[jira] Created: (MAPREDUCE-1648) Use RollingFileAppender to limit tasklogs

["Guilin Sun (JIRA)" <ji...@apache.org>]

Use RollingFileAppender to limit tasklogs
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                 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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