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https://issues.apache.org/jira/browse/MAPREDUCE-1648?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12854051#action_12854051
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Koji Noguchi commented on MAPREDUCE-1648:
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When reviewing the patch, please test the performance and make sure we don't
re-introduce the slowness observed at HADOOP-1553.
> 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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