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From "Henry Robinson (Code Review)" <>
Subject [Impala-ASF-CR] IMPALA-4037,IMPALA-4038: fix locking during query cancellation
Date Fri, 02 Sep 2016 21:15:36 GMT
Henry Robinson has posted comments on this change.

Change subject: IMPALA-4037,IMPALA-4038: fix locking during query cancellation

Patch Set 5: Code-Review+1

File be/src/service/

PS5, Line 171: lock_guard<SpinLock> lock(lock_);
you can avoid this if status.ok(), I think. Not sure if it's worth it.

Line 185:   if (thread == NULL) return Status::OK();
DCHECK(is_cancelled_)? I think that's the only time that thread == nullptr.
File be/src/service/child-query.h:

PS5, Line 148: is
must be

PS5, Line 178: Exec
Is there a more descriptive name than Exec()? Every class seems to have an Exec() method...
maybe ExecSequentially()? ExecChildQueries()?

Line 194:   bool is_running_;
Comment here that, once started, the queries must be allowed to complete or fail (when the
class is destroyed, we dcheck(!is_running); and say what methods force that as a post-condition
(WaitForAll(), Cancel()). You have that in the class comment, but worth a mention here as
well I think.
File be/src/service/query-exec-state.h:

PS5, Line 226: Acquires

PS5, Line 227: acquired

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Gerrit-MessageType: comment
Gerrit-Change-Id: Ibe3024803e03595ee69c47759b58e8443d7bd167
Gerrit-PatchSet: 5
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <>
Gerrit-Reviewer: Alex Behm <>
Gerrit-Reviewer: Henry Robinson <>
Gerrit-Reviewer: Tim Armstrong <>
Gerrit-HasComments: Yes

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