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https://issues.apache.org/jira/browse/LOG4J2-819?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Costa Theodosiou updated LOG4J2-819:
------------------------------------
Attachment: demorun-tomcat6-with-reload.zip
I have attached demorun-tomcat6-with-reload.zip which includes catalina.out
which demonstrates the bug. It seems that the thread starts when the user
requests that the application is reloaded - *not* when it is first deployed.
{code}
public final class CoarseCachedClock implements Clock {
...
private final Thread updater = new Thread("Clock Updater Thread") {
@Override
public void run() {
System.out.println("*************** Clock Updater Thread STARTED
***************");
while (true) {
System.out.println("*************** Clock Updater Thread
RUNNING ***************");
millis = System.currentTimeMillis();
// avoid explicit dependency on sun.misc.Util
LockSupport.parkNanos(1000 * 1000);
}
}
};
private CoarseCachedClock() {
System.out.println("*************** CoarseCachedClock CREATED
***************");
updater.setDaemon(true);
updater.start();
}
{code}
The app is first loaded on line 30 of catalina.out. It is reloaded on line 519.
The thread starts soon after this.
> PermGen OutOfMemoryError when reloading webapp on Tomcat 6
> ----------------------------------------------------------
>
> Key: LOG4J2-819
> URL: https://issues.apache.org/jira/browse/LOG4J2-819
> Project: Log4j 2
> Issue Type: Bug
> Components: Core
> Affects Versions: 2.0.2
> Environment: Tomcat 6
> Reporter: Costa Theodosiou
> Priority: Critical
> Attachments: demo.zip, demorun-tomcat6-with-reload.zip, demorun.zip,
> gg-log4j2-clocks-interrupts.patch, gg-log4j2-clocks-v2.patch
>
>
> When reloading an application 3 or 4 times in Tomcat 6, the application
> crashes with a "java.lang.OutOfMemoryError: PermGen space" exception.
> After some investigation using the "When all else fails" section of
> https://wiki.apache.org/tomcat/OutOfMemory in conjunction with Java VisualVM,
> I have narrowed down the problem to the Thread created within
> org.apache.logging.log4j.core.util.CoarseCachedClock.
> When a Thread is created, it contains a reference to the classloader that it
> was created with. In this case, the Thread's contextClassLoader field
> contains a reference to the WebappClassLoader. When Tomcat attempts to unload
> the webapp, the Thread still holds onto this reference which prevents
> WebappClassLoader from being freed.
> Perhaps the Log4jServletContextListener (Log4jWebInitializerImpl) can be made
> to stop the CoarseCachedClock thread.
> I believe this is not an obvious issue on Tomcat 7 due to
> https://wiki.apache.org/tomcat/MemoryLeakProtection.
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