[Python-ideas] Flagging blocking functions not to be used with asyncio

[Victor Stinner]

It seems different. It looks like Tornado uses an alarm and SIGALRM,
whereas asyncio only checks elapsed time and so is unable to interrupt a
blocked function.

Victor

Le 7 oct. 2016 20:33, "Yury Selivanov" <yselivanov.ml at gmail.com> a écrit :

>
>
> On 2016-10-07 1:31 PM, Giampaolo Rodola' wrote:
>
>> On Fri, Oct 7, 2016 at 6:52 PM, Yury Selivanov <yselivanov.ml at gmail.com>
>> wrote:
>>
>> On 2016-10-07 11:16 AM, Guido van Rossum wrote:
>>>
>>> Maybe a simpler approach would be to write a linter that checks for a
>>>
>>>> known list of common blocking functions, and anything that calls those
>>>> automatically gets the same property?
>>>>
>>>> What if somebody uses logging module and logs to a file?  I think this
>>> is
>>> something that linters can't infer (how logging is configured).
>>>
>>> One way to solve this would be to monkeypatch the io and os modules
>>> (gevent does that, so it's possible) to issue a warning when it's used in
>>> an asyncio context.  This can be done as a module on PyPI.
>>>
>>> Another way would be to add some kind of IO tracing hooks to CPython.
>>>
>>
>> How about something like this?
>> http://www.tornadoweb.org/en/stable/ioloop.html#tornado.iolo
>> op.IOLoop.set_blocking_signal_threshold
>>
>>
> Yes, we already have a similar mechanism in asyncio --
> loop.slow_callback_duration property that is used in debug mode. The thing
> it isn't really precise, as you can have a lot of relatively fast blocking
> calls that harm performance, but complete faster than
> slow_callback_duration.
>
> Yury
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