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From "Feng Honghua (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-10595) HBaseAdmin.getTableDescriptor can wrongly get the previous table's TableDescriptor even after the table dir in hdfs is removed
Date Sun, 23 Feb 2014 08:58:19 GMT

    [ https://issues.apache.org/jira/browse/HBASE-10595?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13909715#comment-13909715
] 

Feng Honghua commented on HBASE-10595:
--------------------------------------

Additional note: TestAssignmentManagerOnCluster#testMoveRegionOfDeletedTable uses an assumption
that regions of a deleted table are guaranteed to be removed from RegionStates in HMaster
after deleteTable() is done and expects to receive a UnknownRegionException(which is by checking
that region is not in RegionStates) when moving a region after its table is deleted.

But this assumption is wrong because though deleteTable() is synchronous but it only verify
the table descriptor is empty before return, but in DeleteTableHandler the regions are removed
from RegionStates *after* region-data-dirs / table-dir are removed and table descriptor is
removed from cache.

Instead of fixing it in the unit test(we could sleep for a while before call move(), but it's
weird since deleteTable() is synchronous!), I let move() throw UnknownRegionException as well
when FSTableDescriptors.get(table) return null (means already deleted, but before regions
are removed from RegionStates)

> HBaseAdmin.getTableDescriptor can wrongly get the previous table's TableDescriptor even
after the table dir in hdfs is removed
> ------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-10595
>                 URL: https://issues.apache.org/jira/browse/HBASE-10595
>             Project: HBase
>          Issue Type: Bug
>          Components: master, util
>            Reporter: Feng Honghua
>            Assignee: Feng Honghua
>         Attachments: HBASE-10595-trunk_v1.patch
>
>
> When a table dir (in hdfs) is removed(by outside), HMaster will still return the cached
TableDescriptor to client for getTableDescriptor request.
> On the contrary, HBaseAdmin.listTables() is handled correctly in current implementation,
for a table whose table dir in hdfs is removed by outside, getTableDescriptor can still retrieve
back a valid (old) table descriptor, while listTables says it doesn't exist, this is inconsistent
> The reason for this bug is because HMaster (via FSTableDescriptors) doesn't check if
the table dir exists for getTableDescriptor() request, (while it lists all existing table
dirs(not firstly respects cache) and returns accordingly for listTables() request)
> When a table is deleted via deleteTable, the cache will be cleared after the table dir
and tableInfo file is removed, listTables/getTableDescriptor inconsistency should be transient(though
still exists, when table dir is removed while cache is not cleared) and harder to expose



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