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From Jeff MAURY <jeffma...@jeffmaury.com>
Subject Re: Issue with keep-alive connections, when using APR Connector on Windows and starting Processes from Servlets
Date Wed, 20 Jun 2012 22:07:22 GMT
Can you verify your 2 threads (reading input an error) are launched ?
Can you confirm you are getting the problem only on Windows ?

Jeff


On Wed, Jun 20, 2012 at 4:19 PM, Laurent Petit <lpetit@yseop.com> wrote:

> Hello,
>
> I have a problem with keep-alive connections, when starting a subprocess
> (via JDK's default ProcessBuilder/Process API), while also having
> started Tomcat with the APR HTTP/1.1 Connector.
>
> The problem symptom is with Keep-Alive connection, as follows:
>
> - the client (browser, jmeter, etc.) sends a first request
>  - the servlet starts a Process for e.g. wordpad.exe
>  - the servlet returns an acknowledgment html content, sets the content
> length, flushes the writer, and returns
> - the client displays the received acknowledgement html content, sends
> the second request to the server.
> - the server doesn't answer. No Tomcat log ever reports the start of
> something received.
> - Then when on the server you close the wordpad.exe instance, the server
> finally handles the second request.
>
> I have created a small servlet code which reproduces the problem.
> For the demo, it suffices to have the started subprocess be
> "wordpad.exe". Of course my real process is more interesting than
> that :-).
>
> You can find the servlet code for reproducing the test here:
>
> https://www.refheap.com/paste/3254
>
>
> To reproduce the problem deterministically, the ConnectionTimeout for
> the APR HTTP Connector in servlet.xml must be set sufficiently low.
> With my boxes, I get a 100% error hit when set at 200 ms.
>
> You can find here the jmeter script which hits the same page again and
> again with "keep-alive" option set on:
>
> https://www.refheap.com/paste/3255
>
>
> So far, the only reliable solution we have found to work around this
> problem is to not use the HTP/1.1 APR Connector.
>
>
> My configuration :
> Windows 2008 US std R2 64bits
> Tomcat 6.0.32 64 bits
> Java 6u30 64 bits(Oracle)
>
> Same issue has been observed on Windows 7 32 bits.
>
> Was not able to reproduce the issue on Linux Ubuntu Desktop 11.10 or
> 12.04.
>
>
> Thanks for your support, ideas, solutions, etc.
>
>
>
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>


-- 
Jeff MAURY


"Legacy code" often differs from its suggested alternative by actually
working and scaling.
 - Bjarne Stroustrup

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