Remko Popma created LOG4J2-1176:
-----------------------------------
Summary: Memory leak in Tomcat when log4j jars are in
$catalina.home/lib folder
Key: LOG4J2-1176
URL: https://issues.apache.org/jira/browse/LOG4J2-1176
Project: Log4j 2
Issue Type: Bug
Components: Configurators, Web/Servlet
Affects Versions: 2.4.1, 2.5
Environment: Tomcat 7.0.50 or Tomcat 7.0.65, jdk1.8.0_51, Win 10
Reporter: Remko Popma
Fix For: 2.5
When the log4j2 jar files are in $catalina.home/lib, the first web application
that is deployed will be reported by Tomcat as having a memory leak from loaded
classes.
*1. Steps to reproduce*
# Install Tomcat 7.0.65 afresh
# Copy log4j-api-2.5-SNAPSHOT.jar, log4j-core-2.5-SNAPSHOT.jar,
log4j-web-2.5-SNAPSHOT.jar into $catalina.home/lib.
# Edit $catalina.home/conf/catalina.properties: add {{log4j2.disable.jmx=true}}
# Edit $catalina.home/conf/tomcat-users.xml to give yourself permission to
access the Tomcat Web App Manager
# Start Tomcat
# Open the [Manager App|http://localhost:8080/manager/html]
# Reload the Tomcat Documentation (/docs) web app
# Click the "Find Leaks" button under Diagnostics at the bottom of the Manager
App page
The following warning is displayed:
{quote}
The following web applications were stopped (reloaded, undeployed), but their
classes from previous runs are still loaded in memory, thus causing a memory
leak (use a profiler to confirm):
/docs
{quote}
The same problem also happens if a log4j2.xml config file is placed in
$catalina.home/lib. Set status="true" in the configuration to confirm that the
web app that is deployed first causes this warning.
*2. With custom web app*
Use the attached web app to test the order of deployment.
# Restart Tomcat
# Deploy web app (containing log4j2.xml)
# Restart Tomcat again (note that the custom web app is loaded first)
# Reload /docs app: no memory leak
# Reload /webapp: gives memory leak warning
Different order:
# Undeploy custom web app
# Restart Tomcat ( /docs web app is loaded first)
# Deploy custom web app
# Reload /docs app: gives memory leak warning
# Reload /webapp: no memory leak
I have tried to use [Eclipse Memory Analyzer|https://eclipse.org/mat/] to find
out where the leak is, but without success.
(Note that the problem also happens with the default configuration (when no
log4j2.xml config is found), this may narrow things down a little...)
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