[jboss-user] [Clustering] - Re: Failure when cleaning up HTTP Session in JBoss AS Cluste

bstansberry@jboss.com do-not-reply at jboss.com
Fri Oct 23 15:00:25 EDT 2009

Re: FileCacheLoader, I think it would be strange if some corruption happened to the same session on 2 different systems.

The limitiations of the FCL are:

* Due to the way the FileCacheLoader represents a tree structure on disk (directories and files) traversal is inefficient for deep trees.
* Usage on shared filesystems like NFS, Windows shares, etc. should be avoided as these do not implement proper file locking and can cause data corruption.
* Usage with an isolation level of NONE can cause corrupt writes as multiple threads attempt to write to the same file.
* File systems are inherently not transactional, so when attempting to use your cache in a transactional context, failures when writing to the file (which happens during the commit phase) cannot be recovered.

I assume you aren't using a shared filesystem for the session store. The isolation level NONE caveat doesn't apply. The problem with not being able to recover if a write failure occurs in a tx is semi-relevant, but I'd expect then you'd have seen some errors in the logs when the session was persisted.

Re: the pattern of failures, how close is the timing of the logging between the servers?

You're using buddy replication, right? That would explain only 2 servers being involved -- the server handling the session and its buddy.

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