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From Boris Cownie <>
Subject Could mod_jk buffer (or other module) buffer incoming requests an d reissue failed requests to healthy tomcat ?
Date Thu, 07 Dec 2000 16:30:18 GMT

 >Isn't it possible to make mod_jk recover gracefully from the loss of
 >Tomcat and try to reconnect with a new instance of Tomcat afterwards?

We're trying to configure apache / tomcat to be super reliable and
get around the jdk1.3 feature of going belly up once in a while on a 
our 4 processor ~700Hmz i86 compaq box running RedHat 6.2.

We currently run apache and a single jvm running tomcat connected
talking via mod_jserv. We also heartbeat even ~2 mins both apache
and tomcat and restart if either fails. The apache heartbeat does an
http request to port 80 the tomcat's to port 8080.

We're thinking of improving this setup with a second JVM running tomcat
then have mod_jserv load balance all requests to the the first instance
but redirect requests to the second tomcat if the first goes south.
(Our application caches objects and is happier with a single JVM.)

This should reduce the downtime while the first tomcat is restarted,
however the failed request (and any others active when tomcat barfed)
will be lost.

If mod_jk (or some other apache module I'm not aware of) could buffer
the incoming requests and reissue them to the backup tomcat if there is
no answer after a preset timeout we should be able to handle tomcat
crashes with no visible downtime or lost requests. 

Ideas ?

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