Tim Armstrong has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/9749 )

Change subject: IMPALA-6694: fix "buffer pool" child profile order
......................................................................


Patch Set 3:

(4 comments)

http://gerrit.cloudera.org:8080/#/c/9749/3/be/src/util/runtime-profile-test.cc
File be/src/util/runtime-profile-test.cc:

http://gerrit.cloudera.org:8080/#/c/9749/3/be/src/util/runtime-profile-test.cc@250
PS3, Line 250: child 2
> child 1?
Done


http://gerrit.cloudera.org:8080/#/c/9749/3/be/src/util/runtime-profile.cc
File be/src/util/runtime-profile.cc:

http://gerrit.cloudera.org:8080/#/c/9749/3/be/src/util/runtime-profile.cc@207
PS3, Line 207: Update
> Could they also come from UpdateAverage()?
Good point


http://gerrit.cloudera.org:8080/#/c/9749/3/be/src/util/runtime-profile.cc@345
PS3, Line 345:     // if children are added after the first Update() call 
(IMPALA-6694).
> I think a very simple example would help to understand this, something like
Thanks, I stole that text.


http://gerrit.cloudera.org:8080/#/c/9749/3/be/src/util/runtime-profile.cc@358
PS3, Line 358: insert_pos != children_.end()
> I can't think of a case where this happens without found_child == true. If
It's possible that the children got reordered in the original profile between 
updates, then the child we're search for could be before the previous insert 
position. I don't think it necessarily happens in practice, but the 
SortChildren() method does allow you to arbitrarily reorder children at any 
point.

I extended the test case to exercise this. Without this check it it runs off 
the end of the vector.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I230f0673edf20a846fdb13191b7a292d329c1bb8
Gerrit-Change-Number: 9749
Gerrit-PatchSet: 3
Gerrit-Owner: Tim Armstrong <[email protected]>
Gerrit-Reviewer: Lars Volker <[email protected]>
Gerrit-Reviewer: Michael Ho <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-Comment-Date: Wed, 28 Mar 2018 04:31:48 +0000
Gerrit-HasComments: Yes

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