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https://issues.apache.org/jira/browse/LOG4J2-327?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13724976#comment-13724976
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Sebastian Oerding commented on LOG4J2-327:
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Hello,
thanks for your hints, playing around with the settings reduced the memory
footprint (by 50 MB).
However we finally found the reason for the high memory usage.
The first reason were the tickets mentioned here (and that caused the
OutOfMemoryError) and that have been solved in the trunk.
The second reason was the usage of a JTextPane that consumes a lot of memory.
The java.swing.JTextPane was configured to hold at most 1,000 lines (which were
in average approximately about 80 characters) but swallows approximately about
100 MB of memory for approximately 80 KB of strings (1000 * 80). It seems to
release the strings / memory by far later than it should ... .
Text was added to the JTextPane by a self-written appender. Due to this the
memory usage was drastically lower with logging / our appender turned of. The
long string we have seen was probably the content of the JTextPane (sorry, I
had not thought of that in that moment), even if it was by far longer than it
should be (372 KB vs. approximately 80 KB). Sorry for setting you on the wrong
track.
Hence as far as it concerns us currently everything is fine with log4j 2 and
this ticket can be closed. Maybe we should extend this ticket referring to the
tickets for beta9 related to performance issues as some people might find this
ticket due to the general description / name.
> Log4j 2 drastical performance loss
> ----------------------------------
>
> Key: LOG4J2-327
> URL: https://issues.apache.org/jira/browse/LOG4J2-327
> Project: Log4j 2
> Issue Type: Bug
> Components: Appenders, Core, Layouts
> Affects Versions: 2.0-beta7, 2.0-beta8
> Environment: Windows 7 64 bit, JDk 1.6.0_43
> Reporter: Sebastian Oerding
> Priority: Blocker
> Labels: performance
>
> Hello,
> we encountered a severe performance loss with log4j 2. Unfortunately we have
> no exact error description such as a stacktrace but I'll give it may best
> shot.
> We are developing an application working with mass data. During the
> development we are running tests such as importing 15,000 files via FTP or
> creating 500,000 business objects and workiong with them.
> Switching from log4j 1.2.17 to log4j 2 we ran into really severe performance
> issues.
> With the beta7 we even get an OutOfMemoryError. Using a profiler we see that
> there was a huge amount of string objects (that were log messages according
> to a control sample).
> Switching to the beta8 the profiler shows there are only 10 % of the string
> objects left that we had before but it still was a big number. Especially the
> strings live for a really long time (> 100 generations).
> Using the RollingFileAppender and ConsoleAppender, (not a FlumeAppender for
> which a memory has been fixed in beta8) and default garbage collection we had
> the following behaviour with beta8:
> Starting the application (each time exactly the same test scenario) the
> machine fastly reaches the memory limit given for the JVM. Afterwards
> periodically garbage collection is invoked, causing a long "Stop the World
> Phase"
> (8 minutes in another scenario), freeing memory down a "base level" and the
> application continues until the memory is full again. The base level remains
> the same for next invocations of the garbage collection.
> This may relate to tickets: https://issues.apache.org/jira/browse/LOG4J2-323,
> https://issues.apache.org/jira/browse/LOG4J2-322,
> https://issues.apache.org/jira/browse/LOG4J2-304.
> Furthermore when looking into one string object being not GCed (372 KB) I
> noticed that it contained a lot of log messages being concatenated. The
> application contains no log statement that logs such a big message.
> Looking at the string towards the end I found even complete log events
> including the log level and so on not only the message. This feels being
> related to https://issues.apache.org/jira/browse/LOG4J2-290, somehow log
> events /
> strings get concatenated / corrupted.
> Maybe it is even a problem with the ParameterizedMessage which we use a lot
> of.
> Switching to the AsyncAppender (FastRollingFile) asynhronously the
> application performs better than with the RollingFile but still bad. Running
> the same scenario with the FastRollingFile "immediateFlush" and "append"
> parameters ommitted in the configuration the FastRollingFile crashed due to a
> IllegalArgumentExeption in class ByteBuffer (stacktrace is lost).
> The blocker priority may be at bit extremen but currently we are thinking of
> going back to log4j 1.2.17, throwing away several days of work and requiring
> a few days for adjusting our code. Hence this is a blocker for us as we could
> not release our software in the current state.
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