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From Remko Popma <remko.po...@gmail.com>
Subject Re: log4j2 + FastFileAppender + Tomcat logrotate problem
Date Fri, 16 Aug 2013 02:17:06 GMT
I raised https://issues.apache.org/jira/browse/LOG4J2-354 to track this
issue.
I'll add questions in the comments of that JIRA ticket.

Remko


On Fri, Aug 16, 2013 at 7:17 AM, Kamil Mroczek <kamil@thinknear.com> wrote:

> Hello,
>
> We decided to try out log4j2-beta8 to see if we could improve our
> logging performance.  We were testing with the disruptor 3.1.1.
> library to make all our appenders async.
>
>
> -DLog4jContextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector
>
> We are running tomcat 7 with Java 1.6.  We use the SLF4J library as well.
>
> The appender that we were using in this case was the Fast File
> Appender with a definition like:
>
> <FastFile name="RequestLog" fileName="requests.log"
> immediateFlush="false" append="true">
>   <PatternLayout>
>     <pattern>%m%n</pattern>
>   </PatternLayout>
> </FastFile>
>
> And logger was..
>
> <logger name="a.namespace" level="info" additivity="false">
>   <appender-ref ref="RequestLog"/>
> </logger>
>
> So the system was designed to allow log4j to do the logging and then
> have logrotate rotate the log files from the host to an external
> destination.
>
> We rotate the logs every 5 minutes with these params (with LZO
> compression).
>
> compress
> compresscmd /bin/lzop
> compressoptions "-U"
> compressext .lzo
>
> What we were seeing was that after a log rotation happened the new
> file would start with a massive chunk of binary data at the start.
> Many times on the order of 100-200MB.  This would turn the logs from
> being on the order of 50-100MB to 200-350MB.
>
> My guess was that it had something to do with the byte buffer flushing
> mid-rotate since these chunks always come at the start of the file.
> But I also saw LOG4J2-295 (Fast(Rolling)FileAppender now correctly
> handles messages exceeding the buffer size. ) which was fixed in beta8
> which my discredit that idea.
>
> We were able to fix the issue by using the regular FileAppender like this:
>
> <File name="RequestLog" fileName="requests.log" immediateFlush="true"
> append="true" bufferedIO="false">
>       <PatternLayout>
>         <pattern>%m%n</pattern>
>       </PatternLayout>
>   </File>
>
> I can't remember for certain, but I am pretty sure that even if we had
> bufferedIO="true" on the FileAppender everything worked okay as well.
>
> We could reproduce it pretty consistently.  I wanted to post to the
> group to see if anyone has seen anything like this before.  Any ideas
> on what the issue could be?
>
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