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From "Guilin Sun (JIRA)" <j...@apache.org>
Subject [jira] Created: (MAPREDUCE-1648) Use RollingFileAppender to limit tasklogs
Date Tue, 30 Mar 2010 12:56:27 GMT
Use RollingFileAppender to limit tasklogs

                 Key: MAPREDUCE-1648
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1648
             Project: Hadoop Map/Reduce
          Issue Type: Improvement
          Components: tasktracker
            Reporter: Guilin Sun
            Priority: Minor

There are at least two types of task-logs: syslog and stdlog

Task-Jvm outputs syslog by log4j with TaskLogAppender, TaskLogAppender looks just like "tail
-c", it stores last N byte/line logs in memory(via queue), and do real output only if all
logs is commit and Appender is going to close.

The common problem of TaskLogAppender and 'tail -c'  is keep everything in memory and user
can't see any log output while task is in progress.

So I'm going to try RollingFileAppender  instead of  TaskLogAppender, use MaxFileSize&MaxBackupIndex
to limit log file size.

RollingFileAppender is also suitable for stdout/stderr, just redirect stdout/stderr to log4j
via LoggingOutputStream, no client code have to be changed, and RollingFileAppender seems
better than 'tail -c' too.

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