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From "Jukka Zitting" <jukka.zitt...@gmail.com>
Subject Clustering and consistency
Date Mon, 08 Oct 2007 23:02:04 GMT

The recent thread about William Louth's JXInsight findings got me
thinking about how the current clustering feature achieves consistency
across cluster nodes.

The current clustering solution uses a journal where it records all
the actions taken by the cluster nodes. However, this journal is only
polled periodically by the nodes to sync up with the rest of the
cluster. Meanwhile the actual workspace persistence stores might be
out of sync from what Jackrabbit expects. This could be a problem
since Jackrabbit core makes a rather fundamental assumption about
always being in control of the persistence store.

The issue shouldn't be that critical for deployments with mostly read
access, or write access happening only on a single cluster node, or
even multiple nodes writing to separate branches of the content tree.
But do we have a good picture of what will happen if multiple cluster
nodes concurrently update the same content nodes?


Jukka Zitting

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