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From "Jim Kellerman (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-1528) HClient for multiple tables
Date Thu, 02 Aug 2007 23:05:53 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-1528?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jim Kellerman updated HADOOP-1528:
----------------------------------

    Status: In Progress  (was: Patch Available)

Hudson never even ran test-contrib

The first test run had the following failures:

    [junit] Running org.apache.hadoop.dfs.TestDFSUpgrade
    [junit] Tests run: 1, Failures: 1, Errors: 0, Time elapsed: 8.789 sec
    [junit] Running org.apache.hadoop.fs.TestCopyFiles
     [junit] Tests run: 4, Failures: 1, Errors: 0, Time elapsed: 51.907 sec

and the second run hung:

    [junit] Running org.apache.hadoop.mapred.TestMiniMRWithDFS
    [junit] Tests run: 1, Failures: 0, Errors: 1, Time elapsed: 733.912 sec

and this patch only effects test-contrib for hbase

> HClient for multiple tables
> ---------------------------
>
>                 Key: HADOOP-1528
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1528
>             Project: Hadoop
>          Issue Type: Task
>          Components: contrib/hbase
>    Affects Versions: 0.15.0
>            Reporter: James Kennedy
>            Assignee: Jim Kellerman
>             Fix For: 0.15.0
>
>         Attachments: HConnection.patch, patch.txt, patch.txt, patch.txt, patch.txt, patch.txt
>
>
> I have an app that needs to access multiple HBase tables concurrently.  The current HClient
can only have one table open at a time even though it caches region servers of multiple tables
as they are looked up.
> This means that my application layer must open multiple HClients, one per table, perhaps
caching those HClients in a pool to reuse them (and their cached table data) as appropriate.
> or
> Shall I write an HClient patch that makes the HClient  multi-table thread-safe?
> Jim's suggestion is to implement an HClient singleton (call it HClientManager?) that
does the actual caching/resync of root/meta regions.  Individual HClients will still be one
table, one update row at a time but will rely on the singleton for the cached table info.
 We want HClients to be created and disposed as fast as possible with a minimum of meta lookups.
> Jim, what about non-root/meta regions, shouldn't they be cached and refreshed via the
singleton also?  It may still be possible that a region split/resync will occur during on
HClient session so does the HClientManager need to be able to notify the corresponding HClients
in that event?

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