[jboss-dev-forums] [Design of JBoss Portal] - Re: portal clustering problem when using optimistic locking

[galder.zamarreno@jboss.com]

Prabhat,

I'll have a look at this in the next couple of days but it's worth noting that with SYNC communication, specially replication, there's always a chance of a deadlock because locks are only acquired at commit time. So, individual nodes could successfully acquire nodes locally, and then cross each other when trying to acquire locks cluster wide. The end result is both nodes timing out in their operation:

Example:
Tx1 acquires WL on N1 for node /a/b
Tx2 acquires WL on N2 for node /a/b
Tx1 tries to commit and attempts to acquire lock for /a/b while Tx2 is trying to commit and attempt to lock that same node cluster wide.
Tx1 rollbacks because it can't acquire locks for /a/b in N2 and viceversa

As I said, I'll check the attached files in the next couple of days to confirm whether this is precisely what you're seeing. However, it's worth keeping it in mind.


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