[mod_cluster-dev] Session temporarily unavailable

Paul Ferraro paul.ferraro at redhat.com
Wed Jul 22 09:53:04 EDT 2009

On Wed, 2009-07-22 at 09:37 -0400, Brian Stansberry wrote:
> If you shut down node 1 cleanly, it should be telling httpd itself that 
> it's gone.

Or, if using HAModClusterService, and node2 was the HA singleton master,
node1 will tell node2 to tell httpd that node1 is gone...

> Bela Ban wrote:
> > When I have 2 nodes (node1, node2), and a session which is created on 
> > node1 (and replicated to node2), the following can happen:
> > 
> >     * I shut down node1 (CTRL-C)
> >     * node1 terminates cleanly
> >     * I access the webapp, but get a "Session temporarily unavailable"
> >       failure message (I guess a 500)
> >     * When I check mod-cluster-manager, information about node1 is still
> >       there !
> >     * Ca 5 seconds later, mod-cluster-manager doesn't show node1 anymore
> >     * When I now access the webapp, I get the proper failed over session
> >       on node2 and all my data is still there
> > 
> > 
> > So my question is why doesn't node2 immediately tell httpd/mod-cluster 
> > that node1 is gone ? It seems that httpd *itself* only learns about this 
> > when it pings the socket to node1...

I should be.  Do you see the appropriate STOP_APP, REMOVE_APP messages
in your httpd access log?
> > I recall Paul once telling me we hadn't implemented that functionality, 
> > but I guess by now this is surely implemented ?

I never said that, but I think I know of the conversation to which you refer...
If you are running mod_cluster via HAModClusterService and node1 crashed
(instead of a clean shut down), node2 will not send any MCMP messages to
httpd on behalf of node1 when it receives a view change.

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