[email protected]
[Top] [All Lists]

Re: Analyzing performance and memory consumption for boolean queries

Subject: Re: Analyzing performance and memory consumption for boolean queries
From: eks dev
Date: Wed, 24 Jun 2009 08:46:06 +0000 GMT
We've also had the same Problem on 150Mio doc setup (Win 2003, java 1.6). After 
monitoring response time distribution over time for couple of weeks, it was 
clear that such long running response times were due to bad warming-up. There 
were peeks short after index reload (even comprehensive warming-up did not 
help?! Maybe we did something wrong) ... We did not use relaod().   After 
loading index into RAMDisk the problems disapeared (proof that this was not 
gc() related). We have tried MMAP as well, but MMAP had the same problems (you 
cannot force OS to load as much as possible into RaM, will soon be possible ). 

What helped us a lot before "RAM luxury" was to give less memory to jvm in 
order to leave more for OS, lucene is fine with less memory.

remaining long runners happen selten, could be that these are due to the gc()...

as you do not care about scoring, I guess you set omitNorms() and omitTf() 
during indexing for all fields? If not, try this. It helps a lot 

good luck, 

----- Original Message ----
> From: Uwe Schindler <[email protected]>
> To: [email protected]
> Sent: Wednesday, 24 June, 2009 9:33:08
> Subject: RE: Analyzing performance and memory consumption for boolean queries
> > 1. For search time to vary from < 1 second => 20 seconds, the only
> > two things I've seen are:
> > 
> > * Serious JVM garbage collection problems.
> > * You're in Linux swap hell.
> > 
> > We tracked similar issued down by creating a testbed that let us run
> > a set of real-world queries, such that we could trigger these types
> > of problems when we had appropriate instrumentation on and recording.
> 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
> This also turns on GC debugging and the ParNewGC and ConcMarkSweepGC works
> much better here (but please do not simply copy these settings, read about
> them in the JVM docs, exact settings depend on your use-case!). I had no
> hangs anymore since this change. The JVM prints information about garbage
> collection to stderr (which you should study, there is a paper from sun
> about it). Our web server (Sun Java System Webserver 7.0, Solaris 10 x64)
> also reports the time used in complete for GC, during a server uptime of 11
> days it used about 4 hours to GC in parallel threads. This config works good
> with multiple CPUs, in our case, one could say: "one CPU is GCing the whole
> time" :-)
> There is also a howto on the lucid imagination page about different GCs and
> Lucene.
> Uwe
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: [email protected]
> For additional commands, e-mail: [email protected]

[email protected]----
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]

<Prev in Thread] Current Thread [Next in Thread>