } builder.append("\n"); // The waited lock. LockInfo li = info.getLockInfo(); if (li != null) { builder.append("Waiting for "); formatLock(builder, li); if (info.getLockOwnerName() != null) { builder.append(" owned by ").append(info.getLockOwnerName()).append("(") .append(info.getLockOwnerId()).append(")"); } builder.append("\n"); } // The stack builder.append("Stack:\n"); printStack(info, builder, getStackForThread(info.getThreadId())); } private static void printThreadSeparator(StringBuilder builder) { builder.append("-------------------------------------\n"); } private static void formatState(final StringBuilder sb, final ThreadInfo info) { final Thread.State state = info.getThreadState(); sb.append(state); switch (state) { case BLOCKED: { sb.append(" (on object monitor owned by \""); sb.append(info.getLockOwnerName()).append("\" Id=").append(info.getLockOwnerId()).append(")"); break; } case WAITING: { final StackTraceElement element = getStackForThread(info.getThreadId())[0]; final String className = element.getClassName(); final String method = element.getMethodName(); if (className.equals("java.lang.Object") && method.equals("wait")) { sb.append(" (on object monitor"); if (info.getLockOwnerName() != null) { sb.append(" owned by \""); sb.append(info.getLockOwnerName()).append("\" Id=").append(info.getLockOwnerId()); } sb.append(")"); } else if (className.equals("java.lang.Thread") && method.equals("join")) { sb.append(" (on completion of thread ").append(info.getLockOwnerId()).append(")"); } else { sb.append(" (parking for lock"); if (info.getLockOwnerName() != null) { sb.append(" owned by \""); sb.append(info.getLockOwnerName()).append("\" Id=").append(info.getLockOwnerId()); } sb.append(")"); } break; } case TIMED_WAITING: { final StackTraceElement element = info.getStackTrace()[0]; final String className = element.getClassName(); final String method = element.getMethodName(); if (className.equals("java.lang.Object") && method.equals("wait")) { sb.append(" (on object monitor"); if (info.getLockOwnerName() != null) { sb.append(" owned by \""); sb.append(info.getLockOwnerName()).append("\" Id=").append(info.getLockOwnerId()); } sb.append(")"); } else if (className.equals("java.lang.Thread") && method.equals("sleep")) { sb.append(" (sleeping)"); } else if (className.equals("java.lang.Thread") && method.equals("join")) { sb.append(" (on completion of thread ").append(info.getLockOwnerId()).append(")"); } else { sb.append(" (parking for lock"); if (info.getLockOwnerName() != null) { sb.append(" owned by \""); sb.append(info.getLockOwnerName()).append("\" Id=").append(info.getLockOwnerId()); } sb.append(")"); } break; } default: break; } } private static void formatLock(final StringBuilder sb, final LockInfo lock) { sb.append("<").append(lock.getIdentityHashCode()).append("> (a "); sb.append(lock.getClassName()).append(")"); } public static void printStack(ThreadInfo info, final StringBuilder sb, final StackTraceElement[] stack) { int i = 0; for (final StackTraceElement element : stack) { sb.append("\tat ").append(element.toString()); sb.append('\n'); if (i == 0 && info.getLockInfo() != null) { final Thread.State ts = info.getThreadState(); switch (ts) { case BLOCKED: sb.append("\t- blocked on "); formatLock(sb, info.getLockInfo()); sb.append('\n'); break; case WAITING: sb.append("\t- waiting on "); formatLock(sb, info.getLockInfo()); sb.append('\n'); break; case TIMED_WAITING: sb.append("\t- waiting on "); formatLock(sb, info.getLockInfo()); sb.append('\n'); break; default: } } for (final MonitorInfo mi : info.getLockedMonitors()) { if (mi.getLockedStackDepth() == i) { sb.append("\t- locked "); formatLock(sb, mi); sb.append('\n'); } } ++i; } final LockInfo[] locks = info.getLockedSynchronizers(); if (locks.length > 0) { sb.append("\n\tNumber of locked synchronizers = ").append(locks.length).append('\n'); for (final LockInfo li : locks) { sb.append("\t- "); formatLock(sb, li); sb.append('\n'); } } } private static StackTraceElement[] getStackForThread(long id) { for (Map.Entry<Thread, StackTraceElement[]> entry : Thread.getAllStackTraces().entrySet()) { if (entry.getKey().getId() == id) { return entry.getValue(); } } return new StackTraceElement[0]; } }