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From Shawn Heisey <s...@elyograg.org>
Subject Re: ping query frequency
Date Mon, 04 Mar 2013 15:18:54 GMT
On 3/4/2013 2:06 AM, adm1n wrote:
> here you go - http://wiki.solarium-project.org/index.php/V1:Ping_query
>
>
> as for my cloud, average response time for ping request is 4 ms. but there
> are several pings that take even 3 seconds. (I have about 100000 pings/day)

I would suspect GC pauses, like I was having.  The following startup 
options are what I use now, and I am no longer having really long GC 
pauses.  They are specifically designed to not require any specific -Xmx 
value.

-XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=75 
-XX:NewRatio=3 -XX:MaxTenuringThreshold=8 -XX:+CMSParallelRemarkEnabled 
-XX:+ParallelRefProcEnabled -XX:+UseLargePages -XX:+AggressiveOpts

A note: I was using some of these options already, even when the pauses 
(sometimes up to 12 seconds!) were happening.  It was when I added these 
particular options that the problem went away:

-XX:CMSInitiatingOccupancyFraction=75 -XX:NewRatio=3 
-XX:MaxTenuringThreshold=8 -XX:+ParallelRefProcEnabled -XX:+UseLargePages

I later added AggressiveOpts, which means "for all options that will get 
new defaults in the next version of java, change to those new defaults." 
  This option has been known to cause problems with some programs, but 
so far I have not seen any problems with Solr 3.5 or 4.2-SNAPSHOT.

Thanks for the Solarium link.  I think their advice is good - don't do 
it before every request.  For me, doing it every five seconds probably 
allows a few dozen queries to go by between each ping.

A question to the experts: Do any of the various Jenkins processes use 
AggressiveOpts?  Would I use the same commandline option to turn it on 
when I run the tests myself with ant, or is there a different syntax?

Thanks,
Shawn


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