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From Rainer Jung <>
Subject Re: mod_jk workers list file update issue
Date Mon, 03 Dec 2007 09:44:25 GMT
James Wen Jun Xue wrote:
> Hi all,
> I am new to mod_jk, and according to my understanding, mod_jk does not 
> support auto update the workers list ( e.g. the requests can't be sent 
> to a subset of the original workers list without change of the list and 
> restart of the apache web server; the requests will still be sent to all 
> the tomcat instances on the list as long as they are all alive).  Is it 
> possible to modify the codes so that mod_jk works in the mentioned way ? 
> any reply will be much appreciated.
> thanks,
> James

Reloading dynamically is hard, because we would have 
to find out, which parts of the initialization code we have to run again 
(and also which parts of the destruction code to run before). The 
problem is not with checking the file timestamp, you would really have 
to reorganize bigger parts of the code.

We plan to do that for JK3, but not for 1.2.x.

There are several partially dynamic things you can already do with 1.2.x:

1) Change the rules, which URL maps to which worker (aka JkMount). If 
you put your rules into a, the mapping will be 
dynamic. The file gets checked for timestamp changes and is 
automatically reloaded after changes. See

2) Member worker of a load balancer can by dynamically 
activated/disabled/atopped using a so called status worker with a web 
gui. Those changes are not persistent though. See

3) Other changes to can only be activated by 
restarting the web server. Although that sounds little heavyweight, in 
fact "apachectl graceful" nowadays works quite well.



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