| /* |
| * Copyright (c) 2004, 2006, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| package sun.jvm.hotspot.runtime; |
| |
| import sun.jvm.hotspot.debugger.*; |
| import sun.jvm.hotspot.memory.*; |
| import sun.jvm.hotspot.oops.*; |
| import java.io.*; |
| import java.util.*; |
| import java.util.Map.Entry; |
| |
| /** Prints information about Java-level deadlocks in supplied 'tty'. */ |
| |
| public class DeadlockDetector { |
| |
| public static void print(PrintStream tty) { |
| print(tty, true); |
| } |
| |
| /** prints zero or more deadlocks into 'tty' taking current |
| snapshot of Java threads and locks */ |
| public static void print(PrintStream tty, boolean concurrentLocks) { |
| tty.println("Deadlock Detection:"); |
| tty.println(); |
| |
| int globalDfn = 0, thisDfn; |
| int numberOfDeadlocks = 0; |
| JavaThread currentThread = null, previousThread = null; |
| ObjectMonitor waitingToLockMonitor = null; |
| Oop waitingToLockBlocker = null; |
| |
| threads = VM.getVM().getThreads(); |
| heap = VM.getVM().getObjectHeap(); |
| createThreadTable(); |
| |
| Iterator i = threadTable.entrySet().iterator(); |
| while (i.hasNext()) { |
| Entry e = (Entry)i.next(); |
| if (dfn(e) >= 0) { |
| // this thread was already visited |
| continue; |
| } |
| |
| thisDfn = globalDfn; |
| JavaThread thread = (JavaThread)e.getKey(); |
| previousThread = thread; |
| |
| // When there is a deadlock, all the monitors involved in the dependency |
| // cycle must be contended and heavyweight. So we only care about the |
| // heavyweight monitor a thread is waiting to lock. |
| try { |
| waitingToLockMonitor = thread.getCurrentPendingMonitor(); |
| } catch (RuntimeException re) { |
| tty.println("This version of HotSpot VM doesn't support deadlock detection."); |
| return; |
| } |
| |
| Klass abstractOwnableSyncKlass = null; |
| if (concurrentLocks) { |
| waitingToLockBlocker = thread.getCurrentParkBlocker(); |
| SystemDictionary sysDict = VM.getVM().getSystemDictionary(); |
| abstractOwnableSyncKlass = sysDict.getAbstractOwnableSynchronizerKlass(); |
| } |
| |
| while (waitingToLockMonitor != null || |
| waitingToLockBlocker != null) { |
| if (waitingToLockMonitor != null) { |
| currentThread = threads.owningThreadFromMonitor(waitingToLockMonitor); |
| } else { |
| if (concurrentLocks) { |
| if (waitingToLockBlocker.isA(abstractOwnableSyncKlass)) { |
| Oop threadOop = OopUtilities.abstractOwnableSynchronizerGetOwnerThread(waitingToLockBlocker); |
| if (threadOop != null) { |
| currentThread = OopUtilities.threadOopGetJavaThread(threadOop); |
| } |
| } |
| } |
| } |
| if (currentThread == null) { |
| // No dependency on another thread |
| break; |
| } |
| if (dfn(currentThread) < 0) { |
| // First visit to this thread |
| threadTable.put(currentThread, new Integer(globalDfn++)); |
| } else if (dfn(currentThread) < thisDfn) { |
| // Thread already visited, and not on a (new) cycle |
| break; |
| } else if (currentThread == previousThread) { |
| // Self-loop, ignore |
| break; |
| } else { |
| // We have a (new) cycle |
| numberOfDeadlocks ++; |
| printOneDeadlock(tty, currentThread, concurrentLocks); |
| break; |
| } |
| previousThread = currentThread; |
| waitingToLockMonitor = (ObjectMonitor)currentThread.getCurrentPendingMonitor(); |
| if (concurrentLocks) { |
| waitingToLockBlocker = currentThread.getCurrentParkBlocker(); |
| } |
| } |
| } |
| |
| switch (numberOfDeadlocks) { |
| case 0: |
| tty.println("No deadlocks found."); |
| break; |
| case 1: |
| tty.println("Found a total of 1 deadlock."); |
| break; |
| default: |
| tty.println("Found a total of " + numberOfDeadlocks + " deadlocks."); |
| break; |
| } |
| tty.println(); |
| } |
| |
| //-- Internals only below this point |
| private static Threads threads; |
| private static ObjectHeap heap; |
| private static HashMap threadTable; |
| |
| private static void createThreadTable() { |
| threadTable = new HashMap(); |
| for (JavaThread cur = threads.first(); cur != null; cur = cur.next()) { |
| // initialize dfn for each thread to -1 |
| threadTable.put(cur, new Integer(-1)); |
| } |
| } |
| |
| private static int dfn(JavaThread thread) { |
| Object obj = threadTable.get(thread); |
| if (obj != null) { |
| return ((Integer)obj).intValue(); |
| } |
| return -1; |
| } |
| |
| private static int dfn(Entry e) { |
| return ((Integer)e.getValue()).intValue(); |
| } |
| |
| private static void printOneDeadlock(PrintStream tty, JavaThread thread, |
| boolean concurrentLocks) { |
| tty.println("Found one Java-level deadlock:"); |
| tty.println("============================="); |
| ObjectMonitor waitingToLockMonitor = null; |
| Oop waitingToLockBlocker = null; |
| JavaThread currentThread = thread; |
| do { |
| tty.println(); |
| tty.println("\"" + currentThread.getThreadName() + "\":"); |
| waitingToLockMonitor = currentThread.getCurrentPendingMonitor(); |
| if (waitingToLockMonitor != null) { |
| tty.print(" waiting to lock Monitor@" + waitingToLockMonitor.getAddress()); |
| OopHandle obj = waitingToLockMonitor.object(); |
| Oop oop = heap.newOop(obj); |
| if (obj != null) { |
| tty.print(" (Object@"); |
| Oop.printOopAddressOn(oop, tty); |
| tty.print(", a " + oop.getKlass().getName().asString() + ")" ); |
| tty.print(",\n which is held by"); |
| } else { |
| // No Java object associated - a raw monitor |
| tty.print(" (raw monitor),\n which is held by"); |
| } |
| currentThread = threads.owningThreadFromMonitor(waitingToLockMonitor); |
| tty.print(" \"" + currentThread.getThreadName() + "\""); |
| } else if (concurrentLocks) { |
| waitingToLockBlocker = currentThread.getCurrentParkBlocker(); |
| tty.print(" waiting for ownable synchronizer "); |
| Oop.printOopAddressOn(waitingToLockBlocker, tty); |
| tty.print(", (a " + waitingToLockBlocker.getKlass().getName().asString() + ")" ); |
| Oop threadOop = OopUtilities.abstractOwnableSynchronizerGetOwnerThread(waitingToLockBlocker); |
| currentThread = OopUtilities.threadOopGetJavaThread(threadOop); |
| tty.print(",\n which is held by"); |
| tty.print(" \"" + currentThread.getThreadName() + "\""); |
| } |
| } while (!currentThread.equals(thread)); |
| tty.println(); |
| tty.println(); |
| } |
| } |