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MAPREDUCE-4808. Refactor MapOutput and MergeManager to facilitate reuse by Shuffle implementations. (masokan via tucu) 

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1436936 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Alejandro Abdelnur 2013-01-22 14:10:42 +00:00
parent cfae13306a
commit 73fd247c76
13 changed files with 1163 additions and 1062 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
hadoop-mapreduce-project/CHANGES.txt
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@ -19,6 +19,8 @@ Trunk (Unreleased)
MAPREDUCE-4887. Add RehashPartitioner, to smooth distributions
with poor implementations of Object#hashCode(). (Radim Kolar via cutting)
MAPREDUCE-4808. Refactor MapOutput and MergeManager to facilitate reuse by Shuffle implementations. (masokan via tucu)
IMPROVEMENTS
MAPREDUCE-3787. [Gridmix] Optimize job monitoring and STRESS mode for

2
hadoop-mapreduce-project/dev-support/findbugs-exclude.xml
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@ -268,7 +268,7 @@
This class is unlikely to get subclassed, so ignore
-->
<Match>
<Class name="org.apache.hadoop.mapreduce.task.reduce.MergeManager" />
<Class name="org.apache.hadoop.mapreduce.task.reduce.MergeManagerImpl" />
<Bug pattern="SC_START_IN_CTOR" />
</Match>

124
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/Fetcher.java
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@ -19,8 +19,6 @@ package org.apache.hadoop.mapreduce.task.reduce;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ConnectException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
@ -38,12 +36,7 @@ import javax.net.ssl.HttpsURLConnection;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.io.compress.CodecPool;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.Decompressor;
import org.apache.hadoop.io.compress.DefaultCodec;
import org.apache.hadoop.mapred.Counters;
import org.apache.hadoop.mapred.IFileInputStream;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapreduce.MRConfig;
@ -51,9 +44,6 @@ import org.apache.hadoop.mapreduce.MRJobConfig;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import org.apache.hadoop.mapreduce.security.SecureShuffleUtils;
import org.apache.hadoop.security.ssl.SSLFactory;
import org.apache.hadoop.mapreduce.task.reduce.MapOutput.Type;
import org.apache.hadoop.util.Progressable;
import org.apache.hadoop.util.ReflectionUtils;
import com.google.common.annotations.VisibleForTesting;
@ -70,7 +60,7 @@ class Fetcher<K,V> extends Thread {
/* Default read timeout (in milliseconds) */
private final static int DEFAULT_READ_TIMEOUT = 3 * 60 * 1000;
private final Progressable reporter;
private final Reporter reporter;
private static enum ShuffleErrors{IO_ERROR, WRONG_LENGTH, BAD_ID, WRONG_MAP,
CONNECTION, WRONG_REDUCE}
@ -92,15 +82,10 @@ class Fetcher<K,V> extends Thread {
private final int connectionTimeout;
private final int readTimeout;
// Decompression of map-outputs
private final CompressionCodec codec;
private final Decompressor decompressor;
private final SecretKey jobTokenSecret;
private volatile boolean stopped = false;
private JobConf job;
private static boolean sslShuffle;
private static SSLFactory sslFactory;
@ -108,7 +93,6 @@ class Fetcher<K,V> extends Thread {
ShuffleScheduler<K,V> scheduler, MergeManager<K,V> merger,
Reporter reporter, ShuffleClientMetrics metrics,
ExceptionReporter exceptionReporter, SecretKey jobTokenSecret) {
this.job = job;
this.reporter = reporter;
this.scheduler = scheduler;
this.merger = merger;
@ -130,16 +114,6 @@ class Fetcher<K,V> extends Thread {
wrongReduceErrs = reporter.getCounter(SHUFFLE_ERR_GRP_NAME,
ShuffleErrors.WRONG_REDUCE.toString());
if (job.getCompressMapOutput()) {
Class<? extends CompressionCodec> codecClass =
job.getMapOutputCompressorClass(DefaultCodec.class);
codec = ReflectionUtils.newInstance(codecClass, job);
decompressor = CodecPool.getDecompressor(codec);
} else {
codec = null;
decompressor = null;
}
this.connectionTimeout =
job.getInt(MRJobConfig.SHUFFLE_CONNECT_TIMEOUT,
DEFAULT_STALLED_COPY_TIMEOUT);
@ -170,7 +144,7 @@ class Fetcher<K,V> extends Thread {
MapHost host = null;
try {
// If merge is on, block
merger.waitForInMemoryMerge();
merger.waitForResource();
// Get a host to shuffle from
host = scheduler.getHost();
@ -386,8 +360,8 @@ class Fetcher<K,V> extends Thread {
mapOutput = merger.reserve(mapId, decompressedLength, id);
// Check if we can shuffle *now* ...
if (mapOutput.getType() == Type.WAIT) {
LOG.info("fetcher#" + id + " - MergerManager returned Status.WAIT ...");
if (mapOutput == null) {
LOG.info("fetcher#" + id + " - MergeManager returned status WAIT ...");
//Not an error but wait to process data.
return EMPTY_ATTEMPT_ID_ARRAY;
}
@ -396,13 +370,9 @@ class Fetcher<K,V> extends Thread {
LOG.info("fetcher#" + id + " about to shuffle output of map " +
mapOutput.getMapId() + " decomp: " +
decompressedLength + " len: " + compressedLength + " to " +
mapOutput.getType());
if (mapOutput.getType() == Type.MEMORY) {
shuffleToMemory(host, mapOutput, input,
(int) decompressedLength, (int) compressedLength);
} else {
shuffleToDisk(host, mapOutput, input, compressedLength);
}
mapOutput.getDescription());
mapOutput.shuffle(host, input, compressedLength, decompressedLength,
metrics, reporter);
// Inform the shuffle scheduler
long endTime = System.currentTimeMillis();
@ -538,84 +508,4 @@ class Fetcher<K,V> extends Thread {
}
}
}
private void shuffleToMemory(MapHost host, MapOutput<K,V> mapOutput,
InputStream input,
int decompressedLength,
int compressedLength) throws IOException {
IFileInputStream checksumIn =
new IFileInputStream(input, compressedLength, job);
input = checksumIn;
// Are map-outputs compressed?
if (codec != null) {
decompressor.reset();
input = codec.createInputStream(input, decompressor);
}
// Copy map-output into an in-memory buffer
byte[] shuffleData = mapOutput.getMemory();
try {
IOUtils.readFully(input, shuffleData, 0, shuffleData.length);
metrics.inputBytes(shuffleData.length);
reporter.progress();
LOG.info("Read " + shuffleData.length + " bytes from map-output for " +
mapOutput.getMapId());
} catch (IOException ioe) {
// Close the streams
IOUtils.cleanup(LOG, input);
// Re-throw
throw ioe;
}
}
private void shuffleToDisk(MapHost host, MapOutput<K,V> mapOutput,
InputStream input,
long compressedLength)
throws IOException {
// Copy data to local-disk
OutputStream output = mapOutput.getDisk();
long bytesLeft = compressedLength;
try {
final int BYTES_TO_READ = 64 * 1024;
byte[] buf = new byte[BYTES_TO_READ];
while (bytesLeft > 0) {
int n = input.read(buf, 0, (int) Math.min(bytesLeft, BYTES_TO_READ));
if (n < 0) {
throw new IOException("read past end of stream reading " +
mapOutput.getMapId());
}
output.write(buf, 0, n);
bytesLeft -= n;
metrics.inputBytes(n);
reporter.progress();
}
LOG.info("Read " + (compressedLength - bytesLeft) +
" bytes from map-output for " +
mapOutput.getMapId());
output.close();
} catch (IOException ioe) {
// Close the streams
IOUtils.cleanup(LOG, input, output);
// Re-throw
throw ioe;
}
// Sanity check
if (bytesLeft != 0) {
throw new IOException("Incomplete map output received for " +
mapOutput.getMapId() + " from " +
host.getHostName() + " (" +
bytesLeft + " bytes missing of " +
compressedLength + ")"
);
}
}
}

127
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/InMemoryMapOutput.java Normal file
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@ -0,0 +1,127 @@
/**
* 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.mapreduce.task.reduce;
import java.io.InputStream;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.BoundedByteArrayOutputStream;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.io.compress.CodecPool;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.Decompressor;
import org.apache.hadoop.mapred.IFileInputStream;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapreduce.TaskAttemptID;
@InterfaceAudience.Private
@InterfaceStability.Unstable
class InMemoryMapOutput<K, V> extends MapOutput<K, V> {
private static final Log LOG = LogFactory.getLog(InMemoryMapOutput.class);
private Configuration conf;
private final MergeManagerImpl<K, V> merger;
private final byte[] memory;
private BoundedByteArrayOutputStream byteStream;
// Decompression of map-outputs
private final CompressionCodec codec;
private final Decompressor decompressor;
public InMemoryMapOutput(Configuration conf, TaskAttemptID mapId,
MergeManagerImpl<K, V> merger,
int size, CompressionCodec codec,
boolean primaryMapOutput) {
super(mapId, (long)size, primaryMapOutput);
this.conf = conf;
this.merger = merger;
this.codec = codec;
byteStream = new BoundedByteArrayOutputStream(size);
memory = byteStream.getBuffer();
if (codec != null) {
decompressor = CodecPool.getDecompressor(codec);
} else {
decompressor = null;
}
}
public byte[] getMemory() {
return memory;
}
public BoundedByteArrayOutputStream getArrayStream() {
return byteStream;
}
@Override
public void shuffle(MapHost host, InputStream input,
long compressedLength, long decompressedLength,
ShuffleClientMetrics metrics,
Reporter reporter) throws IOException {
IFileInputStream checksumIn =
new IFileInputStream(input, compressedLength, conf);
input = checksumIn;
// Are map-outputs compressed?
if (codec != null) {
decompressor.reset();
input = codec.createInputStream(input, decompressor);
}
try {
IOUtils.readFully(input, memory, 0, memory.length);
metrics.inputBytes(memory.length);
reporter.progress();
LOG.info("Read " + memory.length + " bytes from map-output for " +
getMapId());
} catch (IOException ioe) {
// Close the streams
IOUtils.cleanup(LOG, input);
// Re-throw
throw ioe;
} finally {
CodecPool.returnDecompressor(decompressor);
}
}
@Override
public void commit() throws IOException {
merger.closeInMemoryFile(this);
}
@Override
public void abort() {
merger.unreserve(memory.length);
}
@Override
public String getDescription() {
return "MEMORY";
}
}

4
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/InMemoryReader.java
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@ -35,12 +35,12 @@ import org.apache.hadoop.mapreduce.TaskAttemptID;
@InterfaceStability.Unstable
public class InMemoryReader<K, V> extends Reader<K, V> {
private final TaskAttemptID taskAttemptId;
private final MergeManager<K,V> merger;
private final MergeManagerImpl<K,V> merger;
DataInputBuffer memDataIn = new DataInputBuffer();
private int start;
private int length;
public InMemoryReader(MergeManager<K,V> merger, TaskAttemptID taskAttemptId,
public InMemoryReader(MergeManagerImpl<K,V> merger, TaskAttemptID taskAttemptId,
byte[] data, int start, int length)
throws IOException {
super(null, null, length - start, null, null);

155
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MapOutput.java
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@ -17,119 +17,36 @@
*/
package org.apache.hadoop.mapreduce.task.reduce;
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Comparator;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.LocalDirAllocator;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.BoundedByteArrayOutputStream;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapOutputFile;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapreduce.TaskAttemptID;
@InterfaceAudience.LimitedPrivate({"MapReduce"})
@InterfaceStability.Unstable
public class MapOutput<K,V> {
private static final Log LOG = LogFactory.getLog(MapOutput.class);
public abstract class MapOutput<K, V> {
private static AtomicInteger ID = new AtomicInteger(0);
public static enum Type {
WAIT,
MEMORY,
DISK
}
private final int id;
private final MergeManager<K,V> merger;
private final TaskAttemptID mapId;
private final long size;
private final byte[] memory;
private BoundedByteArrayOutputStream byteStream;
private final FileSystem localFS;
private final Path tmpOutputPath;
private final Path outputPath;
private final OutputStream disk;
private final Type type;
private final boolean primaryMapOutput;
public MapOutput(TaskAttemptID mapId, MergeManager<K,V> merger, long size,
JobConf conf, LocalDirAllocator localDirAllocator,
int fetcher, boolean primaryMapOutput, MapOutputFile mapOutputFile)
throws IOException {
public MapOutput(TaskAttemptID mapId, long size, boolean primaryMapOutput) {
this.id = ID.incrementAndGet();
this.mapId = mapId;
this.merger = merger;
type = Type.DISK;
memory = null;
byteStream = null;
this.size = size;
this.localFS = FileSystem.getLocal(conf);
outputPath =
mapOutputFile.getInputFileForWrite(mapId.getTaskID(),size);
tmpOutputPath = outputPath.suffix(String.valueOf(fetcher));
disk = localFS.create(tmpOutputPath);
this.primaryMapOutput = primaryMapOutput;
}
public MapOutput(TaskAttemptID mapId, MergeManager<K,V> merger, int size,
boolean primaryMapOutput) {
this.id = ID.incrementAndGet();
this.mapId = mapId;
this.merger = merger;
type = Type.MEMORY;
byteStream = new BoundedByteArrayOutputStream(size);
memory = byteStream.getBuffer();
this.size = size;
localFS = null;
disk = null;
outputPath = null;
tmpOutputPath = null;
this.primaryMapOutput = primaryMapOutput;
}
public MapOutput(TaskAttemptID mapId) {
this.id = ID.incrementAndGet();
this.mapId = mapId;
type = Type.WAIT;
merger = null;
memory = null;
byteStream = null;
size = -1;
localFS = null;
disk = null;
outputPath = null;
tmpOutputPath = null;
this.primaryMapOutput = false;
}
public boolean isPrimaryMapOutput() {
return primaryMapOutput;
}
@ -147,62 +64,28 @@ public class MapOutput<K,V> {
return id;
}
public Path getOutputPath() {
return outputPath;
}
public byte[] getMemory() {
return memory;
}
public BoundedByteArrayOutputStream getArrayStream() {
return byteStream;
}
public OutputStream getDisk() {
return disk;
}
public TaskAttemptID getMapId() {
return mapId;
}
public Type getType() {
return type;
}
public long getSize() {
return size;
}
public void commit() throws IOException {
if (type == Type.MEMORY) {
merger.closeInMemoryFile(this);
} else if (type == Type.DISK) {
localFS.rename(tmpOutputPath, outputPath);
merger.closeOnDiskFile(outputPath);
} else {
throw new IOException("Cannot commit MapOutput of type WAIT!");
}
}
public void abort() {
if (type == Type.MEMORY) {
merger.unreserve(memory.length);
} else if (type == Type.DISK) {
try {
localFS.delete(tmpOutputPath, false);
} catch (IOException ie) {
LOG.info("failure to clean up " + tmpOutputPath, ie);
}
} else {
throw new IllegalArgumentException
("Cannot commit MapOutput with of type WAIT!");
}
}
public abstract void shuffle(MapHost host, InputStream input,
long compressedLength,
long decompressedLength,
ShuffleClientMetrics metrics,
Reporter reporter) throws IOException;
public abstract void commit() throws IOException;
public abstract void abort();
public abstract String getDescription();
public String toString() {
return "MapOutput(" + mapId + ", " + type + ")";
return "MapOutput(" + mapId + ", " + getDescription() + ")";
}
public static class MapOutputComparator<K, V>

775
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManager.java
View File

@ -15,783 +15,56 @@
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.mapreduce.task.reduce;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.ChecksumFileSystem;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.LocalDirAllocator;
import org.apache.hadoop.fs.LocalFileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DataInputBuffer;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.mapred.Counters;
import org.apache.hadoop.mapred.IFile;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapOutputFile;
import org.apache.hadoop.mapred.Merger;
import org.apache.hadoop.mapred.RawKeyValueIterator;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.Task;
import org.apache.hadoop.mapred.IFile.Reader;
import org.apache.hadoop.mapred.IFile.Writer;
import org.apache.hadoop.mapred.Merger.Segment;
import org.apache.hadoop.mapred.Task.CombineOutputCollector;
import org.apache.hadoop.mapred.Task.CombineValuesIterator;
import org.apache.hadoop.mapreduce.MRJobConfig;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import org.apache.hadoop.mapreduce.TaskID;
import org.apache.hadoop.mapreduce.task.reduce.MapOutput.MapOutputComparator;
import org.apache.hadoop.util.Progress;
import org.apache.hadoop.util.ReflectionUtils;
import com.google.common.annotations.VisibleForTesting;
import java.io.IOException;
@SuppressWarnings(value={"unchecked"})
@InterfaceAudience.LimitedPrivate({"MapReduce"})
/**
* An interface for a reduce side merge that works with the default Shuffle
* implementation.
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public class MergeManager<K, V> {
private static final Log LOG = LogFactory.getLog(MergeManager.class);
/* Maximum percentage of the in-memory limit that a single shuffle can
* consume*/
private static final float DEFAULT_SHUFFLE_MEMORY_LIMIT_PERCENT
= 0.25f;
private final TaskAttemptID reduceId;
private final JobConf jobConf;
private final FileSystem localFS;
private final FileSystem rfs;
private final LocalDirAllocator localDirAllocator;
protected MapOutputFile mapOutputFile;
Set<MapOutput<K, V>> inMemoryMergedMapOutputs =
new TreeSet<MapOutput<K,V>>(new MapOutputComparator<K, V>());
private final IntermediateMemoryToMemoryMerger memToMemMerger;
Set<MapOutput<K, V>> inMemoryMapOutputs =
new TreeSet<MapOutput<K,V>>(new MapOutputComparator<K, V>());
private final MergeThread<MapOutput<K,V>, K,V> inMemoryMerger;
Set<Path> onDiskMapOutputs = new TreeSet<Path>();
private final OnDiskMerger onDiskMerger;
private final long memoryLimit;
private long usedMemory;
private long commitMemory;
private final long maxSingleShuffleLimit;
private final int memToMemMergeOutputsThreshold;
private final long mergeThreshold;
private final int ioSortFactor;
private final Reporter reporter;
private final ExceptionReporter exceptionReporter;
public interface MergeManager<K, V> {
/**
* Combiner class to run during in-memory merge, if defined.
* To wait until merge has some freed resources available so that it can
* accept shuffled data. This will be called before a network connection is
* established to get the map output.
*/
private final Class<? extends Reducer> combinerClass;
public void waitForResource() throws InterruptedException;
/**
* Resettable collector used for combine.
* To reserve resources for data to be shuffled. This will be called after
* a network connection is made to shuffle the data.
* @param mapId mapper from which data will be shuffled.
* @param requestedSize size in bytes of data that will be shuffled.
* @param fetcher id of the map output fetcher that will shuffle the data.
* @return a MapOutput object that can be used by shuffle to shuffle data. If
* required resources cannot be reserved immediately, a null can be returned.
*/
private final CombineOutputCollector<K,V> combineCollector;
public MapOutput<K, V> reserve(TaskAttemptID mapId, long requestedSize,
int fetcher) throws IOException;
private final Counters.Counter spilledRecordsCounter;
private final Counters.Counter reduceCombineInputCounter;
private final Counters.Counter mergedMapOutputsCounter;
private final CompressionCodec codec;
private final Progress mergePhase;
public MergeManager(TaskAttemptID reduceId, JobConf jobConf,
FileSystem localFS,
LocalDirAllocator localDirAllocator,
Reporter reporter,
CompressionCodec codec,
Class<? extends Reducer> combinerClass,
CombineOutputCollector<K,V> combineCollector,
Counters.Counter spilledRecordsCounter,
Counters.Counter reduceCombineInputCounter,
Counters.Counter mergedMapOutputsCounter,
ExceptionReporter exceptionReporter,
Progress mergePhase, MapOutputFile mapOutputFile) {
this.reduceId = reduceId;
this.jobConf = jobConf;
this.localDirAllocator = localDirAllocator;
this.exceptionReporter = exceptionReporter;
this.reporter = reporter;
this.codec = codec;
this.combinerClass = combinerClass;
this.combineCollector = combineCollector;
this.reduceCombineInputCounter = reduceCombineInputCounter;
this.spilledRecordsCounter = spilledRecordsCounter;
this.mergedMapOutputsCounter = mergedMapOutputsCounter;
this.mapOutputFile = mapOutputFile;
this.mapOutputFile.setConf(jobConf);
this.localFS = localFS;
this.rfs = ((LocalFileSystem)localFS).getRaw();
final float maxInMemCopyUse =
jobConf.getFloat(MRJobConfig.SHUFFLE_INPUT_BUFFER_PERCENT, 0.90f);
if (maxInMemCopyUse > 1.0 || maxInMemCopyUse < 0.0) {
throw new IllegalArgumentException("Invalid value for " +
MRJobConfig.SHUFFLE_INPUT_BUFFER_PERCENT + ": " +
maxInMemCopyUse);
}
// Allow unit tests to fix Runtime memory
this.memoryLimit =
(long)(jobConf.getLong(MRJobConfig.REDUCE_MEMORY_TOTAL_BYTES,
Math.min(Runtime.getRuntime().maxMemory(), Integer.MAX_VALUE))
* maxInMemCopyUse);
this.ioSortFactor = jobConf.getInt(MRJobConfig.IO_SORT_FACTOR, 100);
final float singleShuffleMemoryLimitPercent =
jobConf.getFloat(MRJobConfig.SHUFFLE_MEMORY_LIMIT_PERCENT,
DEFAULT_SHUFFLE_MEMORY_LIMIT_PERCENT);
if (singleShuffleMemoryLimitPercent <= 0.0f
|| singleShuffleMemoryLimitPercent > 1.0f) {
throw new IllegalArgumentException("Invalid value for "
+ MRJobConfig.SHUFFLE_MEMORY_LIMIT_PERCENT + ": "
+ singleShuffleMemoryLimitPercent);
}
usedMemory = 0L;
commitMemory = 0L;
this.maxSingleShuffleLimit =
(long)(memoryLimit * singleShuffleMemoryLimitPercent);
this.memToMemMergeOutputsThreshold =
jobConf.getInt(MRJobConfig.REDUCE_MEMTOMEM_THRESHOLD, ioSortFactor);
this.mergeThreshold = (long)(this.memoryLimit *
jobConf.getFloat(MRJobConfig.SHUFFLE_MERGE_PERCENT,
0.90f));
LOG.info("MergerManager: memoryLimit=" + memoryLimit + ", " +
"maxSingleShuffleLimit=" + maxSingleShuffleLimit + ", " +
"mergeThreshold=" + mergeThreshold + ", " +
"ioSortFactor=" + ioSortFactor + ", " +
"memToMemMergeOutputsThreshold=" + memToMemMergeOutputsThreshold);
if (this.maxSingleShuffleLimit >= this.mergeThreshold) {
throw new RuntimeException("Invlaid configuration: "
+ "maxSingleShuffleLimit should be less than mergeThreshold"
+ "maxSingleShuffleLimit: " + this.maxSingleShuffleLimit
+ "mergeThreshold: " + this.mergeThreshold);
}
boolean allowMemToMemMerge =
jobConf.getBoolean(MRJobConfig.REDUCE_MEMTOMEM_ENABLED, false);
if (allowMemToMemMerge) {
this.memToMemMerger =
new IntermediateMemoryToMemoryMerger(this,
memToMemMergeOutputsThreshold);
this.memToMemMerger.start();
} else {
this.memToMemMerger = null;
}
this.inMemoryMerger = createInMemoryMerger();
this.inMemoryMerger.start();
this.onDiskMerger = new OnDiskMerger(this);
this.onDiskMerger.start();
this.mergePhase = mergePhase;
}
protected MergeThread<MapOutput<K,V>, K,V> createInMemoryMerger() {
return new InMemoryMerger(this);
}
TaskAttemptID getReduceId() {
return reduceId;
}
@VisibleForTesting
ExceptionReporter getExceptionReporter() {
return exceptionReporter;
}
public void waitForInMemoryMerge() throws InterruptedException {
inMemoryMerger.waitForMerge();
}
private boolean canShuffleToMemory(long requestedSize) {
return (requestedSize < maxSingleShuffleLimit);
}
final private MapOutput<K,V> stallShuffle = new MapOutput<K,V>(null);
public synchronized MapOutput<K,V> reserve(TaskAttemptID mapId,
long requestedSize,
int fetcher
) throws IOException {
if (!canShuffleToMemory(requestedSize)) {
LOG.info(mapId + ": Shuffling to disk since " + requestedSize +
" is greater than maxSingleShuffleLimit (" +
maxSingleShuffleLimit + ")");
return new MapOutput<K,V>(mapId, this, requestedSize, jobConf,
localDirAllocator, fetcher, true,
mapOutputFile);
}
// Stall shuffle if we are above the memory limit
// It is possible that all threads could just be stalling and not make
// progress at all. This could happen when:
//
// requested size is causing the used memory to go above limit &&
// requested size < singleShuffleLimit &&
// current used size < mergeThreshold (merge will not get triggered)
//
// To avoid this from happening, we allow exactly one thread to go past
// the memory limit. We check (usedMemory > memoryLimit) and not
// (usedMemory + requestedSize > memoryLimit). When this thread is done
// fetching, this will automatically trigger a merge thereby unlocking
// all the stalled threads
if (usedMemory > memoryLimit) {
LOG.debug(mapId + ": Stalling shuffle since usedMemory (" + usedMemory
+ ") is greater than memoryLimit (" + memoryLimit + ")." +
" CommitMemory is (" + commitMemory + ")");
return stallShuffle;
}
// Allow the in-memory shuffle to progress
LOG.debug(mapId + ": Proceeding with shuffle since usedMemory ("
+ usedMemory + ") is lesser than memoryLimit (" + memoryLimit + ")."
+ "CommitMemory is (" + commitMemory + ")");
return unconditionalReserve(mapId, requestedSize, true);
}
/**
* Unconditional Reserve is used by the Memory-to-Memory thread
* @return
* Called at the end of shuffle.
* @return a key value iterator object.
*/
private synchronized MapOutput<K, V> unconditionalReserve(
TaskAttemptID mapId, long requestedSize, boolean primaryMapOutput) {
usedMemory += requestedSize;
return new MapOutput<K,V>(mapId, this, (int)requestedSize,
primaryMapOutput);
}
synchronized void unreserve(long size) {
usedMemory -= size;
}
public synchronized void closeInMemoryFile(MapOutput<K,V> mapOutput) {
inMemoryMapOutputs.add(mapOutput);
LOG.info("closeInMemoryFile -> map-output of size: " + mapOutput.getSize()
+ ", inMemoryMapOutputs.size() -> " + inMemoryMapOutputs.size()
+ ", commitMemory -> " + commitMemory + ", usedMemory ->" + usedMemory);
commitMemory+= mapOutput.getSize();
// Can hang if mergeThreshold is really low.
if (commitMemory >= mergeThreshold) {
LOG.info("Starting inMemoryMerger's merge since commitMemory=" +
commitMemory + " > mergeThreshold=" + mergeThreshold +
". Current usedMemory=" + usedMemory);
inMemoryMapOutputs.addAll(inMemoryMergedMapOutputs);
inMemoryMergedMapOutputs.clear();
inMemoryMerger.startMerge(inMemoryMapOutputs);
commitMemory = 0L; // Reset commitMemory.
}
if (memToMemMerger != null) {
if (inMemoryMapOutputs.size() >= memToMemMergeOutputsThreshold) {
memToMemMerger.startMerge(inMemoryMapOutputs);
}
}
}
public synchronized void closeInMemoryMergedFile(MapOutput<K,V> mapOutput) {
inMemoryMergedMapOutputs.add(mapOutput);
LOG.info("closeInMemoryMergedFile -> size: " + mapOutput.getSize() +
", inMemoryMergedMapOutputs.size() -> " +
inMemoryMergedMapOutputs.size());
}
public synchronized void closeOnDiskFile(Path file) {
onDiskMapOutputs.add(file);
if (onDiskMapOutputs.size() >= (2 * ioSortFactor - 1)) {
onDiskMerger.startMerge(onDiskMapOutputs);
}
}
public RawKeyValueIterator close() throws Throwable {
// Wait for on-going merges to complete
if (memToMemMerger != null) {
memToMemMerger.close();
}
inMemoryMerger.close();
onDiskMerger.close();
List<MapOutput<K, V>> memory =
new ArrayList<MapOutput<K, V>>(inMemoryMergedMapOutputs);
memory.addAll(inMemoryMapOutputs);
List<Path> disk = new ArrayList<Path>(onDiskMapOutputs);
return finalMerge(jobConf, rfs, memory, disk);
}
private class IntermediateMemoryToMemoryMerger
extends MergeThread<MapOutput<K, V>, K, V> {
public IntermediateMemoryToMemoryMerger(MergeManager<K, V> manager,
int mergeFactor) {
super(manager, mergeFactor, exceptionReporter);
setName("InMemoryMerger - Thread to do in-memory merge of in-memory " +
"shuffled map-outputs");
setDaemon(true);
}
@Override
public void merge(List<MapOutput<K, V>> inputs) throws IOException {
if (inputs == null || inputs.size() == 0) {
return;
}
TaskAttemptID dummyMapId = inputs.get(0).getMapId();
List<Segment<K, V>> inMemorySegments = new ArrayList<Segment<K, V>>();
long mergeOutputSize =
createInMemorySegments(inputs, inMemorySegments, 0);
int noInMemorySegments = inMemorySegments.size();
MapOutput<K, V> mergedMapOutputs =
unconditionalReserve(dummyMapId, mergeOutputSize, false);
Writer<K, V> writer =
new InMemoryWriter<K, V>(mergedMapOutputs.getArrayStream());
LOG.info("Initiating Memory-to-Memory merge with " + noInMemorySegments +
" segments of total-size: " + mergeOutputSize);
RawKeyValueIterator rIter =
Merger.merge(jobConf, rfs,
(Class<K>)jobConf.getMapOutputKeyClass(),
(Class<V>)jobConf.getMapOutputValueClass(),
inMemorySegments, inMemorySegments.size(),
new Path(reduceId.toString()),
(RawComparator<K>)jobConf.getOutputKeyComparator(),
reporter, null, null, null);
Merger.writeFile(rIter, writer, reporter, jobConf);
writer.close();
LOG.info(reduceId +
" Memory-to-Memory merge of the " + noInMemorySegments +
" files in-memory complete.");
// Note the output of the merge
closeInMemoryMergedFile(mergedMapOutputs);
}
}
private class InMemoryMerger extends MergeThread<MapOutput<K,V>, K,V> {
public InMemoryMerger(MergeManager<K, V> manager) {
super(manager, Integer.MAX_VALUE, exceptionReporter);
setName
("InMemoryMerger - Thread to merge in-memory shuffled map-outputs");
setDaemon(true);
}
@Override
public void merge(List<MapOutput<K,V>> inputs) throws IOException {
if (inputs == null || inputs.size() == 0) {
return;
}
//name this output file same as the name of the first file that is
//there in the current list of inmem files (this is guaranteed to
//be absent on the disk currently. So we don't overwrite a prev.
//created spill). Also we need to create the output file now since
//it is not guaranteed that this file will be present after merge
//is called (we delete empty files as soon as we see them
//in the merge method)
//figure out the mapId
TaskAttemptID mapId = inputs.get(0).getMapId();
TaskID mapTaskId = mapId.getTaskID();
List<Segment<K, V>> inMemorySegments = new ArrayList<Segment<K, V>>();
long mergeOutputSize =
createInMemorySegments(inputs, inMemorySegments,0);
int noInMemorySegments = inMemorySegments.size();
Path outputPath =
mapOutputFile.getInputFileForWrite(mapTaskId,
mergeOutputSize).suffix(
Task.MERGED_OUTPUT_PREFIX);
Writer<K,V> writer =
new Writer<K,V>(jobConf, rfs, outputPath,
(Class<K>) jobConf.getMapOutputKeyClass(),
(Class<V>) jobConf.getMapOutputValueClass(),
codec, null);
RawKeyValueIterator rIter = null;
try {
LOG.info("Initiating in-memory merge with " + noInMemorySegments +
" segments...");
rIter = Merger.merge(jobConf, rfs,
(Class<K>)jobConf.getMapOutputKeyClass(),
(Class<V>)jobConf.getMapOutputValueClass(),
inMemorySegments, inMemorySegments.size(),
new Path(reduceId.toString()),
(RawComparator<K>)jobConf.getOutputKeyComparator(),
reporter, spilledRecordsCounter, null, null);
if (null == combinerClass) {
Merger.writeFile(rIter, writer, reporter, jobConf);
} else {
combineCollector.setWriter(writer);
combineAndSpill(rIter, reduceCombineInputCounter);
}
writer.close();
LOG.info(reduceId +
" Merge of the " + noInMemorySegments +
" files in-memory complete." +
" Local file is " + outputPath + " of size " +
localFS.getFileStatus(outputPath).getLen());
} catch (IOException e) {
//make sure that we delete the ondisk file that we created
//earlier when we invoked cloneFileAttributes
localFS.delete(outputPath, true);
throw e;
}
// Note the output of the merge
closeOnDiskFile(outputPath);
}
}
private class OnDiskMerger extends MergeThread<Path,K,V> {
public OnDiskMerger(MergeManager<K, V> manager) {
super(manager, Integer.MAX_VALUE, exceptionReporter);
setName("OnDiskMerger - Thread to merge on-disk map-outputs");
setDaemon(true);
}
@Override
public void merge(List<Path> inputs) throws IOException {
// sanity check
if (inputs == null || inputs.isEmpty()) {
LOG.info("No ondisk files to merge...");
return;
}
long approxOutputSize = 0;
int bytesPerSum =
jobConf.getInt("io.bytes.per.checksum", 512);
LOG.info("OnDiskMerger: We have " + inputs.size() +
" map outputs on disk. Triggering merge...");
// 1. Prepare the list of files to be merged.
for (Path file : inputs) {
approxOutputSize += localFS.getFileStatus(file).getLen();
}
// add the checksum length
approxOutputSize +=
ChecksumFileSystem.getChecksumLength(approxOutputSize, bytesPerSum);
// 2. Start the on-disk merge process
Path outputPath =
localDirAllocator.getLocalPathForWrite(inputs.get(0).toString(),
approxOutputSize, jobConf).suffix(Task.MERGED_OUTPUT_PREFIX);
Writer<K,V> writer =
new Writer<K,V>(jobConf, rfs, outputPath,
(Class<K>) jobConf.getMapOutputKeyClass(),
(Class<V>) jobConf.getMapOutputValueClass(),
codec, null);
RawKeyValueIterator iter = null;
Path tmpDir = new Path(reduceId.toString());
try {
iter = Merger.merge(jobConf, rfs,
(Class<K>) jobConf.getMapOutputKeyClass(),
(Class<V>) jobConf.getMapOutputValueClass(),
codec, inputs.toArray(new Path[inputs.size()]),
true, ioSortFactor, tmpDir,
(RawComparator<K>) jobConf.getOutputKeyComparator(),
reporter, spilledRecordsCounter, null,
mergedMapOutputsCounter, null);
Merger.writeFile(iter, writer, reporter, jobConf);
writer.close();
} catch (IOException e) {
localFS.delete(outputPath, true);
throw e;
}
closeOnDiskFile(outputPath);
LOG.info(reduceId +
" Finished merging " + inputs.size() +
" map output files on disk of total-size " +
approxOutputSize + "." +
" Local output file is " + outputPath + " of size " +
localFS.getFileStatus(outputPath).getLen());
}
}
private void combineAndSpill(
RawKeyValueIterator kvIter,
Counters.Counter inCounter) throws IOException {
JobConf job = jobConf;
Reducer combiner = ReflectionUtils.newInstance(combinerClass, job);
Class<K> keyClass = (Class<K>) job.getMapOutputKeyClass();
Class<V> valClass = (Class<V>) job.getMapOutputValueClass();
RawComparator<K> comparator =
(RawComparator<K>)job.getOutputKeyComparator();
try {
CombineValuesIterator values = new CombineValuesIterator(
kvIter, comparator, keyClass, valClass, job, Reporter.NULL,
inCounter);
while (values.more()) {
combiner.reduce(values.getKey(), values, combineCollector,
Reporter.NULL);
values.nextKey();
}
} finally {
combiner.close();
}
}
private long createInMemorySegments(List<MapOutput<K,V>> inMemoryMapOutputs,
List<Segment<K, V>> inMemorySegments,
long leaveBytes
) throws IOException {
long totalSize = 0L;
// We could use fullSize could come from the RamManager, but files can be
// closed but not yet present in inMemoryMapOutputs
long fullSize = 0L;
for (MapOutput<K,V> mo : inMemoryMapOutputs) {
fullSize += mo.getMemory().length;
}
while(fullSize > leaveBytes) {
MapOutput<K,V> mo = inMemoryMapOutputs.remove(0);
byte[] data = mo.getMemory();
long size = data.length;
totalSize += size;
fullSize -= size;
Reader<K,V> reader = new InMemoryReader<K,V>(MergeManager.this,
mo.getMapId(),
data, 0, (int)size);
inMemorySegments.add(new Segment<K,V>(reader, true,
(mo.isPrimaryMapOutput() ?
mergedMapOutputsCounter : null)));
}
return totalSize;
}
class RawKVIteratorReader extends IFile.Reader<K,V> {
private final RawKeyValueIterator kvIter;
public RawKVIteratorReader(RawKeyValueIterator kvIter, long size)
throws IOException {
super(null, null, size, null, spilledRecordsCounter);
this.kvIter = kvIter;
}
public boolean nextRawKey(DataInputBuffer key) throws IOException {
if (kvIter.next()) {
final DataInputBuffer kb = kvIter.getKey();
final int kp = kb.getPosition();
final int klen = kb.getLength() - kp;
key.reset(kb.getData(), kp, klen);
bytesRead += klen;
return true;
}
return false;
}
public void nextRawValue(DataInputBuffer value) throws IOException {
final DataInputBuffer vb = kvIter.getValue();
final int vp = vb.getPosition();
final int vlen = vb.getLength() - vp;
value.reset(vb.getData(), vp, vlen);
bytesRead += vlen;
}
public long getPosition() throws IOException {
return bytesRead;
}
public void close() throws IOException {
kvIter.close();
}
}
private RawKeyValueIterator finalMerge(JobConf job, FileSystem fs,
List<MapOutput<K,V>> inMemoryMapOutputs,
List<Path> onDiskMapOutputs
) throws IOException {
LOG.info("finalMerge called with " +
inMemoryMapOutputs.size() + " in-memory map-outputs and " +
onDiskMapOutputs.size() + " on-disk map-outputs");
final float maxRedPer =
job.getFloat(MRJobConfig.REDUCE_INPUT_BUFFER_PERCENT, 0f);
if (maxRedPer > 1.0 || maxRedPer < 0.0) {
throw new IOException(MRJobConfig.REDUCE_INPUT_BUFFER_PERCENT +
maxRedPer);
}
int maxInMemReduce = (int)Math.min(
Runtime.getRuntime().maxMemory() * maxRedPer, Integer.MAX_VALUE);
// merge config params
Class<K> keyClass = (Class<K>)job.getMapOutputKeyClass();
Class<V> valueClass = (Class<V>)job.getMapOutputValueClass();
boolean keepInputs = job.getKeepFailedTaskFiles();
final Path tmpDir = new Path(reduceId.toString());
final RawComparator<K> comparator =
(RawComparator<K>)job.getOutputKeyComparator();
// segments required to vacate memory
List<Segment<K,V>> memDiskSegments = new ArrayList<Segment<K,V>>();
long inMemToDiskBytes = 0;
boolean mergePhaseFinished = false;
if (inMemoryMapOutputs.size() > 0) {
TaskID mapId = inMemoryMapOutputs.get(0).getMapId().getTaskID();
inMemToDiskBytes = createInMemorySegments(inMemoryMapOutputs,
memDiskSegments,
maxInMemReduce);
final int numMemDiskSegments = memDiskSegments.size();
if (numMemDiskSegments > 0 &&
ioSortFactor > onDiskMapOutputs.size()) {
// If we reach here, it implies that we have less than io.sort.factor
// disk segments and this will be incremented by 1 (result of the
// memory segments merge). Since this total would still be
// <= io.sort.factor, we will not do any more intermediate merges,
// the merge of all these disk segments would be directly fed to the
// reduce method
mergePhaseFinished = true;
// must spill to disk, but can't retain in-mem for intermediate merge
final Path outputPath =
mapOutputFile.getInputFileForWrite(mapId,
inMemToDiskBytes).suffix(
Task.MERGED_OUTPUT_PREFIX);
final RawKeyValueIterator rIter = Merger.merge(job, fs,
keyClass, valueClass, memDiskSegments, numMemDiskSegments,
tmpDir, comparator, reporter, spilledRecordsCounter, null,
mergePhase);
final Writer<K,V> writer = new Writer<K,V>(job, fs, outputPath,
keyClass, valueClass, codec, null);
try {
Merger.writeFile(rIter, writer, reporter, job);
// add to list of final disk outputs.
onDiskMapOutputs.add(outputPath);
} catch (IOException e) {
if (null != outputPath) {
try {
fs.delete(outputPath, true);
} catch (IOException ie) {
// NOTHING
}
}
throw e;
} finally {
if (null != writer) {
writer.close();
}
}
LOG.info("Merged " + numMemDiskSegments + " segments, " +
inMemToDiskBytes + " bytes to disk to satisfy " +
"reduce memory limit");
inMemToDiskBytes = 0;
memDiskSegments.clear();
} else if (inMemToDiskBytes != 0) {
LOG.info("Keeping " + numMemDiskSegments + " segments, " +
inMemToDiskBytes + " bytes in memory for " +
"intermediate, on-disk merge");
}
}
// segments on disk
List<Segment<K,V>> diskSegments = new ArrayList<Segment<K,V>>();
long onDiskBytes = inMemToDiskBytes;
Path[] onDisk = onDiskMapOutputs.toArray(new Path[onDiskMapOutputs.size()]);
for (Path file : onDisk) {
onDiskBytes += fs.getFileStatus(file).getLen();
LOG.debug("Disk file: " + file + " Length is " +
fs.getFileStatus(file).getLen());
diskSegments.add(new Segment<K, V>(job, fs, file, codec, keepInputs,
(file.toString().endsWith(
Task.MERGED_OUTPUT_PREFIX) ?
null : mergedMapOutputsCounter)
));
}
LOG.info("Merging " + onDisk.length + " files, " +
onDiskBytes + " bytes from disk");
Collections.sort(diskSegments, new Comparator<Segment<K,V>>() {
public int compare(Segment<K, V> o1, Segment<K, V> o2) {
if (o1.getLength() == o2.getLength()) {
return 0;
}
return o1.getLength() < o2.getLength() ? -1 : 1;
}
});
// build final list of segments from merged backed by disk + in-mem
List<Segment<K,V>> finalSegments = new ArrayList<Segment<K,V>>();
long inMemBytes = createInMemorySegments(inMemoryMapOutputs,
finalSegments, 0);
LOG.info("Merging " + finalSegments.size() + " segments, " +
inMemBytes + " bytes from memory into reduce");
if (0 != onDiskBytes) {
final int numInMemSegments = memDiskSegments.size();
diskSegments.addAll(0, memDiskSegments);
memDiskSegments.clear();
// Pass mergePhase only if there is a going to be intermediate
// merges. See comment where mergePhaseFinished is being set
Progress thisPhase = (mergePhaseFinished) ? null : mergePhase;
RawKeyValueIterator diskMerge = Merger.merge(
job, fs, keyClass, valueClass, diskSegments,
ioSortFactor, numInMemSegments, tmpDir, comparator,
reporter, false, spilledRecordsCounter, null, thisPhase);
diskSegments.clear();
if (0 == finalSegments.size()) {
return diskMerge;
}
finalSegments.add(new Segment<K,V>(
new RawKVIteratorReader(diskMerge, onDiskBytes), true));
}
return Merger.merge(job, fs, keyClass, valueClass,
finalSegments, finalSegments.size(), tmpDir,
comparator, reporter, spilledRecordsCounter, null,
null);
}
public RawKeyValueIterator close() throws Throwable;
}

797
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManagerImpl.java Normal file
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@ -0,0 +1,797 @@
/**
* 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.mapreduce.task.reduce;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.ChecksumFileSystem;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.LocalDirAllocator;
import org.apache.hadoop.fs.LocalFileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DataInputBuffer;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.mapred.Counters;
import org.apache.hadoop.mapred.IFile;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapOutputFile;
import org.apache.hadoop.mapred.Merger;
import org.apache.hadoop.mapred.RawKeyValueIterator;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.Task;
import org.apache.hadoop.mapred.IFile.Reader;
import org.apache.hadoop.mapred.IFile.Writer;
import org.apache.hadoop.mapred.Merger.Segment;
import org.apache.hadoop.mapred.Task.CombineOutputCollector;
import org.apache.hadoop.mapred.Task.CombineValuesIterator;
import org.apache.hadoop.mapreduce.MRJobConfig;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import org.apache.hadoop.mapreduce.TaskID;
import org.apache.hadoop.mapreduce.task.reduce.MapOutput.MapOutputComparator;
import org.apache.hadoop.util.Progress;
import org.apache.hadoop.util.ReflectionUtils;
import com.google.common.annotations.VisibleForTesting;
@SuppressWarnings(value={"unchecked"})
@InterfaceAudience.LimitedPrivate({"MapReduce"})
@InterfaceStability.Unstable
public class MergeManagerImpl<K, V> implements MergeManager<K, V> {
private static final Log LOG = LogFactory.getLog(MergeManagerImpl.class);
/* Maximum percentage of the in-memory limit that a single shuffle can
* consume*/
private static final float DEFAULT_SHUFFLE_MEMORY_LIMIT_PERCENT
= 0.25f;
private final TaskAttemptID reduceId;
private final JobConf jobConf;
private final FileSystem localFS;
private final FileSystem rfs;
private final LocalDirAllocator localDirAllocator;
protected MapOutputFile mapOutputFile;
Set<InMemoryMapOutput<K, V>> inMemoryMergedMapOutputs =
new TreeSet<InMemoryMapOutput<K,V>>(new MapOutputComparator<K, V>());
private IntermediateMemoryToMemoryMerger memToMemMerger;
Set<InMemoryMapOutput<K, V>> inMemoryMapOutputs =
new TreeSet<InMemoryMapOutput<K,V>>(new MapOutputComparator<K, V>());
private final MergeThread<InMemoryMapOutput<K,V>, K,V> inMemoryMerger;
Set<Path> onDiskMapOutputs = new TreeSet<Path>();
private final OnDiskMerger onDiskMerger;
private final long memoryLimit;
private long usedMemory;
private long commitMemory;
private final long maxSingleShuffleLimit;
private final int memToMemMergeOutputsThreshold;
private final long mergeThreshold;
private final int ioSortFactor;
private final Reporter reporter;
private final ExceptionReporter exceptionReporter;
/**
* Combiner class to run during in-memory merge, if defined.
*/
private final Class<? extends Reducer> combinerClass;
/**
* Resettable collector used for combine.
*/
private final CombineOutputCollector<K,V> combineCollector;
private final Counters.Counter spilledRecordsCounter;
private final Counters.Counter reduceCombineInputCounter;
private final Counters.Counter mergedMapOutputsCounter;
private final CompressionCodec codec;
private final Progress mergePhase;
public MergeManagerImpl(TaskAttemptID reduceId, JobConf jobConf,
FileSystem localFS,
LocalDirAllocator localDirAllocator,
Reporter reporter,
CompressionCodec codec,
Class<? extends Reducer> combinerClass,
CombineOutputCollector<K,V> combineCollector,
Counters.Counter spilledRecordsCounter,
Counters.Counter reduceCombineInputCounter,
Counters.Counter mergedMapOutputsCounter,
ExceptionReporter exceptionReporter,
Progress mergePhase, MapOutputFile mapOutputFile) {
this.reduceId = reduceId;
this.jobConf = jobConf;
this.localDirAllocator = localDirAllocator;
this.exceptionReporter = exceptionReporter;
this.reporter = reporter;
this.codec = codec;
this.combinerClass = combinerClass;
this.combineCollector = combineCollector;
this.reduceCombineInputCounter = reduceCombineInputCounter;
this.spilledRecordsCounter = spilledRecordsCounter;
this.mergedMapOutputsCounter = mergedMapOutputsCounter;
this.mapOutputFile = mapOutputFile;
this.mapOutputFile.setConf(jobConf);
this.localFS = localFS;
this.rfs = ((LocalFileSystem)localFS).getRaw();
final float maxInMemCopyUse =
jobConf.getFloat(MRJobConfig.SHUFFLE_INPUT_BUFFER_PERCENT, 0.90f);
if (maxInMemCopyUse > 1.0 || maxInMemCopyUse < 0.0) {
throw new IllegalArgumentException("Invalid value for " +
MRJobConfig.SHUFFLE_INPUT_BUFFER_PERCENT + ": " +
maxInMemCopyUse);
}
// Allow unit tests to fix Runtime memory
this.memoryLimit =
(long)(jobConf.getLong(MRJobConfig.REDUCE_MEMORY_TOTAL_BYTES,
Math.min(Runtime.getRuntime().maxMemory(), Integer.MAX_VALUE))
* maxInMemCopyUse);
this.ioSortFactor = jobConf.getInt(MRJobConfig.IO_SORT_FACTOR, 100);
final float singleShuffleMemoryLimitPercent =
jobConf.getFloat(MRJobConfig.SHUFFLE_MEMORY_LIMIT_PERCENT,
DEFAULT_SHUFFLE_MEMORY_LIMIT_PERCENT);
if (singleShuffleMemoryLimitPercent <= 0.0f
|| singleShuffleMemoryLimitPercent > 1.0f) {
throw new IllegalArgumentException("Invalid value for "
+ MRJobConfig.SHUFFLE_MEMORY_LIMIT_PERCENT + ": "
+ singleShuffleMemoryLimitPercent);
}
usedMemory = 0L;
commitMemory = 0L;
this.maxSingleShuffleLimit =
(long)(memoryLimit * singleShuffleMemoryLimitPercent);
this.memToMemMergeOutputsThreshold =
jobConf.getInt(MRJobConfig.REDUCE_MEMTOMEM_THRESHOLD, ioSortFactor);
this.mergeThreshold = (long)(this.memoryLimit *
jobConf.getFloat(MRJobConfig.SHUFFLE_MERGE_PERCENT,
0.90f));
LOG.info("MergerManager: memoryLimit=" + memoryLimit + ", " +
"maxSingleShuffleLimit=" + maxSingleShuffleLimit + ", " +
"mergeThreshold=" + mergeThreshold + ", " +
"ioSortFactor=" + ioSortFactor + ", " +
"memToMemMergeOutputsThreshold=" + memToMemMergeOutputsThreshold);
if (this.maxSingleShuffleLimit >= this.mergeThreshold) {
throw new RuntimeException("Invlaid configuration: "
+ "maxSingleShuffleLimit should be less than mergeThreshold"
+ "maxSingleShuffleLimit: " + this.maxSingleShuffleLimit
+ "mergeThreshold: " + this.mergeThreshold);
}
boolean allowMemToMemMerge =
jobConf.getBoolean(MRJobConfig.REDUCE_MEMTOMEM_ENABLED, false);
if (allowMemToMemMerge) {
this.memToMemMerger =
new IntermediateMemoryToMemoryMerger(this,
memToMemMergeOutputsThreshold);
this.memToMemMerger.start();
} else {
this.memToMemMerger = null;
}
this.inMemoryMerger = createInMemoryMerger();
this.inMemoryMerger.start();
this.onDiskMerger = new OnDiskMerger(this);
this.onDiskMerger.start();
this.mergePhase = mergePhase;
}
protected MergeThread<InMemoryMapOutput<K,V>, K,V> createInMemoryMerger() {
return new InMemoryMerger(this);
}
TaskAttemptID getReduceId() {
return reduceId;
}
@VisibleForTesting
ExceptionReporter getExceptionReporter() {
return exceptionReporter;
}
@Override
public void waitForResource() throws InterruptedException {
inMemoryMerger.waitForMerge();
}
private boolean canShuffleToMemory(long requestedSize) {
return (requestedSize < maxSingleShuffleLimit);
}
@Override
public synchronized MapOutput<K,V> reserve(TaskAttemptID mapId,
long requestedSize,
int fetcher
) throws IOException {
if (!canShuffleToMemory(requestedSize)) {
LOG.info(mapId + ": Shuffling to disk since " + requestedSize +
" is greater than maxSingleShuffleLimit (" +
maxSingleShuffleLimit + ")");
return new OnDiskMapOutput<K,V>(mapId, reduceId, this, requestedSize,
jobConf, mapOutputFile, fetcher, true);
}
// Stall shuffle if we are above the memory limit
// It is possible that all threads could just be stalling and not make
// progress at all. This could happen when:
//
// requested size is causing the used memory to go above limit &&
// requested size < singleShuffleLimit &&
// current used size < mergeThreshold (merge will not get triggered)
//
// To avoid this from happening, we allow exactly one thread to go past
// the memory limit. We check (usedMemory > memoryLimit) and not
// (usedMemory + requestedSize > memoryLimit). When this thread is done
// fetching, this will automatically trigger a merge thereby unlocking
// all the stalled threads
if (usedMemory > memoryLimit) {
LOG.debug(mapId + ": Stalling shuffle since usedMemory (" + usedMemory
+ ") is greater than memoryLimit (" + memoryLimit + ")." +
" CommitMemory is (" + commitMemory + ")");
return null;
}
// Allow the in-memory shuffle to progress
LOG.debug(mapId + ": Proceeding with shuffle since usedMemory ("
+ usedMemory + ") is lesser than memoryLimit (" + memoryLimit + ")."
+ "CommitMemory is (" + commitMemory + ")");
return unconditionalReserve(mapId, requestedSize, true);
}
/**
* Unconditional Reserve is used by the Memory-to-Memory thread
* @return
*/
private synchronized InMemoryMapOutput<K, V> unconditionalReserve(
TaskAttemptID mapId, long requestedSize, boolean primaryMapOutput) {
usedMemory += requestedSize;
return new InMemoryMapOutput<K,V>(jobConf, mapId, this, (int)requestedSize,
codec, primaryMapOutput);
}
synchronized void unreserve(long size) {
usedMemory -= size;
}
public synchronized void closeInMemoryFile(InMemoryMapOutput<K,V> mapOutput) {
inMemoryMapOutputs.add(mapOutput);
LOG.info("closeInMemoryFile -> map-output of size: " + mapOutput.getSize()
+ ", inMemoryMapOutputs.size() -> " + inMemoryMapOutputs.size()
+ ", commitMemory -> " + commitMemory + ", usedMemory ->" + usedMemory);
commitMemory+= mapOutput.getSize();
// Can hang if mergeThreshold is really low.
if (commitMemory >= mergeThreshold) {
LOG.info("Starting inMemoryMerger's merge since commitMemory=" +
commitMemory + " > mergeThreshold=" + mergeThreshold +
". Current usedMemory=" + usedMemory);
inMemoryMapOutputs.addAll(inMemoryMergedMapOutputs);
inMemoryMergedMapOutputs.clear();
inMemoryMerger.startMerge(inMemoryMapOutputs);
commitMemory = 0L; // Reset commitMemory.
}
if (memToMemMerger != null) {
if (inMemoryMapOutputs.size() >= memToMemMergeOutputsThreshold) {
memToMemMerger.startMerge(inMemoryMapOutputs);
}
}
}
public synchronized void closeInMemoryMergedFile(InMemoryMapOutput<K,V> mapOutput) {
inMemoryMergedMapOutputs.add(mapOutput);
LOG.info("closeInMemoryMergedFile -> size: " + mapOutput.getSize() +
", inMemoryMergedMapOutputs.size() -> " +
inMemoryMergedMapOutputs.size());
}
public synchronized void closeOnDiskFile(Path file) {
onDiskMapOutputs.add(file);
if (onDiskMapOutputs.size() >= (2 * ioSortFactor - 1)) {
onDiskMerger.startMerge(onDiskMapOutputs);
}
}
@Override
public RawKeyValueIterator close() throws Throwable {
// Wait for on-going merges to complete
if (memToMemMerger != null) {
memToMemMerger.close();
}
inMemoryMerger.close();
onDiskMerger.close();
List<InMemoryMapOutput<K, V>> memory =
new ArrayList<InMemoryMapOutput<K, V>>(inMemoryMergedMapOutputs);
memory.addAll(inMemoryMapOutputs);
List<Path> disk = new ArrayList<Path>(onDiskMapOutputs);
return finalMerge(jobConf, rfs, memory, disk);
}
private class IntermediateMemoryToMemoryMerger
extends MergeThread<InMemoryMapOutput<K, V>, K, V> {
public IntermediateMemoryToMemoryMerger(MergeManagerImpl<K, V> manager,
int mergeFactor) {
super(manager, mergeFactor, exceptionReporter);
setName("InMemoryMerger - Thread to do in-memory merge of in-memory " +
"shuffled map-outputs");
setDaemon(true);
}
@Override
public void merge(List<InMemoryMapOutput<K, V>> inputs) throws IOException {
if (inputs == null || inputs.size() == 0) {
return;
}
TaskAttemptID dummyMapId = inputs.get(0).getMapId();
List<Segment<K, V>> inMemorySegments = new ArrayList<Segment<K, V>>();
long mergeOutputSize =
createInMemorySegments(inputs, inMemorySegments, 0);
int noInMemorySegments = inMemorySegments.size();
InMemoryMapOutput<K, V> mergedMapOutputs =
unconditionalReserve(dummyMapId, mergeOutputSize, false);
Writer<K, V> writer =
new InMemoryWriter<K, V>(mergedMapOutputs.getArrayStream());
LOG.info("Initiating Memory-to-Memory merge with " + noInMemorySegments +
" segments of total-size: " + mergeOutputSize);
RawKeyValueIterator rIter =
Merger.merge(jobConf, rfs,
(Class<K>)jobConf.getMapOutputKeyClass(),
(Class<V>)jobConf.getMapOutputValueClass(),
inMemorySegments, inMemorySegments.size(),
new Path(reduceId.toString()),
(RawComparator<K>)jobConf.getOutputKeyComparator(),
reporter, null, null, null);
Merger.writeFile(rIter, writer, reporter, jobConf);
writer.close();
LOG.info(reduceId +
" Memory-to-Memory merge of the " + noInMemorySegments +
" files in-memory complete.");
// Note the output of the merge
closeInMemoryMergedFile(mergedMapOutputs);
}
}
private class InMemoryMerger extends MergeThread<InMemoryMapOutput<K,V>, K,V> {
public InMemoryMerger(MergeManagerImpl<K, V> manager) {
super(manager, Integer.MAX_VALUE, exceptionReporter);
setName
("InMemoryMerger - Thread to merge in-memory shuffled map-outputs");
setDaemon(true);
}
@Override
public void merge(List<InMemoryMapOutput<K,V>> inputs) throws IOException {
if (inputs == null || inputs.size() == 0) {
return;
}
//name this output file same as the name of the first file that is
//there in the current list of inmem files (this is guaranteed to
//be absent on the disk currently. So we don't overwrite a prev.
//created spill). Also we need to create the output file now since
//it is not guaranteed that this file will be present after merge
//is called (we delete empty files as soon as we see them
//in the merge method)
//figure out the mapId
TaskAttemptID mapId = inputs.get(0).getMapId();
TaskID mapTaskId = mapId.getTaskID();
List<Segment<K, V>> inMemorySegments = new ArrayList<Segment<K, V>>();
long mergeOutputSize =
createInMemorySegments(inputs, inMemorySegments,0);
int noInMemorySegments = inMemorySegments.size();
Path outputPath =
mapOutputFile.getInputFileForWrite(mapTaskId,
mergeOutputSize).suffix(
Task.MERGED_OUTPUT_PREFIX);
Writer<K,V> writer =
new Writer<K,V>(jobConf, rfs, outputPath,
(Class<K>) jobConf.getMapOutputKeyClass(),
(Class<V>) jobConf.getMapOutputValueClass(),
codec, null);
RawKeyValueIterator rIter = null;
try {
LOG.info("Initiating in-memory merge with " + noInMemorySegments +
" segments...");
rIter = Merger.merge(jobConf, rfs,
(Class<K>)jobConf.getMapOutputKeyClass(),
(Class<V>)jobConf.getMapOutputValueClass(),
inMemorySegments, inMemorySegments.size(),
new Path(reduceId.toString()),
(RawComparator<K>)jobConf.getOutputKeyComparator(),
reporter, spilledRecordsCounter, null, null);
if (null == combinerClass) {
Merger.writeFile(rIter, writer, reporter, jobConf);
} else {
combineCollector.setWriter(writer);
combineAndSpill(rIter, reduceCombineInputCounter);
}
writer.close();
LOG.info(reduceId +
" Merge of the " + noInMemorySegments +
" files in-memory complete." +
" Local file is " + outputPath + " of size " +
localFS.getFileStatus(outputPath).getLen());
} catch (IOException e) {
//make sure that we delete the ondisk file that we created
//earlier when we invoked cloneFileAttributes
localFS.delete(outputPath, true);
throw e;
}
// Note the output of the merge
closeOnDiskFile(outputPath);
}
}
private class OnDiskMerger extends MergeThread<Path,K,V> {
public OnDiskMerger(MergeManagerImpl<K, V> manager) {
super(manager, Integer.MAX_VALUE, exceptionReporter);
setName("OnDiskMerger - Thread to merge on-disk map-outputs");
setDaemon(true);
}
@Override
public void merge(List<Path> inputs) throws IOException {
// sanity check
if (inputs == null || inputs.isEmpty()) {
LOG.info("No ondisk files to merge...");
return;
}
long approxOutputSize = 0;
int bytesPerSum =
jobConf.getInt("io.bytes.per.checksum", 512);
LOG.info("OnDiskMerger: We have " + inputs.size() +
" map outputs on disk. Triggering merge...");
// 1. Prepare the list of files to be merged.
for (Path file : inputs) {
approxOutputSize += localFS.getFileStatus(file).getLen();
}
// add the checksum length
approxOutputSize +=
ChecksumFileSystem.getChecksumLength(approxOutputSize, bytesPerSum);
// 2. Start the on-disk merge process
Path outputPath =
localDirAllocator.getLocalPathForWrite(inputs.get(0).toString(),
approxOutputSize, jobConf).suffix(Task.MERGED_OUTPUT_PREFIX);
Writer<K,V> writer =
new Writer<K,V>(jobConf, rfs, outputPath,
(Class<K>) jobConf.getMapOutputKeyClass(),
(Class<V>) jobConf.getMapOutputValueClass(),
codec, null);
RawKeyValueIterator iter = null;
Path tmpDir = new Path(reduceId.toString());
try {
iter = Merger.merge(jobConf, rfs,
(Class<K>) jobConf.getMapOutputKeyClass(),
(Class<V>) jobConf.getMapOutputValueClass(),
codec, inputs.toArray(new Path[inputs.size()]),
true, ioSortFactor, tmpDir,
(RawComparator<K>) jobConf.getOutputKeyComparator(),
reporter, spilledRecordsCounter, null,
mergedMapOutputsCounter, null);
Merger.writeFile(iter, writer, reporter, jobConf);
writer.close();
} catch (IOException e) {
localFS.delete(outputPath, true);
throw e;
}
closeOnDiskFile(outputPath);
LOG.info(reduceId +
" Finished merging " + inputs.size() +
" map output files on disk of total-size " +
approxOutputSize + "." +
" Local output file is " + outputPath + " of size " +
localFS.getFileStatus(outputPath).getLen());
}
}
private void combineAndSpill(
RawKeyValueIterator kvIter,
Counters.Counter inCounter) throws IOException {
JobConf job = jobConf;
Reducer combiner = ReflectionUtils.newInstance(combinerClass, job);
Class<K> keyClass = (Class<K>) job.getMapOutputKeyClass();
Class<V> valClass = (Class<V>) job.getMapOutputValueClass();
RawComparator<K> comparator =
(RawComparator<K>)job.getOutputKeyComparator();
try {
CombineValuesIterator values = new CombineValuesIterator(
kvIter, comparator, keyClass, valClass, job, Reporter.NULL,
inCounter);
while (values.more()) {
combiner.reduce(values.getKey(), values, combineCollector,
Reporter.NULL);
values.nextKey();
}
} finally {
combiner.close();
}
}
private long createInMemorySegments(List<InMemoryMapOutput<K,V>> inMemoryMapOutputs,
List<Segment<K, V>> inMemorySegments,
long leaveBytes
) throws IOException {
long totalSize = 0L;
// We could use fullSize could come from the RamManager, but files can be
// closed but not yet present in inMemoryMapOutputs
long fullSize = 0L;
for (InMemoryMapOutput<K,V> mo : inMemoryMapOutputs) {
fullSize += mo.getMemory().length;
}
while(fullSize > leaveBytes) {
InMemoryMapOutput<K,V> mo = inMemoryMapOutputs.remove(0);
byte[] data = mo.getMemory();
long size = data.length;
totalSize += size;
fullSize -= size;
Reader<K,V> reader = new InMemoryReader<K,V>(MergeManagerImpl.this,
mo.getMapId(),
data, 0, (int)size);
inMemorySegments.add(new Segment<K,V>(reader, true,
(mo.isPrimaryMapOutput() ?
mergedMapOutputsCounter : null)));
}
return totalSize;
}
class RawKVIteratorReader extends IFile.Reader<K,V> {
private final RawKeyValueIterator kvIter;
public RawKVIteratorReader(RawKeyValueIterator kvIter, long size)
throws IOException {
super(null, null, size, null, spilledRecordsCounter);
this.kvIter = kvIter;
}
public boolean nextRawKey(DataInputBuffer key) throws IOException {
if (kvIter.next()) {
final DataInputBuffer kb = kvIter.getKey();
final int kp = kb.getPosition();
final int klen = kb.getLength() - kp;
key.reset(kb.getData(), kp, klen);
bytesRead += klen;
return true;
}
return false;
}
public void nextRawValue(DataInputBuffer value) throws IOException {
final DataInputBuffer vb = kvIter.getValue();
final int vp = vb.getPosition();
final int vlen = vb.getLength() - vp;
value.reset(vb.getData(), vp, vlen);
bytesRead += vlen;
}
public long getPosition() throws IOException {
return bytesRead;
}
public void close() throws IOException {
kvIter.close();
}
}
private RawKeyValueIterator finalMerge(JobConf job, FileSystem fs,
List<InMemoryMapOutput<K,V>> inMemoryMapOutputs,
List<Path> onDiskMapOutputs
) throws IOException {
LOG.info("finalMerge called with " +
inMemoryMapOutputs.size() + " in-memory map-outputs and " +
onDiskMapOutputs.size() + " on-disk map-outputs");
final float maxRedPer =
job.getFloat(MRJobConfig.REDUCE_INPUT_BUFFER_PERCENT, 0f);
if (maxRedPer > 1.0 || maxRedPer < 0.0) {
throw new IOException(MRJobConfig.REDUCE_INPUT_BUFFER_PERCENT +
maxRedPer);
}
int maxInMemReduce = (int)Math.min(
Runtime.getRuntime().maxMemory() * maxRedPer, Integer.MAX_VALUE);
// merge config params
Class<K> keyClass = (Class<K>)job.getMapOutputKeyClass();
Class<V> valueClass = (Class<V>)job.getMapOutputValueClass();
boolean keepInputs = job.getKeepFailedTaskFiles();
final Path tmpDir = new Path(reduceId.toString());
final RawComparator<K> comparator =
(RawComparator<K>)job.getOutputKeyComparator();
// segments required to vacate memory
List<Segment<K,V>> memDiskSegments = new ArrayList<Segment<K,V>>();
long inMemToDiskBytes = 0;
boolean mergePhaseFinished = false;
if (inMemoryMapOutputs.size() > 0) {
TaskID mapId = inMemoryMapOutputs.get(0).getMapId().getTaskID();
inMemToDiskBytes = createInMemorySegments(inMemoryMapOutputs,
memDiskSegments,
maxInMemReduce);
final int numMemDiskSegments = memDiskSegments.size();
if (numMemDiskSegments > 0 &&
ioSortFactor > onDiskMapOutputs.size()) {
// If we reach here, it implies that we have less than io.sort.factor
// disk segments and this will be incremented by 1 (result of the
// memory segments merge). Since this total would still be
// <= io.sort.factor, we will not do any more intermediate merges,
// the merge of all these disk segments would be directly fed to the
// reduce method
mergePhaseFinished = true;
// must spill to disk, but can't retain in-mem for intermediate merge
final Path outputPath =
mapOutputFile.getInputFileForWrite(mapId,
inMemToDiskBytes).suffix(
Task.MERGED_OUTPUT_PREFIX);
final RawKeyValueIterator rIter = Merger.merge(job, fs,
keyClass, valueClass, memDiskSegments, numMemDiskSegments,
tmpDir, comparator, reporter, spilledRecordsCounter, null,
mergePhase);
final Writer<K,V> writer = new Writer<K,V>(job, fs, outputPath,
keyClass, valueClass, codec, null);
try {
Merger.writeFile(rIter, writer, reporter, job);
// add to list of final disk outputs.
onDiskMapOutputs.add(outputPath);
} catch (IOException e) {
if (null != outputPath) {
try {
fs.delete(outputPath, true);
} catch (IOException ie) {
// NOTHING
}
}
throw e;
} finally {
if (null != writer) {
writer.close();
}
}
LOG.info("Merged " + numMemDiskSegments + " segments, " +
inMemToDiskBytes + " bytes to disk to satisfy " +
"reduce memory limit");
inMemToDiskBytes = 0;
memDiskSegments.clear();
} else if (inMemToDiskBytes != 0) {
LOG.info("Keeping " + numMemDiskSegments + " segments, " +
inMemToDiskBytes + " bytes in memory for " +
"intermediate, on-disk merge");
}
}
// segments on disk
List<Segment<K,V>> diskSegments = new ArrayList<Segment<K,V>>();
long onDiskBytes = inMemToDiskBytes;
Path[] onDisk = onDiskMapOutputs.toArray(new Path[onDiskMapOutputs.size()]);
for (Path file : onDisk) {
onDiskBytes += fs.getFileStatus(file).getLen();
LOG.debug("Disk file: " + file + " Length is " +
fs.getFileStatus(file).getLen());
diskSegments.add(new Segment<K, V>(job, fs, file, codec, keepInputs,
(file.toString().endsWith(
Task.MERGED_OUTPUT_PREFIX) ?
null : mergedMapOutputsCounter)
));
}
LOG.info("Merging " + onDisk.length + " files, " +
onDiskBytes + " bytes from disk");
Collections.sort(diskSegments, new Comparator<Segment<K,V>>() {
public int compare(Segment<K, V> o1, Segment<K, V> o2) {
if (o1.getLength() == o2.getLength()) {
return 0;
}
return o1.getLength() < o2.getLength() ? -1 : 1;
}
});
// build final list of segments from merged backed by disk + in-mem
List<Segment<K,V>> finalSegments = new ArrayList<Segment<K,V>>();
long inMemBytes = createInMemorySegments(inMemoryMapOutputs,
finalSegments, 0);
LOG.info("Merging " + finalSegments.size() + " segments, " +
inMemBytes + " bytes from memory into reduce");
if (0 != onDiskBytes) {
final int numInMemSegments = memDiskSegments.size();
diskSegments.addAll(0, memDiskSegments);
memDiskSegments.clear();
// Pass mergePhase only if there is a going to be intermediate
// merges. See comment where mergePhaseFinished is being set
Progress thisPhase = (mergePhaseFinished) ? null : mergePhase;
RawKeyValueIterator diskMerge = Merger.merge(
job, fs, keyClass, valueClass, diskSegments,
ioSortFactor, numInMemSegments, tmpDir, comparator,
reporter, false, spilledRecordsCounter, null, thisPhase);
diskSegments.clear();
if (0 == finalSegments.size()) {
return diskMerge;
}
finalSegments.add(new Segment<K,V>(
new RawKVIteratorReader(diskMerge, onDiskBytes), true));
}
return Merger.merge(job, fs, keyClass, valueClass,
finalSegments, finalSegments.size(), tmpDir,
comparator, reporter, spilledRecordsCounter, null,
null);
}
}

4
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeThread.java
View File

@ -34,12 +34,12 @@ abstract class MergeThread<T,K,V> extends Thread {
private AtomicInteger numPending = new AtomicInteger(0);
private LinkedList<List<T>> pendingToBeMerged;
protected final MergeManager<K,V> manager;
protected final MergeManagerImpl<K,V> manager;
private final ExceptionReporter reporter;
private boolean closed = false;
private final int mergeFactor;
public MergeThread(MergeManager<K,V> manager, int mergeFactor,
public MergeThread(MergeManagerImpl<K,V> manager, int mergeFactor,
ExceptionReporter reporter) {
this.pendingToBeMerged = new LinkedList<List<T>>();
this.manager = manager;

131
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/OnDiskMapOutput.java Normal file
View File

@ -0,0 +1,131 @@
/**
* 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.mapreduce.task.reduce;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.MapOutputFile;
import org.apache.hadoop.mapreduce.TaskAttemptID;
@InterfaceAudience.Private
@InterfaceStability.Unstable
class OnDiskMapOutput<K, V> extends MapOutput<K, V> {
private static final Log LOG = LogFactory.getLog(OnDiskMapOutput.class);
private final FileSystem localFS;
private final Path tmpOutputPath;
private final Path outputPath;
private final MergeManagerImpl<K, V> merger;
private final OutputStream disk;
public OnDiskMapOutput(TaskAttemptID mapId, TaskAttemptID reduceId,
MergeManagerImpl<K, V> merger, long size,
JobConf conf,
MapOutputFile mapOutputFile,
int fetcher, boolean primaryMapOutput)
throws IOException {
super(mapId, size, primaryMapOutput);
this.merger = merger;
this.localFS = FileSystem.getLocal(conf);
outputPath =
mapOutputFile.getInputFileForWrite(mapId.getTaskID(),size);
tmpOutputPath = outputPath.suffix(String.valueOf(fetcher));
disk = localFS.create(tmpOutputPath);
}
@Override
public void shuffle(MapHost host, InputStream input,
long compressedLength, long decompressedLength,
ShuffleClientMetrics metrics,
Reporter reporter) throws IOException {
// Copy data to local-disk
long bytesLeft = compressedLength;
try {
final int BYTES_TO_READ = 64 * 1024;
byte[] buf = new byte[BYTES_TO_READ];
while (bytesLeft > 0) {
int n = input.read(buf, 0, (int) Math.min(bytesLeft, BYTES_TO_READ));
if (n < 0) {
throw new IOException("read past end of stream reading " +
getMapId());
}
disk.write(buf, 0, n);
bytesLeft -= n;
metrics.inputBytes(n);
reporter.progress();
}
LOG.info("Read " + (compressedLength - bytesLeft) +
" bytes from map-output for " + getMapId());
disk.close();
} catch (IOException ioe) {
// Close the streams
IOUtils.cleanup(LOG, input, disk);
// Re-throw
throw ioe;
}
// Sanity check
if (bytesLeft != 0) {
throw new IOException("Incomplete map output received for " +
getMapId() + " from " +
host.getHostName() + " (" +
bytesLeft + " bytes missing of " +
compressedLength + ")");
}
}
@Override
public void commit() throws IOException {
localFS.rename(tmpOutputPath, outputPath);
merger.closeOnDiskFile(outputPath);
}
@Override
public void abort() {
try {
localFS.delete(tmpOutputPath, false);
} catch (IOException ie) {
LOG.info("failure to clean up " + tmpOutputPath, ie);
}
}
@Override
public String getDescription() {
return "DISK";
}
}

33
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/Shuffle.java
View File

@ -21,17 +21,10 @@ import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.LocalDirAllocator;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.mapred.Counters;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapOutputFile;
import org.apache.hadoop.mapred.RawKeyValueIterator;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.Task;
import org.apache.hadoop.mapred.Task.CombineOutputCollector;
import org.apache.hadoop.mapred.TaskStatus;
import org.apache.hadoop.mapred.TaskUmbilicalProtocol;
import org.apache.hadoop.mapred.ShuffleConsumerPlugin;
@ -77,17 +70,21 @@ public class Shuffle<K, V> implements ShuffleConsumerPlugin<K, V>, ExceptionRepo
this.taskStatus = context.getStatus();
this.reduceTask = context.getReduceTask();
scheduler =
new ShuffleScheduler<K,V>(jobConf, taskStatus, this, copyPhase,
context.getShuffledMapsCounter(),
context.getReduceShuffleBytes(), context.getFailedShuffleCounter());
merger = new MergeManager<K, V>(reduceId, jobConf, context.getLocalFS(),
context.getLocalDirAllocator(), reporter, context.getCodec(),
context.getCombinerClass(), context.getCombineCollector(),
context.getSpilledRecordsCounter(),
context.getReduceCombineInputCounter(),
context.getMergedMapOutputsCounter(),
this, context.getMergePhase(), context.getMapOutputFile());
scheduler = new ShuffleScheduler<K,V>(jobConf, taskStatus, this,
copyPhase, context.getShuffledMapsCounter(),
context.getReduceShuffleBytes(), context.getFailedShuffleCounter());
merger = createMergeManager(context);
}
protected MergeManager<K, V> createMergeManager(
ShuffleConsumerPlugin.Context context) {
return new MergeManagerImpl<K, V>(reduceId, jobConf, context.getLocalFS(),
context.getLocalDirAllocator(), reporter, context.getCodec(),
context.getCombinerClass(), context.getCombineCollector(),
context.getSpilledRecordsCounter(),
context.getReduceCombineInputCounter(),
context.getMergedMapOutputsCounter(), this, context.getMergePhase(),
context.getMapOutputFile());
}
@Override

11
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/task/reduce/TestFetcher.java
View File

@ -53,7 +53,7 @@ public class TestFetcher {
private HttpURLConnection connection;
public FakeFetcher(JobConf job, TaskAttemptID reduceId,
ShuffleScheduler<K,V> scheduler, MergeManager<K,V> merger, Reporter reporter,
ShuffleScheduler<K,V> scheduler, MergeManagerImpl<K,V> merger, Reporter reporter,
ShuffleClientMetrics metrics, ExceptionReporter exceptionReporter,
SecretKey jobTokenSecret, HttpURLConnection connection) {
super(job, reduceId, scheduler, merger, reporter, metrics, exceptionReporter,
@ -77,7 +77,7 @@ public class TestFetcher {
JobConf job = new JobConf();
TaskAttemptID id = TaskAttemptID.forName("attempt_0_1_r_1_1");
ShuffleScheduler<Text, Text> ss = mock(ShuffleScheduler.class);
MergeManager<Text, Text> mm = mock(MergeManager.class);
MergeManagerImpl<Text, Text> mm = mock(MergeManagerImpl.class);
Reporter r = mock(Reporter.class);
ShuffleClientMetrics metrics = mock(ShuffleClientMetrics.class);
ExceptionReporter except = mock(ExceptionReporter.class);
@ -132,7 +132,7 @@ public class TestFetcher {
JobConf job = new JobConf();
TaskAttemptID id = TaskAttemptID.forName("attempt_0_1_r_1_1");
ShuffleScheduler<Text, Text> ss = mock(ShuffleScheduler.class);
MergeManager<Text, Text> mm = mock(MergeManager.class);
MergeManagerImpl<Text, Text> mm = mock(MergeManagerImpl.class);
Reporter r = mock(Reporter.class);
ShuffleClientMetrics metrics = mock(ShuffleClientMetrics.class);
ExceptionReporter except = mock(ExceptionReporter.class);
@ -167,10 +167,9 @@ public class TestFetcher {
header.write(new DataOutputStream(bout));
ByteArrayInputStream in = new ByteArrayInputStream(bout.toByteArray());
when(connection.getInputStream()).thenReturn(in);
//Defaults to WAIT, which is what we want to test
MapOutput<Text,Text> mapOut = new MapOutput<Text, Text>(map1ID);
//Defaults to null, which is what we want to test
when(mm.reserve(any(TaskAttemptID.class), anyLong(), anyInt()))
.thenReturn(mapOut);
.thenReturn(null);
underTest.copyFromHost(host);

60
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/task/reduce/TestMergeManager.java
View File

@ -32,13 +32,13 @@ import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapOutputFile;
import org.apache.hadoop.mapreduce.MRJobConfig;
import org.apache.hadoop.mapreduce.task.reduce.MapOutput.Type;
import org.junit.Assert;
import org.junit.Test;
public class TestMergeManager {
@Test(timeout=10000)
@SuppressWarnings("unchecked")
public void testMemoryMerge() throws Exception {
final int TOTAL_MEM_BYTES = 10000;
final int OUTPUT_SIZE = 7950;
@ -55,45 +55,47 @@ public class TestMergeManager {
// reserve enough map output to cause a merge when it is committed
MapOutput<Text, Text> out1 = mgr.reserve(null, OUTPUT_SIZE, 0);
Assert.assertEquals("Should be a memory merge",
Type.MEMORY, out1.getType());
fillOutput(out1);
Assert.assertTrue("Should be a memory merge",
(out1 instanceof InMemoryMapOutput));
InMemoryMapOutput<Text, Text> mout1 = (InMemoryMapOutput<Text, Text>)out1;
fillOutput(mout1);
MapOutput<Text, Text> out2 = mgr.reserve(null, OUTPUT_SIZE, 0);
Assert.assertEquals("Should be a memory merge",
Type.MEMORY, out2.getType());
fillOutput(out2);
Assert.assertTrue("Should be a memory merge",
(out2 instanceof InMemoryMapOutput));
InMemoryMapOutput<Text, Text> mout2 = (InMemoryMapOutput<Text, Text>)out2;
fillOutput(mout2);
// next reservation should be a WAIT
MapOutput<Text, Text> out3 = mgr.reserve(null, OUTPUT_SIZE, 0);
Assert.assertEquals("Should be told to wait",
Type.WAIT, out3.getType());
Assert.assertEquals("Should be told to wait", null, out3);
// trigger the first merge and wait for merge thread to start merging
// and free enough output to reserve more
out1.commit();
out2.commit();
mout1.commit();
mout2.commit();
mergeStart.await();
Assert.assertEquals(1, mgr.getNumMerges());
// reserve enough map output to cause another merge when committed
out1 = mgr.reserve(null, OUTPUT_SIZE, 0);
Assert.assertEquals("Should be a memory merge",
Type.MEMORY, out1.getType());
fillOutput(out1);
Assert.assertTrue("Should be a memory merge",
(out1 instanceof InMemoryMapOutput));
mout1 = (InMemoryMapOutput<Text, Text>)out1;
fillOutput(mout1);
out2 = mgr.reserve(null, OUTPUT_SIZE, 0);
Assert.assertEquals("Should be a memory merge",
Type.MEMORY, out2.getType());
fillOutput(out2);
Assert.assertTrue("Should be a memory merge",
(out2 instanceof InMemoryMapOutput));
mout2 = (InMemoryMapOutput<Text, Text>)out2;
fillOutput(mout2);
// next reservation should be a WAIT
// next reservation should be null
out3 = mgr.reserve(null, OUTPUT_SIZE, 0);
Assert.assertEquals("Should be told to wait",
Type.WAIT, out3.getType());
Assert.assertEquals("Should be told to wait", null, out3);
// commit output *before* merge thread completes
out1.commit();
out2.commit();
mout1.commit();
mout2.commit();
// allow the first merge to complete
mergeComplete.await();
@ -110,7 +112,7 @@ public class TestMergeManager {
0, reporter.getNumExceptions());
}
private void fillOutput(MapOutput<Text, Text> output) throws IOException {
private void fillOutput(InMemoryMapOutput<Text, Text> output) throws IOException {
BoundedByteArrayOutputStream stream = output.getArrayStream();
int count = stream.getLimit();
for (int i=0; i < count; ++i) {
@ -118,7 +120,7 @@ public class TestMergeManager {
}
}
private static class StubbedMergeManager extends MergeManager<Text, Text> {
private static class StubbedMergeManager extends MergeManagerImpl<Text, Text> {
private TestMergeThread mergeThread;
public StubbedMergeManager(JobConf conf, ExceptionReporter reporter,
@ -129,7 +131,7 @@ public class TestMergeManager {
}
@Override
protected MergeThread<MapOutput<Text, Text>, Text, Text> createInMemoryMerger() {
protected MergeThread<InMemoryMapOutput<Text, Text>, Text, Text> createInMemoryMerger() {
mergeThread = new TestMergeThread(this, getExceptionReporter());
return mergeThread;
}
@ -140,12 +142,12 @@ public class TestMergeManager {
}
private static class TestMergeThread
extends MergeThread<MapOutput<Text,Text>, Text, Text> {
extends MergeThread<InMemoryMapOutput<Text,Text>, Text, Text> {
private AtomicInteger numMerges;
private CyclicBarrier mergeStart;
private CyclicBarrier mergeComplete;
public TestMergeThread(MergeManager<Text, Text> mergeManager,
public TestMergeThread(MergeManagerImpl<Text, Text> mergeManager,
ExceptionReporter reporter) {
super(mergeManager, Integer.MAX_VALUE, reporter);
numMerges = new AtomicInteger(0);
@ -162,11 +164,11 @@ public class TestMergeManager {
}
@Override
public void merge(List<MapOutput<Text, Text>> inputs)
public void merge(List<InMemoryMapOutput<Text, Text>> inputs)
throws IOException {
synchronized (this) {
numMerges.incrementAndGet();
for (MapOutput<Text, Text> input : inputs) {
for (InMemoryMapOutput<Text, Text> input : inputs) {
manager.unreserve(input.getSize());
}
}