/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.mapred;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.PrintStream;
import java.net.InetSocketAddress;
import java.security.PrivilegedExceptionAction;
import java.util.Arrays;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.FSError;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.LocalDirAllocator;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.mapreduce.security.TokenCache;
import org.apache.hadoop.mapreduce.security.token.JobTokenIdentifier;
import org.apache.hadoop.mapreduce.security.token.JobTokenSecretManager;
import org.apache.hadoop.mapreduce.server.tasktracker.JVMInfo;
import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
import org.apache.hadoop.metrics2.source.JvmMetricsSource;
import org.apache.hadoop.net.NetUtils;
import org.apache.hadoop.security.Credentials;
import org.apache.hadoop.security.SecurityUtil;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.security.token.Token;
import org.apache.hadoop.util.Shell;
import org.apache.hadoop.util.StringUtils;
import org.apache.log4j.LogManager;
/**
* The main() for child processes.
*/
class Child {
public static final Log LOG =
LogFactory.getLog(Child.class);
static volatile TaskAttemptID taskid = null;
static volatile boolean currentJobSegmented = true;
static volatile boolean isCleanup;
static String cwd;
static boolean logIsSegmented(JobConf job) {
return (job.getNumTasksToExecutePerJvm() != 1);
}
public static void main(String[] args) throws Throwable {
LOG.debug("Child starting");
final JobConf defaultConf = new JobConf();
String host = args[0];
int port = Integer.parseInt(args[1]);
final InetSocketAddress address = NetUtils.makeSocketAddr(host, port);
final TaskAttemptID firstTaskid = TaskAttemptID.forName(args[2]);
final String logLocation = args[3];
final int SLEEP_LONGER_COUNT = 5;
int jvmIdInt = Integer.parseInt(args[4]);
JVMId jvmId = new JVMId(firstTaskid.getJobID(),firstTaskid.isMap(),jvmIdInt);
String prefix = firstTaskid.isMap() ? "MapTask" : "ReduceTask";
cwd = System.getenv().get(TaskRunner.HADOOP_WORK_DIR);
if (cwd == null) {
throw new IOException("Environment variable " +
TaskRunner.HADOOP_WORK_DIR + " is not set");
}
// file name is passed thru env
String jobTokenFile =
System.getenv().get(UserGroupInformation.HADOOP_TOKEN_FILE_LOCATION);
Credentials credentials =
TokenCache.loadTokens(jobTokenFile, defaultConf);
LOG.debug("loading token. # keys =" +credentials.numberOfSecretKeys() +
"; from file=" + jobTokenFile);
Token<JobTokenIdentifier> jt = TokenCache.getJobToken(credentials);
SecurityUtil.setTokenService(jt, address);
UserGroupInformation current = UserGroupInformation.getCurrentUser();
current.addToken(jt);
UserGroupInformation taskOwner
= UserGroupInformation.createRemoteUser(firstTaskid.getJobID().toString());
taskOwner.addToken(jt);
// Set the credentials
defaultConf.setCredentials(credentials);
final TaskUmbilicalProtocol umbilical =
taskOwner.doAs(new PrivilegedExceptionAction<TaskUmbilicalProtocol>() {
@Override
public TaskUmbilicalProtocol run() throws Exception {
return (TaskUmbilicalProtocol)RPC.getProxy(TaskUmbilicalProtocol.class,
TaskUmbilicalProtocol.versionID,
address,
defaultConf);
}
});
int numTasksToExecute = -1; //-1 signifies "no limit"
int numTasksExecuted = 0;
Runtime.getRuntime().addShutdownHook(new Thread() {
public void run() {
try {
if (taskid != null) {
TaskLog.syncLogs
(logLocation, taskid, isCleanup, currentJobSegmented);
}
} catch (Throwable throwable) {
}
}
});
Thread t = new Thread() {
public void run() {
//every so often wake up and syncLogs so that we can track
//logs of the currently running task
while (true) {
try {
Thread.sleep(5000);
if (taskid != null) {
TaskLog.syncLogs
(logLocation, taskid, isCleanup, currentJobSegmented);
}
} catch (InterruptedException ie) {
} catch (IOException iee) {
LOG.error("Error in syncLogs: " + iee);
System.exit(-1);
}
}
}
};
t.setName("Thread for syncLogs");
t.setDaemon(true);
t.start();
String pid = "";
if (!Shell.WINDOWS) {
pid = System.getenv().get("JVM_PID");
}
JvmContext context = new JvmContext(jvmId, pid);
int idleLoopCount = 0;
Task task = null;
UserGroupInformation childUGI = null;
final JvmContext jvmContext = context;
try {
while (true) {
taskid = null;
currentJobSegmented = true;
JvmTask myTask = umbilical.getTask(context);
if (myTask.shouldDie()) {
break;
} else {
if (myTask.getTask() == null) {
taskid = null;
currentJobSegmented = true;
if (++idleLoopCount >= SLEEP_LONGER_COUNT) {
//we sleep for a bigger interval when we don't receive
//tasks for a while
Thread.sleep(1500);
} else {
Thread.sleep(500);
}
continue;
}
}
idleLoopCount = 0;
task = myTask.getTask();
task.setJvmContext(jvmContext);
taskid = task.getTaskID();
// Create the JobConf and determine if this job gets segmented task logs
final JobConf job = new JobConf(task.getJobFile());
currentJobSegmented = logIsSegmented(job);
isCleanup = task.isTaskCleanupTask();
// reset the statistics for the task
FileSystem.clearStatistics();
// Set credentials
job.setCredentials(defaultConf.getCredentials());
//forcefully turn off caching for localfs. All cached FileSystems
//are closed during the JVM shutdown. We do certain
//localfs operations in the shutdown hook, and we don't
//want the localfs to be "closed"
job.setBoolean("fs.file.impl.disable.cache", false);
// set the jobTokenFile into task
task.setJobTokenSecret(JobTokenSecretManager.
createSecretKey(jt.getPassword()));
// setup the child's mapred-local-dir. The child is now sandboxed and
// can only see files down and under attemtdir only.
TaskRunner.setupChildMapredLocalDirs(task, job);
// setup the child's attempt directories
localizeTask(task, job, logLocation);
//setupWorkDir actually sets up the symlinks for the distributed
//cache. After a task exits we wipe the workdir clean, and hence
//the symlinks have to be rebuilt.
TaskRunner.setupWorkDir(job, new File(cwd));
//create the index file so that the log files
//are viewable immediately
TaskLog.syncLogs
(logLocation, taskid, isCleanup, logIsSegmented(job));
numTasksToExecute = job.getNumTasksToExecutePerJvm();
assert(numTasksToExecute != 0);
task.setConf(job);
// Initiate Java VM metrics
initMetrics(prefix, jvmId.toString(), job.getSessionId());
LOG.debug("Creating remote user to execute task: " + job.get("user.name"));
childUGI = UserGroupInformation.createRemoteUser(job.get("user.name"));
// Add tokens to new user so that it may execute its task correctly.
for(Token<?> token : UserGroupInformation.getCurrentUser().getTokens()) {
childUGI.addToken(token);
}
// Create a final reference to the task for the doAs block
final Task taskFinal = task;
childUGI.doAs(new PrivilegedExceptionAction<Object>() {
@Override
public Object run() throws Exception {
try {
// use job-specified working directory
FileSystem.get(job).setWorkingDirectory(job.getWorkingDirectory());
taskFinal.run(job, umbilical); // run the task
} finally {
TaskLog.syncLogs
(logLocation, taskid, isCleanup, logIsSegmented(job));
TaskLogsTruncater trunc = new TaskLogsTruncater(defaultConf);
trunc.truncateLogs(new JVMInfo(
TaskLog.getAttemptDir(taskFinal.getTaskID(),
taskFinal.isTaskCleanupTask()), Arrays.asList(taskFinal)));
}
return null;
}
});
if (numTasksToExecute > 0 && ++numTasksExecuted == numTasksToExecute) {
break;
}
}
} catch (FSError e) {
LOG.fatal("FSError from child", e);
umbilical.fsError(taskid, e.getMessage(), jvmContext);
} catch (Exception exception) {
LOG.warn("Error running child", exception);
try {
if (task != null) {
// do cleanup for the task
if(childUGI == null) {
task.taskCleanup(umbilical);
} else {
final Task taskFinal = task;
childUGI.doAs(new PrivilegedExceptionAction<Object>() {
@Override
public Object run() throws Exception {
taskFinal.taskCleanup(umbilical);
return null;
}
});
}
}
} catch (Exception e) {
LOG.info("Error cleaning up", e);
}
// Report back any failures, for diagnostic purposes
ByteArrayOutputStream baos = new ByteArrayOutputStream();
exception.printStackTrace(new PrintStream(baos));
if (taskid != null) {
umbilical.reportDiagnosticInfo(taskid, baos.toString(), jvmContext);
}
} catch (Throwable throwable) {
LOG.fatal("Error running child : "
+ StringUtils.stringifyException(throwable));
if (taskid != null) {
Throwable tCause = throwable.getCause();
String cause = tCause == null
? throwable.getMessage()
: StringUtils.stringifyException(tCause);
umbilical.fatalError(taskid, cause, jvmContext);
}
} finally {
RPC.stopProxy(umbilical);
shutdownMetrics();
// Shutting down log4j of the child-vm...
// This assumes that on return from Task.run()
// there is no more logging done.
LogManager.shutdown();
}
}
private static void initMetrics(String prefix, String procName,
String sessionId) {
DefaultMetricsSystem.initialize(prefix);
JvmMetricsSource.create(procName, sessionId);
}
private static void shutdownMetrics() {
DefaultMetricsSystem.INSTANCE.shutdown();
}
static void localizeTask(Task task, JobConf jobConf, String logLocation)
throws IOException{
// Do the task-type specific localization
task.localizeConfiguration(jobConf);
//write the localized task jobconf
LocalDirAllocator lDirAlloc =
new LocalDirAllocator(JobConf.MAPRED_LOCAL_DIR_PROPERTY);
Path localTaskFile =
lDirAlloc.getLocalPathForWrite(TaskTracker.JOBFILE, jobConf);
JobLocalizer.writeLocalJobFile(localTaskFile, jobConf);
task.setJobFile(localTaskFile.toString());
task.setConf(jobConf);
}
}