G1GC: many consecutive full gcs (was Re: hotspot-gc-use Digest, Vol 40, Issue 4)
Alex Aisinzon
aaisinzon at guidewire.com
Thu Jun 16 16:27:47 PDT 2011
Ramki
Thanks for the attention.
Comments are inlined.
Regards
Alex A
-----Original Message-----
From: Y. S. Ramakrishna [mailto:y.s.ramakrishna at oracle.com]
Sent: Thursday, June 16, 2011 3:20 PM
To: Alex Aisinzon
Cc: hotspot-gc-use at openjdk.java.net; stefan.wachter at gmx.de
Subject: Re: G1GC: many consecutive full gcs (was Re: hotspot-gc-use
Digest, Vol 40, Issue 4)
Stefan and Alex --
(1) what's the version of the JVM used?
Sun JVM 1.6 64 bit update 25.
(2) could you try PermSize == MaxPermSize and see if it made any
difference?
I always used PermSize == MaxPermSize.
(3) do you have lots of WeakReference or Finalizer objects in your
system?
I am not sure about Weak references. I know that some finalizers exist
and come from open source package we leverage.
Do you want me to ask further about weak references?
(4) is what you have below your complete GC log (i.e. no gaps between
first and last line?)
I am happy to share my own GC logs. They are monstrous.
(5) what do you see when using CMS (in case you tried it)?
CMS worked surprisingly well: it scales to a higher load and experienced
some very rare longer pauses. At this stage, CMS seemed a better bet
than G1.
(6) do you have a simple test case that you can share with
us that exhibits this behaviour?
Our performance test involves running our full app and operating many
workflows. This is done only in in house performance tests and cannot be
easily replicated outside.
thanks!
-- ramki
On 06/16/11 14:02, Alex Aisinzon wrote:
> Stefan
>
> I have had similar experience with G1 and reported it here.
> I tried the option to try to limit GC pauses (-XX:MaxGCPauseMillis
with
> 1s and then 2s). It did not improve things.
> I am happy to try anything else to help improve G1.
>
> Alex A
>
> -----Original Message-----
> From: hotspot-gc-use-bounces at openjdk.java.net
> [mailto:hotspot-gc-use-bounces at openjdk.java.net] On Behalf Of
> hotspot-gc-use-request at openjdk.java.net
> Sent: Thursday, June 16, 2011 12:00 PM
> To: hotspot-gc-use at openjdk.java.net
> Subject: hotspot-gc-use Digest, Vol 40, Issue 4
>
> Send hotspot-gc-use mailing list submissions to
> hotspot-gc-use at openjdk.java.net
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
> or, via email, send a message with subject or body 'help' to
> hotspot-gc-use-request at openjdk.java.net
>
> You can reach the person managing the list at
> hotspot-gc-use-owner at openjdk.java.net
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of hotspot-gc-use digest..."
>
>
> Today's Topics:
>
> 1. G1GC: many consecutive full gcs (Stefan Wachter)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 16 Jun 2011 09:23:05 +0200
> From: Stefan Wachter <Stefan.Wachter at gmx.de>
> Subject: G1GC: many consecutive full gcs
> To: hotspot-gc-use at openjdk.java.net
> Message-ID: <4DF9AF59.90708 at gmx.de>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi all,
>
> the G1GC runs nicely for some time but then it starts to have bursts
of
> consecutive full gcs (see log below). Can anyone explain that
behaviour?
>
> The JVM is stared with these options:
>
> -Xmx10000M
> -Xms1024M
> -XX:MaxPermSize=1024m
> -XX:+UseG1GC
> -XX:MaxGCPauseMillis=2000
> -XX:GCPauseIntervalMillis=10000
>
> --Stefan
>
>
> 31314.569: [GC pause (young) 3286M->3234M(8937M), 0.0485530 secs]
> 31374.932: [GC pause (young) 3279M->3236M(8937M), 0.0486560 secs]
> 31837.688: [GC pause (young) 4614M->3252M(8937M), 0.0739370 secs]
> 33528.784: [GC pause (young) 5997M->3330M(8937M), 0.1543940 secs]
> 35372.029: [GC pause (young) 6038M->3405M(8937M), 0.2364930 secs]
> 36508.343: [Full GC 8525M->2903M(9678M), 8.9121160 secs]
> 38204.291: [Full GC 8647M->2295M(10000M), 7.4105940 secs]
> 39038.017: [Full GC 8790M->2092M(6975M), 6.7242110 secs]
> 39047.736: [Full GC 8996M->2089M(9998M), 6.0741630 secs]
> 39095.551: [Full GC 8936M->2090M(6969M), 5.5573390 secs]
> 39104.326: [Full GC 9175M->2092M(9997M), 5.3413860 secs]
> 39112.760: [Full GC 9392M->2094M(9978M), 5.4884150 secs]
> 41965.304: [Full GC 9549M->2112M(7043M), 6.4774550 secs]
> 43830.656: [GC pause (young) 4615M->2309M(7043M), 0.1727720 secs]
> 46024.398: [GC pause (young) 4638M->2497M(7043M), 0.3039900 secs]
> 46068.009: [Full GC 8832M->2237M(10000M), 6.6717340 secs]
> 46077.691: [Full GC 9322M->2187M(9987M), 5.8603570 secs]
> 46086.731: [Full GC 9487M->2189M(9996M), 5.8521360 secs]
> 46124.713: [Full GC 8792M->2185M(9895M), 5.7782260 secs]
> 46133.366: [Full GC 9297M->2188M(9999M), 5.7263360 secs]
> 46142.238: [Full GC 9509M->2189M(9985M), 5.5704850 secs]
> 47454.530: [Full GC 9676M->2295M(7653M), 7.3169840 secs]
> 48163.422: [GC pause (young) 4937M->2431M(7653M), 0.2379570 secs]
> 48887.388: [GC pause (young) 5007M->2497M(7653M), 0.1999790 secs]
>
>
>
> ------------------------------
>
> _______________________________________________
> hotspot-gc-use mailing list
> hotspot-gc-use at openjdk.java.net
> http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
>
>
> End of hotspot-gc-use Digest, Vol 40, Issue 4
> *********************************************
> _______________________________________________
> hotspot-gc-use mailing list
> hotspot-gc-use at openjdk.java.net
> http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
More information about the hotspot-gc-use
mailing list