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From "Ghorpade, Rajendra" <>
Subject Conncurency issue with tomcat???
Date Thu, 16 May 2002 10:15:55 GMT
Hi all,

I have a strange problem to discuss.

Background :
 We are using a servlet as an entry point to our application.We are using
tomcat as the servlet engine.
So the concurrent users to our application depends on the concurrecy support
by the tomcat.We have developed a simulator to send the request to our
application throught this servlet.

Now the problem :
We use to send requests to tomcat.Each user send
5 requests with different parameters.The simulator was set to 60 concurrent
users and for 10 times each. i.e number of concurrent request are 60 and
total requests are 3000(60 * 5 * 10).
Each response from the server is roughly a string of 6000 bytes. We are
reading asynchronously (InputStream in a new thread) on the simulator side.
With 60 users it works fine. But when we increase the number of conncurrent
users to 90 the server behave strangely.
like :
	1. Sometimes we see that the same session is started in two threads
	2. Sometimes one of the request for the user is processed  two

I wonder where is the problem. In the HttpUrlConenction or in the servlet
What we think is it may be due to the speed of reading the bytes from the
input stream of HttpUrlConnection.Because when we read the data with the
BufferedInputStream we get the same problem with even 60 concurrent
users.This was solved by useing the Asyncronous Input stream.

But above all I wonder how can a client influence the behaviour of the

Ur help is highly appreciated.
I am using tomcat 4.0.1

Rajendra Ghorpade
   Software Engineer

   OneBridge AG - simplifying voice technologies -
   D 51429 Bergisch Gladbach

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