Flavio Paiva Junqueira commented on ZOOKEEPER-702:
Abmar, It would be nice if you could add some comments to the pseudo-code of
each FD, especially for the variables and parameters, and also provide the
On your first point above, it would be nice if we could keep using zookeeper
messages as heartbeats.
On your second point, I believe that the problem you're alluding to will exist
in any implementation, since scheduling a message to be sent doesn't guarantee
that it will be sent right away. Is there any different issue you're seeing
here that I'm overlooking?
> GSoC 2010: Failure Detector Model
> Key: ZOOKEEPER-702
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
> Project: Zookeeper
> Issue Type: Wish
> Reporter: Henry Robinson
> Assignee: Abmar Barros
> Attachments: bertier-pseudo.txt, chen-pseudo.txt,
> phiaccrual-pseudo.txt, ZOOKEEPER-702.patch
> Failure Detector Module
> Possible Mentor
> Henry Robinson (henry at apache dot org)
> Java, some distributed systems knowledge, comfort implementing distributed
> systems protocols
> ZooKeeper servers detects the failure of other servers and clients by
> counting the number of 'ticks' for which it doesn't get a heartbeat from
> other machines. This is the 'timeout' method of failure detection and works
> very well; however it is possible that it is too aggressive and not easily
> tuned for some more unusual ZooKeeper installations (such as in a wide-area
> network, or even in a mobile ad-hoc network).
> This project would abstract the notion of failure detection to a dedicated
> Java module, and implement several failure detectors to compare and contrast
> their appropriateness for ZooKeeper. For example, Apache Cassandra uses a
> phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which
> is much more tunable and has some very interesting properties. This is a
> great project if you are interested in distributed algorithms, or want to
> help re-factor some of ZooKeeper's internal code.
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