/*
* 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 static org.apache.hadoop.test.MetricsAsserts.assertCounter;
import static org.apache.hadoop.test.MetricsAsserts.assertGauge;
import static org.apache.hadoop.test.MetricsAsserts.getMetrics;
import static org.apache.hadoop.test.MockitoMaker.make;
import static org.apache.hadoop.test.MockitoMaker.stub;
import static org.jboss.netty.buffer.ChannelBuffers.wrappedBuffer;
import static org.jboss.netty.handler.codec.http.HttpResponseStatus.OK;
import static org.jboss.netty.handler.codec.http.HttpVersion.HTTP_1_1;
import static org.junit.Assert.assertEquals;
import static org.junit.Assume.assumeTrue;
import java.io.DataInputStream;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.SocketException;
import java.net.URL;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.zip.CheckedOutputStream;
import java.util.zip.Checksum;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DataOutputBuffer;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.nativeio.NativeIO;
import org.apache.hadoop.mapreduce.security.token.JobTokenIdentifier;
import org.apache.hadoop.mapreduce.task.reduce.ShuffleHeader;
import org.apache.hadoop.metrics2.MetricsRecordBuilder;
import org.apache.hadoop.metrics2.MetricsSource;
import org.apache.hadoop.metrics2.MetricsSystem;
import org.apache.hadoop.metrics2.impl.MetricsSystemImpl;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.security.token.Token;
import org.apache.hadoop.util.PureJavaCrc32;
import org.apache.hadoop.util.StringUtils;
import org.apache.hadoop.yarn.api.records.ApplicationId;
import org.apache.hadoop.yarn.conf.YarnConfiguration;
import org.apache.hadoop.yarn.server.api.ApplicationInitializationContext;
import org.apache.hadoop.yarn.server.nodemanager.containermanager.localizer.ContainerLocalizer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.http.DefaultHttpResponse;
import org.jboss.netty.handler.codec.http.HttpRequest;
import org.jboss.netty.handler.codec.http.HttpResponse;
import org.jboss.netty.handler.codec.http.HttpResponseStatus;
import org.junit.Assert;
import org.junit.Test;
import org.mortbay.jetty.HttpHeaders;
public class TestShuffleHandler {
static final long MiB = 1024 * 1024;
private static final Log LOG = LogFactory.getLog(TestShuffleHandler.class);
/**
* Test the validation of ShuffleHandler's meta-data's serialization and
* de-serialization.
*
* @throws Exception exception
*/
@Test (timeout = 10000)
public void testSerializeMeta() throws Exception {
assertEquals(1, ShuffleHandler.deserializeMetaData(
ShuffleHandler.serializeMetaData(1)));
assertEquals(-1, ShuffleHandler.deserializeMetaData(
ShuffleHandler.serializeMetaData(-1)));
assertEquals(8080, ShuffleHandler.deserializeMetaData(
ShuffleHandler.serializeMetaData(8080)));
}
/**
* Validate shuffle connection and input/output metrics.
*
* @throws Exception exception
*/
@Test (timeout = 10000)
public void testShuffleMetrics() throws Exception {
MetricsSystem ms = new MetricsSystemImpl();
ShuffleHandler sh = new ShuffleHandler(ms);
ChannelFuture cf = make(stub(ChannelFuture.class).
returning(true, false).from.isSuccess());
sh.metrics.shuffleConnections.incr();
sh.metrics.shuffleOutputBytes.incr(1*MiB);
sh.metrics.shuffleConnections.incr();
sh.metrics.shuffleOutputBytes.incr(2*MiB);
checkShuffleMetrics(ms, 3*MiB, 0 , 0, 2);
sh.metrics.operationComplete(cf);
sh.metrics.operationComplete(cf);
checkShuffleMetrics(ms, 3*MiB, 1, 1, 0);
}
static void checkShuffleMetrics(MetricsSystem ms, long bytes, int failed,
int succeeded, int connections) {
MetricsSource source = ms.getSource("ShuffleMetrics");
MetricsRecordBuilder rb = getMetrics(source);
assertCounter("ShuffleOutputBytes", bytes, rb);
assertCounter("ShuffleOutputsFailed", failed, rb);
assertCounter("ShuffleOutputsOK", succeeded, rb);
assertGauge("ShuffleConnections", connections, rb);
}
/**
* Verify client prematurely closing a connection.
*
* @throws Exception exception.
*/
@Test (timeout = 10000)
public void testClientClosesConnection() throws Exception {
final ArrayList<Throwable> failures = new ArrayList<Throwable>(1);
Configuration conf = new Configuration();
conf.setInt(ShuffleHandler.SHUFFLE_PORT_CONFIG_KEY, 0);
ShuffleHandler shuffleHandler = new ShuffleHandler() {
@Override
protected Shuffle getShuffle(Configuration conf) {
// replace the shuffle handler with one stubbed for testing
return new Shuffle(conf) {
@Override
protected MapOutputInfo getMapOutputInfo(String base, String mapId,
int reduce, String user) throws IOException {
return null;
}
@Override
protected void populateHeaders(List<String> mapIds, String jobId,
String user, int reduce, HttpRequest request,
HttpResponse response, boolean keepAliveParam,
Map<String, MapOutputInfo> infoMap) throws IOException {
// Only set response headers and skip everything else
// send some dummy value for content-length
super.setResponseHeaders(response, keepAliveParam, 100);
}
@Override
protected void verifyRequest(String appid, ChannelHandlerContext ctx,
HttpRequest request, HttpResponse response, URL requestUri)
throws IOException {
}
@Override
protected ChannelFuture sendMapOutput(ChannelHandlerContext ctx,
Channel ch, String user, String mapId, int reduce,
MapOutputInfo info)
throws IOException {
// send a shuffle header and a lot of data down the channel
// to trigger a broken pipe
ShuffleHeader header =
new ShuffleHeader("attempt_12345_1_m_1_0", 5678, 5678, 1);
DataOutputBuffer dob = new DataOutputBuffer();
header.write(dob);
ch.write(wrappedBuffer(dob.getData(), 0, dob.getLength()));
dob = new DataOutputBuffer();
for (int i = 0; i < 100000; ++i) {
header.write(dob);
}
return ch.write(wrappedBuffer(dob.getData(), 0, dob.getLength()));
}
@Override
protected void sendError(ChannelHandlerContext ctx,
HttpResponseStatus status) {
if (failures.size() == 0) {
failures.add(new Error());
ctx.getChannel().close();
}
}
@Override
protected void sendError(ChannelHandlerContext ctx, String message,
HttpResponseStatus status) {
if (failures.size() == 0) {
failures.add(new Error());
ctx.getChannel().close();
}
}
};
}
};
shuffleHandler.init(conf);
shuffleHandler.start();
// simulate a reducer that closes early by reading a single shuffle header
// then closing the connection
URL url = new URL("http://127.0.0.1:"
+ shuffleHandler.getConfig().get(ShuffleHandler.SHUFFLE_PORT_CONFIG_KEY)
+ "/mapOutput?job=job_12345_1&reduce=1&map=attempt_12345_1_m_1_0");
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestProperty(ShuffleHeader.HTTP_HEADER_NAME,
ShuffleHeader.DEFAULT_HTTP_HEADER_NAME);
conn.setRequestProperty(ShuffleHeader.HTTP_HEADER_VERSION,
ShuffleHeader.DEFAULT_HTTP_HEADER_VERSION);
conn.connect();
DataInputStream input = new DataInputStream(conn.getInputStream());
Assert.assertEquals(HttpURLConnection.HTTP_OK, conn.getResponseCode());
Assert.assertEquals("close", conn.getHeaderField(HttpHeaders.CONNECTION));
ShuffleHeader header = new ShuffleHeader();
header.readFields(input);
input.close();
shuffleHandler.stop();
Assert.assertTrue("sendError called when client closed connection",
failures.size() == 0);
}
@Test(timeout = 10000)
public void testKeepAlive() throws Exception {
final ArrayList<Throwable> failures = new ArrayList<Throwable>(1);
Configuration conf = new Configuration();
conf.setInt(ShuffleHandler.SHUFFLE_PORT_CONFIG_KEY, 0);
conf.setBoolean(ShuffleHandler.SHUFFLE_CONNECTION_KEEP_ALIVE_ENABLED, true);
// try setting to -ve keep alive timeout.
conf.setInt(ShuffleHandler.SHUFFLE_CONNECTION_KEEP_ALIVE_TIME_OUT, -100);
ShuffleHandler shuffleHandler = new ShuffleHandler() {
@Override
protected Shuffle getShuffle(final Configuration conf) {
// replace the shuffle handler with one stubbed for testing
return new Shuffle(conf) {
@Override
protected MapOutputInfo getMapOutputInfo(String base, String mapId,
int reduce, String user) throws IOException {
return null;
}
@Override
protected void verifyRequest(String appid, ChannelHandlerContext ctx,
HttpRequest request, HttpResponse response, URL requestUri)
throws IOException {
}
@Override
protected void populateHeaders(List<String> mapIds, String jobId,
String user, int reduce, HttpRequest request,
HttpResponse response, boolean keepAliveParam,
Map<String, MapOutputInfo> infoMap) throws IOException {
// Send some dummy data (populate content length details)
ShuffleHeader header =
new ShuffleHeader("attempt_12345_1_m_1_0", 5678, 5678, 1);
DataOutputBuffer dob = new DataOutputBuffer();
header.write(dob);
dob = new DataOutputBuffer();
for (int i = 0; i < 100000; ++i) {
header.write(dob);
}
long contentLength = dob.getLength();
// for testing purpose;
// disable connectinKeepAliveEnabled if keepAliveParam is available
if (keepAliveParam) {
connectionKeepAliveEnabled = false;
}
super.setResponseHeaders(response, keepAliveParam, contentLength);
}
@Override
protected ChannelFuture sendMapOutput(ChannelHandlerContext ctx,
Channel ch, String user, String mapId, int reduce,
MapOutputInfo info) throws IOException {
HttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK);
// send a shuffle header and a lot of data down the channel
// to trigger a broken pipe
ShuffleHeader header =
new ShuffleHeader("attempt_12345_1_m_1_0", 5678, 5678, 1);
DataOutputBuffer dob = new DataOutputBuffer();
header.write(dob);
ch.write(wrappedBuffer(dob.getData(), 0, dob.getLength()));
dob = new DataOutputBuffer();
for (int i = 0; i < 100000; ++i) {
header.write(dob);
}
return ch.write(wrappedBuffer(dob.getData(), 0, dob.getLength()));
}
@Override
protected void sendError(ChannelHandlerContext ctx,
HttpResponseStatus status) {
if (failures.size() == 0) {
failures.add(new Error());
ctx.getChannel().close();
}
}
@Override
protected void sendError(ChannelHandlerContext ctx, String message,
HttpResponseStatus status) {
if (failures.size() == 0) {
failures.add(new Error());
ctx.getChannel().close();
}
}
};
}
};
shuffleHandler.init(conf);
shuffleHandler.start();
String shuffleBaseURL = "http://127.0.0.1:"
+ shuffleHandler.getConfig().get(
ShuffleHandler.SHUFFLE_PORT_CONFIG_KEY);
URL url =
new URL(shuffleBaseURL + "/mapOutput?job=job_12345_1&reduce=1&"
+ "map=attempt_12345_1_m_1_0");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestProperty(ShuffleHeader.HTTP_HEADER_NAME,
ShuffleHeader.DEFAULT_HTTP_HEADER_NAME);
conn.setRequestProperty(ShuffleHeader.HTTP_HEADER_VERSION,
ShuffleHeader.DEFAULT_HTTP_HEADER_VERSION);
conn.connect();
DataInputStream input = new DataInputStream(conn.getInputStream());
Assert.assertEquals(HttpHeaders.KEEP_ALIVE,
conn.getHeaderField(HttpHeaders.CONNECTION));
Assert.assertEquals("timeout=1",
conn.getHeaderField(HttpHeaders.KEEP_ALIVE));
Assert.assertEquals(HttpURLConnection.HTTP_OK, conn.getResponseCode());
ShuffleHeader header = new ShuffleHeader();
header.readFields(input);
input.close();
// For keepAlive via URL
url =
new URL(shuffleBaseURL + "/mapOutput?job=job_12345_1&reduce=1&"
+ "map=attempt_12345_1_m_1_0&keepAlive=true");
conn = (HttpURLConnection) url.openConnection();
conn.setRequestProperty(ShuffleHeader.HTTP_HEADER_NAME,
ShuffleHeader.DEFAULT_HTTP_HEADER_NAME);
conn.setRequestProperty(ShuffleHeader.HTTP_HEADER_VERSION,
ShuffleHeader.DEFAULT_HTTP_HEADER_VERSION);
conn.connect();
input = new DataInputStream(conn.getInputStream());
Assert.assertEquals(HttpHeaders.KEEP_ALIVE,
conn.getHeaderField(HttpHeaders.CONNECTION));
Assert.assertEquals("timeout=1",
conn.getHeaderField(HttpHeaders.KEEP_ALIVE));
Assert.assertEquals(HttpURLConnection.HTTP_OK, conn.getResponseCode());
header = new ShuffleHeader();
header.readFields(input);
input.close();
}
/**
* simulate a reducer that sends an invalid shuffle-header - sometimes a wrong
* header_name and sometimes a wrong version
*
* @throws Exception exception
*/
@Test (timeout = 10000)
public void testIncompatibleShuffleVersion() throws Exception {
final int failureNum = 3;
Configuration conf = new Configuration();
conf.setInt(ShuffleHandler.SHUFFLE_PORT_CONFIG_KEY, 0);
ShuffleHandler shuffleHandler = new ShuffleHandler();
shuffleHandler.init(conf);
shuffleHandler.start();
// simulate a reducer that closes early by reading a single shuffle header
// then closing the connection
URL url = new URL("http://127.0.0.1:"
+ shuffleHandler.getConfig().get(ShuffleHandler.SHUFFLE_PORT_CONFIG_KEY)
+ "/mapOutput?job=job_12345_1&reduce=1&map=attempt_12345_1_m_1_0");
for (int i = 0; i < failureNum; ++i) {
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestProperty(ShuffleHeader.HTTP_HEADER_NAME,
i == 0 ? "mapreduce" : "other");
conn.setRequestProperty(ShuffleHeader.HTTP_HEADER_VERSION,
i == 1 ? "1.0.0" : "1.0.1");
conn.connect();
Assert.assertEquals(
HttpURLConnection.HTTP_BAD_REQUEST, conn.getResponseCode());
}
shuffleHandler.stop();
shuffleHandler.close();
}
/**
* Validate the limit on number of shuffle connections.
*
* @throws Exception exception
*/
@Test (timeout = 10000)
public void testMaxConnections() throws Exception {
Configuration conf = new Configuration();
conf.setInt(ShuffleHandler.SHUFFLE_PORT_CONFIG_KEY, 0);
conf.setInt(ShuffleHandler.MAX_SHUFFLE_CONNECTIONS, 3);
ShuffleHandler shuffleHandler = new ShuffleHandler() {
@Override
protected Shuffle getShuffle(Configuration conf) {
// replace the shuffle handler with one stubbed for testing
return new Shuffle(conf) {
@Override
protected MapOutputInfo getMapOutputInfo(String base, String mapId,
int reduce, String user) throws IOException {
// Do nothing.
return null;
}
@Override
protected void populateHeaders(List<String> mapIds, String jobId,
String user, int reduce, HttpRequest request,
HttpResponse response, boolean keepAliveParam,
Map<String, MapOutputInfo> infoMap) throws IOException {
// Do nothing.
}
@Override
protected void verifyRequest(String appid, ChannelHandlerContext ctx,
HttpRequest request, HttpResponse response, URL requestUri)
throws IOException {
// Do nothing.
}
@Override
protected ChannelFuture sendMapOutput(ChannelHandlerContext ctx,
Channel ch, String user, String mapId, int reduce,
MapOutputInfo info)
throws IOException {
// send a shuffle header and a lot of data down the channel
// to trigger a broken pipe
ShuffleHeader header =
new ShuffleHeader("dummy_header", 5678, 5678, 1);
DataOutputBuffer dob = new DataOutputBuffer();
header.write(dob);
ch.write(wrappedBuffer(dob.getData(), 0, dob.getLength()));
dob = new DataOutputBuffer();
for (int i=0; i<100000; ++i) {
header.write(dob);
}
return ch.write(wrappedBuffer(dob.getData(), 0, dob.getLength()));
}
};
}
};
shuffleHandler.init(conf);
shuffleHandler.start();
// setup connections
int connAttempts = 3;
HttpURLConnection conns[] = new HttpURLConnection[connAttempts];
for (int i = 0; i < connAttempts; i++) {
String URLstring = "http://127.0.0.1:"
+ shuffleHandler.getConfig().get(ShuffleHandler.SHUFFLE_PORT_CONFIG_KEY)
+ "/mapOutput?job=job_12345_1&reduce=1&map=attempt_12345_1_m_"
+ i + "_0";
URL url = new URL(URLstring);
conns[i] = (HttpURLConnection)url.openConnection();
conns[i].setRequestProperty(ShuffleHeader.HTTP_HEADER_NAME,
ShuffleHeader.DEFAULT_HTTP_HEADER_NAME);
conns[i].setRequestProperty(ShuffleHeader.HTTP_HEADER_VERSION,
ShuffleHeader.DEFAULT_HTTP_HEADER_VERSION);
}
// Try to open numerous connections
for (int i = 0; i < connAttempts; i++) {
conns[i].connect();
}
//Ensure first connections are okay
conns[0].getInputStream();
int rc = conns[0].getResponseCode();
Assert.assertEquals(HttpURLConnection.HTTP_OK, rc);
conns[1].getInputStream();
rc = conns[1].getResponseCode();
Assert.assertEquals(HttpURLConnection.HTTP_OK, rc);
// This connection should be closed because it to above the limit
try {
conns[2].getInputStream();
rc = conns[2].getResponseCode();
Assert.fail("Expected a SocketException");
} catch (SocketException se) {
LOG.info("Expected - connection should not be open");
} catch (Exception e) {
Assert.fail("Expected a SocketException");
}
shuffleHandler.stop();
}
/**
* Validate the ownership of the map-output files being pulled in. The
* local-file-system owner of the file should match the user component in the
*
* @throws Exception exception
*/
@Test(timeout = 100000)
public void testMapFileAccess() throws IOException {
// This will run only in NativeIO is enabled as SecureIOUtils need it
assumeTrue(NativeIO.isAvailable());
Configuration conf = new Configuration();
conf.setInt(ShuffleHandler.SHUFFLE_PORT_CONFIG_KEY, 0);
conf.setInt(ShuffleHandler.MAX_SHUFFLE_CONNECTIONS, 3);
conf.set(CommonConfigurationKeysPublic.HADOOP_SECURITY_AUTHENTICATION,
"kerberos");
UserGroupInformation.setConfiguration(conf);
File absLogDir = new File("target",
TestShuffleHandler.class.getSimpleName() + "LocDir").getAbsoluteFile();
conf.set(YarnConfiguration.NM_LOCAL_DIRS, absLogDir.getAbsolutePath());
ApplicationId appId = ApplicationId.newInstance(12345, 1);
LOG.info(appId.toString());
String appAttemptId = "attempt_12345_1_m_1_0";
String user = "randomUser";
String reducerId = "0";
List<File> fileMap = new ArrayList<File>();
createShuffleHandlerFiles(absLogDir, user, appId.toString(), appAttemptId,
conf, fileMap);
ShuffleHandler shuffleHandler = new ShuffleHandler() {
@Override
protected Shuffle getShuffle(Configuration conf) {
// replace the shuffle handler with one stubbed for testing
return new Shuffle(conf) {
@Override
protected void verifyRequest(String appid, ChannelHandlerContext ctx,
HttpRequest request, HttpResponse response, URL requestUri)
throws IOException {
// Do nothing.
}
};
}
};
shuffleHandler.init(conf);
try {
shuffleHandler.start();
DataOutputBuffer outputBuffer = new DataOutputBuffer();
outputBuffer.reset();
Token<JobTokenIdentifier> jt =
new Token<JobTokenIdentifier>("identifier".getBytes(),
"password".getBytes(), new Text(user), new Text("shuffleService"));
jt.write(outputBuffer);
shuffleHandler
.initializeApplication(new ApplicationInitializationContext(user,
appId, ByteBuffer.wrap(outputBuffer.getData(), 0,
outputBuffer.getLength())));
URL url =
new URL(
"http://127.0.0.1:"
+ shuffleHandler.getConfig().get(
ShuffleHandler.SHUFFLE_PORT_CONFIG_KEY)
+ "/mapOutput?job=job_12345_0001&reduce=" + reducerId
+ "&map=attempt_12345_1_m_1_0");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestProperty(ShuffleHeader.HTTP_HEADER_NAME,
ShuffleHeader.DEFAULT_HTTP_HEADER_NAME);
conn.setRequestProperty(ShuffleHeader.HTTP_HEADER_VERSION,
ShuffleHeader.DEFAULT_HTTP_HEADER_VERSION);
conn.connect();
byte[] byteArr = new byte[10000];
try {
DataInputStream is = new DataInputStream(conn.getInputStream());
is.readFully(byteArr);
} catch (EOFException e) {
// ignore
}
// Retrieve file owner name
FileInputStream is = new FileInputStream(fileMap.get(0));
String owner = NativeIO.POSIX.getFstat(is.getFD()).getOwner();
is.close();
String message =
"Owner '" + owner + "' for path " + fileMap.get(0).getAbsolutePath()
+ " did not match expected owner '" + user + "'";
Assert.assertTrue((new String(byteArr)).contains(message));
} finally {
shuffleHandler.stop();
}
}
private static void createShuffleHandlerFiles(File logDir, String user,
String appId, String appAttemptId, Configuration conf,
List<File> fileMap) throws IOException {
String attemptDir =
StringUtils.join(Path.SEPARATOR,
Arrays.asList(new String[] { logDir.getAbsolutePath(),
ContainerLocalizer.USERCACHE, user,
ContainerLocalizer.APPCACHE, appId, "output", appAttemptId }));
File appAttemptDir = new File(attemptDir);
appAttemptDir.mkdirs();
System.out.println(appAttemptDir.getAbsolutePath());
File indexFile = new File(appAttemptDir, "file.out.index");
fileMap.add(indexFile);
createIndexFile(indexFile, conf);
File mapOutputFile = new File(appAttemptDir, "file.out");
fileMap.add(mapOutputFile);
createMapOutputFile(mapOutputFile, conf);
}
private static void
createMapOutputFile(File mapOutputFile, Configuration conf)
throws IOException {
FileOutputStream out = new FileOutputStream(mapOutputFile);
out.write("Creating new dummy map output file. Used only for testing"
.getBytes());
out.flush();
out.close();
}
private static void createIndexFile(File indexFile, Configuration conf)
throws IOException {
if (indexFile.exists()) {
System.out.println("Deleting existing file");
indexFile.delete();
}
indexFile.createNewFile();
FSDataOutputStream output = FileSystem.getLocal(conf).getRaw().append(
new Path(indexFile.getAbsolutePath()));
Checksum crc = new PureJavaCrc32();
crc.reset();
CheckedOutputStream chk = new CheckedOutputStream(output, crc);
String msg = "Writing new index file. This file will be used only " +
"for the testing.";
chk.write(Arrays.copyOf(msg.getBytes(),
MapTask.MAP_OUTPUT_INDEX_RECORD_LENGTH));
output.writeLong(chk.getChecksum().getValue());
output.close();
}
}