Re: [JBoss-user] Mod_JK Failover

[Jules G. <ju...@co...>]

Felipe Oliveira wrote:
> Hi Jules,
> 
> That doesn't work. I had tried before, and just tried again. Actually I 
> tried passing all kinds of http status. The only way so far I have found 
> to tell mod_jk to failover is closing the port AJP is binding on.

Maybe mod_jk is just not up to it....

> 
> On the Jetty list Greg mentioned you did some work for a client, some 
> kind of filter. Could you give us more details about it? I am sure a lot 
> of people are having this problem of 404 when the app gets redeployed, etc.
> http://www.mail-archive.com/jbo...@li.../msg31780.html 

The filter wouldn't be any good to you, because it would be undeployed 
with the app...

I scrapped it in the end, it was too unreliable and slow. It basically 
allowed you to toggle a flag after which requests arriving without a 
session could be redirected or meta-refreshed back up to the 
loadbalancer. This gave us a way of 'bleeding' sessions off a node 
gradually, before finally taking it down....

> 
> 
> I read your comment but I am not sure exactly what to do to fix this issue.
> 

We have [tentative] plans for a mod_jetty. This will address this and a 
multitude of other issues - however it is someway away.

For the moment, you should be able to go in through the jmx-console and 
stop() the AJPListener, redeploy your webapp and the re-start() the 
listener. I haven't tried it, but it should work.

My client currently alters the weighting in the workers.properties files 
to '-1', gracefuls each apache, waits for the sessions to die away, 
redeploys the webapp, replaces the weighting in the workers.properties 
files and gracefuls the whole apache tier again -  simple and no scope 
for human error :-) - seriously, this is an issue I shall address as 
soon as I find the time.

I looked at mod_jk2, which has an API for changing worker attributes via 
http - but I found it too unstable for production.


Jules



> Any ideas?
> 
> Any help would greatly appreciated.
> 
> Felipe
> 
> 
> Jules Gosnell wrote:
> 
>> I think that if you send back a 404, mod_jk will fail-over to the next 
>> node.
>>
>> If you try this and it works, please confirm to the list.
>>
>> Cheers,
>>
>>
>> Jules
>>
>>
>> Felipe Oliveira wrote:
>>
>>> Does anyone know how to explicitly tell mod_jk to failover and send 
>>> the request to the other server on the cluster?
>>>
>>> I have a filter that catches any exception that happens on the 
>>> servlets...If an exception is throwed I want mod_jk to try to send 
>>> the same request to the other server?
>>>
>>> Any ideas?
>>>
>>> Thanks in advance,
>>>
>>> Felipe
>>>
>>>
>>>
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>>
>>
>>
> 
> 
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  * Jules Gosnell
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