G1 discovers same garbage again?

Vitaly Davidovich vitalyd at gmail.com
Mon Dec 12 14:45:19 UTC 2011


I wonder - did it actually complete after 4000 seconds? Maybe the process
was restarted before it finished but it had been running for that long up
to that point; if so maybe GC hit some bug and would never have terminated?
I guess something for Florian to answer.
On Dec 12, 2011 9:34 AM, "Tony Printezis" <tony.printezis at oracle.com> wrote:

>  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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