Do not top-post. It makes it difficult to follow the conversation, who answers
to what etc.
From: Daniel Mikusa <dmik...@gopivotal.com>
To: "Tomcat Users List" <users@tomcat.apache.org>
Date: 09/20/2013 07:10 PM
Subject: Re: MaxClients and maxThreads
On Sep 20, 2013, at 9:27 AM, mohan.radhakrish...@polarisft.com wrote:
Is this a hard limit ?
No.
So if there are 4 cores there can only be 800
concurrent clients. None of our banks is calculating this like this and
some have Apache and JBoss on the same machine which further limits the
threads.
Appreciate any help.
Hi,
I am following the instructions in
https://access.redhat.com/site/articles/15786 to tune MaxClients in
httpd.conf and maxThreads in JBoss Tomcat.
" The recommended value of maxThreads is 200 per CPU, so here we assume
the server is a single core machine. If it had
been quad core we could push that value to 800 or more depending on RAM
and other machine specs. The total threads
is an aggregate value. If Apache and JBOSS are on the same server, and
that server has four cores, then you would halve
the maxThreads and MaxClients to 400 each."
Don't base your performance tuning on values you found in an article
online. The author of this article has no idea what kind of hardware you
are running, what your application is doing or what your needs are for the
application. By these metrics, I should setup 800 threads on a quad core
system, but if my application is only supporting 10 users that's way too
many. Examine your needs, set the values you think will work and then
load test to see how things perform. Adjust the settings further based on
your load testing results.
mohan.radhakrish...@polarisft.com wrote:
Yes. I understand the need for capacity planning.
It probably involves concurrency, think time analysis etc. I was wondering
if maxThreads and MaxClients are the same value. In a worker mpm
MaxClients is the Apache setting and maxThreads is the JBoss setting.
In your kind of configuration, MaxClients are maxThreads are related, but they are not the
same. They may be the same if every request received by Apache httpd is always
transmitted to Tomcat. But then what would be the point of having httpd in front ?
Moreover how does a figure of 200 for a core justified.
So you mean that the figure of 200 is not based on any analysis.
Exactly. Not all requests are equal, and not all applications are equal. And in
processing a request, there is not only CPU time to take into account, there is memory,
I/O etc. So who, other than you, can tell how many of *your* requests one "core" can
handle in any amount of time ? It is ridiculous to provide such a number as if it was
based on anything serious.
Thanks.
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