Python: co-routines in multi-threading/processing

[dvas0004]

Asyncio contains the event_loop.run_in_executor function which allows you to run co-routines in a separate executor - this being a Thread or Processor pool (via the concurrent.futures module):

def blocking_task(i):
   print(i) #or some other useful task...

async def run_blocking_tasks(executor):
    loop = asyncio.get_event_loop()
    blocking_tasks = [
        loop.run_in_executor(executor, blocking_task, i)
        for i in range(6)
    ]

    completed, pending = await asyncio.wait(blocking_tasks)
    results = [t.result() for t in completed]
    return results

event_loop = asyncio.get_event_loop()
try:
    event_loop.run_until_complete(
        run_blocking_tasks(executor)
    )
finally:
    event_loop.close()

Important: note that the last argument to run_in_executor is *args, i.e. the arguments to pass to the blocking task. Passing the argument directly (blocking_task(i)) will not work as expected

[dvas0004]

https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.loop.run_in_executor
https://pymotw.com/3/asyncio/executors.html