[Python-ideas] Timing hefty or long-running blocks of code

[Steven D'Aprano]

The timeit module is great for timing small code snippets, but it is rather inconvenient for timing larger blocks of code. It's also over-kill: under normal circumstances, there is little need for the heroic measures timeit goes through to accurately time long-running code.

When people want to time something that doesn't require timeit, they have to write their own timer boilerplate:

from time import time
t = time()
do_this()
do_that()
print(time() - t)


Although only a few lines of boilerplate, this has a few problems, the biggest two being:

* the user has to decide which of the many clocks provided by Python
   is suitable (hint: time.time is not necessarily the best);

* this is inconvenient at the interactive interpreter, since the timer
   is started before the code being typed has been entered.

I propose a context manager in the timeit module:

with Stopwatch():
     do_this()
     do_that()

=> results are automatically printed, or available for programmatic access

I have had a recipe for this on ActiveState for about 18 months, where it is relatively popular:

http://code.activestate.com/recipes/577896-benchmark-code-with-the-with-statement

and I have extensively used it interactively, in Python 2.6 through 3.3 inclusive. The latest version can be found here:

https://code.google.com/p/my-startup-file/source/browse/timer.py

This solves the two problems listed above:

* the Stopwatch can use the most appropriate timer by default, and
   allow the user to override it if they so choose;

* the Stopwatch will not start until the with-block is actually
   entered.


Is there interest in seeing this in the standard library?


-- 
Steven