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Hadoop is the distributed computing framework of Apache; hadoop-core contains
the filesystem, job tracker and map/reduce modules
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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.mapred;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.LocalFileSystem;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.Path;
import org.apache.log4j.Appender;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;
/**
* A simple logger to handle the task-specific user logs.
* This class uses the system property hadoop.log.dir.
*
*/
public class TaskLog {
private static final Log LOG =
LogFactory.getLog(TaskLog.class.getName());
private static final File LOG_DIR =
new File(System.getProperty("hadoop.log.dir"),
"userlogs").getAbsoluteFile();
static LocalFileSystem localFS = null;
static {
try {
localFS = FileSystem.getLocal(new Configuration());
} catch (IOException ioe) {
LOG.warn("Getting local file system failed.");
}
if (!LOG_DIR.exists()) {
LOG_DIR.mkdirs();
}
}
public static File getTaskLogFile(TaskAttemptID taskid, LogName filter) {
return new File(getBaseDir(taskid.toString()), filter.toString());
}
public static File getRealTaskLogFileLocation(TaskAttemptID taskid,
LogName filter) {
LogFileDetail l;
try {
l = getTaskLogFileDetail(taskid, filter);
} catch (IOException ie) {
LOG.error("getTaskLogFileDetail threw an exception " + ie);
return null;
}
return new File(getBaseDir(l.location), filter.toString());
}
private static class LogFileDetail {
final static String LOCATION = "LOG_DIR:";
String location;
long start;
long length;
}
private static LogFileDetail getTaskLogFileDetail(TaskAttemptID taskid,
LogName filter) throws IOException {
return getLogFileDetail(taskid, filter, false);
}
private static LogFileDetail getLogFileDetail(TaskAttemptID taskid,
LogName filter,
boolean isCleanup)
throws IOException {
File indexFile = getIndexFile(taskid.toString(), isCleanup);
BufferedReader fis = new BufferedReader(new java.io.FileReader(indexFile));
//the format of the index file is
//LOG_DIR:
//stdout:
//stderr:
//syslog:
LogFileDetail l = new LogFileDetail();
String str = fis.readLine();
if (str == null) { //the file doesn't have anything
throw new IOException ("Index file for the log of " + taskid+" doesn't exist.");
}
l.location = str.substring(str.indexOf(LogFileDetail.LOCATION)+
LogFileDetail.LOCATION.length());
//special cases are the debugout and profile.out files. They are guaranteed
//to be associated with each task attempt since jvm reuse is disabled
//when profiling/debugging is enabled
if (filter.equals(LogName.DEBUGOUT) || filter.equals(LogName.PROFILE)) {
l.length = new File(getBaseDir(l.location), filter.toString()).length();
l.start = 0;
fis.close();
return l;
}
str = fis.readLine();
while (str != null) {
//look for the exact line containing the logname
if (str.contains(filter.toString())) {
str = str.substring(filter.toString().length()+1);
String[] startAndLen = str.split(" ");
l.start = Long.parseLong(startAndLen[0]);
l.length = Long.parseLong(startAndLen[1]);
break;
}
str = fis.readLine();
}
fis.close();
return l;
}
private static File getTmpIndexFile(String taskid) {
return new File(getBaseDir(taskid), "log.tmp");
}
public static File getIndexFile(String taskid) {
return getIndexFile(taskid, false);
}
public static File getIndexFile(String taskid, boolean isCleanup) {
if (isCleanup) {
return new File(getBaseDir(taskid), "log.index.cleanup");
} else {
return new File(getBaseDir(taskid), "log.index");
}
}
private static File getBaseDir(String taskid) {
return new File(LOG_DIR, taskid);
}
private static long prevOutLength;
private static long prevErrLength;
private static long prevLogLength;
private static void writeToIndexFile(TaskAttemptID firstTaskid,
boolean isCleanup)
throws IOException {
// To ensure atomicity of updates to index file, write to temporary index
// file first and then rename.
File tmpIndexFile = getTmpIndexFile(currentTaskid.toString());
BufferedOutputStream bos =
new BufferedOutputStream(new FileOutputStream(tmpIndexFile,false));
DataOutputStream dos = new DataOutputStream(bos);
//the format of the index file is
//LOG_DIR:
//STDOUT:
//STDERR:
//SYSLOG:
dos.writeBytes(LogFileDetail.LOCATION + firstTaskid.toString()+"\n"+
LogName.STDOUT.toString()+":");
dos.writeBytes(Long.toString(prevOutLength)+" ");
dos.writeBytes(Long.toString(getTaskLogFile(firstTaskid, LogName.STDOUT)
.length() - prevOutLength)+"\n"+LogName.STDERR+":");
dos.writeBytes(Long.toString(prevErrLength)+" ");
dos.writeBytes(Long.toString(getTaskLogFile(firstTaskid, LogName.STDERR)
.length() - prevErrLength)+"\n"+LogName.SYSLOG.toString()+":");
dos.writeBytes(Long.toString(prevLogLength)+" ");
dos.writeBytes(Long.toString(getTaskLogFile(firstTaskid, LogName.SYSLOG)
.length() - prevLogLength)+"\n");
dos.close();
File indexFile = getIndexFile(currentTaskid.toString(), isCleanup);
Path indexFilePath = new Path(indexFile.getAbsolutePath());
Path tmpIndexFilePath = new Path(tmpIndexFile.getAbsolutePath());
localFS.rename (tmpIndexFilePath, indexFilePath);
}
private static void resetPrevLengths(TaskAttemptID firstTaskid) {
prevOutLength = getTaskLogFile(firstTaskid, LogName.STDOUT).length();
prevErrLength = getTaskLogFile(firstTaskid, LogName.STDERR).length();
prevLogLength = getTaskLogFile(firstTaskid, LogName.SYSLOG).length();
}
private volatile static TaskAttemptID currentTaskid = null;
public synchronized static void syncLogs(TaskAttemptID firstTaskid,
TaskAttemptID taskid)
throws IOException {
syncLogs(firstTaskid, taskid, false);
}
@SuppressWarnings("unchecked")
public synchronized static void syncLogs(TaskAttemptID firstTaskid,
TaskAttemptID taskid,
boolean isCleanup)
throws IOException {
System.out.flush();
System.err.flush();
Enumeration allLoggers = LogManager.getCurrentLoggers();
while (allLoggers.hasMoreElements()) {
Logger l = allLoggers.nextElement();
Enumeration allAppenders = l.getAllAppenders();
while (allAppenders.hasMoreElements()) {
Appender a = allAppenders.nextElement();
if (a instanceof TaskLogAppender) {
((TaskLogAppender)a).flush();
}
}
}
if (currentTaskid != taskid) {
currentTaskid = taskid;
resetPrevLengths(firstTaskid);
}
writeToIndexFile(firstTaskid, isCleanup);
}
/**
* The filter for userlogs.
*/
public static enum LogName {
/** Log on the stdout of the task. */
STDOUT ("stdout"),
/** Log on the stderr of the task. */
STDERR ("stderr"),
/** Log on the map-reduce system logs of the task. */
SYSLOG ("syslog"),
/** The java profiler information. */
PROFILE ("profile.out"),
/** Log the debug script's stdout */
DEBUGOUT ("debugout");
private String prefix;
private LogName(String prefix) {
this.prefix = prefix;
}
@Override
public String toString() {
return prefix;
}
}
private static class TaskLogsPurgeFilter implements FileFilter {
long purgeTimeStamp;
TaskLogsPurgeFilter(long purgeTimeStamp) {
this.purgeTimeStamp = purgeTimeStamp;
}
public boolean accept(File file) {
LOG.debug("PurgeFilter - file: " + file + ", mtime: " + file.lastModified() + ", purge: " + purgeTimeStamp);
return file.lastModified() < purgeTimeStamp;
}
}
/**
* Purge old user logs.
*
* @throws IOException
*/
public static synchronized void cleanup(int logsRetainHours
) throws IOException {
// Purge logs of tasks on this tasktracker if their
// mtime has exceeded "mapred.task.log.retain" hours
long purgeTimeStamp = System.currentTimeMillis() -
(logsRetainHours*60L*60*1000);
File[] oldTaskLogs = LOG_DIR.listFiles
(new TaskLogsPurgeFilter(purgeTimeStamp));
if (oldTaskLogs != null) {
for (int i=0; i < oldTaskLogs.length; ++i) {
FileUtil.fullyDelete(oldTaskLogs[i]);
}
}
}
static class Reader extends InputStream {
private long bytesRemaining;
private FileInputStream file;
public Reader(TaskAttemptID taskid, LogName kind,
long start, long end) throws IOException {
this(taskid, kind, start, end, false);
}
/**
* Read a log file from start to end positions. The offsets may be negative,
* in which case they are relative to the end of the file. For example,
* Reader(taskid, kind, 0, -1) is the entire file and
* Reader(taskid, kind, -4197, -1) is the last 4196 bytes.
* @param taskid the id of the task to read the log file for
* @param kind the kind of log to read
* @param start the offset to read from (negative is relative to tail)
* @param end the offset to read upto (negative is relative to tail)
* @param isCleanup whether the attempt is cleanup attempt or not
* @throws IOException
*/
public Reader(TaskAttemptID taskid, LogName kind,
long start, long end, boolean isCleanup) throws IOException {
// find the right log file
LogFileDetail fileDetail = getLogFileDetail(taskid, kind, isCleanup);
// calculate the start and stop
long size = fileDetail.length;
if (start < 0) {
start += size + 1;
}
if (end < 0) {
end += size + 1;
}
start = Math.max(0, Math.min(start, size));
end = Math.max(0, Math.min(end, size));
start += fileDetail.start;
end += fileDetail.start;
bytesRemaining = end - start;
file = new FileInputStream(new File(getBaseDir(fileDetail.location),
kind.toString()));
// skip upto start
long pos = 0;
while (pos < start) {
long result = file.skip(start - pos);
if (result < 0) {
bytesRemaining = 0;
break;
}
pos += result;
}
}
@Override
public int read() throws IOException {
int result = -1;
if (bytesRemaining > 0) {
bytesRemaining -= 1;
result = file.read();
}
return result;
}
@Override
public int read(byte[] buffer, int offset, int length) throws IOException {
length = (int) Math.min(length, bytesRemaining);
int bytes = file.read(buffer, offset, length);
if (bytes > 0) {
bytesRemaining -= bytes;
}
return bytes;
}
@Override
public int available() throws IOException {
return (int) Math.min(bytesRemaining, file.available());
}
@Override
public void close() throws IOException {
file.close();
}
}
private static final String bashCommand = "bash";
private static final String tailCommand = "tail";
/**
* Get the desired maximum length of task's logs.
* @param conf the job to look in
* @return the number of bytes to cap the log files at
*/
public static long getTaskLogLength(JobConf conf) {
return conf.getLong("mapred.userlog.limit.kb", 100) * 1024;
}
/**
* Wrap a command in a shell to capture stdout and stderr to files.
* If the tailLength is 0, the entire output will be saved.
* @param cmd The command and the arguments that should be run
* @param stdoutFilename The filename that stdout should be saved to
* @param stderrFilename The filename that stderr should be saved to
* @param tailLength The length of the tail to be saved.
* @return the modified command that should be run
*/
public static List captureOutAndError(List cmd,
File stdoutFilename,
File stderrFilename,
long tailLength
) throws IOException {
return captureOutAndError(null, cmd, stdoutFilename,
stderrFilename, tailLength, null );
}
/**
* Wrap a command in a shell to capture stdout and stderr to files.
* Setup commands such as setting memory limit can be passed which
* will be executed before exec.
* If the tailLength is 0, the entire output will be saved.
* @param setup The setup commands for the execed process.
* @param cmd The command and the arguments that should be run
* @param stdoutFilename The filename that stdout should be saved to
* @param stderrFilename The filename that stderr should be saved to
* @param tailLength The length of the tail to be saved.
* @return the modified command that should be run
*/
public static List captureOutAndError(List setup,
List cmd,
File stdoutFilename,
File stderrFilename,
long tailLength
) throws IOException {
return captureOutAndError(setup, cmd, stdoutFilename, stderrFilename,
tailLength, null);
}
/**
* Wrap a command in a shell to capture stdout and stderr to files.
* Setup commands such as setting memory limit can be passed which
* will be executed before exec.
* If the tailLength is 0, the entire output will be saved.
* @param setup The setup commands for the execed process.
* @param cmd The command and the arguments that should be run
* @param stdoutFilename The filename that stdout should be saved to
* @param stderrFilename The filename that stderr should be saved to
* @param tailLength The length of the tail to be saved.
* @param pidFileName The name of the pid-file
* @return the modified command that should be run
*/
public static List captureOutAndError(List setup,
List cmd,
File stdoutFilename,
File stderrFilename,
long tailLength,
String pidFileName
) throws IOException {
String stdout = FileUtil.makeShellPath(stdoutFilename);
String stderr = FileUtil.makeShellPath(stderrFilename);
List result = new ArrayList(3);
result.add(bashCommand);
result.add("-c");
StringBuffer mergedCmd = new StringBuffer();
// Spit out the pid to pidFileName
if (pidFileName != null) {
mergedCmd.append("echo $$ > ");
mergedCmd.append(pidFileName);
mergedCmd.append(" ;");
}
if (setup != null && setup.size() > 0) {
mergedCmd.append(addCommand(setup, false));
mergedCmd.append(";");
}
if (tailLength > 0) {
mergedCmd.append("(");
} else {
mergedCmd.append("exec ");
}
mergedCmd.append(addCommand(cmd, true));
mergedCmd.append(" < /dev/null ");
if (tailLength > 0) {
mergedCmd.append(" | ");
mergedCmd.append(tailCommand);
mergedCmd.append(" -c ");
mergedCmd.append(tailLength);
mergedCmd.append(" >> ");
mergedCmd.append(stdout);
mergedCmd.append(" ; exit $PIPESTATUS ) 2>&1 | ");
mergedCmd.append(tailCommand);
mergedCmd.append(" -c ");
mergedCmd.append(tailLength);
mergedCmd.append(" >> ");
mergedCmd.append(stderr);
mergedCmd.append(" ; exit $PIPESTATUS");
} else {
mergedCmd.append(" 1>> ");
mergedCmd.append(stdout);
mergedCmd.append(" 2>> ");
mergedCmd.append(stderr);
}
result.add(mergedCmd.toString());
return result;
}
/**
* Add quotes to each of the command strings and
* return as a single string
* @param cmd The command to be quoted
* @param isExecutable makes shell path if the first
* argument is executable
* @return returns The quoted string.
* @throws IOException
*/
public static String addCommand(List cmd, boolean isExecutable)
throws IOException {
StringBuffer command = new StringBuffer();
for(String s: cmd) {
command.append('\'');
if (isExecutable) {
// the executable name needs to be expressed as a shell path for the
// shell to find it.
command.append(FileUtil.makeShellPath(new File(s)));
isExecutable = false;
} else {
command.append(s);
}
command.append('\'');
command.append(" ");
}
return command.toString();
}
/**
* Wrap a command in a shell to capture debug script's
* stdout and stderr to debugout.
* @param cmd The command and the arguments that should be run
* @param debugoutFilename The filename that stdout and stderr
* should be saved to.
* @return the modified command that should be run
* @throws IOException
*/
public static List captureDebugOut(List cmd,
File debugoutFilename
) throws IOException {
String debugout = FileUtil.makeShellPath(debugoutFilename);
List result = new ArrayList(3);
result.add(bashCommand);
result.add("-c");
StringBuffer mergedCmd = new StringBuffer();
mergedCmd.append("exec ");
boolean isExecutable = true;
for(String s: cmd) {
if (isExecutable) {
// the executable name needs to be expressed as a shell path for the
// shell to find it.
mergedCmd.append(FileUtil.makeShellPath(new File(s)));
isExecutable = false;
} else {
mergedCmd.append(s);
}
mergedCmd.append(" ");
}
mergedCmd.append(" < /dev/null ");
mergedCmd.append(" >");
mergedCmd.append(debugout);
mergedCmd.append(" 2>&1 ");
result.add(mergedCmd.toString());
return result;
}
} // TaskLog