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https://issues.apache.org/jira/browse/HBASE-543?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12658619#action_12658619
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Jim Kellerman commented on HBASE-543:
-------------------------------------
A separate problem I found is related to the regionsToClose map:
{code}
private final Map<String, Map<byte [], HRegionInfo>> regionsToClose =
new ConcurrentHashMap<String, Map<byte [], HRegionInfo>>();
{code}
Note that the internal map is a HashMap. HashMaps do not work with byte[] as a
key because the hash value will be different for two byte arrays, even if they
have the same content. If byte[] is the key, then you must use a TreeMap with a
Bytes.BYTES_COMPARATOR. Unless the TreeMap with comparator is used operations
on the map such as get(), containsKey(), etc., will not work.
> A region's state is kept in several places in the master opening the
> possibility for race conditions
> ----------------------------------------------------------------------------------------------------
>
> Key: HBASE-543
> URL: https://issues.apache.org/jira/browse/HBASE-543
> Project: Hadoop HBase
> Issue Type: Bug
> Components: master
> Affects Versions: 0.1.0, 0.1.1, 0.2.0
> Reporter: Jim Kellerman
> Assignee: Jim Kellerman
> Fix For: 0.19.0
>
> Attachments: 543.patch, 543.patch, recent-changes.patch,
> regionstate.txt
>
>
> A region's state exists in multiple maps in the RegionManager:
> unassignedRegions, pendingRegions, regionsToClose, closingRegions,
> regionsToDelete, etc.
> One of these race conditions was found in HBASE-534.
> For HBase-0.1.x, we should just patch the holes we find.
> The ultimate solution (which requires a lot of changes in HMaster) should be
> applied to HBase trunk.
> Proposed solution:
> Create a class that encapsulates a region's state and provide synchronized
> access to the class that validates state changes.
> There should be a single structure that holds regions in these transitional
> states and it should be a synchronized collection of some kind.
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