Hello Tomcat-Developers,
we are currently experiencing some problems with mod_jk with
loadbalancing:
(A) when a post-request fails while receiving data from tomcat, the
loadbalancer tries to send the request to the other tomcat, but
"forgets" the post body content (i.e. login and password submitted by
the user). The size of the body content is only a few bytes (< 100), so
it's not the "known" problem with bodies longer than 8k.
(B) it seems that sometimes after a POST-failover body data from an old request is sent to the other tomcat when the first connection failed. This leads to a session mix-up & user mix-up!
The setup is a simple cluster configuration: one apache httpd with
mod_ssl in front, mod_jk with one configured loadbalance worker with
sticky sessions and two child ajp13 workers in the middle, two tomcats
in the back.
Versions involved: mod_jk 1.2.4, Tomcat 4.1.27 (but also tested with mod_jk 1.2.5 and Tomcat 4.1.29). Apache on AIX, version 1.3.29. The latest version of jk_ajp_common.c in CVS don't seem to have relevant changes. We have searched the mailinglists, the only source I have found is in tomcat-user-mailinglist where Jean-Philippe Belanger describes a similar problem in the mails from 14 Jan 2004 (the empty POST body) and 12 Jan 2004 (the empty POST body and the session mixup). He didn't investigate further but got himself a cisco load balancer. Another post is here, but I found no replies/solutions.
http://www.mail-archive.com/[EMAIL PROTECTED]/msg48833.html
(A) can be reproduced quite easily using "netcat" as a simulator of the
first tomcat and a second real tomcat. If you kill netcat after it has
accepted a POST-connection from a mod_jk, mod_jk will forward the
request to the other tomcat without the POST-body
But we can't reproduce (B), but it has definitely happened. We suspect
that POST-Recovery code might send an old request body while executing
the following statements. Please note that the log statement refers to
op->reply while the following if statement refers to op->post! (this is
cut and paste from the orginal source):
It used to works but it was before the content-header add-on code.
This piece of is a nightmare, and I see no easier solution than copying the HEAD+POST in temp buffer but I'd like to have Bill, Mladen and JFC advices...
BTW, could you send the code as diff -Nru ?
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