[mod_cluster-dev] Failover failed
bela at jboss.com
Mon Dec 15 09:25:03 EST 2008
First off, shouldn't we set the maxThreads in server.xml in the AJP
connector to a higher value that the (default I think) value of 40 ? The
demo creates 80 clients and if we have only 1 node up and running, it
has to serve 80 connections !
Secondly, why is load-demo.war/WEB-INF/web.xml not marked as
Then, I ran 2 experiments and they didn't behave as I expected them. Can
you confirm/reject my assumptions ?
* Run httpd, then only node1. The only change I made from the
default is to set maxThreads=100 in the AJP connector, and to use
* Run the demo app with 80 clients
* You'll see that node1 was serving 80 sessions
* Start node2, keep the demo running
* My expectation is that now node1's sessions will go down to 40 and
node will serve roughly 40 sessions
* Result: node2 picked up 46 sessions, and node1 went down to 34. I
waited for the session life timeout (120 secs), but the result was
still the same. Question: why didn't both nodes serve 40 sessions
* Update: the # of sessions in node1 and node2 got closer after some
time, I guess my session life of 120 secs was the reason for this !
* Update 2: I see that with a session life of 10, node1 and node2
take turns at allocating new sessions, sometimes node1 is on top,
sometimes node2, but on average both nodes serve 40 sessions !
Great ! Disregard this first item !
* Start httpd
* Start node1
* Start node2
* Start the demo with 80 clients
* Observer the same as above: node1 serves roughly 40 sessions and
so does node2
* Kill node2
* Now I have 80 failed clients and 0 active clients !
* 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 ?
* 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
Lead JGroups / Clustering Team
JBoss - a division of Red Hat
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