jdk8 metaspace problem with indy

[Jon Masamitsu]

On 9/30/13 11:49 AM, Jochen Theodorou wrote:
> 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

The OOME was for an attempted allocation from the Java heap?  In 
particular it was not an out-of-memory
from an attempted metadata allocation?

Jon

> 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
>