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From Ariel Weisberg <aweisb...@voltdb.com>
Subject Session expiration mechanism
Date Tue, 07 Jun 2011 21:19:20 GMT

I am working on a modified version of ZooKeeper, and I am having some
trouble understanding how session expiration is implemented.

It appears that once a create session requested is submitted it is
forwarded as a proposal to all followers. This means that the session
will be tracked by the SessionTracker at each member of the ensemble
(registration is done in FinalRequestProcessor), but as far as I can
tell the pings that would touch the session are only received by the
node where the session is currently active, and the leader which polls
the pings from all followers.

If that were true it seems like they would promptly time out at all
other nodes, and they would race to submit a request to close the

Am I wrong about session information being tracked at all members of the
ensemble or am I wrong about the pings propagating only to the leader
and the directly connected node? Possibly something else?

Ariel Weisberg

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