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From <cost...@covalent.net>
Subject RE: PROPOSAL: mod_jk2: Group/Instance
Date Thu, 02 May 2002 14:44:51 GMT
On Thu, 2 May 2002, Amund Elstad wrote:

> (1) all requests without a session are routed to a specific tomcat instance
> (if that instance is working). 

That has been added, and it should work in both jk1 and jk2 ( I don't 
remember who sent the patch, but I remember adding it ). If it doesn't 
work yet, is easy to fix.

This is essential for jk2's JNI worker, which fits perfectly this case
( you don't want to send via TCP when you have a tomcat instance in the 
same process ).


> (2) Tomcat instances in standby or "soft shutdown" mode where they serve
> requests bound by established sessions, and requests without a session only
> if all non-standby instances have failed.

That's what the SHM scoreboard is going to do ( among other things ). 
You can register tomcat instances ( which will be added automatically ),
or unregister - in which case no new requests ( except the old sessions )
will go to the unregistered tomcat.


Costin

> costinm@covalent.net wrote:
> 
> >On Tue, 30 Apr 2002, Bernd Koecke wrote:
> >
> >> some weeks ago I send a patch for mod_jk for an only routing lb_worker. A
> few 
> >> days later I sent the docu. Henry Gomez said, that it should be commited.
> But it 
> >> I think it isn't in the repository. But its the same  with me here, to
> mutch 
> >> work for to less time :).
> >
> >I think it is in mod_jk, I remember seeing the commit. 
> >
> >And I think I commited it in jk2 as well ( after some modifications ).
> >
> >> I need sticky sessions but no loadbalancing in the module. If a request
> without 
> >> a session comes in, it should be routed to the _local_ tomcat.
> >
> >Well, there is another use-case with the exact same behavior - Apache2 
> >with tomcat in JNI mode. All requests without session should be routed to 
> >the _jni_ channel ( i.e. in-process, minimal overhead ).
> >
> >It's exacly the same - so be sure I do my best to handle this case :-)
> >
> >Apache2 acts like a 'natural' load-balancer/fail-over, with the parent
> >process monitoring for crashes and it starts/stop childs based on 
> >load.
> >
> >
> >> I think this could be possible with the associated instance of a channel
> (item 
> >> 7). Then I have to configure all four nodes for the same group. Because
> all 
> >> nodes will serve the same webapps and associate the channel with this
> group. But 
> >> for this I need a non balancing group. I don't see if the default
> behavior of a 
> >> group is balancing and if this can be switched off. Is this right or do I
> miss 
> >> something?
> >
> >The default is balancing, but you can tune this using weithgs ( and I 
> >think we use your code for making one instance 'top priority').
> >
> >Please check the code, take a look and send additional comments/patches.
> >
> >It's not yet completely done, of course.
> >
> >
> >Thanks,
> >Costin 
> 
> 
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