GitHub user viirya opened a pull request:
https://github.com/apache/spark/pull/11759
[SPARK-13930][SQL] Apply fast serialization on collect limit operator
## What changes were proposed in this pull request?
JIRA: https://issues.apache.org/jira/browse/SPARK-13930
Recently the fast serialization has been introduced to collecting
DataFrame/Dataset (#11664). The same technology can be used on collect limit
operator too.
## How was this patch tested?
Add a benchmark for collect limit to `BenchmarkWholeStageCodegen`.
Without this patch:
model name : Westmere E56xx/L56xx/X56xx (Nehalem-C)
collect limit: Best/Avg Time(ms) Rate(M/s)
Per Row(ns) Relative
-------------------------------------------------------------------------------------------
collect limit 1 million 3413 / 3768 0.3
3255.0 1.0X
collect limit 2 millions 9728 / 10440 0.1
9277.3 0.4X
With this patch:
model name : Westmere E56xx/L56xx/X56xx (Nehalem-C)
collect limit: Best/Avg Time(ms) Rate(M/s)
Per Row(ns) Relative
-------------------------------------------------------------------------------------------
collect limit 1 million 833 / 1284 1.3
794.4 1.0X
collect limit 2 millions 3348 / 4005 0.3
3193.3 0.2X
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/viirya/spark-1 execute-take
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/11759.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #11759
----
commit 16ac5fe6325c2cf7638faab854c09dc50de94f18
Author: Liang-Chi Hsieh <sim...@tw.ibm.com>
Date: 2016-03-16T08:41:36Z
init import.
commit d1306ade2efa407ce0785650d08aef4129aab2c3
Author: Liang-Chi Hsieh <sim...@tw.ibm.com>
Date: 2016-03-16T09:06:35Z
Use fast serialization on collect limit too.
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