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Message-ID: <39629E87.AAF5FAC7@eng.sun.com>
Date: Tue, 04 Jul 2000 19:33:43 -0700
From: Costin Manolache <costin@eng.sun.com>
MIME-Version: 1.0
To: tomcat-dev@jakarta.apache.org
Subject: Re: Scalability/concurrent users
References: <20000704203812.33057.qmail@hotmail.com>
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John Econopouly wrote:

> I'm trying to get tomcat to work with alot of concurrent user connections.
> So far, I can't seem to get it to work past about 250, and it seems very
> slow - do any of you feel it can handle more?  I was hoping for 1000...

:-)
I am more than happy we can handle 250 in this release, but you'll have to wait
for next one for 1000 !


> Details:
> I'm running Redhat Linux 6.1, on a 500 MHz 686 w/ 1 gig of memory.
> I'm using the Blackdown 1.2.2 JVM, and have tried up to -Xms512m -Xmx768m,
> -green vs -native, jit/no jit.  I also tried the Sun JVM 1.2.2.  None of
> this seems to have much affect - adding all that memory just sped it up
> a bit, but once I went past 250 concurrent users, some users got dropped,
> I got connection exceptions, etc.  I've been wondering if there is a hard
> limit of 256 somewhere in the code...

I don't think so, at least not in tomcat. >256 threads is a not easy - even for
unix.

You can of course use load balancing - and add a Unix process for each 100
concurent users ( 100 is a decent number, away from the limit ).

I never tried more than 120, all my performance tests are done with 40 clients,
which IMHO is a reasonable number for one instance.

> Any info at all greatly appreciated, I'm getting desperate...

Load balancing or a different  protocol - multicast may be a bit difficult, but
seems a good solution.

Costin