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From "Scott (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (LOG4J2-570) Memory Leak
Date Thu, 20 Mar 2014 13:54:46 GMT

     [ https://issues.apache.org/jira/browse/LOG4J2-570?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Scott updated LOG4J2-570:
-------------------------

    Description: 
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.

  was:
Dynamically loading a JAR that uses log4j2 results in a memory leak when the JAR is unloaded.
 This can be observed in the while 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.


> 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 bos-lpuv7 3.2.0-58-generic #88-Ubuntu SMP Tue Dec 3 17:37:58 UTC 2013 x86_64 x86_64
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
>         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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