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From "Alan Gates (JIRA)" <>
Subject [jira] [Commented] (HIVE-10249) ACID: show locks should show who the lock is waiting for
Date Thu, 07 Jan 2016 18:56:40 GMT


Alan Gates commented on HIVE-10249:

I don't think the perf hit is that bad.  When we first discover that the lock has to wait
we have to do an update to indicate what it has to wait on.  We only have to change the record
again if the blocking record changes.

> ACID: show locks should show who the lock is waiting for
> --------------------------------------------------------
>                 Key: HIVE-10249
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>          Components: Transactions
>    Affects Versions: 1.0.0
>            Reporter: Eugene Koifman
>            Assignee: Eugene Koifman
> instead of just showing state WAITING, we should include what the lock is waiting for.
 It will make diagnostics easier.
> It would also be useful to add QueryPlan.getQueryId() so it's easy to see which query
the lock belongs to.
> # need to store this in HIVE_LOCKS (additional field); this has a perf hit to do another
update on failed attempt and to clear filed on successful attempt.  (Actually on success,
we update anyway).  How exactly would this be displayed?  Each lock can block but we acquire
all parts of external lock at once.  Since we stop at first one that blocked, we’d only
update that one…
> # This needs a matching Thrift change to pass to client: ShowLocksResponse
> # Perhaps we can start updating this info after lock was in W state for some time to
reduce perf hit.
> # This is mostly useful for “Why is my query stuck”

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