# HG changeset patch
# User Gregory Szorc <gregory.szorc@gmail.com>
# Date 1489454202 25200
# Node ID 8f5ed8fa39f8fe3bd33440315d1a905e974f002a
# Parent  ab3e9eab754f2c714004d8dfa01ec8611b930b39
perf: perform a garbage collection before each iteration

Currently, no explicit garbage collection is performed when running
the microbenchmarks in `hg perf`. I think this is wrong because
garbage collection can have a significant impact on execution times.
And, if gc is triggered via the default heuristics, it will
fire effectively randomly during subsequent benchmark iterations
due to variable amount of garbage left over from previous runs.

Running a gc before invoking the measured function will help ensure
state is more consistent across all iterations.

diff -r ab3e9eab754f -r 8f5ed8fa39f8 contrib/perf.py
--- a/contrib/perf.py	Mon Mar 13 18:31:29 2017 -0700
+++ b/contrib/perf.py	Mon Mar 13 18:16:42 2017 -0700
@@ -20,6 +20,7 @@
 
 from __future__ import absolute_import
 import functools
+import gc
 import os
 import random
 import sys
@@ -189,6 +190,7 @@
     func()
 
 def _timer(fm, func, title=None):
+    gc.collect()
     results = []
     begin = util.timer()
     count = 0