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From "Cox, Charlie" <c...@cincom.com>
Subject RE: Simultaneous request from same IP
Date Tue, 17 Dec 2002 14:01:52 GMT
this goes along with the suggestion I made of using RequestDumperValve to
dump the request to ensure that you are receiving 2 different requests.

Charlie

> -----Original Message-----
> From: Mike W-M [mailto:mike@ward-murphy.co.uk]
> Sent: Monday, December 16, 2002 8:08 PM
> To: Tomcat Users List
> Subject: Re: Simultaneous request from same IP
> 
> 
> 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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