[ https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12879450#action_12879450 ]
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.