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From "Todd Lipcon (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4654: KuduScanner must return when ReachedLimit()
Date Wed, 14 Dec 2016 01:51:22 GMT
Todd Lipcon has posted comments on this change.

Change subject: IMPALA-4654: KuduScanner must return when ReachedLimit()
......................................................................


Patch Set 2:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/5493/2/be/src/exec/kudu-scanner.cc
File be/src/exec/kudu-scanner.cc:

PS2, Line 200: scan_node_->ReachedLimit()
this isn't specific to Kudu, but it seems wrong that in this and other places, you're calling
ReachedLimit() from a different thread than the one updating rows_returned. The compiler in
theory is free to notice that you're not updating the rows_returned_ variable in this thread
and hoist the load up out of loops, etc.

Apparently it's not happening, but it would probably be a good idea to make that a NoBarrier_Load(...).

</peanut-gallery>


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Gerrit-MessageType: comment
Gerrit-Change-Id: Iaddd51111a1b2647995d68e6d37d0500b3a322de
Gerrit-PatchSet: 2
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Matthew Jacobs <mj@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Matthew Jacobs <mj@cloudera.com>
Gerrit-Reviewer: Sailesh Mukil <sailesh@cloudera.com>
Gerrit-Reviewer: Todd Lipcon <todd@apache.org>
Gerrit-HasComments: Yes

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