Henry Robinson has posted comments on this change.

Change subject: IMPALA-4348 / IMPALA-4333: Improve coordinator fragment 
cancellation
......................................................................


Patch Set 1:

(4 comments)

http://gerrit.cloudera.org:8080/#/c/4865/1/be/src/exec/plan-root-sink.cc
File be/src/exec/plan-root-sink.cc:

Line 163:     consumer_cv_.wait(l);
> As far as I can see, PlanRootSink can still be destroyed while a thread A i
You're right, but the lifetime of the PRS is managed by the consumer and the 
sender, which coordinate out-of-scope here. 

In this patch we do that via the shared_ptr to the fragment instance.


http://gerrit.cloudera.org:8080/#/c/4865/1/be/src/runtime/coordinator.cc
File be/src/runtime/coordinator.cc:

Line 520:       return Status(Substitute("Root fragment instance ($0) failed", 
PrintId(query_id_)));
> would the query ultimately fail with this status or with the status returne
The query will fail with this error message. We're in a tricky position here - 
do we wait for an error report from the fragment, or do we return quickly? 
Waiting seems a bad idea to me.

What we could do is try and read the status of the root fragment - if it is in 
error, we'll return it, otherwise we'll return the more generic message.


Line 1196:     // CloseConsumer() here). See IMPALA-4275 for details.
> is this still accurate? if we moved this, would that eliminate the need to 
TearDown() also calls CloseConsumer() - so I think that moving this call 
wouldn't change whether we need PFE::Cancel() to call it as well.


http://gerrit.cloudera.org:8080/#/c/4865/1/be/src/runtime/plan-fragment-executor.cc
File be/src/runtime/plan-fragment-executor.cc:

Line 509:   }
> nit:could be one line
Done


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Gerrit-MessageType: comment
Gerrit-Change-Id: I5b4e25c1d658b3929182ba5e56b5c5e881dd394a
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Henry Robinson <[email protected]>
Gerrit-Reviewer: Dan Hecht <[email protected]>
Gerrit-Reviewer: Henry Robinson <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
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