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From Carl Trusiak <catman412...@yahoo.com>
Subject Re: Simultaneous request from same IP
Date Tue, 17 Dec 2002 01:15:24 GMT
I have seen this.  The only time was caused by html
and javascript.  We had
<input type="submit"
onclick="javascript:doSomething();">

Then in the doSomething() method, we did a
form.submit();

The click of the submit input caused a submit of the
form, followed by a submit by the javascript.  We
corrected this by changing the input type to button.

May not help in your case but, felt I should relate my
experience.


--- Mike W-M <mike@ward-murphy.co.uk> wrote:
> Chris,
> 
> I've played around with a servlet almost identical
> to your original (not
> full!) test-case (below).  (Did you actually get the
> problem to appear on
> this one or is it just a theoretical cut-down of the
> larger example you
> posted later?)
> I've made - not exactly concurrent, but definitely
> sub-second-apart -
> requests from two instances of Internet Explorer. 
> (Nifty finger/mouse
> coordination.)
> I cannot reproduce your "confused" results.  [I've
> even added a
> thread.sleep(10000) into the servlet to ensure that
> the requests are running
> (or at least in existence) concurrently. ]
> 
> I still can't think of anything you're doing in the
> servlet that would
> produce the results you describe.
> I (still) think that the problem is most likely with
> your "simultaneous
> requests" themselves.  How are you making these
> requests - via code?  Can
> you reproduce the problem with nifty-I.E.
> fingerwork?
> 
> 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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