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https://issues.apache.org/jira/browse/HBASE-5494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13267728#comment-13267728
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Phabricator commented on HBASE-5494:
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avf has commented on the revision "[jira] [HBASE-5494] [89-fb] Table-level
locks for schema changing operations.".
Thanks for the inline comments, @tedyu -- I've replied to a few quick ones
inline.
INLINE COMMENTS
src/main/java/org/apache/hadoop/hbase/master/TableLockManager.java:27
DistributedLock is implemented as part of the patch (see DistributedLock.java)
src/main/java/org/apache/hadoop/hbase/master/TableLockManager.java:47
Metadata for table level locks is stored as plain text -- this is to allow
operations to view lock information from the zookeeper CLI: toStringBinary()
would not be needed here.
src/main/java/org/apache/hadoop/hbase/master/TableLockManager.java:137 In
this case, an IOException is thrown up to the caller: this is to indicate a
non-recoverable ZooKeeper error (DistributedLock uses RecoverableZooKeeper
class under the covers). .release() may also throw an IllegalStateException --
but this is essentially used an assertion in this case (releasing a lock that
isn't held).
REVISION DETAIL
https://reviews.facebook.net/D2997
> Introduce a zk hosted table-wide read/write lock so only one table operation
> at a time
> --------------------------------------------------------------------------------------
>
> Key: HBASE-5494
> URL: https://issues.apache.org/jira/browse/HBASE-5494
> Project: HBase
> Issue Type: Improvement
> Reporter: stack
> Attachments: D2997.3.patch
>
>
> I saw this facility over in the accumulo code base.
> Currently we just try to sort out the mess when splits come in during an
> online schema edit; somehow we figure we can figure all possible region
> transition combinations and make the right call.
> We could try and narrow the number of combinations by taking out a zk table
> lock when doing table operations.
> For example, on split or merge, we could take a read-only lock meaning the
> table can't be disabled while these are running.
> We could then take a write only lock if we want to ensure the table doesn't
> change while disabling or enabling process is happening.
> Shouldn't be too hard to add.
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