Paul Ferraro wrote:
> Secondly, why is load-demo.war/WEB-INF/web.xml not marked as
> <distributable/> ?
>
Session replication was not part of our original scope for the demo.
Though - I see no reason not to enable it.
Got you
>
>
> #2
>
> * Start httpd
> * Start node1
> * Start node2
Which server.xml Listener are you using? ModClusterListener,
ModClusterService, or HAModClusterService? Only the latter 2 use the
config from mod-cluster-jboss-beans.xml.
HAModClusterService
> * Start the demo with 80 clients
> * Observer the same as above: node1 serves roughly 40 sessions and
> so does node2
> * Kill node2
Gracefully shutdown? or killed?
CTRL-C.
> * Now I have 80 failed clients and 0 active clients !
OK - that's weird. Let me try to reproduce this on my end.
OK
> * If I call Server.shutdown() on node2 (via JMX), then node1 serves
> 40 sessions. But why does node1 not pick up the other 40 sessions
> from left node2 ? Is this the client, which simply terminates
> threads which got a 500 ?
Yes
Why don't we change that, and ignore HTTP error responses ? This way,
eventually, all clients would fail over to the running node.
> * I guess we don't send a DISABLE-NODE, STOP-SERVER or
DISABLE-APP
> to httpd when we kill a server ? Can we do this, e.g. by adding a
> shutdown hook ? Or can I at least try this out through the command
> line ? What's the recommended way of doing this currently (JMX
> console) ?
The [STOP_APP, REMOVE-APP, REMOVE-APP *] message sequence is only sent
during graceful shutdown of a server.
So Server.shutdown() should have triggered this right ?
If the node is killed, then
mod_cluster httpd modules will follow traditional failover logic (same
as mod_jk/mod_proxy).
OK
I've a tentative plan to enhance this in a later release to
utilize
jgroups view change to allow the ha singleton master to send these
message on behalf of the failed server. This sounds more useful than it
actually is, since with high volume, it is likely that httpd will have
already detected the failure before the master has the chance to send
the corresponding shutdown message sequence
Agreed. But the graceful shutdown case (maybe complemented with a
shutdown hook) should allow us to tell httpd to redirect requests for
all apps of a given node before the node shuts down.
--
Bela Ban
Lead JGroups / Clustering Team
JBoss - a division of Red Hat