Matthew Jacobs has posted comments on this change.

Change subject: IMPALA-3857: KuduScanNode race on returning "optional" threads
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Patch Set 1:

(3 comments)

http://gerrit.cloudera.org:8080/#/c/3637/1/be/src/exec/kudu-scan-node.cc
File be/src/exec/kudu-scan-node.cc:

Line 421:   bool optional_threads_exceeded = false;
> anyway to add a simple directed test to kudu-scan-node-test.cc for this?
I'll take a look, though I'm not too worried about it because it repros 
constantly when I run our regular tpch tests which we will be added shortly 
(Dimitris is working on that as we speak).


PS1, Line 450: return
> rephrase "return this thread"
Done


Line 480:   if (!optional_threads_exceeded) --num_active_scanners_;
> do we even need this bool? seems like the only case when the condition is f
I don't think it's so easy. The issue is that if we don't check the state and 
update num_active_scanners_ within the while() loop above, there may be 2 
remaining threads that both think they are optional threads, and thus will goto 
done. But if they do, then there are no more threads left. I don't love the 
bool, but I thought about how to do this cleanly and I don't see a better way. 
Maybe I'm missing your point though.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I22adf2109b43b1b37d9a597de85e063431dff155
Gerrit-PatchSet: 1
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Matthew Jacobs <[email protected]>
Gerrit-Reviewer: David Ribeiro Alves <[email protected]>
Gerrit-Reviewer: Matthew Jacobs <[email protected]>
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