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From "Mike W-M" <m...@ward-murphy.co.uk>
Subject Re: Simultaneous request from same IP
Date Mon, 16 Dec 2002 15:27:57 GMT
I might be missing the point!
What exactly is the problem?  I didn't think there was any rule that said
you couldn't have two "identical" requests running at the same time (as long
as the outputs don't get mixed up).
As I understand it, requests will be differentiated by the fact that they
come from different TCP/IP port-numbers on the client machine.  (Not sure
whether that info is available to your servlet, but I suspect Tomcat will
have to know it.)

Mike.


----- Original Message -----
From: "Chris Bick" <cbick@wurldmedia.com>
To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
Sent: Monday, December 16, 2002 3:13 PM
Subject: RE: Simultaneous request from same IP


Thanks for responding.  I don't think it is an instance variable
problem. Here is the code to reproduce the problem:

public class AServlet extends HttpServlet {
  public void doGet(HttpServletRequest request, HttpServletResponse
reponse) throws ServletException, IOException {

  printWriter pw = reponse.getWriter();
  reponse.setContentType("text/html");

  synchronized(System.out)
  {
System.out.println("Query String: " + request.getQueryString());
      System.our.println("Header      : "
+request.getHeader("Test-Header");
  }

  out.println("Done");
}

Two different request hit this servlet about 1 sec apart everything is
fine.  It's only when they enter the servlet at the same time.

I will submit a bug report if know one sees a problem with the above
code.

-cb
-----Original Message-----
From: Craig R. McClanahan [mailto:craigmcc@apache.org]
Sent: Sunday, December 15, 2002 10:22 PM
To: Tomcat Users List
Subject: Re: Simultaneous request from same IP



On Sun, 15 Dec 2002, Chris Bick wrote:

> Date: Sun, 15 Dec 2002 22:05:45 -0500
> From: Chris Bick <cbick@wurldmedia.com>
> Reply-To: Tomcat Users List <tomcat-user@jakarta.apache.org>
> To: tomcat-user@jakarta.apache.org
> Subject: Simultaneous request from same IP
>
> Hello,
>             Has anyone seen two requests from the same IP hitting a
> servlet at approximately the time result in the same query string and
> headers?
>
> I can reproduce this every time.  Make two requests from one machine
> that hits my servlet at approximately the same time.   Both
> HttpServletRequest objects contain query string and header information
> of the first request in.  If the IPs are different everything works
> properly.
>

This seems *much* more likely to be a thread-safety problem in your user
code than a bug in Tomcat.  For example, using instance variables in
your
servlet to store per-request state information is pretty much guaranteed
to have difficulties.

The only way to know for sure would be for you to post a bug report
(http://nagoya.apache.org/bugzilla/) with a reproducible test case, so
that Tomcat developers can see what you are seeing.

> Thanks,
> -cb
>

Craig



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