org.apache.hadoop.mapred.ShuffleExceptionTracker.java Source code

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Here is the source code for org.apache.hadoop.mapred.ShuffleExceptionTracker.java

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/**
 * 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 org.apache.hadoop.mapred;

import java.io.IOException;
import java.util.BitSet;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * This class is used to track shuffle exceptions. It contains routines
 * to check an exception that occurred while fetching the Map output to see if it
 * matches what was configured. It also provides functions to keep track of
 * the number of exceptions that occurred and if a limit is set, it will
 * abort the TT.  The limit is a percent of exceptions of the last X number of
 * requests.
 *
 */
public class ShuffleExceptionTracker {
    public static final Log LOG = LogFactory.getLog(ShuffleExceptionTracker.class);

    // a clear bit is success, set bit is exception occurred
    private BitSet requests;
    final private int size;
    private int index;
    final private String exceptionStackRegex;
    final private String exceptionMsgRegex;
    final private float shuffleExceptionLimit;

    /**
     * Constructor
     *
     * @param numberRequests
     *          the tailing number of requests to track
     * @param exceptionStackRegex
     *          the exception stack regular expression to look for
     * @param exceptionMsgRegex
     *          the exception message regular expression to look for
     * @param shuffleExceptionLimit
     *          the exception limit (0-1.0) representing a percent. 0 disables the
     *          abort check.
     */
    ShuffleExceptionTracker(int numberRequests, String exceptionStackRegex, String exceptionMsgRegex,
            float shuffleExceptionLimit) {
        this.exceptionStackRegex = exceptionStackRegex;
        this.exceptionMsgRegex = exceptionMsgRegex;
        this.shuffleExceptionLimit = shuffleExceptionLimit;
        this.size = numberRequests;
        this.index = 0;
        this.requests = new BitSet(size);
    }

    /**
     * Gets the number of requests we are tracking
     *
     * @return number of requests
     */
    public int getNumRequests() {
        return this.size;
    }

    /**
     * Gets the percent of the requests that had exceptions occur.
     *
     * @return percent failures as float
     */
    public synchronized float getPercentExceptions() {
        return (float) requests.cardinality() / (float) size;
    }

    /**
     * Mark the request as success.
     */
    public synchronized void success() {
        if (shuffleExceptionLimit > 0) {
            requests.clear(index);
            incrIndex();
        }
    }

    /**
     * Mark the request as an exception occurred.
     */
    public synchronized void exception() {
        if (shuffleExceptionLimit > 0) {
            requests.set(index);
            incrIndex();
        }
    }

    /**
     * Parse the exception to see if it matches the regular expression you
     * configured. If both msgRegex and StackRegex are set then make sure both
     * match, otherwise only one has to match. Abort if the limit is hit.
     * @param ie - the shuffle exception that occurred
     * @return true if the exception matches, false otherwise
     */
    public boolean checkException(IOException ie) {
        if (exceptionMsgRegex != null) {
            String msg = ie.getMessage();
            if (msg == null || !msg.matches(exceptionMsgRegex)) {
                // for exception tracking purposes, if the exception didn't
                // match the one we are looking for consider it a successful
                // request
                this.success();
                return false;
            }
        }
        if (exceptionStackRegex != null && !checkStackException(ie)) {
            this.success();
            return false;
        }
        this.exception();
        if (shuffleExceptionLimit > 0 && this.getPercentExceptions() >= shuffleExceptionLimit) {
            LOG.fatal("************************************************************\n"
                    + "Shuffle exception count is greater than the fatal limit: " + shuffleExceptionLimit
                    + "Aborting JVM.\n" + "************************************************************");
            doAbort();
        }

        return true;
    }

    private boolean checkStackException(IOException ie) {
        StackTraceElement[] stack = ie.getStackTrace();

        for (StackTraceElement elem : stack) {
            String stacktrace = elem.toString();
            if (stacktrace.matches(exceptionStackRegex)) {
                return true;
            }
        }
        return false;
    }

    protected void doAbort() {
        System.exit(1);
    }

    private void incrIndex() {
        if (index == (size - 1)) {
            index = 0;
        } else {
            index++;
        }
    }

}