Tim Armstrong has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/13178 )

Change subject: IMPALA-4658: Potential race if compiler reorders ReachedLimit() 
usage.
......................................................................


Patch Set 2:

(6 comments)

I did a pass over this. Looks good - just had a couple of suggestions for 
cleanup. I wanted to do another final pass after follow-on changes just to 
double-check that the new version was identical to the old version.

http://gerrit.cloudera.org:8080/#/c/13178/2//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/13178/2//COMMIT_MSG@46
PS2, Line 46: The scan nodes with task based multi-threading (MT) also use the 
new
This seems reasonable. Ideally we could avoid this for DataSourceScanNode and 
HBaseScanNode though, since those don't have MT implementations. Maybe we can 
just make an exception in the DCHECK - we have the TPlanNodeType in the 
ExecNode.


http://gerrit.cloudera.org:8080/#/c/13178/2/be/src/exec/exec-node.h
File be/src/exec/exec-node.h:

http://gerrit.cloudera.org:8080/#/c/13178/2/be/src/exec/exec-node.h@209
PS2, Line 209: retrurned
typo


http://gerrit.cloudera.org:8080/#/c/13178/2/be/src/exec/exec-node.h@215
PS2, Line 215: retrurned
typo


http://gerrit.cloudera.org:8080/#/c/13178/2/be/src/exec/exec-node.h@216
PS2, Line 216:   /// rows_returned().
Can you add a short TODO that these can be removed if we remove the legacy 
multi-threaded scan nodes.


http://gerrit.cloudera.org:8080/#/c/13178/2/be/src/exec/exec-node.h@236
PS2, Line 236: resturned
typo: returned


http://gerrit.cloudera.org:8080/#/c/13178/2/be/src/exec/exec-node.h@391
PS2, Line 391:   AtomicInt64 num_rows_returned_shared_;
It's a bit of a matter of taste but I think it would be better to just have a 
single member and use the atomic Acquire_Load, Release_Store, 
Barrier_AtomicIncrement operations on it directly. It's well-encapsulated in 
these functions so should be ok



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I4cbbfad80f7ab87dd6f192a24e2c68f7c66b047e
Gerrit-Change-Number: 13178
Gerrit-PatchSet: 2
Gerrit-Owner: Abhishek Rawat <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-Comment-Date: Tue, 30 Apr 2019 15:47:41 +0000
Gerrit-HasComments: Yes

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