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From "Uwe Schindler" <...@thetaphi.de>
Subject RE: Analyzing performance and memory consumption for boolean queries
Date Wed, 24 Jun 2009 20:47:58 GMT
Have you tried out, if GC affects you? A first step would be to turn on GC
logging with -verbosegc -XX:+PrintGCDetails

If you see some relation between query time and gc messages, you should try
to use a better parallelized GC and change the perm size and so on (se docs
about GC tuning).

-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: uwe@thetaphi.de

> -----Original Message-----
> From: Nigel [mailto:nigelspleen@gmail.com]
> Sent: Wednesday, June 24, 2009 8:54 PM
> To: java-user@lucene.apache.org
> Subject: Re: Analyzing performance and memory consumption for boolean
> queries
> 
> Hi Uwe,
> 
> Good points, thank you.  The obvious place where GC really has to work
> hard
> is when index changes are rsync'd over and we have to open the new index
> and
> close the old one.  Our slow performance times don't seem to be directly
> correlated with the index rotation, but maybe it just appears that way,
> since it may take a little while before GC kicks in to try to recover the
> objects used by the closed index.
> 
> Chris
> 
> On Wed, Jun 24, 2009 at 3:33 AM, Uwe Schindler <uwe@thetaphi.de> wrote:
> 
> > I had similar problems with our configuration, too. Suddenly sometimes
> the
> > server even did not respond. The problem was (I think is the same here):
> > the
> > GC. The standard Java GC is not multithreaded, so if you have lots of
> > traffic at some time, the JVM halts all threads and starts to GC, which
> can
> > take very long time with so big heap sizes.
> >
> > On our server with indexes of similar disk space size (not documents), I
> > changed the JVM options to use:
> >
> > -Xms4096M -Xmx8192M -XX:MaxPermSize=512M -Xrs -XX:+UseConcMarkSweepGC
> > -XX:+UseParNewGC -verbosegc -XX:+PrintGCDetails -XX:+UseLargePages
> >
> >


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