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https://issues.apache.org/jira/browse/GROOVY-6704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14951758#comment-14951758
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Jochen Theodorou commented on GROOVY-6704:
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you can make the class public, then it should work. But 20 minutes for 4 MB
mx... wow, I remember that failing faster. Anyway, it fails.
As for why LeakTest.groovy does not hit the problem.. my assumption is the
following: The error happens only for class values added to higher class
loaders, maybe it is even limited to application and or system classloader. So
Integer would be an example for this.
In LeakTest you do generate a big amount of clases, but they are children of a
class loader hosting the registry. For classes like Integer there will be only
one entry for the life cycle of that test.
I extracted that failing test from a problem Cedric had with Gradle, that
caused the Groovy runtime to load many many times. Took a while of our both
time to condense it to a test case as simple as the one in the java bug tracker
;) But I am happy I was able to exclude all of Groovy in that.
> Memory leak in ClassInfo when using MetaClasses
> -----------------------------------------------
>
> Key: GROOVY-6704
> URL: https://issues.apache.org/jira/browse/GROOVY-6704
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 2.0.8, 2.1.9
> Reporter: Craig
> Assignee: Jochen Theodorou
> Priority: Critical
> Fix For: 2.4.0-beta-2
>
> Attachments: CVTest.java, LeakTest.groovy, MyClassValue.java
>
>
> I'm trying to track down a memory leak in Grails and I'm pretty sure I've
> discovered the root cause of the leak is in Groovy. For reference, here's the
> thread on the grails-dev list on this topic:
> http://grails.1312388.n4.nabble.com/Easily-reproducible-memory-leak-in-Grails-td4655816.html
> I also raised this issue on the groovy-dev mailing list at
> http://groovy.329449.n5.nabble.com/Memory-leak-in-ClassInfo-when-using-MetaClasses-td5719218.html
> The problem is that when a class is loaded, then a metaclass is assigned,
> then the class is no longer reachable, the metaclass remains in memory. When
> this happens many times, lots of metaclasses are leaked, which becomes a
> significant problem. I discovered this problem because this how Grails
> implements GSPs - by loading the GSP as a groovy class, then when the GSP
> changes, loading a new class. The old class is unreachable, except for some
> internal Groovy structures... hence the memory leak.
> Attached there is a junit test that reproduces this problem:
> [^LeakTest.groovy]
> Eventually, that results in an OutOfMemoryError. Using a tool like visualvm,
> it is clear that the number of classes constantly rises, none are ever
> unloaded, and the permgen keeps getting used. The heap also rises. In my
> tests, it usually dies after about 5,000 iterations.
> In my opinion, this shouldn't happen - this test case should run without
> leaking memory. Groovy should allow the MetaClasses to be garbage collected
> once the Class is no longer referenced by anything else. In other words,
> Groovy should hold a weak reference to the MetaClass/ClassInfo/etc for the
> Class based on the reachability of the Class.
> By taking a heap dump in visualvm, I found that there are lots of instances
> of org.codehaus.groovy.runtime.metaclass.MetaMethodIndex$Entry.
> The problem areas (that are GC roots) seem to be:
> org.codehaus.groovy.reflection.ClassInfo's static field modifiedExpandos
> org.codehaus.groovy.reflection.ClassInfo's static field globalClassSet
> The classes that area created by classLoader.parseClass also stick around,
> which is why the permgen is leaking.
> Can someone please help me determine how to fix this problem in Groovy?
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