[jira] [Comment Edited] (HBASE-22855) Find the root cause why still using the old hbase:meta location after meta region moving.

["jianghua zhu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-22855?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16908073#comment-16908073 ] 

jianghua zhu edited comment on HBASE-22855 at 8/15/19 1:36 PM:
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There is a possibility:

If there are HMaster, HRegion Server 1, HRegion Server 2, the following process occurs.

1. HMaster sends requests to HRegionServer1 through RPC through assignment mechanism, and loads the region information corresponding to hbase: meta.

2. For some reason, HRegion Server itself did not report its status to HMaster. HMaster believed that HRegion Server had died at this time.

3. HMaster requests HRegionServer2 through assignment mechanism and loads the region information corresponding to hbase: meta. And HRegionServer2 loads quickly.

4. At this time, the location of hbase: meta is located at the HRegionServer2 node.

5. At this point, HRegionServer1 itself restores, reloads hbase: meta, and completes. At this point, the location of hbase: meta changes.


was (Author: jianghuazhu):
There is one possibility:

Assuming that HMaster, HRegionServer1, and HRegionServer2 exist, the following processes occur.

1.HMaster sends a request to HRegionServer1 via RPC via the assign mechanism to load the Region information corresponding to hbase:meta.

2. The HRegionServer itself, for some reason, failed to report state to HMaster, and HMaster assumed that the HRegionServer was dead.

3.HMaster makes a request to HRegionServer2 via the assign mechanism to load the Region information corresponding to hbase:meta. And the HRegionServer2 loads quickly.

4. Retrieve the location of the hbase:meta at HRegionServer2

> Find the root cause why still using the old hbase:meta location after meta region moving.
> -----------------------------------------------------------------------------------------
>
>                 Key: HBASE-22855
>                 URL: https://issues.apache.org/jira/browse/HBASE-22855
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Zheng Hu
>            Assignee: Zheng Hu
>            Priority: Major
>
> In HBASE-214644, [~andrew.purtell@gmail.com]  had a nice fix about the using the stale hbase:meta location, say update the hbase:meta location periodically.    Also someone in user list also encountered this bug in HBASE1.4.9 [1].
> [~wenbang] from DiDi also have a question about the root cause under HBASE-214644 [2]. 
> I think we need to find out the root cause and fix it ? 
> [1]. https://mail-archives.apache.org/mod_mbox/hbase-user/201908.mbox/%3C114F31E6-B7F9-4209-AAE3-32A022729593%40gmail.com%3E
> [2]. https://issues.apache.org/jira/browse/HBASE-21464?focusedCommentId=16902808&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-16902808



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