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Date: Wed, 20 Apr 2011 03:14:39 +0000 (UTC)
From: "Ted Yu (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
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Subject: [jira] [Commented] (HBASE-3777) Redefine Identity Of HBase
 Configuration
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    [ https://issues.apache.org/jira/browse/HBASE-3777?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13021932#comment-13021932 ] 

Ted Yu commented on HBASE-3777:
-------------------------------

We can break out of the loop in HConnectionManager.putConnection() if the reference count reaches 0, right ?
{code}
          if (entry.getValue().decRef() > 0) {
            connectionKey = null;
          } else break;
{code}

> 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-V2.patch, HBASE-3777-V3.patch, 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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