我在这个python asyncio主题中很新。我有一个简单的问题: 我有一个包含两个协同程序的任务,可以同时运行。第一个协程(my_coroutine)只会连续打印一些内容,直到达到second_to_sleep。第二个协程(seq_coroutine)将依次调用其他4个协同程序。我的目标是在seq_coroutine完全结束时停止循环。确切地说,我希望my_coroutine在seq_coroutine完成之前保持活着状态。有人可以帮我吗?
我的代码是这样的:
import asyncio
async def my_coroutine(task, seconds_to_sleep = 3):
print("{task_name} started\n".format(task_name=task))
for i in range(1, seconds_to_sleep):
await asyncio.sleep(1)
print("\n{task_name}: second {seconds}\n".format(task_name=task, seconds=i))
async def coroutine1():
print("coroutine 1 started")
await asyncio.sleep(1)
print("coroutine 1 finished\n")
async def coroutine2():
print("coroutine 2 started")
await asyncio.sleep(1)
print("coroutine 2 finished\n")
async def coroutine3():
print("coroutine 3 started")
await asyncio.sleep(1)
print("coroutine 3 finished\n")
async def coroutine4():
print("coroutine 4 started")
await asyncio.sleep(1)
print("coroutine 4 finished\n")
async def seq_coroutine():
await coroutine1()
await coroutine2()
await coroutine3()
await coroutine4()
def main():
main_loop = asyncio.get_event_loop()
task = [asyncio.ensure_future(my_coroutine("task1", 11)),
asyncio.ensure_future(seq_coroutine())]
try:
print('loop is started\n')
main_loop.run_until_complete(asyncio.gather(*task))
finally:
print('loop is closed')
main_loop.close()
if __name__ == "__main__":
main()
这是该程序的输出:
loop is started
task1 started
coroutine 1 started
task1: second 1
coroutine 1 finished
coroutine 2 started
task1: second 2
coroutine 2 finished
coroutine 3 started
task1: second 3
coroutine 3 finished
coroutine 4 started
task1: second 4
coroutine 4 finished
task1: second 5
task1: second 6
task1: second 7
task1: second 8
task1: second 9
task1: second 10
loop is closed
我只想要这样的东西:
loop is started
task1 started
coroutine 1 started
task1: second 1
coroutine 1 finished
coroutine 2 started
task1: second 2
coroutine 2 finished
coroutine 3 started
task1: second 3
coroutine 3 finished
coroutine 4 started
task1: second 4
coroutine 4 finished
loop is closed
答案 0 :(得分:7)
我刚刚为我的问题找到了合适的解决方案。
我不会删除我的帖子,我会发布我的解决方案,这样可以帮助其他人面对同样的问题。
我使用了asyncio.wait(task, return_when=asyncio.FIRST_COMPLETED)
,只要第一个任务完成,它就会返回结果。
这是解决方案:
import asyncio
from asyncio.tasks import FIRST_COMPLETED
from concurrent.futures import CancelledError
async def my_coroutine(task, seconds_to_sleep = 3):
print("{task_name} started\n".format(task_name=task))
for i in range(1, seconds_to_sleep):
await asyncio.sleep(1)
print("\n{task_name}: second {seconds}\n".format(task_name=task, seconds=i))
async def coroutine1():
print("coroutine 1 started")
await asyncio.sleep(1)
print("coroutine 1 finished\n")
async def coroutine2():
print("coroutine 2 started")
await asyncio.sleep(1)
print("coroutine 2 finished\n")
async def coroutine3():
print("coroutine 3 started")
await asyncio.sleep(1)
print("coroutine 3 finished\n")
async def coroutine4():
print("coroutine 4 started")
await asyncio.sleep(1)
print("coroutine 4 finished\n")
async def seq_coroutine(loop):
await coroutine1()
await coroutine2()
await coroutine3()
await coroutine4()
def main():
main_loop = asyncio.get_event_loop()
task = [asyncio.ensure_future(my_coroutine("task1", 11)),
asyncio.ensure_future(seq_coroutine(main_loop))]
try:
print('loop is started\n')
done, pending = main_loop.run_until_complete(asyncio.wait(task, return_when=asyncio.FIRST_COMPLETED))
print("Completed tasks: {completed}\nPending tasks: {pending}".format(completed = done, pending = pending))
#canceling the tasks
for task in pending:
print("Cancelling {task}: {task_cancel}".format(task=task, task_cancel=task.cancel()))
except CancelledError as e:
print("Error happened while canceling the task: {e}".format(e=e))
finally:
print('loop is closed')
if __name__ == "__main__":
main()
答案 1 :(得分:0)
您可以使用变量向另一个协程发信号。通常使用asyncio.Event
:
import asyncio
import random
async def clock(name, event):
print("* {} started".format(name))
i = 0
while not event.is_set():
await asyncio.sleep(0.1)
i += 1
print("* {}: {}".format(name, i))
print("* {} done".format(name))
return i
async def coro(x):
print("coro() started", x)
await asyncio.sleep(random.uniform(0.2, 0.5))
print("coro() finished", x)
async def seq_coroutine(name):
event = asyncio.Event()
clock_task = asyncio.ensure_future(clock(name, event))
# await asyncio.sleep(0) # if you want to give a chance to clock() to start
await coro(1)
await coro(2)
await coro(3)
await coro(4)
event.set()
i = await clock_task
print("Got:", i)
def main():
main_loop = asyncio.get_event_loop()
main_loop.run_until_complete(seq_coroutine("foo"))
main_loop.close()
if __name__ == "__main__":
main()
您还可以使用await event.wait()
来阻止一段代码,直到设置了该事件:
async def xxx(event):
print("xxx started")
await event.wait()
print("xxx ended")