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From Andrew Cowie <>
Subject Load balancing
Date Fri, 18 Aug 2000 19:20:00 GMT

	I'm going to try again. Still, no one either here or on -user has
answered my query about whether or not the load balancing between multiple
machines running tomcat works as purported. 

	We have a problem whereby the ApJservRoute is NOT appended by Tomcat
to the JSESSIONID cookie and so subsequent requests go to a random server,
rather than the one hosting that users session. Crunch.

	I have worked around the problem by disabling load balancing
entirely and using a Cisco Local Director to load balance in sticky mode,
but this is a kludge and it is disappointing that one of the key reasons we
chose Tomcat doesn't actually work.

	If anyone can confirm that the code either works or doesn't, then we
can explore the question of whether or not there is a configuration issue -
but every message I've seen on the subject has always talked about
configuring the Apache servers to control mod_jserv (no problem) and claimed
that no alterations need to be made to the Tomcat servers. Packet sniffing
ajp show our JSERV_ROUTE going by, but the cookies returned ultimately to
the Browsers don't have the JSERV_ROUTE appended.

	Extensive examination of the code makes it appear that all the
pieces are there; we tried our best to figure it out but, frankly, nothing
at the individual statement level in the code seems wrong. We just weren't
able to determine if all the pieces are working together correctly, but
something doesn't work, causing the symptoms described above.

	We're about to go live on this hardware, after which I won't be able
to test alternate anymore, so if anyone has any specific queries to try and
help debug this I'd be happy to probe it now.

	Look forward to hearing from you,


Andrew Frederick Cowie
Director of Operations
Upoc, Inc

cell: 917-217-4578  office: 212-405-1044

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