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From Rainer Jung <rainer.j...@kippdata.de>
Subject Re: jk Status not showing errors
Date Tue, 02 Jun 2009 20:10:09 GMT
On 02.06.2009 21:46, Matthew Laird wrote:
> 
> Rainer Jung wrote:
> 
>> Assuming that you did refresh the jkstatus display: what is your test
>> client? The fact that you see OK/IDLE, but all requests go to the other
>> node indicates, that you are using requests with associated session, so
>> the balancer is not allowed to send them to the other node and thus does
>> not detect the down node. Check to remove the JSESSIONID cookie before
>> sending requests, or use a client which allows cookie disabling (like
>> curl).
> 
> Is there any way to make it ping and detect a dead Tomcat without a
> request coming in?  I thought I was doing that with the
> worker.lbbasic.ping_mode=CI setting.

Yes, but:

- you need to activate a watchdog thread by using JkWatchdogInterval
- you might need to tune connection_ping_interval
- finally you will end up not getting what you want, because all of that
doesn't give you real time monitoring

The idea of this type of ping is to detect connections that are no
longer usable, because they were idle for to long and have been cut e.g.
by a firewall.

Broken backends usually are detected reliable, e.g. via prepost ping.
Yes, that only happens when you start to use them. There is no backend
probing in the watchdog thread at the moment. Yes that's one of the
enhancements on the list for a future release. Usually detecting on
demand is enough.

You can have your own probing: regularly probe your service, using a
dummy session cookie of the form

JSESSIONID=X.NODE

where you replace NODE with the jvmRoute of the backend you want to probe.

Regards,

Rainer



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