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https://issues.apache.org/jira/browse/LOG4J2-570?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13945763#comment-13945763
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Matt Sicker commented on LOG4J2-570:
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The runtime shutdown hook is just for non-container contexts. I think it would
be better to use a more generic start/stop interface for dealing with
LoggerContext objects. Selection of the proper context is already implemented
through the ContextSelector interface. Initialization and destruction logic is
handled in LoggerContext, but the hooks to start and stop them could be handled
better.
In the servlet context, there is no reason for the shutdown hook to be enabled.
Due to the difficulty in overriding that shutdown hook in the current code is
why I suggested we refactor that to be more generic to support more contexts.
> Memory Leak
> -----------
>
> Key: LOG4J2-570
> URL: https://issues.apache.org/jira/browse/LOG4J2-570
> Project: Log4j 2
> Issue Type: Bug
> Components: Core
> Affects Versions: 2.0-rc1
> Environment: Ubuntu 12.04
> Linux 3.2.0-58-generic x86_64 GNU/Linux
> 8 GB RAM
> java version "1.7.0_51"
> Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
> Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)
> JAVA_OPTS=-Xmx1024m -Dsun.net.inetaddr.ttl=60
> -Dsun.net.inetaddr.negative.ttl=60 -Djava.net.preferIPv4Stack=true
> -XX:PermSize=128m -XX:MaxPermSize=256m -XX:+UseConcMarkSweepGC
> -XX:+CMSClassUnloadingEnabled
> <log4j.version>2.0-rc1</log4j.version>
> log4j-api
> log4j-core
> log4j-jcl
> Spring webmvc 4.0.2.RELEASE application (simple hello world) deployed in
> tomcat7.0.52 container.
> Reporter: Scott
> Assignee: Matt Sicker
> Priority: Blocker
> Labels: memory_leak
> Fix For: 2.0-rc2
>
> Attachments: spring_log4j2_memory_leak.tbz2
>
>
> Dynamically loading a JAR that uses log4j2 results in a memory leak when the
> JAR is unloaded. This can be observed by deploying a web application to
> tomcat7 and exercising the stop, undeploy, or redeploy actions. The memory
> leak is believed to be caused by log4j for the following reasons:
> 1)Heap Dump reveals the classloader instance responsible for the WAR plugin
> (of type org.apache.catalina.loader.WebappClassLoader) has 2 non weak/soft
> reference which are of type
> (org.apache.logging.log4j.core.LoggerContext$ShutdownThread) and
> (org.apache.logging.log4j.core.jmx.LoggerContextAdmin) after the WAR has been
> stopped or undeployed.
> 2)Using SLF4J (slf4j-api, jcl-over-slf4j) to logback-classic logging output
> is equivalent but all memory is gc as expected (the
> org.apache.catalina.loader.WebappClassLoader which loaded the WAR is no
> longer referenced by any hard references)
> 3)Using the SLF4J NOP logger implementation all memory is gc as expected (the
> org.apache.catalina.loader.WebappClassLoader which loaded the WAR is no
> longer referenced by any hard references)
> This may not be unique to 2.0rc-1 and I have seen similar behavior in
> previous 2.0 beta releases.
> This is reproducible with a very simple spring hello world application. Code
> and/or heap dumps can be provided upon request.
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