[Python-ideas] api suggestions for the cProfile module

[Giampaolo Rodola']

On Wed, Dec 21, 2016 at 1:50 AM, Thane Brimhall <thane.brimhall at gmail.com>
wrote:

> 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.
>

I think this makes sense.
I did that in https://bugs.python.org/issue9285 but unfortunately I got
stuck and the issue remained stagnant.
Signaling it here just in case somebody has some insights on how to proceed.



> 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'm not sure about this. I agree the current API is not the nicest one. I
use a wrapper on top of cProfile which does this:

                stats = pstats.Stats(file.name)
                if strip_dirs:
                    stats.strip_dirs()
                if isinstance(sort, (tuple, list)):
                    stats.sort_stats(*sort)
                else:
                    stats.sort_stats(sort)
                stats.print_stats(lines)

With your proposal we would have 2 ways of doing the same thing and I'm not
entirely sure that is good.



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.
>
> 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.
>
> What do you think? Thank you in advance for your time!
>
> /Thane
>
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-- 
Giampaolo - http://grodola.blogspot.com
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