Change Time Unit with Kernprof

Question

I've started looking for bottlenecks in Python using line_profiler. Right now, I am doing that by running

kernprof -l -v myFile.py

However, the unit of time seems to be at 1e-6, which lead to output results such as 132329040. How can I increase the time interval to make the output more readable for larger time deltas?

The time unit seems to be set in the timer.c code so unless changing that you could divide by 1000000 — Padraic Cunningham, Feb 08 '15 at 19:39
If the reason you are doing this is to find "bottlenecks" (as opposed to measuring for the sake of measuring), [*there's a completely different way to do it.*](http://stackoverflow.com/a/4299378/23771) Measurements of time are completely beside the point. — Mike Dunlavey, Feb 08 '15 at 21:03

score 9 · Answer 1 · answered May 29 '19 at 09:11

That is a feature so far only present via Jupyter line magic, as discussed here. It can be accessed via the "-u" flag, followed by the timer unit, in seconds. This is a sample usage:

def m():
  return [0]*10**8

%lprun -u 1e-3 -f m m()

Which displays the output with timer unit in milliseconds:

Out:
Timer unit: 0.001 s

Total time: 0.363548 s
File: 
Function: m at line 1

Line # Hits Time Per Hit % Time Line Contents
==============================================================
1 def m():
2 1 363.5 363.5 100.0 return [0]*10**8

As documented in this PR.

This works on normal version now. – MBV Jan 27 '22 at 17:12 — MBV, Jan 27 '22 at 17:12

score 5 · Answer 2 · answered Apr 11 '19 at 15:38

I find the solution by reading LineProfiler source code. you can use the following parameter "output_unit" to change the time unit.

profiler.print_stats(output_unit=1e-03)

output_unit=1e-03, the console will output "Timer unit: 0.001 s" output_unit=1, the console will output "Timer unit: 1 s"

score 1 · Answer 3 · answered Nov 14 '19 at 04:01

In show_func function; around line num 202:

if output_unit is None:
    output_unit = unit

Change it to:

if output_unit is None:
    output_unit = unit*1000000

Secondly, in the function show_text; around line num 254:

if output_unit is not None:
    stream.write('Timer unit: %g s\n\n' % output_unit)
else:
    stream.write('Timer unit: %g s\n\n' % unit)

Change it to:

if output_unit is not None:
    stream.write('Timer unit: %g s\n\n' % output_unit)
else:
    stream.write('Timer unit: %g s\n\n' % (unit*1000000))

Use the same factor in both places.

I have made the above changes as I use line commands to run line_profiler and not ipython/jupyter.

The output file looks like following. The time units are so much more readable!

executed
Wrote profile results to test.py.lprof
Timer unit: 0.1 s

Total time: 1.00024 s
File: test.py
Function: testfunc at line 5

Line #      Hits         Time  Per Hit   % Time  Line Contents
==============================================================
     5                                           @profile
     6                                           def testfunc():
     7         1         10.0     10.0    100.0      time.sleep(1)
     8         1          0.0      0.0      0.0      print('executed')

score 0 · Answer 4 · answered Jun 16 '22 at 17:20

As mentioned by @mbv above, this is now available with latest line_profiler, as of PR#34 (See PR#22 for more details), which allows one to use --unit command line option for kernprof, such as:

$ kernprof -l -v --unit 1e-3 myFile.py # milliseconds

$ kernprof -l -v --unit 1e-9 myFile.py # nanoseconds

etc.

score -2 · Answer 5 · answered May 17 '17 at 00:54

-2

use "ms" to display:

edit line_profiler.py -> show_func -> find for lineno, nhits, time in timings: this line -> change time to time * 10-03

answered May 17 '17 at 00:54

tuxpy

1
1

that's not a very convenient way to change the source code every time you want to change the time unit. – marscher Nov 21 '19 at 13:21

Change Time Unit with Kernprof

5 Answers5