/**
* 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.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.LocalFileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.apache.hadoop.io.DataOutputBuffer;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.io.serializer.SerializationFactory;
import org.apache.hadoop.io.serializer.Serializer;
import org.apache.hadoop.mapred.Task.TaskReporter;
import junit.framework.TestCase;
@SuppressWarnings(value={"unchecked", "deprecation"})
/**
* This test tests the support for a merge operation in Hadoop. The input files
* are already sorted on the key. This test implements an external
* MapOutputCollector implementation that just copies the records to different
* partitions while maintaining the sort order in each partition. The Hadoop
* framework's merge on the reduce side will merge the partitions created to
* generate the final output which is sorted on the key.
*/
public class TestMerge extends TestCase {
private static final int NUM_HADOOP_DATA_NODES = 2;
// Number of input files is same as the number of mappers.
private static final int NUM_MAPPERS = 10;
// Number of reducers.
private static final int NUM_REDUCERS = 4;
// Number of lines per input file.
private static final int NUM_LINES = 1000;
// Where MR job's input will reside.
private static final Path INPUT_DIR = new Path("/testplugin/input");
// Where output goes.
private static final Path OUTPUT = new Path("/testplugin/output");
public void testMerge() throws Exception {
MiniDFSCluster dfsCluster = null;
MiniMRClientCluster mrCluster = null;
FileSystem fileSystem = null;
try {
Configuration conf = new Configuration();
// Start the mini-MR and mini-DFS clusters
dfsCluster = new MiniDFSCluster(conf, NUM_HADOOP_DATA_NODES, true, null);
fileSystem = dfsCluster.getFileSystem();
mrCluster = MiniMRClientClusterFactory.create(this.getClass(),
NUM_HADOOP_DATA_NODES, conf);
// Generate input.
createInput(fileSystem);
// Run the test.
runMergeTest(new JobConf(mrCluster.getConfig()), fileSystem);
} finally {
if (dfsCluster != null) {
dfsCluster.shutdown();
}
if (mrCluster != null) {
mrCluster.stop();
}
}
}
private void createInput(FileSystem fs) throws Exception {
fs.delete(INPUT_DIR, true);
for (int i = 0; i < NUM_MAPPERS; i++) {
OutputStream os = fs.create(new Path(INPUT_DIR, "input_" + i + ".txt"));
Writer writer = new OutputStreamWriter(os);
for (int j = 0; j < NUM_LINES; j++) {
// Create sorted key, value pairs.
int k = j + 1;
String formattedNumber = String.format("%09d", k);
writer.write(formattedNumber + " " + formattedNumber + "\n");
}
writer.close();
}
}
private void runMergeTest(JobConf job, FileSystem fileSystem)
throws Exception {
// Delete any existing output.
fileSystem.delete(OUTPUT, true);
job.setJobName("MergeTest");
JobClient client = new JobClient(job);
RunningJob submittedJob = null;
FileInputFormat.setInputPaths(job, INPUT_DIR);
FileOutputFormat.setOutputPath(job, OUTPUT);
job.set("mapreduce.output.textoutputformat.separator", " ");
job.setInputFormat(TextInputFormat.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(Text.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
job.setMapperClass(MyMapper.class);
job.setPartitionerClass(MyPartitioner.class);
job.setOutputFormat(TextOutputFormat.class);
job.setNumReduceTasks(NUM_REDUCERS);
job.set(JobContext.MAP_OUTPUT_COLLECTOR_CLASS_ATTR,
MapOutputCopier.class.getName());
try {
submittedJob = client.submitJob(job);
try {
if (! client.monitorAndPrintJob(job, submittedJob)) {
throw new IOException("Job failed!");
}
} catch(InterruptedException ie) {
Thread.currentThread().interrupt();
}
} catch(IOException ioe) {
System.err.println("Job failed with: " + ioe);
} finally {
verifyOutput(submittedJob, fileSystem);
}
}
private void verifyOutput(RunningJob submittedJob, FileSystem fileSystem)
throws Exception {
FSDataInputStream dis = null;
long numValidRecords = 0;
long numInvalidRecords = 0;
long numMappersLaunched = NUM_MAPPERS;
String prevKeyValue = "000000000";
Path[] fileList =
FileUtil.stat2Paths(fileSystem.listStatus(OUTPUT,
new Utils.OutputFileUtils.OutputFilesFilter()));
for (Path outFile : fileList) {
try {
dis = fileSystem.open(outFile);
String record;
while((record = dis.readLine()) != null) {
// Split the line into key and value.
int blankPos = record.indexOf(" ");
String keyString = record.substring(0, blankPos);
String valueString = record.substring(blankPos+1);
// Check for sorted output and correctness of record.
if (keyString.compareTo(prevKeyValue) >= 0
&& keyString.equals(valueString)) {
prevKeyValue = keyString;
numValidRecords++;
} else {
numInvalidRecords++;
}
}
} finally {
if (dis != null) {
dis.close();
dis = null;
}
}
}
// Make sure we got all input records in the output in sorted order.
assertEquals((long)(NUM_MAPPERS*NUM_LINES), numValidRecords);
// Make sure there is no extraneous invalid record.
assertEquals(0, numInvalidRecords);
}
/**
* A mapper implementation that assumes that key text contains valid integers
* in displayable form.
*/
public static class MyMapper extends MapReduceBase
implements Mapper<LongWritable, Text, Text, Text> {
private Text keyText;
private Text valueText;
public MyMapper() {
keyText = new Text();
valueText = new Text();
}
@Override
public void map(LongWritable key, Text value,
OutputCollector<Text, Text> output,
Reporter reporter) throws IOException {
String record = value.toString();
int blankPos = record.indexOf(" ");
keyText.set(record.substring(0, blankPos));
valueText.set(record.substring(blankPos+1));
output.collect(keyText, valueText);
}
public void close() throws IOException {
}
}
/**
* Partitioner implementation to make sure that output is in total sorted
* order. We basically route key ranges to different reducers such that
* key values monotonically increase with the partition number. For example,
* in this test, the keys are numbers from 1 to 1000 in the form "000000001"
* to "000001000" in each input file. The keys "000000001" to "000000250" are
* routed to partition 0, "000000251" to "000000500" are routed to partition 1
* and so on since we have 4 reducers.
*/
static class MyPartitioner implements Partitioner<Text, Text> {
public MyPartitioner() {
}
public void configure(JobConf job) {
}
public int getPartition(Text key, Text value, int numPartitions) {
int keyValue = 0;
try {
keyValue = Integer.parseInt(key.toString());
} catch(NumberFormatException nfe) {
keyValue = 0;
}
int partitionNumber = (numPartitions*(Math.max(0, keyValue-1)))/NUM_LINES;
return partitionNumber;
}
}
/**
* Implementation of map output copier(that avoids sorting) on the map side.
* It maintains keys in the input order within each partition created for
* reducers.
*/
static class MapOutputCopier<K, V>
implements MapOutputCollector<K, V> {
private static final int BUF_SIZE = 128*1024;
private MapTask mapTask;
private JobConf jobConf;
private TaskReporter reporter;
private int numberOfPartitions;
private Class<K> keyClass;
private Class<V> valueClass;
private KeyValueWriter<K, V> recordWriters[];
private ByteArrayOutputStream outStreams[];
public MapOutputCopier() {
}
@SuppressWarnings("unchecked")
public void init(MapOutputCollector.Context context)
throws IOException, ClassNotFoundException {
this.mapTask = context.getMapTask();
this.jobConf = context.getJobConf();
this.reporter = context.getReporter();
numberOfPartitions = jobConf.getNumReduceTasks();
keyClass = (Class<K>)jobConf.getMapOutputKeyClass();
valueClass = (Class<V>)jobConf.getMapOutputValueClass();
recordWriters = new KeyValueWriter[numberOfPartitions];
outStreams = new ByteArrayOutputStream[numberOfPartitions];
// Create output streams for partitions.
for (int i = 0; i < numberOfPartitions; i++) {
outStreams[i] = new ByteArrayOutputStream();
recordWriters[i] = new KeyValueWriter<K, V>(jobConf, outStreams[i],
keyClass, valueClass);
}
}
public synchronized void collect(K key, V value, int partitionNumber
) throws IOException, InterruptedException {
if (partitionNumber >= 0 && partitionNumber < numberOfPartitions) {
recordWriters[partitionNumber].write(key, value);
} else {
throw new IOException("Invalid partition number: " + partitionNumber);
}
reporter.progress();
}
public void close() throws IOException, InterruptedException {
long totalSize = 0;
for (int i = 0; i < numberOfPartitions; i++) {
recordWriters[i].close();
outStreams[i].close();
totalSize += outStreams[i].size();
}
MapOutputFile mapOutputFile = mapTask.getMapOutputFile();
Path finalOutput = mapOutputFile.getOutputFileForWrite(totalSize);
Path indexPath = mapOutputFile.getOutputIndexFileForWrite(
numberOfPartitions*mapTask.MAP_OUTPUT_INDEX_RECORD_LENGTH);
// Copy partitions to final map output.
copyPartitions(finalOutput, indexPath);
}
public void flush() throws IOException, InterruptedException,
ClassNotFoundException {
}
private void copyPartitions(Path mapOutputPath, Path indexPath)
throws IOException {
FileSystem localFs = FileSystem.getLocal(jobConf);
FileSystem rfs = ((LocalFileSystem)localFs).getRaw();
FSDataOutputStream rawOutput = rfs.create(mapOutputPath, true, BUF_SIZE);
SpillRecord spillRecord = new SpillRecord(numberOfPartitions);
IndexRecord indexRecord = new IndexRecord();
for (int i = 0; i < numberOfPartitions; i++) {
indexRecord.startOffset = rawOutput.getPos();
byte buffer[] = outStreams[i].toByteArray();
IFileOutputStream checksumOutput = new IFileOutputStream(rawOutput);
checksumOutput.write(buffer);
// Write checksum.
checksumOutput.finish();
// Write index record
indexRecord.rawLength = (long)buffer.length;
indexRecord.partLength = rawOutput.getPos() - indexRecord.startOffset;
spillRecord.putIndex(indexRecord, i);
reporter.progress();
}
rawOutput.close();
spillRecord.writeToFile(indexPath, jobConf);
}
}
static class KeyValueWriter<K, V> {
private Class<K> keyClass;
private Class<V> valueClass;
private DataOutputBuffer dataBuffer;
private Serializer<K> keySerializer;
private Serializer<V> valueSerializer;
private DataOutputStream outputStream;
public KeyValueWriter(Configuration conf, OutputStream output,
Class<K> kyClass, Class<V> valClass
) throws IOException {
keyClass = kyClass;
valueClass = valClass;
dataBuffer = new DataOutputBuffer();
SerializationFactory serializationFactory
= new SerializationFactory(conf);
keySerializer
= (Serializer<K>)serializationFactory.getSerializer(keyClass);
keySerializer.open(dataBuffer);
valueSerializer
= (Serializer<V>)serializationFactory.getSerializer(valueClass);
valueSerializer.open(dataBuffer);
outputStream = new DataOutputStream(output);
}
public void write(K key, V value) throws IOException {
if (key.getClass() != keyClass) {
throw new IOException("wrong key class: "+ key.getClass()
+" is not "+ keyClass);
}
if (value.getClass() != valueClass) {
throw new IOException("wrong value class: "+ value.getClass()
+" is not "+ valueClass);
}
// Append the 'key'
keySerializer.serialize(key);
int keyLength = dataBuffer.getLength();
if (keyLength < 0) {
throw new IOException("Negative key-length not allowed: " + keyLength +
" for " + key);
}
// Append the 'value'
valueSerializer.serialize(value);
int valueLength = dataBuffer.getLength() - keyLength;
if (valueLength < 0) {
throw new IOException("Negative value-length not allowed: " +
valueLength + " for " + value);
}
// Write the record out
WritableUtils.writeVInt(outputStream, keyLength);
WritableUtils.writeVInt(outputStream, valueLength);
outputStream.write(dataBuffer.getData(), 0, dataBuffer.getLength());
// Reset
dataBuffer.reset();
}
public void close() throws IOException {
keySerializer.close();
valueSerializer.close();
WritableUtils.writeVInt(outputStream, IFile.EOF_MARKER);
WritableUtils.writeVInt(outputStream, IFile.EOF_MARKER);
outputStream.close();
}
}
}