How to await a list of tasks in python?-CodePudding

In .Net c# there is a function Task.WhenAll that can take a list of tasks to await them. What should I use in python? I am trying to do the same with this:

tasks = ... #list of coroutines

for task in tasks:
 await task

CodePudding user response：

Use asyncio.gather if you're on Python 3.7 or above. From the docs:

Run awaitable objects in the aws sequence concurrently. If any awaitable in aws is a coroutine, it is automatically scheduled as a Task. If all awaitables are completed successfully, the result is an aggregate list of returned values. The order of result values corresponds to the order of awaitables in aws.

CodePudding user response：

After adding tasks to a list, you should use asyncio.gather that gives coroutines as an argument list and executes them asynchronously. Also, you could use asyncio.create_task that gives a coroutine and calls concurrent tasks in the event loop.

import asyncio


async def coro(i):
    await asyncio.sleep(i//2)


async def main():
    tasks = []
    for i in range(5):
        tasks.append(coro(i))
    await asyncio.gather(*tasks)


if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())
    loop.close()