com.alibaba.metrics.jvm.ThreadDeadlockDetector Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package com.alibaba.metrics.jvm;
import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
/**
* A utility class for detecting deadlocked threads.
*/
public class ThreadDeadlockDetector {
private static final int MAX_STACK_TRACE_DEPTH = 100;
private final ThreadMXBean threads;
/**
* Creates a new detector.
*/
public ThreadDeadlockDetector() {
this(ManagementFactory.getThreadMXBean());
}
/**
* Creates a new detector using the given {@link ThreadMXBean}.
*
* @param threads a {@link ThreadMXBean}
*/
public ThreadDeadlockDetector(ThreadMXBean threads) {
this.threads = threads;
}
/**
* Returns a set of diagnostic stack traces for any deadlocked threads. If no threads are
* deadlocked, returns an empty set.
*
* @return stack traces for deadlocked threads or an empty set
*/
public Set getDeadlockedThreads() {
final long[] ids = threads.findDeadlockedThreads();
if (ids != null) {
final Set deadlocks = new HashSet();
for (ThreadInfo info : threads.getThreadInfo(ids, MAX_STACK_TRACE_DEPTH)) {
final StringBuilder stackTrace = new StringBuilder();
for (StackTraceElement element : info.getStackTrace()) {
stackTrace.append("\t at ")
.append(element.toString())
.append(String.format("%n"));
}
deadlocks.add(
String.format("%s locked on %s (owned by %s):%n%s",
info.getThreadName(),
info.getLockName(),
info.getLockOwnerName(),
stackTrace.toString()
)
);
}
return Collections.unmodifiableSet(deadlocks);
}
return Collections.emptySet();
}
public int getDeadlockedThreadCount() {
return threads.findDeadlockedThreads() == null ? 0 : threads.findDeadlockedThreads().length;
}
}