[Python-ideas] api suggestions for the cProfile module

[Ethan Furman]

On 01/10/2017 08:36 AM, Thane Brimhall wrote:

> Does anyone have thoughts on this topic? I assume the silence is because
>  this suggestion is too trivial to matter.

Sometimes it's just a matter of timing.  :)

> I use cProfile a lot, and would like to suggest three backwards-compatible
>  improvements to the API.
>
> 1: When using cProfile on a specific piece of code I often use the
>  enable() and disable() methods. It occurred to me that this would
>  be an obvious place to use a context manager.

Absolutely.

> 2: Enhance the `print_stats` method on Profile to accept more options
>  currently available only through the pstats.Stats class. For example,
>  strip_dirs could be a boolean argument, and limit could accept an int.
>  This would reduce the number of cases you'd need to use the more complex
>  API.

I don't have much experience with cProfile, but this seems reasonable.

> 3: I often forget which string keys are available for sorting. It would
>  be nice to add an enum for these so a user could have their linter and
>  IDE check that value pre-runtime. Since it would subclass `str` and
>  `Enum` it would still work with all currently existing code.

Absolutely!  :)

> The current documentation contains the following code:
>
>     import cProfile, pstats, io
>     pr = cProfile.Profile()
>     pr.enable()
>     # ... do something ...
>     pr.disable()
>     s = io.StringIO()
>     sortby = 'cumulative'
>     ps = pstats.Stats(pr, stream=s).sort_stats(sortby)
>     ps.print_stats()
>     print(s.getvalue())
>
> While the code below doesn't exactly match the functionality above (eg. not
>  using StringIO), I envision the context manager working like this, along
>  with some adjustments on how to get the stats from the profiler:
>
>     import cProfile, pstats
>     with cProfile.Profile() as pr:
>          # ... do something ...
>          pr.print_stats(sort=pstats.Sort.cumulative, limit=10, strip_dirs=True)
>
> As you can see, the code is shorter and somewhat more self-documenting. The
>  best thing about these suggestions is that as far as I can tell they would
>  be backwards-compatible API additions.

The `pr.print_stats... line should not be inside the `with` block unless you want to profile that part as well.

These suggestions seem fairly uncontroversial.  Have you opened an issue on the issue tracker?

The fun part of the patch will be the C code, but a Python proof-of-concept would be useful.

--
~Ethan~