[Python-ideas] api suggestions for the cProfile module

[Jelle Zijlstra]

2017-01-10 8:57 GMT-08:00 Ethan Furman <ethan at stoneleaf.us>:

> 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.
>
> These changes may not even require C code, since (contrary to its name)
cProfile actually is implemented partly in Python. For example, the context
manager change could be made simply by adding __enter__ and __exit__ to the
cProfile.Profile class.

> --
> ~Ethan~
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