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From "Tim Armstrong (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-5199: prevent hang on empty row batch exchange
Date Fri, 08 Sep 2017 15:43:33 GMT
Tim Armstrong has posted comments on this change.

Change subject: IMPALA-5199: prevent hang on empty row batch exchange
......................................................................


Patch Set 2:

I think there is a fundamental problem with the "closed streams cache" mechanism and long-running
queries with limits in the middle of the plan though - IMPALA-3990 - which can happen even
not under load. I think that's the bug you're describing.

I guess this change makes IMPALA-3990 possible when 0 rows are sent. To me, it seems better
to make behaviour consistent and avoid this hang even if adds another presumably rare case
to IMPALA-3990. I don't think we've seen IMPALA-3990 in practice. 

I can see the argument though for just leaving this alone given the hang also seems to be
rare. What do you think?

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Gerrit-MessageType: comment
Gerrit-Change-Id: Ib370ebe44e3bb34d3f0fb9f05aa6386eb91c8645
Gerrit-PatchSet: 2
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-Reviewer: Sailesh Mukil <sailesh@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-HasComments: No

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