Abmar Barros commented on ZOOKEEPER-702:
As I was refactoring server-to-server monitoring, I noticed that Leaders cannot
process the client session heartbeats received by Learners, once they only
track the last heartbeat (or app message) received from the clients, in order
to report to the Leader (LearnerSessionTracker).
I am thinking of tracking the heartbeats (not app messages) received from the
clients in the LearnerSessionTracker, so the Learners can send them to the
Leader, and the Leader itself can do an adaptive monitoring on these clients
What do you think?
> 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, bertier-pseudo.txt, chen-pseudo.txt,
> chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt,
> ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 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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