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https://issues.apache.org/jira/browse/HDFS-13779?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16598050#comment-16598050
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Erik Krogen commented on HDFS-13779:
------------------------------------

Looks like me and Konstantin hit a race condition :) Comments 2 and 4 were 
fixed in v001 patch.

I just attached v002 which addresses 1 and 3. Konstantin and I discussed 
offline and realized that the caching done in {{ipc.Client}} will make the two 
ProxyProviders share a single connection per NameNode regardless of the caching 
of the proxies themselves, so I agree that the {{CachingHAProxyFactory}} is not 
necessary. This also makes my changes to the constructor (accepting a class and 
using reflection, instead of directly accepting an instance) unnecessary. 

> 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-12943.000.patch, 
> HDFS-13779-HDFS-12943.001.patch, HDFS-13779-HDFS-12943.002.patch, 
> 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.



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