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From "Mostafa Mokhtar (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-5926 : Avoid printing expensive stack when closing a session
Date Wed, 13 Sep 2017 23:09:59 GMT
Mostafa Mokhtar has uploaded a new change for review.

  http://gerrit.cloudera.org:8080/8060

Change subject: IMPALA-5926 : Avoid printing expensive stack when closing a session
......................................................................

IMPALA-5926 : Avoid printing expensive stack when closing a session

When conducting high concurrency tests for short running queries
 noticed that queries are spending lots of time in Unregister query.
Investigation showed that CloseSessionInternal calls
status("Session closed") which unnecessarily prints the stack
to the log which is expensive and not required, refer to IMPALA-5275.

The fix uses Expected(const std::string& error_msg) which doesn't
print the stack.

Table below summarizes speedup for highly selective scan query.

+-----------+--------------------------+---------------------+---------+
| Num users | Baseline Queries/minutes | Fix Queries/minutes | Speedup |
+-----------+--------------------------+---------------------+---------+
| 1         | 19                       | 24                  | 1.23x   |
| 2         | 41                       | 48                  | 1.17x   |
| 4         | 71                       | 91                  | 1.28x   |
| 8         | 96                       | 161                 | 1.67x   |
| 16        | 117                      | 226                 | 1.92x   |
| 32        | 140                      | 266                 | 1.90x   |
| 64        | 174                      | 269                 | 1.54x   |
| 128       | 202                      | 265                 | 1.31x   |
+-----------+--------------------------+---------------------+---------+

Change-Id: I9d0ca485dd17bca758d916040745288c1a20c69f
---
M be/src/service/impala-server.cc
1 file changed, 1 insertion(+), 1 deletion(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/60/8060/1
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I9d0ca485dd17bca758d916040745288c1a20c69f
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Mostafa Mokhtar <mmokhtar@cloudera.com>

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