Hi,
/Httpd 2.2.17, mod_jk 1.2.31, tomcat 7.0.10, OSX 10.6.5/
Looks like there is something I do not get regarding Tomcat clustering, so I do
here a sanity check :-)
I have two machines with one tomcat on both.
I use one of the machines as reverse proxy. here is the reverse proxy conf
from the httpd.conf file:
ProxyRequests Off
<Proxy balancer://pathCluster>
BalancerMember http://bml0065.yalepath.org loadfactor=10
BalancerMember http://bml0066.yalepath.org loadfactor=10
ProxySet lbmethod=bytraffic
</Proxy>
ProxyPass /tc/ balancer://pathCluster/
ProxyPassReverse /tc/ balancer://pathCluster/
ProxyPassReverseCookiePAth / /
ProxyPassReverseCookieDomain / /
The reverse proxy passes the request to one of the balance members. The
balance member see that the request is for tomcat and passes it to mod_jk.
Mod_jk is checking its workers.properties file and based upon the load it
passes the request to one of the two Tomcat instances. Here is one of the
workers.properties file:
bml0065:local administrator$ cat apache2/conf/workers.properties
worker.list = lb,jkstatus
worker.lb.type=lb
worker.lb.balance_workers=tomcat1,tomcat3
worker.lb.sticky_session = True
worker.lb.sticky_session_force = False
worker.jkstatus.type=status
worker.tomcat1.type = ajp13
worker.tomcat1.host = bml0066.yalepath.org
worker.tomcat1.port = 8109
worker.tomcat1.lbfactor = 1
worker.tomcat1.redirect=tomcat3
worker.tomcat3.type = ajp13
worker.tomcat3.host = bml0065.yalepath.org
worker.tomcat3.port = 8309
worker.tomcat3.lbfactor = 1
worker.tomcat3.redirect=tomcat1
To check session replication and session failover, I use the SessionExmaple
servlet from the supplied examples webapp this way:
http://bml0065.yalepath.org/tc/examples/servlets/servlet/SessionExample
bml0065 is the reverse proxy. When I see that the session is created I shut
down that tomcat which hosts the session and add another session attribute via
the SessionExample servlet. The mechanism is working fine, the session fails
over to the other tomcat instance. I add more session attribute, and start up
the previously shouted down tomcat instance, add more attribute, then I shut
down the other tomcat instance and check for fail over, etc..etc.. Everything
works.
Then I do not shut down tomcat, just stop the examples webapp on that tomcat
instance where currently the session resides and try to add more session
attribute. Instead of failing over, I receive a 404 error:
HTTP Status 404 - /examples/servlets/servlet/SessionExample
type Status report
message /examples/servlets/servlet/SessionExample
description The requested resource (/examples/servlets/servlet/SessionExample)
is not available.
Apache Tomcat/7.0.10
My understanding is that the request should be rerouted to the other tomcat
instance and present the sessions from that machine, the same way when tomcat
itself was stopped. However that is not what happenzzzz.
So the question is what do I miss in this process ?
Thanks ahead,
János
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