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Subject: Re: Improve Groovy class loading performance and memory management
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From: Jochen Theodorou <blackdrag@gmx.org>
Message-ID: <574A999A.3090900@gmx.org>
Date: Sun, 29 May 2016 09:26:18 +0200
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archived-at: Sun, 29 May 2016 07:26:34 -0000

On 29.05.2016 08:44, Alain Stalder wrote:
[...]
> If I use a WeakHashMap or Collections.synchronizedMap(WeakHashMap)
> instead of the map from the Spring Framework, classes are not
> collectable in the script-running-use-case (OutOfMemoryError) unless I
> replace klazz in ClassInfo with a WeakRefererence and then it becomes
> (only) softly-collectable.

which is no wonder if the value strongly references the key

> All in all, I think this means that universally weakly-collectable
> Groovy classes are more of a dream at the moment, at least before a
> Groovy 3, and the merge requests for GROOVY-7683 (weak reference to
> Class in ClassInfo) and GROOVY-7646 (explicit cleanup after running
> scripts in GroovyShell) seem to be the best that can be done at the moment?

at least the weak reference to Class in ClassInfo is something I think 
we can do without too much danger. Of course we may have to handle the 
case in which a ClassInfo still exists, but the class is collected...

As for the introspector. My suggestion would be to clean the 
introspector of the specific class at the end of MetaclassImpl#addProperties

> PS: Just for fun, I wrote a version where the map from the Spring
> Framework is using soft references for
> java.*/javax.*/groovy.*/org.codehaus.groovy.* classes and weak
> references for all others, and that passed all my test scripts.

yeah.... I think, that's not good enough for us. You can have extension 
methods to ther classes, so it is no good if these get collected without 
recovery for the extension methods

bye Jochen