org.apache.tez.mapreduce.processor.SimpleMRProcessor.java Source code

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Here is the source code for org.apache.tez.mapreduce.processor.SimpleMRProcessor.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.tez.mapreduce.processor;

import java.io.IOException;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.classification.InterfaceAudience.Public;
import org.apache.hadoop.classification.InterfaceStability.Evolving;
import org.apache.tez.mapreduce.output.MROutput;
import org.apache.tez.runtime.api.LogicalOutput;
import org.apache.tez.runtime.api.Processor;
import org.apache.tez.runtime.api.ProcessorContext;
import org.apache.tez.runtime.library.processor.SimpleProcessor;

import com.google.common.collect.Lists;

/**
 * A {@link SimpleProcessor} that provides Map Reduce specific post
 * processing by calling commit (if needed) on all {@link MROutput}s 
 * connected to this {@link Processor}. 
 */
@Public
@Evolving
public abstract class SimpleMRProcessor extends SimpleProcessor {
    private static final Logger LOG = LoggerFactory.getLogger(SimpleMRProcessor.class);

    public SimpleMRProcessor(ProcessorContext context) {
        super(context);
    }

    @Override
    protected void postOp() throws Exception {
        if (getOutputs() == null) {
            return; // No post op
        }
        List<MROutput> mrOuts = Lists.newLinkedList();
        for (LogicalOutput output : getOutputs().values()) {
            if (output instanceof MROutput) {
                MROutput mrOutput = (MROutput) output;
                mrOutput.flush();
                if (mrOutput.isCommitRequired()) {
                    mrOuts.add((MROutput) output);
                }
            }
        }
        if (mrOuts.size() > 0) {
            // This will loop till the AM asks for the task to be killed. As
            // against, the AM sending a signal to the task to kill itself
            // gracefully. The AM waits for the current committer to successfully
            // complete and then kills us. Until then we wait in case the
            // current committer fails and we get chosen to commit.
            while (!getContext().canCommit()) {
                Thread.sleep(100);
            }
            boolean willAbort = false;
            Exception savedEx = null;
            for (MROutput output : mrOuts) {
                try {
                    output.commit();
                } catch (IOException ioe) {
                    LOG.warn("Error in committing output", ioe);
                    willAbort = true;
                    savedEx = ioe;
                    break;
                }
            }
            if (willAbort == true) {
                for (MROutput output : mrOuts) {
                    try {
                        output.abort();
                    } catch (IOException ioe) {
                        LOG.warn("Error in aborting output", ioe);
                    }
                }
                throw savedEx;
            }
        }
    }
}