[Yum-devel] [UG] Caching urllib2 openers performance improvements

[Ryan Tomayko]

We shaved a clean millisecond from all times and I'm sure this will help
memory usage as there won't be a ton of unused object laying around
after each request. I think this puts us pretty close to where we were
before the redesign.

Here are results when we build an opener for each request:

1 KB Results:
[full] mean: 2.116 ms, median: 2.069 ms, min: 2.026 ms, max: 5.397 ms
[raw]  mean: 1.828 ms, median: 1.778 ms, min: 1.745 ms, max: 5.206 ms
10 KB Results:
[full] mean: 2.252 ms, median: 2.205 ms, min: 2.166 ms, max: 5.553 ms
[raw]  mean: 1.907 ms, median: 1.859 ms, min: 1.824 ms, max: 5.704 ms
100 KB Results:
[full] mean: 3.628 ms, median: 3.504 ms, min: 3.438 ms, max: 40.062 ms
[raw]  mean: 2.711 ms, median: 2.658 ms, min: 2.620 ms, max: 6.013 ms
1000 KB Results:
[full] mean: 16.037 ms, median: 15.905 ms, min: 15.668 ms, max: 19.309 ms
[raw]  mean: 10.297 ms, median: 10.188 ms, min: 10.022 ms, max: 16.264 ms


And the results when caching the openers:

1 KB Results:
[full] mean: 1.137 ms, median: 1.118 ms, min: 1.101 ms, max: 2.243 ms
[raw]  mean: 0.844 ms, median: 0.833 ms, min: 0.816 ms, max: 1.557 ms
10 KB Results:
[full] mean: 1.265 ms, median: 1.248 ms, min: 1.234 ms, max: 2.003 ms
[raw]  mean: 0.915 ms, median: 0.907 ms, min: 0.891 ms, max: 1.918 ms
100 KB Results:
[full] mean: 2.572 ms, median: 2.541 ms, min: 2.504 ms, max: 8.396 ms
[raw]  mean: 1.721 ms, median: 1.699 ms, min: 1.674 ms, max: 2.670 ms
1000 KB Results:
[full] mean: 15.133 ms, median: 14.991 ms, min: 14.839 ms, max: 22.028 ms
[raw]  mean: 9.352 ms, median: 9.285 ms, min: 9.179 ms, max: 10.435 ms