AW: ridiculous ParNew pause times

[Cornelius Riemenschneider]

Yes, these settings are currently set to the default values.
I'll investigate changing them as well, but for now I'll move the gc log to a ramdisk - 
waiting for the log to be written is a very stupid reason to delay something awful as a garbage collection.

Regards,
Cornelius Riemenschneider
--
ITscope GmbH
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Email: cornelius.riemenschneider at itscope.de
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-----Ursprüngliche Nachricht-----
Von: hotspot-gc-use [mailto:hotspot-gc-use-bounces at openjdk.java.net] Im Auftrag von Holger Hoffstätte
Gesendet: Mittwoch, 9. April 2014 19:42
An: hotspot-gc-use
Betreff: Re: ridiculous ParNew pause times

On 04/09/14 18:40, Cornelius Riemenschneider wrote:
> Bingo! First, i tried to get a tool which shows me which process 
> writes to which file and how long that takes, but I was unable to find 
> one I could master to use. Based on your suggestion I moved the log.gc 
> file to a ramdisk and performed extensive load testing - now my 
> biggest outlier is 2014-04-09T18:29:13.873+0200: 383.372:
> [GC2014-04-09T18:29:13.874+0200: 383.372: [ParNew:
> 431041K->208698K(3145728K), 1.8312460 secs]
> 11055599K->11203421K(21495808K), 1.8315130 secs] [Times: user=2.61
> sys=0.03, real=1.83 secs] which is okay.

Another idea: are your vm.dirty_(expire|writeback)_centisecs and especially vm.dirty_(background)_ratio sysctl settings default, aka ridiculously high? This can result in writeback storms of a huge number of accumulated dirty buffers and is a common reason for periodic stalls, which can take forever when another process issues fsync() at inappropriate moments.

Just a guess.

-h

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