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From Rainer Jung <rainer.j...@kippdata.de>
Subject Re: 2 POST requests to underlying Server
Date Wed, 11 Aug 2010 22:13:13 GMT
On 10.08.2010 09:38, Karthik Nanjangude wrote:
> Hi
>
> Spec
> Java 1.5
> O/s : Linux
> APP Server        :  JBOSS4.2.1 (Tomcat built with)
> HTTP Server      :  apache_2.2.11 [ With out SSL ]
> Mod library        :  mod_jk-1.2.28-httpd-2.2.X.so
> LB  1 Apache     :  1 JBOSS:Port of application
>
>
> Question :  Some times We have observed that  on WEB Application  ( click on  button
in jsp )
>                   Apache is sending 2 POST requests to underlying JBOSS ( Tomcat server
).
>
> Note: We even put a Java script filter to disable multiple Clicks for the page,
>
>
> How we Observed :  Via TCP Thread dump using command    "tcpdump -i bond0 -s 1500 -w
/ tmp / test.pcap "
>
>
> Can this configuration "worker.node1.socket_timeout=10" got any thing to do with this
multiple request activity?

I'm a bit afraid that everyone who was arguing against the above claim 
will jump at me but still ...

It could be the missing "recovery_options" setting. See

http://tomcat.apache.org/connectors-doc/reference/workers.html

and do also read a bit about timeouts at

http://tomcat.apache.org/connectors-doc/generic_howto/timeouts.html

If you want to disallow resending any requests in case of communication 
errors, you need to set recovery_options to "7", if you want to allow 
resending for HEAD and GET, you can use "31".

As others have mentioned we could easily see from your jk log files with 
increased log level, whether resending because of errors happens here. 
Since you have a 10 second socket_timeout and the two requests are 12 
seconds apart, this is likely to happen (10 seconds timeout plus 2 
seconds connection draining).

You might want to have a close look at the example config contained in 
the mod_jk 1.2.30 source download, which looks better for production 
than you config above and is well commented. Note that although that 
config uses many timeouts, it does *not* use the general "socket_timeout".

Regards,

Rainer

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