[Python-checkins] cpython: timeit: change default repeat to 5, instead of 3

Tue Oct 18 11:14:49 EDT 2016

https://hg.python.org/cpython/rev/2dafb2f3e7ff
changeset: 104538:2dafb2f3e7ff
user: Victor Stinner <victor.stinner at gmail.com>
date: Tue Oct 18 17:13:22 2016 +0200
summary:
 timeit: change default repeat to 5, instead of 3
Issue #28240: timeit now repeats the benchmarks 5 times instead of only 3 to
make benchmarks more reliable.
files:
 Lib/test/test_timeit.py | 34 ++++++++++++++--------------
 Lib/timeit.py | 2 +-
 Misc/NEWS | 3 ++
 3 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/Lib/test/test_timeit.py b/Lib/test/test_timeit.py
--- a/Lib/test/test_timeit.py
+++ b/Lib/test/test_timeit.py
@@ -12,7 +12,7 @@
 DEFAULT_NUMBER = 1000000
 
 # timeit's default number of repetitions.
-DEFAULT_REPEAT = 3
+DEFAULT_REPEAT = 5
 
 # XXX: some tests are commented out that would improve the coverage but take a
 # long time to run because they test the default number of loops, which is
@@ -226,7 +226,7 @@
 t.print_exc(s)
 self.assert_exc_string(s.getvalue(), 'ZeroDivisionError')
 
- MAIN_DEFAULT_OUTPUT = "1 loop, best of 3: 1 sec per loop\n"
+ MAIN_DEFAULT_OUTPUT = "1 loop, best of 5: 1 sec per loop\n"
 
 def run_main(self, seconds_per_increment=1.0, switches=None, timer=None):
 if timer is None:
@@ -252,31 +252,31 @@
 
 def test_main_seconds(self):
 s = self.run_main(seconds_per_increment=5.5)
- self.assertEqual(s, "1 loop, best of 3: 5.5 sec per loop\n")
+ self.assertEqual(s, "1 loop, best of 5: 5.5 sec per loop\n")
 
 def test_main_milliseconds(self):
 s = self.run_main(seconds_per_increment=0.0055)
- self.assertEqual(s, "100 loops, best of 3: 5.5 msec per loop\n")
+ self.assertEqual(s, "100 loops, best of 5: 5.5 msec per loop\n")
 
 def test_main_microseconds(self):
 s = self.run_main(seconds_per_increment=0.0000025, switches=['-n100'])
- self.assertEqual(s, "100 loops, best of 3: 2.5 usec per loop\n")
+ self.assertEqual(s, "100 loops, best of 5: 2.5 usec per loop\n")
 
 def test_main_fixed_iters(self):
 s = self.run_main(seconds_per_increment=2.0, switches=['-n35'])
- self.assertEqual(s, "35 loops, best of 3: 2 sec per loop\n")
+ self.assertEqual(s, "35 loops, best of 5: 2 sec per loop\n")
 
 def test_main_setup(self):
 s = self.run_main(seconds_per_increment=2.0,
 switches=['-n35', '-s', 'print("CustomSetup")'])
- self.assertEqual(s, "CustomSetup\n" * 3 +
- "35 loops, best of 3: 2 sec per loop\n")
+ self.assertEqual(s, "CustomSetup\n" * DEFAULT_REPEAT +
+ "35 loops, best of 5: 2 sec per loop\n")
 
 def test_main_multiple_setups(self):
 s = self.run_main(seconds_per_increment=2.0,
 switches=['-n35', '-s', 'a = "CustomSetup"', '-s', 'print(a)'])
- self.assertEqual(s, "CustomSetup\n" * 3 +
- "35 loops, best of 3: 2 sec per loop\n")
+ self.assertEqual(s, "CustomSetup\n" * DEFAULT_REPEAT +
+ "35 loops, best of 5: 2 sec per loop\n")
 
 def test_main_fixed_reps(self):
 s = self.run_main(seconds_per_increment=60.0, switches=['-r9'])
@@ -309,8 +309,8 @@
 s = self.run_main(switches=['-v'])
 self.assertEqual(s, dedent("""\
 1 loop -> 1 secs
- raw times: 1 1 1
- 1 loop, best of 3: 1 sec per loop
+ raw times: 1 1 1 1 1
+ 1 loop, best of 5: 1 sec per loop
 """))
 
 def test_main_very_verbose(self):
@@ -321,23 +321,23 @@
 100 loops -> 0.005 secs
 1000 loops -> 0.05 secs
 10000 loops -> 0.5 secs
- raw times: 0.5 0.5 0.5
- 10000 loops, best of 3: 50 usec per loop
+ raw times: 0.5 0.5 0.5 0.5 0.5
+ 10000 loops, best of 5: 50 usec per loop
 """))
 
 def test_main_with_time_unit(self):
 unit_sec = self.run_main(seconds_per_increment=0.002,
 switches=['-u', 'sec'])
 self.assertEqual(unit_sec,
- "100 loops, best of 3: 0.002 sec per loop\n")
+ "100 loops, best of 5: 0.002 sec per loop\n")
 unit_msec = self.run_main(seconds_per_increment=0.002,
 switches=['-u', 'msec'])
 self.assertEqual(unit_msec,
- "100 loops, best of 3: 2 msec per loop\n")
+ "100 loops, best of 5: 2 msec per loop\n")
 unit_usec = self.run_main(seconds_per_increment=0.002,
 switches=['-u', 'usec'])
 self.assertEqual(unit_usec,
- "100 loops, best of 3: 2e+03 usec per loop\n")
+ "100 loops, best of 5: 2e+03 usec per loop\n")
 # Test invalid unit input
 with captured_stderr() as error_stringio:
 invalid = self.run_main(seconds_per_increment=0.002,
diff --git a/Lib/timeit.py b/Lib/timeit.py
--- a/Lib/timeit.py
+++ b/Lib/timeit.py
@@ -59,7 +59,7 @@
 
 dummy_src_name = "<timeit-src>"
 default_number = 1000000
-default_repeat = 3
+default_repeat = 5
 default_timer = time.perf_counter
 
 _globals = globals
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -88,6 +88,9 @@
 Library
 -------
 
+- Issue #28240: timeit now repeats the benchmarks 5 times instead of only 3
+ to make benchmarks more reliable.
+
 - Issue #28240: timeit autorange now uses a single loop iteration if the
 benchmark takes less than 10 seconds, instead of 10 iterations.
 "python3 -m timeit -s 'import time' 'time.sleep(1)'" now takes 4 seconds
-- 
Repository URL: https://hg.python.org/cpython
