Async-sig

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async-sig@python.org

August 2018

8 participants
2 discussions

concurrency mistake
by saurabh singh Aug. 28, 2018

Aug. 28, 2018

my question is 1st one is concurrent but 2nd one is not, how and please correct me, what i miss and what should i know more thank you import asyncio # 1st code async def say(what, when): await asyncio.sleep(when) print(what) loop = asyncio.get_event_loop() loop.create_task(say('first hello', 2)) loop.create_task(say('second hello', 1)) loop.run_forever() loop.close() ''' result >>> second hello >>> first hello ''' # 2nd code async def say(what, when): await asyncio.sleep(when) print(what) async def main(loop): yield from loop.create_task(say('first hello', 2)) yield from loop.create_task(say('second hello', 1)) print('close') loop = asyncio.get_event_loop() loop.run_until_complete(main(loop)) loop.close() ''' result >>> first hello >>> second hello '''

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new library: sniffio – Sniff out which async library your code is running under
by Nathaniel Smith Aug. 21, 2018

Aug. 21, 2018

Hi all, A number of people are working on packages that support multiple async backends (e.g., asyncio + trio, or trio + curio, or trio + twisted, ...). So then the question arises... how can I figure out which async library my user is actually using? Answer: install sniffio, and then call sniffio.current_async_library(), and it tells you. Well, right now it only works for trio and asyncio, but if you maintain an async library and you want to make it easier for packages to detect you, then it's easy to add support – see the manual. We considered various clever things, but ultimately decided that the best approach was to use a ContextVar and make it the coroutine runner's responsibility to advertise which async flavor it uses. In particular, this approach works even for hybrid programs that are using multiple coroutine runners in the same loop, like a Twisted program with asyncio-flavored and twisted-flavored coroutines in the same thread, or a Trio program using trio-asyncio to run both asyncio-flavored and trio-flavored coroutines in the same thread. Github: https://github.com/python-trio/sniffio Manual: https://sniffio.readthedocs.io/ PyPI: https://pypi.org/p/sniffio -n -- Nathaniel J. Smith -- https://vorpus.org

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