G1 discovers same garbage again?

Tony Printezis tony.printezis at oracle.com
Mon Dec 12 14:32:25 UTC 2011


Ramki.,

On 12/09/2011 07:34 PM, Srinivas Ramakrishna wrote:
>
>
> A couple of things caught my eye....
>
>     On 12/05/2011 02:19 PM, Florian Binder wrote:
>     >> I assume you know when the data will be dropped and reinitialized,
>     >> right? Can you do a Full GC (with System.gc()) after you
>     re-initialize
>     >> the heap. This typically helps a lot with CMS.
>     > Yes, this is exactly what we are trying at this time ;-)
>     > Either this Full-GC pauses are very long (60-300 seconds) they
>     are much
>     > shorter than after a CMS-failure (when they take sometimes more than
>     > 4000 seconds ;-)) and we can define when they occure.
>
>
> A full GC that takes an hour is definitely a bug.

Good catch, I clearly didn't do the translation. :-) Could it be paging?

Tony

> Have you logged that bug?
> Or at least share the GC log? What's the version of the JDK that this 
> behaviour
> was seen with?
>
> ...
>
>     > Furthermore this should not increase the total-heap-space:
>     > http://java4.info/g1/all.png
>
>
>  Remember that jconsole asynchronously samples the heap, whose size is
> read "with possible glitches". Rather, you should probably rely on the 
> GC log in order to assess
> the heap size after each GC event, rather than the asynchronous 
> samples from
> jconsole. I myself have not had the chance to look at yr GC logs to see
> what that indicated wrt the size of Eden and of the Heap.
>
> -- ramki
>
>
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