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https://issues.apache.org/jira/browse/HBASE-3777?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13019574#comment-13019574
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Ted Yu commented on HBASE-3777:
-------------------------------
For a), I like the idea of adding uniquifier to HBaseConfiguration. This is can
be standardized through a well-known configuration parameter, such as
"hbase.zookeeper.uniquifier" (a secondary key really).
For b), I don't have strong opinion about particular implementation. What I
have yet to propose is that we can implement (optional) timeout mechanism for
connections to address the issue under the thread "hbase -0.90.x upgrade -
zookeeper exception in mapreduce job" on user mailing list.
Maybe it's easier to enforce timeout policy in HCM, hence the centralized
reference counting.
> Redefine Identity Of HBase Configuration
> ----------------------------------------
>
> Key: HBASE-3777
> URL: https://issues.apache.org/jira/browse/HBASE-3777
> Project: HBase
> Issue Type: Improvement
> Components: client, ipc
> Affects Versions: 0.90.2
> Reporter: Karthick Sankarachary
> Assignee: Karthick Sankarachary
> Priority: Minor
> Fix For: 0.92.0
>
> Attachments: HBASE-3777.patch
>
>
> Judging from the javadoc in {{HConnectionManager}}, sharing connections
> across multiple clients going to the same cluster is supposedly a good thing.
> However, the fact that there is a one-to-one mapping between a configuration
> and connection instance, kind of works against that goal. Specifically, when
> you create {{HTable}} instances using a given {{Configuration}} instance and
> a copy thereof, we end up with two distinct {{HConnection}} instances under
> the covers. Is this really expected behavior, especially given that the
> configuration instance gets cloned a lot?
> Here, I'd like to play devil's advocate and propose that we "deep-compare"
> {{HBaseConfiguration}} instances, so that multiple {{HBaseConfiguration}}
> instances that have the same properties map to the same {{HConnection}}
> instance. In case one is "concerned that a single {{HConnection}} is
> insufficient for sharing amongst clients", to quote the javadoc, then one
> should be able to mark a given {{HBaseConfiguration}} instance as being
> "uniquely identifiable".
> Note that "sharing connections makes clean up of {{HConnection}} instances a
> little awkward", unless of course, you apply the change described in
> HBASE-3766.
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