A guarantee failure with CMSClassUnloadingMaxInterval

Stefan Karlsson stefan.karlsson at oracle.com
Thu May 16 21:24:53 UTC 2013

On 5/16/13 11:16 PM, Stefan Karlsson wrote:
> On 5/16/13 10:31 PM, Hiroshi Yamauchi wrote:
>> Hi Ramki,
>>> I can't recall the history behind the flag for class unloading every 
>>> N Concurrent collections, but your analysis appears spot on to me. I 
>>> can review the code tomorrow morning and confirm since its been a 
>>> while since I looked at this code...
>> I suppose that it's not a flag that's commonly used. It'd be great if
>> you can take a look.
> FYI, I ran some parallel class loading tests with with 
> -XX:CMSClassUnloadingMaxInterval=5 and get similar kind of failures.
> We probably treat the Klasses as weak roots when we shouldn't, or 
> something similar.

And now I re-read your first post and see that you have already come to 
that conclusion. FWIW, I get verification failures if I run this with 
JDK8 + -XX:+UnlockDiagnosticVMOptions -XX:+VerifyBeforeGC 

> StefanK
>> Thanks.

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