How do I get time of a Python program's execut

Question

I have a command line program in Python that takes a while to finish. I want to know the exact time it takes to finish running.

I've looked at the timeit module, but it seems it's only for small snippets of code. I want to time the whole program.

Answer 1

I've looked at the timeit module, but it seems it's only for small snippets of code. I want to time the whole program.

$ python -mtimeit -n1 -r1 -t -s "from your_module import main" "main()"

It runs your_module.main() function one time and print the elapsed time using time.time() function as a timer.

To emulate /usr/bin/time in Python see Python subprocess with /usr/bin/time: how to capture timing info but ignore all other output?.

To measure CPU time (e.g., don't include time during time.sleep()) for each function, you could use profile module (cProfile on Python 2):

$ python3 -mprofile your_module.py

You could pass -p to timeit command above if you want to use the same timer as profile module uses.

See How can you profile a Python script?

Answer 2

Timeit is a class in python used to calculate the execution time of small blocks of code.

Default_timer is a method in this class which is used to measure the wall clock timing not CPU execution time. Thus other process execution might interfere with this. Thus it is useful for small blocks of code.

A sample of the code is as follows:

from timeit import default_timer as timer

start= timer()

#some logic 

end = timer() 

print("Time taken:", end-start) 

Answer 3

The simplest way in Python:

import time
start_time = time.time()
main()
print("--- %s seconds ---" % (time.time() - start_time))

This assumes that your program takes at least a tenth of second to run.

Prints:

--- 0.764891862869 seconds ---

Answer 4

You can use the python profiler cProfile to measure CPU time and additionally how much time is spent inside each function and how many times each function is called. This is very useful if you want to improve performance of your script without knowing where to start. This answer to another SO question is pretty good. It's always good to have a look in the docs too.

Here's an example how to profile a script using cProfile from a command line:

$ python -m cProfile euler048.py

1007 function calls in 0.061 CPU seconds

Ordered by: standard name
ncalls  tottime  percall  cumtime  percall filename:lineno(function)
    1    0.000    0.000    0.061    0.061 <string>:1(<module>)
 1000    0.051    0.000    0.051    0.000 euler048.py:2(<lambda>)
    1    0.005    0.005    0.061    0.061 euler048.py:2(<module>)
    1    0.000    0.000    0.061    0.061 {execfile}
    1    0.002    0.002    0.053    0.053 {map}
    1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler objects}
    1    0.000    0.000    0.000    0.000 {range}
    1    0.003    0.003    0.003    0.003 {sum}

Answer 5

time.clock()

Deprecated since version 3.3: The behavior of this function depends on the platform: use perf_counter() or process_time() instead, depending on your requirements, to have a well-defined behavior.

time.perf_counter()

Return the value (in fractional seconds) of a performance counter, i.e. a clock with the highest available resolution to measure a short duration. It does include time elapsed during sleep and is system-wide.

time.process_time()

Return the value (in fractional seconds) of the sum of the system and user CPU time of the current process. It does not include time elapsed during sleep.

start = time.process_time()
... do something
elapsed = (time.process_time() - start)

Answer 6

This is Paul McGuire's answer that works for me. Just in case someone was having trouble running that one.

import atexit
from time import clock

def reduce(function, iterable, initializer=None):
    it = iter(iterable)
    if initializer is None:
        value = next(it)
    else:
        value = initializer
    for element in it:
        value = function(value, element)
    return value

def secondsToStr(t):
    return "%d:%02d:%02d.%03d" % \
        reduce(lambda ll,b : divmod(ll[0],b) + ll[1:],
            [(t*1000,),1000,60,60])

line = "="*40
def log(s, elapsed=None):
    print (line)
    print (secondsToStr(clock()), '-', s)
    if elapsed:
        print ("Elapsed time:", elapsed)
    print (line)

def endlog():
    end = clock()
    elapsed = end-start
    log("End Program", secondsToStr(elapsed))

def now():
    return secondsToStr(clock())

def main():
    start = clock()
    atexit.register(endlog)
    log("Start Program")

call timing.main() from your program after importing the file.