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Chen Liang commented on HDFS-13779: ----------------------------------- Thanks for the correction [~xkrogen]! Makes sense to me. I recall one example case I was thinking of was say there are 0, 1, 2 proxies, and currentIndex = 2. If 1 gets removed and the list shrinks to 0, 2. Due to modulo on size, seems currentIndex would effectively point to 2%size (2) = 0, but it was meant to point to 2. I guess the whole point I was concerning was that since {{currentObservers}} is based on modulo of size, but size can be changing at any point of time, {{currentIndex}} can become not so current over time. But seems even if {{currentIndex}} is wrong, it should be eventually fixed by the for loop, and thanks for point out that this should only happen in failover actions. I agree this should not be an issue. > Implement performFailover logic for ObserverReadProxyProvider. > -------------------------------------------------------------- > > Key: HDFS-13779 > URL: https://issues.apache.org/jira/browse/HDFS-13779 > Project: Hadoop HDFS > Issue Type: Sub-task > Components: hdfs-client > Reporter: Konstantin Shvachko > Assignee: Erik Krogen > Priority: Major > Attachments: HDFS-13779-HDFS-12943.WIP00.patch > > > Currently {{ObserverReadProxyProvider}} inherits {{performFailover()}} method > from {{ConfiguredFailoverProxyProvider}}, which simply increments the index > and switches over to another NameNode. The logic for ORPP should be smart > enough to choose another observer, otherwise it can switch to a SBN, where > reads are disallowed, or to an ANN, which defeats the purpose of reads from > standby. > This was discussed in HDFS-12976. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org