Github user yucai commented on a diff in the pull request:
https://github.com/apache/spark/pull/22823#discussion_r231198094
--- Diff: sql/core/benchmarks/WideTableBenchmark-results.txt ---
@@ -0,0 +1,17 @@
+================================================================================================
+projection on wide table
+================================================================================================
+
+OpenJDK 64-Bit Server VM 1.8.0_191-b12 on Linux 3.10.0-862.3.2.el7.x86_64
+Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
+projection on wide table: Best/Avg Time(ms) Rate(M/s)
Per Row(ns) Relative
+------------------------------------------------------------------------------------------------
+split threshold 10 38932 / 39307 0.0
37128.1 1.0X
+split threshold 100 31991 / 32556 0.0
30508.8 1.2X
+split threshold 1024 10993 / 11041 0.1
10483.5 3.5X
+split threshold 2048 8959 / 8998 0.1
8543.8 4.3X
--- End diff --
I tested it with openjdk (in one Linux VM), `2048` is also the best.
```
================================================================================================
projection on wide table
================================================================================================
OpenJDK 64-Bit Server VM 1.8.0_171-b10 on Linux 3.10.0-693.11.1.el7.x86_64
Intel Core Processor (Haswell)
projection on wide table: Best/Avg Time(ms) Rate(M/s)
Per Row(ns) Relative
------------------------------------------------------------------------------------------------
split threshold 10 23995 / 25673 0.0
22883.7 1.0X
split threshold 100 12881 / 13419 0.1
12284.3 1.9X
split threshold 1024 6435 / 7402 0.2
6137.2 3.7X
split threshold 2048 5861 / 6766 0.2
5589.2 4.1X
split threshold 4096 6464 / 7825 0.2
6164.6 3.7X
split threshold 8192 7886 / 8742 0.1
7520.7 3.0X
split threshold 65536 46143 / 48029 0.0
44005.6 0.5X
```
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