jdk8 metaspace problem with indy

[Jochen Theodorou]

Am 30.09.2013 17:10, schrieb Stefan Karlsson:
[...]
> First, my experiments were done without --indy so I might be seeing a
> different issue than you are. On the other hand, the experiments shows a
> real problem with our Metaspace and GC interaction, so I think that's
> worth investigating.
>
> The root cause of the problem I'm seeing is that SoftReferences are not
> cleared when the GC is triggered because of high metaspace memory
> pressure. I've created the bug:
> https://bugs.openjdk.java.net/browse/JDK-8025635 - SoftReferences are
> not cleared before metaspace OOME are thrown

SoftReferences not cleared.. especially SoftReferences to Class and in 
worst case a soft reference to an object that has a hard reference to a 
class was always a critical point. We have some history with that. And 
this I see as critical bug for us. So I am very happy if it gets fixed 
before the final jdk8 ;)

I did read your description and I think you should try with indy (also 
see http://groovy.codehaus.org/InvokeDynamic+support). What I have seen 
is not that metaspace increases indefinitely. Instead there is an OOME, 
before free memory is exhausted. Granted, jdk8 did, as far as I 
remember, allow about 4 times more classes to be created than jdk4u25, 
but it failed to clear the number of loaded classes at one point... 
afaik that was somewhere at 40k classes being loaded (and 38k of them 
dead). But of course it is possible I missed that there can be no free 
memory claimed and maybe the fix for JDK-8025635 is a fix for what I did 
see as well

bye Jochen

-- 
Jochen "blackdrag" Theodorou - Groovy Project Tech Lead
blog: http://blackdragsview.blogspot.com/
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