[Python-Dev] PEP 525, fourth update (original) (raw)

Yury Selivanov yselivanov.ml at gmail.com
Wed Sep 7 12:33:15 EDT 2016

Thank you, Guido!

I've updated the PEP to make shutdown_asyncgens a coroutine, as we discussed.

Yury

On 2016-09-06 7:10 PM, Guido van Rossum wrote:

Thanks Yury!

I am hereby accepting PEP 525 provisionally. The acceptance is so that you can go ahead and merge this into 3.6 before the feature freeze this weekend. The provisional status is because this is a big project and it's likely that we'll need to tweak some small aspect of the API once the code is in, even after 3.6.0 is out. (Similar to the way PEP 492, async/await, was accepted provisionally.) But I am cautiously optimistic and I am grateful to Yury for the care and effort he has put into it. --Guido On Tue, Sep 6, 2016 at 5:10 PM, Yury Selivanov <yselivanov.ml at gmail.com> wrote: Hi,

I've updated PEP 525 with a new section about asyncio changes. Essentially, asyncio event loop will get a new "shutdownasyncgens" method that allows to close the loop and all associated AGs with it reliably. Only the updated section is pasted below:

asyncio ------- The asyncio event loop will use sys.setasyncgenhooks() API to maintain a weak set of all scheduled asynchronous generators, and to schedule their aclose() coroutine methods when it is time for generators to be GCed. To make sure that asyncio programs can finalize all scheduled asynchronous generators reliably, we propose to add a new event loop method loop.shutdownasyncgens(*, timeout=30). The method will schedule all currently open asynchronous generators to close with an aclose() call. After calling the loop.shutdownasyncgens() method, the event loop will issue a warning whenever a new asynchronous generator is iterated for the first time. The idea is that after requesting all asynchronous generators to be shutdown, the program should not execute code that iterates over new asynchronous generators. An example of how shutdownasyncgens should be used:: try: loop.runforever() # or loop.rununtilcomplete(...) finally: loop.shutdownasyncgens() loop.close() - Yury

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