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From Thom May <tho...@amxstudios.com>
Subject Re: jserv SHUTDOWN_GRACEFULLY functionality with mod_jk?
Date Fri, 26 Jan 2001 19:10:14 GMT
* Dan Milstein (danmil@shore.net) wrote on Fri Jan 26, 2001 at 01:27:09 -0500:
> Thom,
> 
> Thanks for the feedback.  
> 
> 1) The mod_jk howto / vhosts
> 
> The mod_jk user docs are (as far as I can tell) kind of a mess.  I have a
> medium-term goal of overhauling them and cleaning them up, but I haven't
> done so yet.  I'm not clear on what they say about vhosts, and, to be
> honest, I'm no major expert on vhost configuration.  I'll try to take a look
> at this when I get a chance -- could you maybe send me the following:
> 
>  - A piece of a sample vhost config / mod_jk config which "should" work.
> 
>  - The specs for the system where it's currently not working.  Specifically:
> Apache version, TC version, connector protocol (e.g. ajp12, ajp13).
> 
> That would be very, very helpful.
OK, i'll get those to you on monday am - right now it's 18:45 Friday
evening, and the pub is beckoning :-)
I posted a patch against the workers howto to the list a week or so ago, but
I'd love to help with documentation.
> 
> 
> 2) Word-wrapping
> 
> <RED-FACED WITH SHAME>Thanks for pointing this out -- I had totally
> forgotten that I had this set this way.</SHAME>  Hopefully I have now fixed
> that.
Heh :) looks good to me.
> 
> 3) Restarting Apache == Bad
> 
> Makes sense to me.  Anyone else?  
> 
> A heartbeat would be a nice addition -- however, in the case of the specific
> functionality requested (stopping new sessions from going to a TC instance),
> you still need to somehow let an administrator tell the system to stop using
> that instance for *new* sessions (while still sending current ones there). 
> The instance is functioning fine, but you decide proactively that you'll
> want to shut it down soon.  So you (the admin) somehow need to tell the
> lb_worker to move that instance onto a special list.
OK, that makes sense.
> 
> If we don't restart Apache, does anyone have any grand ideas about how to
> communicate to the mod_jk plugin that it should shift a particular worker
> into this state?  We could put it on the TC side, but then we'd have to
> modify all the protocols to communicate back to the plugin that they should
> no longer get new sessions.  That seems tricky to me.  Or maybe the
> lb_worker should open up an out-of-band communication channel with TC?  That
> would be nice, because it could then control all of the workers, regardless
> of protocol.  Opinions?
I think that a solution that ends up with the load balancer controlling the
other workers is the ideal solution - and out of band communication sounds
like a pretty nice way of achieving that.
> 
> Can anyone comment on how hard/easy this would be to do entirely on the
> Apache side? 
> 
> -Dan
> 

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