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Vinod K V commented on MAPREDUCE-1648:
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OK, I cannot apply the patch since it isn't for apache svn trunk, so I still cannot comment
whether your explanations validate my questions. Please supply a trunk patch atleast for demonstration
at your own time.
In the interim, please make sure that we have the complete picture of logging for java, streaming
*and* pipe tasks with *and* without reuse of JVMs (HADOOP-249). Also as Koji rightly mentioned
above, we need to performant - HADOOP-1553.
> Use rolling 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
> Attachments: syslog.patch
>
>
> 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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