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From Yoav Shapira <yo...@apache.org>
Subject Re: Extending PersistentValve ?
Date Mon, 16 Jan 2006 19:33:41 GMT
Hi,
I don't have much to comment besides what you already pointed out:
this approach would suffer a performance penalty on each and every
request, and (on a decently configured network) would end up slower
than the SimpleTcpCluster multicast solution.  Why can't you use the
latter?

Before you reply: now that you've solved your ClassCastException, this
becomes more of a user issue, so please take the discussion to
users@tomcat.apache.org rather than dev@tomcat.  Thanks,

Yoav

On 1/16/06, Gary Blomquist <gblomquist@net2phone.com> wrote:
>
> The ClassCastException fixed.  I had the valve configured incorreclty in
> the server.xml.
>
> Would still appreciate feedback on the approach discussed below.
>
> Thanks,
>
> Gary
>
> -----Original Message-----
> From: Gary Blomquist [mailto:gblomquist@net2phone.com]
> Sent: Monday, January 16, 2006 2:12 PM
> To: Tomcat Developers List
> Subject: Extending PersistentValve ?
>
> I would like to be able to use round robin loading balancing with a
> JDBCStore.  However, it appears that using the PersistentManager with
> JDBC store could cause the sessions to be stale when a session migrates
> between workers due to the asyncronous behavior of the
> PersistentManager.  (I realize their is a SimpleTcpCluster available as
> a clusterering solution but I can not use because it relies on
> multicast.)
>
> Viewing the source it appears that the PersistentValve with the
> PersistentManager  and JDBCStore could be a solution.   It appears that
> it would load a session from the store at the begging of each request
> and save it back to the store at the end of the request.  I would like
> to modify the behavior to only load/save when the session is dirty based
> on the last_access timestamps.
>
> Any comments on the solution? ( I realize their is some performance
> penalty due to object serialization and writing blobs to the database;
> however, in our case I think this would not be prohibitive esp. if there
> is a small amount of data in the session.)
>
> Also,  when I attempt to run Tomcat with the PersistentValve I get the
> following exception:
>
> SEVERE: An exception or error occurred in the container during the
> request processing
> java.lang.ClassCastException: org.apache.catalina.core.StandardEngine
>         at
> org.apache.catalina.valves.PersistentValve.invoke(PersistentValve.java:9
> 9)
>         at
> org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:1
> 48)
>         at
> org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:199)
>         at
> org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:282)
>         at
> org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:744)
>         at
> org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:
> 674)
>         at
> org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.
> java:866)
>         at
> org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool
> .java:684)
>         at java.lang.Thread.run(Thread.java:595)
>
> Note:  (I have not yet made mods to the PersistentValue)
>
>
> Thanks for your assistance,
>
> Gary Blomquist
>
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>


--
Yoav Shapira
System Design and Management Fellow
MIT Sloan School of Management
Cambridge, MA, USA
yoavs@computer.org / www.yoavshapira.com

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