Tim Armstrong has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/9282 )

Change subject: IMPALA-6116: Bound memory usage of DataStreamSevice's service 
queue
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Patch Set 1:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/9282/1//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/9282/1//COMMIT_MSG@20
PS1, Line 20: this flag is left at 0, in which case it will be set to 20% of 
process
Devoting 20% of the process limit to this seems very high. The buffer pool is 
given 80% of the process limit, so this leaves no guaranteed headroom for 
anything else.

I.e. if the service expands up to its limit, it will squeeze out any 
non-buffer-pool memory from queries and likely cause query failures. It seems 
to somewhat defeat the purpose of limiting the amount of memory consumed if 
we're not limiting it low enough to prevent query failures.

I'd be interested in learning more about how the number was obtained and what 
the trade-offs are in setting it to a lower value



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Idea4262dfb0e0aa8d58ff6ea6a8aaaa248e880b9
Gerrit-Change-Number: 9282
Gerrit-PatchSet: 1
Gerrit-Owner: Michael Ho <k...@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhe...@cloudera.com>
Gerrit-Reviewer: Lars Volker <l...@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstr...@cloudera.com>
Gerrit-Comment-Date: Mon, 12 Feb 2018 19:59:09 +0000
Gerrit-HasComments: Yes

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