Github user a-roberts commented on the issue:
https://github.com/apache/spark/pull/15736
Passed on your question to our JIT developers
> The sense* of the test can have an impact of the VM interpreter
performance, but that is not usually much of a component of actual throughput
since important methods will be JIT'd very quickly regardless of which specific
JVM you use. The J9 VM is capable of profiling the branch and flipping the
sense when JITing the code
>
> The sense refers to the way a code branches, so either down the equals
branch or not equals branch
Numbers for us
**Refactored further as above**
```
ScalaSparkPagerank 2016-11-30 14:27:49 259928115 49.841
5215146
ScalaSparkPagerank 2016-11-30 14:29:52 259928115 51.310
5065837
ScalaSparkPagerank 2016-11-30 14:31:59 259928115 52.086
4990364
ScalaSparkPagerank 2016-11-30 14:34:05 259928115 50.667
5130126
ScalaSparkPagerank 2016-11-30 14:36:04 259928115 47.096
5519112
ScalaSparkPagerank 2016-11-30 14:38:04 259928115 48.244
5387781
ScalaSparkPagerank 2016-11-30 14:40:10 259928115 48.734
5333609
ScalaSparkPagerank 2016-11-30 14:42:12 259928115 49.295
5272910
397.273 / 8 = 49.659 sec average
```
**initial commit**
```
ScalaSparkPagerank 2016-11-30 14:48:01 259928115 46.442
5596832
ScalaSparkPagerank 2016-11-30 14:50:06 259928115 50.016
5196899
ScalaSparkPagerank 2016-11-30 14:52:12 259928115 51.113
5085362
ScalaSparkPagerank 2016-11-30 14:54:12 259928115 46.424
5599002
ScalaSparkPagerank 2016-11-30 14:56:15 259928115 47.604
5460215
ScalaSparkPagerank 2016-11-30 14:58:14 259928115 46.802
5553782
ScalaSparkPagerank 2016-11-30 15:00:16 259928115 47.021
5527915
ScalaSparkPagerank 2016-11-30 15:02:16 259928115 47.072
5521926
382.494 / 8 = 47.811s average
```
The first commit performs better on average, I'd like to next add the
improved compare code as above and "push this down" into the subclasses to see
how this performs
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