Allan Yang created HBASE-21469:
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Summary: Re-visit post* hooks in DDL operations
Key: HBASE-21469
URL: https://issues.apache.org/jira/browse/HBASE-21469
Project: HBase
Issue Type: Bug
Affects Versions: 2.0.2, 2.1.1
Reporter: Allan Yang
Assignee: Allan Yang
I have some discuss in HBASE-19953 from
[here|https://issues.apache.org/jira/browse/HBASE-19953?focusedCommentId=16673126&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-16673126]
In HBASE-19953,[~elserj] want to make sure that the post* hooks are called only
when the procedures finish.But it accidentally turns modifytable and truncate
table request into a sync call, which make clients RPC timeout easily on big
tables.
We should re-visit those postxxx hooks in DDL operations, because they are now
not consistent now:
For DDLs other than modifytable and truncate table, although the call will wait
on the latch, the latch is actually released just after prepare state, so we
still call postxxx hooks before the operation finish.
For DDLs of modifytable and truncate, the latch is only released after the
whole procedure finish. So the effort works(but will cause RPC timeout)
I think these latches are designed for compatibility with 1.x clients. Take
ModifyTable for example, in 1.x, we use admin.getAlterStauts() to check the
alter status, but in 2.x, this method is deprecated and returning inaccurate
result, we have to make 1.x client in a sync wait.
And for the semantics of postxxx hooks in 1.x, we will call them after the
corresponding DDL request return, but actually, the DDL request may not
finished also since we don't want for region assignment.
So, here, we need to discuss the semantics of postxxx hooks in DDL operations,
we need to make it consistent in every DDL operations, do we really need to
make sure this hooks being called only after the operation finish? What's more,
we have postCompletedxxx hooks for that need.
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