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From: Peter Crowther <Peter.Crowther@melandra.com>
To: 'Tomcat Users List' <users@tomcat.apache.org>
Date: Mon, 1 Jun 2009 15:10:36 +0100
Subject: RE: Tomcat Concurrent Requests
Thread-Topic: Tomcat Concurrent Requests
Thread-Index: Acniwda+XfRUp+FWQgqSyfjbcOELxQAAEsnA
Message-ID: <6715CF65287F8F408DA109EC03AC6C0DBCA5C4C72B@puma.melandra.net>
References: <23815501.post@talk.nabble.com>
In-Reply-To: <23815501.post@talk.nabble.com>
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> From: CrystalCracker [mailto:sudarshan.acharya@gmail.com]
> Given that each request takes 2 seconds on average. Among
> them, some of them
> take less than 500ms, and some take as long as 5 seconds or
> even a little more sometimes.
>
> How many  such concurrent request would a tomcat server
> running on a double quad-core server handle?

It's totally dependent on your application.  If a 5-second request is CPU-b=
ound for all that time, very few.  If it's mostly waiting for data to be re=
turned from a database or web service, probably quite a lot - but you may b=
e saturating the database.  At the extreme, I could write a webapp that sle=
pt for 500ms to 5 seconds, then returned some fixed output - almost no memo=
ry use, almost no CPU use, and it would scale very well indeed.

There is only one way to find out how your application will perform: measur=
e it.  And measure end-to-end, with measurements of load-balancers, databas=
es, web service back-ends and so on.  Anything else won't give you a true p=
icture.

There is one general point, though.  You'll need to set up enough threads o=
n your connector that you can handle that degree of concurrency, or Tomcat =
will become a bottleneck.

                - Peter

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