G1 discovers same garbage again?

Srinivas Ramakrishna ysr1729 at gmail.com
Sat Dec 10 00:34:09 UTC 2011

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. Have you logged that bug?
Or at least share the GC log? What's the version of the JDK that this
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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