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From Toke Eskildsen ...@statsbiblioteket.dk>
Subject Re: Analyzing performance and memory consumption for boolean queries
Date Fri, 26 Jun 2009 09:14:24 GMT
On Wed, 2009-06-24 at 21:38 +0200, Nigel wrote:
> It sounds like surely any swapping out of the JVM memory could cause big and
> unpredictable performance drops.  As I just mentioned in reply to Uwe, our
> poor performance times don't always directly correlate with index updates,
> but it may be that the damage is done and the effects are only seen sometime
> later.

We were hit by GC hell some time ago when we ran JVMs with 5-7GB
allocated. It turned out that using Sun's RMI forces a total garbage
collection once a minute. At least for the version we used at the time.

Some info at http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6200091

> p.s. I haven't tried SSDs yet, or for that matter faster disks of any sort.

We've tested MTRON-SSDs from 2007 vs. 10.000 and 15.000 RPM harddisks in
RAID 0 and 1 on a dual-core Intel Xeon machine. There was no doubt that
the SSDs were substantially faster than the harddisks for searching.
Some related observations was that the need for warm-up and disk-cache
was greatly reduced.

Regards,
Toke Eskildsen


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