Hi,
In our production envt,we are making use of a configuration of
Apache(2.2.10-1)+Mod_jk(1.2.27)+JBOSS(4.0.5)+ATG 2007.1.

We are facing a problem where multiple content is being displayed to the
customer.It was observed that the pages were being periodically rendered
or rendered multiple times.The page was rendered with a standard
navigational header showing two times. Depending on the browser, the
duplicate headers was stacked vertically or horizontally. The issue was
further exasperated because a particular fragment was cached at Akamai,
and once this double header was served up by origin, it was then cached
at Akamai and included in customer pages at a very high rate.

Our Analysis So far

We did a local setup of the above configuration and we are able to
recreate the multiple content problem.The setup involves apache
configured with mod_jk having two worker nodes balanced by a load
balancer worker.The problem occurs when the app code takes a longer time
than the time defined in the socket_timeout parameter of the worker
nodes. We have set the socket_timeout config of the worker nodes to be 2
secs for both nodes and the appserver jsp logic is made to sleep for
3secs.

The behaviour observed is as follows:

The first worker node fails after the socket timeout time and the second
worker node is able to retreive the response from the app server.However
while turning on the debug of mod_jk,we are observing that a partial
content has been served by the AJP Connector/Container from the App
server for the node 1.Also,a full content has been served for the
request initiated by node2.The full content follows the partial content
that has been already sent to the client .Hence the browser has a
duplicate/multiple content shown to the customers.

What are we looking for?

The open question at this point that we have is how/what configuration
could either limit this partial response (or) send an error response to
the client when the worker node is found to be inactive? (or) handling
the situation of the app server taking a longer time to respond than the
defined timeouts (in mod_jk) and a partial content being writtent into
the socket,received by mod_jk and sent to the client?

 The problem gets aggravated when we akamai comes into picture.


Thanks for your help!

Regards,
Bala Karthik

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