[英]How to run an Asyncio task without awaiting?
我需要定期调用一个任务,但(a)等待时间几乎超过了这个时期。
在以下代码中,如何运行do_something()
任务而无需await
结果?
import asyncio
import time
from random import randint
period = 1 # Second
def get_epoch_ms():
return int(time.time() * 1000.0)
async def do_something(name):
print("Start :", name, get_epoch_ms())
try:
# Do something which may takes more than 1 secs.
slp = randint(1, 5)
print("Sleep :", name, get_epoch_ms(), slp)
await asyncio.sleep(slp)
except Exception as e:
print("Error :", e)
print("Finish :", name, get_epoch_ms())
async def main():
i = 0
while True:
i += 1
# Todo : this line should be change
await do_something('T' + str(i))
await asyncio.sleep(period)
asyncio.get_event_loop().run_until_complete(main())
您的问题是使用不满足您的并发目的的run_until_complete(main())
。 因此,假设您的协程任务( do_something()
)被限制为5
,您的代码将如下所示:
import time
from random import randint
period = 1 # Second
def get_epoch_ms():
return int(time.time() * 1000.0)
async def do_something(name):
print("Start :", name, get_epoch_ms())
try:
# Do something which may takes more than 1 secs.
slp = randint(1, 5)
print("Sleep :", name, get_epoch_ms(), slp)
await asyncio.sleep(slp)
except Exception as e:
print("Error :", e)
print("Finish :", name, get_epoch_ms())
loop = asyncio.get_event_loop()
futures = [loop.create_task(do_something('T' + str(i)))
for i in range(5)]
loop.run_forever()
for f in futures:
f.cancel()
这是其输出中的并发工作流:
Start : T0 1558937750705
Sleep : T0 1558937750705 5
Start : T1 1558937750705
Sleep : T1 1558937750705 1
Start : T2 1558937750705
Sleep : T2 1558937750705 4
Start : T3 1558937750705
Sleep : T3 1558937750705 5
Start : T4 1558937750705
Sleep : T4 1558937750705 5
Finish : T1 1558937751707
Finish : T2 1558937754709
Finish : T0 1558937755707
Finish : T3 1558937755708
Finish : T4 1558937755708
但是,如果您的协程任务不受限制,您可以这样做:
...
async def main(loop):
i = 0
while True:
i += 1
loop.create_task(do_something('T' + str(i)))
await asyncio.sleep(period)
loop = asyncio.get_event_loop()
loop.run_until_complete(main(loop))
不是await
协程,而是调用asyncio.create_task
来生成在后台运行的任务对象。 在您的下一次迭代中,您可以检查任务是否完成并相应地等待/取消它。 (否则 asyncio 会抱怨未等待的任务被垃圾收集。)
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