Although similar in general cases (“run and get results for many tasks”), each function has some specific functionality for other cases:
asyncio.gather()
Returns a Future instance, allowing high level grouping of tasks:
import asyncio from pprint import pprint import random async def coro(tag): print(">", tag) await asyncio.sleep(random.uniform(1, 3)) print("<", tag) return tag loop = asyncio.get_event_loop() group1 = asyncio.gather(*[coro("group 1.{}".format(i)) for i in range(1, 6)]) group2 = asyncio.gather(*[coro("group 2.{}".format(i)) for i in range(1, 4)]) group3 = asyncio.gather(*[coro("group 3.{}".format(i)) for i in range(1, 10)]) all_groups = asyncio.gather(group1, group2, group3) results = loop.run_until_complete(all_groups) loop.close() pprint(results)
All tasks in a group can be cancelled by calling group2.cancel()
or even all_groups.cancel()
. See also .gather(..., return_exceptions=True)
,
asyncio.wait()
Supports waiting to be stopped after the first task is done, or after a specified timeout, allowing lower level precision of operations:
import asyncio import random async def coro(tag): print(">", tag) await asyncio.sleep(random.uniform(0.5, 5)) print("<", tag) return tag loop = asyncio.get_event_loop() tasks = [coro(i) for i in range(1, 11)] print("Get first result:") finished, unfinished = loop.run_until_complete( asyncio.wait(tasks, return_when=asyncio.FIRST_COMPLETED)) for task in finished: print(task.result()) print("unfinished:", len(unfinished)) print("Get more results in 2 seconds:") finished2, unfinished2 = loop.run_until_complete( asyncio.wait(unfinished, timeout=2)) for task in finished2: print(task.result()) print("unfinished2:", len(unfinished2)) print("Get all other results:") finished3, unfinished3 = loop.run_until_complete(asyncio.wait(unfinished2)) for task in finished3: print(task.result()) loop.close()