Abmar Barros commented on ZOOKEEPER-702:

Once ZooKeeper  guarantees delivery order, I can ignore the seq field in 
heartbeat and pings messages. 
Now I am implementing the methods on the interface I proposed and two issues 
came to mind:
* ZooKeeper uses application messages as hearbeats, so actual pings and 
heartbeats are used only at idle states. The proposed methods must be adapted 
to consider this scenario.
* Regarding that a single thread is being used for the app and the FD, there is 
a delay between the time a monitored must be pinged and the time it is actually 
pinged. The impact of this delay in the FD QoS must be analyzed.

> 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.

This message is automatically generated by JIRA.
You can reply to this email to add a comment to the issue online.

Reply via email to