3 Replies Latest reply on Nov 24, 2015 3:04 AM by fabian.chanton

Undertow Subsystem Memory Leak upon WAR Redeployments

catandgrep Oct 9, 2015 8:58 AM

Wildfly doesn't seem not to release "io.undertow.servlet.spec.ServletContextImpl" properly after undeployment of a web application. This results in memory leak after contiuous redeployments of a single application - see Eclipse Memory Analyzer:

6 instances of "io.undertow.servlet.spec.ServletContextImpl", loaded by "org.jboss.modules.ModuleClassLoader @ 0xe0226c10" occupy 5,051,528 (14.46%) bytes.

Biggest instances:

io.undertow.servlet.spec.ServletContextImpl @ 0xe1b64db8 - 1,039,080 (2.97%) bytes.

io.undertow.servlet.spec.ServletContextImpl @ 0xe1e7bfe8 - 1,038,960 (2.97%) bytes.

io.undertow.servlet.spec.ServletContextImpl @ 0xe16e23f8 - 1,038,536 (2.97%) bytes.

io.undertow.servlet.spec.ServletContextImpl @ 0xe1a745d0 - 1,038,488 (2.97%) bytes.

io.undertow.servlet.spec.ServletContextImpl @ 0xe1696090 - 893,456 (2.56%) bytes.

I've created a simple Test for reproducing this issue:
https://github.com/catandgrep/wildfly-undertow-mem-leak

Is this already known, or should I file a bug.

1. Re: Undertow Subsystem Memory Leak upon WAR Redeployments

ctomc Oct 9, 2015 12:50 PM (in response to catandgrep)

It is indeed memory leak, but triggered by arquillian servlet protocol testing.

I've send PR with fix described what is going one more in issue you created Undertow Memory Leak · Issue #8263 · wildfly/wildfly · GitHub
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2. Re: Undertow Subsystem Memory Leak upon WAR Redeployments

fabian.chanton Nov 23, 2015 8:27 AM (in response to ctomc)

I encounter a very similar problem if I repeatedly (manually) redeploy a war containing just a very simple servlet class. So there is no arquillian involved. After each undeploy the servlet class remains in memory. So this should mean there is something wrong with undertow or the way wildfly uses it. Can anyone else confirm this problem?
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3. Re: Undertow Subsystem Memory Leak upon WAR Redeployments

ctomc Nov 23, 2015 5:33 PM (in response to fabian.chanton)

how are you verifying that class is still loaded?
do you do few full GC cycles before checking for leftover classes
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4. Re: Undertow Subsystem Memory Leak upon WAR Redeployments

fabian.chanton Nov 24, 2015 3:04 AM (in response to ctomc)

Hi Tomaz
I tried it again, but this time waited longer and forced more garbage collections via yourkit profiler. It seems that i did not wait long enough. After several minutes / garbage collections the servlet object is collected.
Sorry for the false alarm and thank you for your answer!
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