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how many users tomcat support concurrently

Shiva Kumar V

Joined: Mar 23, 2009
Posts: 6
Hi Folks,

I want to know how many concurrent users tomcat 6.0 can support. There is no hard ware constarint.

I am new to web development. One of my friend said it is 50.

Thanks in Advance
Ninad Kulkarni
Ranch Hand

Joined: Aug 31, 2007
Posts: 802

See this

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Ulf Dittmer

Joined: Mar 22, 2005
Posts: 42965
While that article is interesting, it doesn't really address the question. But "50" is definitely not a correct answer. The real answer depends on the definition of "concurrent", on the Tomcat setup, and on the web app in question.

Tomcat has a maximum number of concurrent threads it uses to service requests; this can be configured in conf/server.xml and is by default set to 50. But even if there are more than 50 concurrent requests, those are simply put in a waiting queue (I think) and will be serviced once threads become available.

But "users" is not the same as "requests". Users do not constantly fire requests to the server, and requests are generally handled quickly (generally no more than 10 seconds, and possibly much quicker). So a lot more users can all be using a web app at the same time before the number of 50 active threads is reached. How many that might be depends on the nature of the web app.
Tim Holloway
Saloon Keeper

Joined: Jun 25, 2001
Posts: 17423

"Concurrent" is also not the same as "simultaneous". The thread pool size determines maximum thread-simultaneous requests, with the number of CPUs limiting the number of actual-simultaneous requests. The total number of concurrent users of a Tomcat server, however, is limited by the service rate. If a system has a high service rate, it can handle a lot of concurrent users. If it has a low service rate, the thread queues start backing up and the system overloads.

An IDE is no substitute for an Intelligent Developer.
Kees Jan Koster
JavaMonitor Support

Joined: Mar 31, 2009
Posts: 251
Dear Shiva,

Your friend is misguided. I have seen bad webapps that stumble and grind to a halt under the load of a dozen or so users and I have seen Tomcats scale to thousands of concurrent users.

If there is no hardware constraint, then that leaves your programming style and the application requirements as the constraints. You need to program in a scalable way. Your application requirements are such that it is easy to partition the application to allow more hardware to have benefit when added.

Without knowing how well your application can be partitioned and how well your code is architected, we cannot answer your question.

Kees Jan

Java-monitor, JVM monitoring made easy <- right here on Java Ranch
Joanna Spark

Joined: Aug 03, 2010
Posts: 1
Hey there -

We actually answered this question over at today. Check out the post here:

I agree. Here's the link:
subject: how many users tomcat support concurrently
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