python3.8运行时错误: no running event loop

Question

我从作者 caleb hattingh 的书中摘录了以下代码片段。我尝试运行代码片段并遇到此错误。(练习)

我该如何解决？

import asyncio

async def f(delay):
    await asyncio.sleep(1 / delay)
    return delay

loop = asyncio.get_event_loop()
for i in range(10):
    loop.create_task(f(i))

print(loop)
pending = asyncio.all_tasks()
group = asyncio.gather(*pending, return_exceptions=True)
results = loop.run_until_complete(group)
print(f'Results: {results}')
loop.close()

Answer 1

您必须将 loop 作为参数传递给 .all_tasks() 函数:

pending = asyncio.all_tasks(loop)

输出:

<_UnixSelectorEventLoop running=False closed=False debug=False>
<_GatheringFuture pending>
Results: [8, 5, 2, 9, 6, 3, ZeroDivisionError('division by zero'), 7, 4, 1]

因此，为了全面更正您的脚本:

import asyncio

async def f(delay):
    if delay:
        await asyncio.sleep(1 / delay)
    return delay

loop = asyncio.get_event_loop()
for i in range(10):
    loop.create_task(f(i))

print(loop)
pending = asyncio.all_tasks(loop)
group = asyncio.gather(*pending, return_exceptions=True)
results = loop.run_until_complete(group)
print(f'Results: {results}')
loop.close()