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From "Flavio Paiva Junqueira (JIRA)" <j...@apache.org>
Subject [jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model
Date Sun, 20 Jun 2010 11:38:23 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12880618#action_12880618
] 

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 corresponding references. 

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)
> Requirements
> Java, some distributed systems knowledge, comfort implementing distributed systems protocols
> Description
> 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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