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From "Stephen Yuan Jiang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16668) Admin class should have a synchronous Admin#mergeRegions* method
Date Wed, 30 Nov 2016 00:59:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16668?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15707106#comment-15707106
] 

Stephen Yuan Jiang commented on HBASE-16668:
--------------------------------------------

As a side effect :-) of HBASE-14552, I created a synchronous version of merge region - {{HBaseAdmin#mergeRegionsSync()
}} - for testing-only in HBaseAdmin class

{code}
  /**
   * Merge two regions. Synchronous operation.
   * Note: It is not feasible to predict the length of merge.
   *   Therefore, this is for internal testing only.
   * @param nameOfRegionA encoded or full name of region a
   * @param nameOfRegionB encoded or full name of region b
   * @param forcible true if do a compulsory merge, otherwise we will only merge
   *          two adjacent regions
   * @throws IOException
   */
  @VisibleForTesting
  public void mergeRegionsSync(
      final byte[] nameOfRegionA,
      final byte[] nameOfRegionB,
      final boolean forcible) throws IOException {
    get(
      mergeRegionsAsync(nameOfRegionA, nameOfRegionB, forcible),
      syncWaitTimeout,
      TimeUnit.MILLISECONDS);
  }
{code}



> Admin class should have a synchronous Admin#mergeRegions* method 
> -----------------------------------------------------------------
>
>                 Key: HBASE-16668
>                 URL: https://issues.apache.org/jira/browse/HBASE-16668
>             Project: HBase
>          Issue Type: Bug
>          Components: hbase
>    Affects Versions: 2.0.0
>            Reporter: Jonathan Hsieh
>             Fix For: 2.0.0
>
>
> In trunk from HBASE-14552, we have deprecated {{void Admin#mergeRegions}} (in 1.x this
was an asynchronous call) and replaced it with {{Future<Void> Admin#mergeRegionsAsync}}
which is clearly async.    
> This leaves us only with the async version.
> We should have an easy way to make {{mergeRegions}} or an equivalant behave synchronously.
 
> For normal java Futures, we could just call the future's {{get()}} method. Unforutnately,
the future this method returns doesn't follow java Future convention and throws Unimplemented
operation when a  plain {{get()}} is called and makes the api harder to use and read.  We
could make this future act more normally, and have the timeout throw an InterruptedException.
> Alternately, we could expose a new method in {{Admin}} that behaves synchronously such
as {{HBaseAdmin#mergeRegionsSync}}. The caveat here is that we shouldn't use the name {{#mergeRegions}}
since it exists in 1.x with async semantics. 



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