G1GC, Java8u40ea, Metaspace questions

Bengt Rutisson bengt.rutisson at oracle.com
Fri Apr 24 15:06:20 UTC 2015


Hi Wolfgang,

Thanks a lot for sharing this! Really nice!

Bengt

On 2015-04-24 11:14, Wolfgang Pedot wrote:
> Hi,
>
> after all my questions/tests I just wanted to share what happened when 
> I finally switched a production system from 7u60 to 8u40:
> The system has 13.6GB Heap, ~4.5GB usage after mixed collects during 
> the day, target pause-time is 250ms but most collects take 100-160ms.
>
> It has been two weeks now (unfortunately not continuous uptime due to 
> bugfixes) and I can really see the improvements made to G1.
> Recorded GC-Time has been reduced by at least 40% and I have not had a 
> single Full-GC during the day yet (I still trigger a manual Full-GC in 
> the night so I can see where collection-usage is going).
> Metaspace-usage is coninuously lower than PermGen was before because 
> it is usually kept in check by the 5-6 mixed collects I see during a 
> normal day.
> So far its been quite a success, thanks for all your input!
>
> regards
> Wolfgang Pedot
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