为什么get_event_loop不能与run_in_executor一起使用

谁能说出下面的代码为什么

import asyncio
import time
from concurrent.futures import ThreadPoolExecutor

ASYNC_INTERVAL = 0.1

def plain_hello_world(name):
    s = "Hello world "+str(name)
    print(s)
    return s

def plain_loop(name, t):
    start_time = time.time()
    prev_time = start_time
    while (time.time() - start_time < t):
        if time.time() - prev_time > ASYNC_INTERVAL:
            prev_time = time.time()
            plain_hello_world(name)

def task1():
    loop = asyncio.get_event_loop()
    task = loop.run_in_executor(None, plain_loop, "func", 1)
    loop.run_until_complete(task)

def task2():
    loop = asyncio.get_event_loop()
    task = loop.run_in_executor(None, task1)
    loop.run_until_complete(task)

if __name__ == "__main__":
    task2()

出现以下错误：

Traceback (most recent call last):
  File "asyncio_practice4.py", line 28, in <module>
    task2()
  File "asyncio_practice4.py", line 25, in task2
    loop.run_until_complete(task)
  File "/usr/lib/python3.6/asyncio/base_events.py", line 484, in run_until_complete
    return future.result()
  File "/usr/lib/python3.6/concurrent/futures/thread.py", line 56, in run
    result = self.fn(\*elf.args, \*self.kwargs)
  File "asyncio_practice4.py", line 18, in task1
    loop = asyncio.get_event_loop()
  File "/usr/lib/python3.6/asyncio/events.py", line 694, in get_event_loop
    return get_event_loop_policy().get_event_loop()
  File "/usr/lib/python3.6/asyncio/events.py", line 602, in get_event_loop
    % threading.current_thread().name)
RuntimeError: There is no current event loop in thread 'ThreadPoolExecutor-0_0'.

题：

我不明白为什么会发生这种错误。

仅运行task1（）可以，但是与另一run_in_executor（）一起运行时，它表示当前没有evet循环。（但是我认为应该，我没有创建新线程）

有人知道发生了什么吗？

以及假设我们只能在task2（）上工作，如何解决？

注意：

调用2run_in_executor（）的原因是因为上面的代码模仿了将第3个lib集成到异步代码中。

plain_hello_world（），plain_loop（）和task1（）是lib中的代码，我无法修改。

Assuming task1() runs for 100s and I do not want to wait for it, so I try to run it in executor as how other plain functions work with asyncio.

Edit: Based on the answer, here is the revision that works:

def task2():
    loop = asyncio.get_event_loop()
    def wrapper():
        asyncio.set_event_loop(asyncio.new_event_loop())
        task1()
    task = loop.run_in_executor(None, wrapper)
    loop.run_until_complete(task)

Though I am not sure how "correct" or good it is.

问题来源: stackoverflow