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From "huaxiang sun (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16345) RpcRetryingCallerWithReadReplicas#call() should catch some RegionServer Exceptions
Date Thu, 08 Sep 2016 23:19:20 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16345?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15475327#comment-15475327
] 

huaxiang sun commented on HBASE-16345:
--------------------------------------

A side note, we found that the current scan does not honor the following
{code}
      scan.setConsistency(Consistency.TIMELINE);
      scan.setReplicaId(1);
{code}

The scan actually scans all replicas. This is not consistent with the Get. If this is an issue,
I can create a new jira to address it.
The following testing case shows the issue:

{code}
  @Test public void testReplicaScanWithReplica() throws IOException {
    // Create table then get the single region for our new table.
    HTableDescriptor hdt = HTU.createTableDescriptor("testReplicaScanTable");
    hdt.setRegionReplication(NB_SERVERS);

    try {
      Table table = HTU.createTable(hdt, new byte[][] { f }, null);

      Put p = new Put(row);
      p.addColumn(f, row, row);
      table.put(p);

      // Flush so it can be picked by the replica refresher thread
      HTU.flush(table.getName());

      // Sleep for some time until data is picked up by replicas
      try {
        Thread.sleep(2 * REFRESH_PERIOD);
      } catch (InterruptedException e1) {
        LOG.error(e1);
      }

      // But if we ask for stale we will get it
      // Instantiating the Scan class
      Scan scan = new Scan();

      // Scanning the required columns
      scan.addFamily(f);
      scan.setConsistency(Consistency.TIMELINE);
      scan.setReplicaId(1);

      // Getting the scan result
      ResultScanner scanner = table.getScanner(scan);

      Result r = scanner.next();

      Assert.assertTrue(r.isStale());
    } finally {

      HTU.getHBaseAdmin().disableTable(hdt.getTableName());
      HTU.deleteTable(hdt.getTableName());
    }
  }
{code}

> RpcRetryingCallerWithReadReplicas#call() should catch some RegionServer Exceptions
> ----------------------------------------------------------------------------------
>
>                 Key: HBASE-16345
>                 URL: https://issues.apache.org/jira/browse/HBASE-16345
>             Project: HBase
>          Issue Type: Bug
>          Components: Client
>    Affects Versions: 2.0.0
>            Reporter: huaxiang sun
>            Assignee: huaxiang sun
>         Attachments: HBASE-16345-v001.patch, HBASE-16345.master.001.patch, HBASE-16345.master.002.patch,
HBASE-16345.master.003.patch, HBASE-16345.master.004.patch, HBASE-16345.master.005.patch
>
>
> Update for the description. Debugged more at this front based on the comments from Enis.

> The cause is that for the primary replica, if its retry is exhausted too fast, f.get()
[1] returns ExecutionException. This Exception needs to be ignored and continue with the replicas.
> The other issue is that after adding calls for the replicas, if the first completed task
gets ExecutionException (due to the retry exhausted), it throws the exception to the client[2].
> In this case, it needs to loop through these tasks, waiting for the success one. If no
one succeeds, throw exception.
> Similar for the scan as well
> [1] https://github.com/apache/hbase/blob/master/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcRetryingCallerWithReadReplicas.java#L197
> [2] https://github.com/apache/hbase/blob/master/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcRetryingCallerWithReadReplicas.java#L219



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