First experience with asyncio

Question

I am learning python-asyncio, and I'm trying to write a simple model.

I have a function handling tasks. While handling, it goes to another remote service for data and then prints a message.

My code:

dd = 0 @asyncio.coroutine def slow_operation(): global dd dd += 1 print('Future is started!', dd) yield from asyncio.sleep(10 - dd) # request to another server print('Future is done!', dd) def add(): while True: time.sleep(1) asyncio.ensure_future(slow_operation(), loop=loop) loop = asyncio.get_event_loop() future = asyncio.Future() asyncio.ensure_future(slow_operation(), loop=loop) th.Thread(target=add).start() loop.run_forever()

But this code doesn't switch the context while sleeping in:

yield from asyncio.sleep(10 - dd)

How can I fix that?

ty @Mogsdad for your fixes

Ruslan Galimov
– Ruslan Galimov

2015-12-21 15:47:31 +00:00
Commented Dec 21, 2015 at 15:47 — Ruslan Galimov
– Ruslan Galimov, Commented Dec 21, 2015 at 15:47

Vincent · Accepted Answer · 2015-12-21 08:51:10Z

asyncio.ensure_future is not thread-safe, that's why slow_operation tasks are not started when they should be. Use loop.call_soon_threadsafe:

 callback = lambda: asyncio.ensure_future(slow_operation(), loop=loop) loop.call_soon_threadsafe(cb)

Or asyncio.run_coroutine_threadsafe if you're running python 3.5.1:

 asyncio.run_coroutine_threadsafe(slow_operation(), loop)

However, you should probably keep the use of threads to the minimum. Unless you use a library running tasks in its own thread, all the code should run inside the event loop (or inside an executor, see loop.run_in_executor).

Collectives™ on Stack Overflow

First experience with asyncio

1 Answer 1

Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Related