perf: add threading capability to perfbdiff
Since we are releasing the GIL during diffing, it is interesting to see how a
thread pool would perform on diffing. We add a new `--threads` argument to
commands. Synchronizing the thread pool is a bit complex because we want to be
able to reuse it from one run to another.
On my computer (i7 with 4 cores + hyperthreading), I get the following data for
about 12000 revisions:
threads wall comb wall gain comb overhead
none 31.596715 31.59 0.00% 0.00%
1 31.621228 31.62 -0.08% 0.09%
2 16.406202 32.8 48.08% 3.83%
3 11.598334 34.76 63.29% 10.03%
4 9.205421 36.77 70.87% 16.40%
5 8.517604 42.51 73.04% 34.57%
6 7.94645 47.58 74.85% 50.62%
7 7.434972 51.92 76.47% 64.36%
8 7.070638 55.34 77.62% 75.18%
Compared to the feature disabled (threads=0), the overhead is negligible with
the threading code (threads=1), and the gain is already 48% with two threads.
#require test-repo
$ . "$TESTDIR/helpers-testrepo.sh"
$ cd "`dirname "$TESTDIR"`"
look for python scripts that do not use /usr/bin/env
$ testrepohg files 'set:grep(r"^#!.*?python") and not grep(r"^#!/usr/bi{1}n/env python") - **/*.t'
[1]
In tests, enforce $PYTHON and *not* /usr/bin/env python or similar:
$ testrepohg files 'set:grep(r"#!.*?python") and **/*.t' \
> -X tests/test-check-execute.t \
> -X tests/test-check-module-imports.t \
> -X tests/test-check-pyflakes.t \
> -X tests/test-check-shbang.t
[1]
The above exclusions are because they're looking for files that
contain Python but don't end in .py - please avoid adding more.
look for shell scripts that do not use /bin/sh
$ testrepohg files 'set:grep(r"^#!.*/bi{1}n/sh") and not grep(r"^#!/bi{1}n/sh")'
[1]