Parallel deployment and session replication

[Aristedes Maniatis <am...@apache.org>]

I am an enthusiastic user of the new parallel deployment feature of tomcat 7. But I'm a little unclear about how it interacts with session replication.

If I have a cluster of tomcat instances:

instance1/A#001.war
instance2/A#001.war
instance3/A#001.war

And they are all replicating sessions (say using SimpleTcpCluster). Then I want to upgrade, so I introduce more war files:

instance1/A#001.war
instance1/A#002.war
instance2/A#001.war
instance2/A#002.war
instance3/A#001.war
instance3/A#002.war

Now, since these are effectively the same applications, they are all on the same multicast address and port. So I assume that sessions will now replicate between all 6 instances.

* Will the old instances ever shut down? That is, will the sessions ever die on the old instances if they are part of the session replication cluster?

* Is parallel deployment only designed to work with sticky sessions?


Thanks
Ari


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Aristedes Maniatis
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Re: Parallel deployment and session replication

[ma...@apache.org]

Aristedes Maniatis <am...@apache.org> wrote:

>I am an enthusiastic user of the new parallel deployment feature of
>tomcat 7. But I'm a little unclear about how it interacts with session
>replication.

Each version of a webapp is treated as a separate webapp.

>If I have a cluster of tomcat instances:
>
>instance1/A#001.war
>instance2/A#001.war
>instance3/A#001.war
>
>And they are all replicating sessions (say using SimpleTcpCluster).
>Then I want to upgrade, so I introduce more war files:
>
>instance1/A#001.war
>instance1/A#002.war
>instance2/A#001.war
>instance2/A#002.war
>instance3/A#001.war
>instance3/A#002.war
>
>Now, since these are effectively the same applications, they are all on
>the same multicast address and port. So I assume that sessions will now
>replicate between all 6 instances.

Nope. You have a three node cluster with two webapps deployed on each node with sessions replicating within each cluster of three webapps but not between versions of the webapp.

>* Will the old instances ever shut down? That is, will the sessions
>ever die on the old instances if they are part of the session
>replication cluster?

Yes. They'll timeout normally. Note clustered sessions will take longer to completely timeout to allow for replication delays around session expiry time.

>* Is parallel deployment only designed to work with sticky sessions?

No.

Mark




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