[jira] [Commented] (HBASE-20133) Calculate correct assignment and build region movement plans for mis-placed regions in one pass

["Xiang Li (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-20133?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16387596#comment-16387596 ] 

Xiang Li commented on HBASE-20133:
----------------------------------

Uploaded patch 000 for review.
# correctAssignments() is updated to calculate correct assignment as well as RegionPlan for mis-placed regions. correct assignment is returned by return value, while RegionPlan is returned by the input parameter
# findServerForRegion could be removed. By the way, I think the following code 
{code}
    throw new IllegalStateException("Could not find server for region "
        + region.getShortNameToLog());
{code}
could not be reached so no similar logic is add after the change.

> Calculate correct assignment and build region movement plans for mis-placed regions in one pass
> -----------------------------------------------------------------------------------------------
>
>                 Key: HBASE-20133
>                 URL: https://issues.apache.org/jira/browse/HBASE-20133
>             Project: HBase
>          Issue Type: Improvement
>          Components: rsgroup
>            Reporter: Xiang Li
>            Assignee: Xiang Li
>            Priority: Critical
>         Attachments: HBASE-20133.master.000.patch
>
>
> In RSGroupBasedLoadBalancer#balanceCluster(clusterState), the logic could be improved:
> correctAssignment() builds a map for mis-placed and placed regions. For mis-placed regions, the key(ServerName) is BOGUS_SERVER_NAME. Then the logic gets those mis-paced regions out and calls findServerForRegion() several times to find out the current host server, in order to build RegionPlan for movement.
> Some logic in correctAssignment() and findServerForRegion() could be merged so as to build both corrected assignment and RegionPlan for mis-placed region in one pass. As a result, findServerForRegion() could be removed if I get it correctly.



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