001/**
002* Licensed to the Apache Software Foundation (ASF) under one
003* or more contributor license agreements.  See the NOTICE file
004* distributed with this work for additional information
005* regarding copyright ownership.  The ASF licenses this file
006* to you under the Apache License, Version 2.0 (the
007* "License"); you may not use this file except in compliance
008* with the License.  You may obtain a copy of the License at
009*
010*     http://www.apache.org/licenses/LICENSE-2.0
011*
012* Unless required by applicable law or agreed to in writing, software
013* distributed under the License is distributed on an "AS IS" BASIS,
014* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015* See the License for the specific language governing permissions and
016* limitations under the License.
017*/
018
019package org.apache.hadoop.yarn;
020
021import java.lang.Thread.UncaughtExceptionHandler;
022
023import org.apache.commons.logging.Log;
024import org.apache.commons.logging.LogFactory;
025import org.apache.hadoop.classification.InterfaceAudience.Public;
026import org.apache.hadoop.classification.InterfaceStability.Evolving;
027import org.apache.hadoop.util.ExitUtil;
028import org.apache.hadoop.util.ShutdownHookManager;
029
030/**
031 * This class is intended to be installed by calling 
032 * {@link Thread#setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler)}
033 * In the main entry point.  It is intended to try and cleanly shut down
034 * programs using the Yarn Event framework.
035 * 
036 * Note: Right now it only will shut down the program if a Error is caught, but
037 * not any other exception.  Anything else is just logged.
038 */
039@Public
040@Evolving
041public class YarnUncaughtExceptionHandler implements UncaughtExceptionHandler {
042  private static final Log LOG = LogFactory.getLog(YarnUncaughtExceptionHandler.class);
043  
044  @Override
045  public void uncaughtException(Thread t, Throwable e) {
046    if(ShutdownHookManager.get().isShutdownInProgress()) {
047      LOG.error("Thread " + t + " threw an Throwable, but we are shutting " +
048                "down, so ignoring this", e);
049    } else if(e instanceof Error) {
050      try {
051        LOG.fatal("Thread " + t + " threw an Error.  Shutting down now...", e);
052      } catch (Throwable err) {
053        //We don't want to not exit because of an issue with logging
054      }
055      if(e instanceof OutOfMemoryError) {
056        //After catching an OOM java says it is undefined behavior, so don't
057        //even try to clean up or we can get stuck on shutdown.
058        try {
059          System.err.println("Halting due to Out Of Memory Error...");
060        } catch (Throwable err) {
061          //Again we done want to exit because of logging issues.
062        }
063        ExitUtil.halt(-1);
064      } else {
065        ExitUtil.terminate(-1);
066      }
067    } else {
068      LOG.error("Thread " + t + " threw an Exception.", e);
069    }
070  }
071}