Unexpected output of (Python) time.clock()

Question

Having some trouble understanding the output from time.clock():

Linux 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:31:23 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux Distributor ID: LinuxMint Description: Linux Mint 14 Nadia Release: 14 Codename: nadia

Python 2.7.3 (default, Sep 26 2012, 21:51:14) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from time import clock, sleep, time
>>> while True: sleep(1); print clock()
... 
0.03
0.03
0.03
0.03
0.03
^CTraceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyboardInterrupt
>>> while True: sleep(1); print time()
... 
1382460160.37
1382460161.37
1382460162.37
1382460163.38
1382460164.38
^CTraceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyboardInterrupt

# ...wait a few minutes...

>>> while True: sleep(1); print clock()
... 
0.04
0.04
0.04
0.04
0.04
0.04
^CTraceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyboardInterrupt
>>> 

$ cat test.py
#! /usr/bin/python

from time import sleep, time, clock

while True:
    print clock(), time()
    sleep(1)


$ python test.py
0.02 1382460623.39
0.02 1382460624.39
0.02 1382460625.39
0.02 1382460626.39
0.02 1382460627.39
0.02 1382460628.39
0.02 1382460629.4
0.02 1382460630.4
0.02 1382460631.4
0.02 1382460632.4
0.02 1382460633.4
0.02 1382460634.4
0.02 1382460635.4
0.02 1382460636.4
0.02 1382460637.41
0.02 1382460638.41
0.02 1382460639.41
0.02 1382460640.41
0.02 1382460641.41
0.02 1382460642.41
0.02 1382460643.41
0.02 1382460644.41
0.02 1382460645.41
0.02 1382460646.42
0.02 1382460647.42
0.02 1382460648.42
0.02 1382460649.42
0.02 1382460650.42
^CTraceback (most recent call last):
  File "test.py", line 7, in <module>
    sleep(1)
KeyboardInterrupt

I'm obviously missing something obvious here?

@CoreyGoldberg - yeah, I looked over all the various questions having to do with time.clock(), including that one, but I don't see any that explain why time.clock() would return the same (unexpected) value repeatedly, second after second. — dwelch91
– dwelch91, Commented Oct 22, 2013 at 17:02
see my answer. it's because you have not used many processor cycles.. so not much processor time used... lost in the granularity. — Corey Goldberg
– Corey Goldberg, Commented Oct 22, 2013 at 17:03
OK, got it. I guess the name of the function and the fact it works differently than on other platforms threw me off. Thanks. — dwelch91
– dwelch91, Commented Oct 22, 2013 at 18:02

Corey Goldberg · Accepted Answer · 2013-10-22 17:01:47Z

3

on Linux systems, time.clock() returns "processor time", not "wall time".

answered Oct 22, 2013 at 17:01

Corey Goldberg

61.5k30 gold badges135 silver badges148 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Unexpected output of (Python) time.clock()

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related