是什么导致asyncio.new_event_loop（）的简单调用挂起？ [英] What can cause the simple invocation of asyncio.new_event_loop() to hang?

问题描述

我正在使用以下功能来强制协程同步运行：

I am using the following function to force a coroutine to run synchronously:

import asyncio
import inspect
import types
from asyncio import BaseEventLoop
from concurrent import futures


def await_sync(coro: types.CoroutineType, timeout_s: int=None):
    """

    :param coro: a coroutine or lambda loop: coroutine(loop)
    :param timeout_s:
    :return:
    """
    loop = asyncio.new_event_loop()  # type: BaseEventLoop
    if not is_awaitable(coro):
        coro = coro(loop)
    if timeout_s is None:
        fut = asyncio.ensure_future(coro, loop=loop)
    else:
        fut = asyncio.ensure_future(asyncio.wait_for(coro, timeout=timeout_s, loop=loop), loop=loop)
    loop.run_until_complete(fut)
    return fut.result()

def is_awaitable(coro_or_future):
    if isinstance(coro_or_future, futures.Future):
        return coro_or_future
    elif asyncio.coroutines.iscoroutine(coro_or_future):
        return True
    elif asyncio.compat.PY35 and inspect.isawaitable(coro_or_future):
        return True
    else:
        return False

但是，间歇性地，它只会在尝试创建一个新值时冻结循环： loop = asyncio.new_event_loop（）。检查堆栈跟踪会向我显示其挂起的确切位置：

However, intermittently, it will freeze upon simply trying to create a new loop: loop = asyncio.new_event_loop(). Inspecting the stack traces shows me the exact location where it hangs:

File: "/src\system\utils.py", line 34, in await_sync
  loop = asyncio.new_event_loop()  # type: BaseEventLoop
File: "\lib\asyncio\events.py", line 636, in new_event_loop
  return get_event_loop_policy().new_event_loop()
File: "\lib\asyncio\events.py", line 587, in new_event_loop
  return self._loop_factory()
File: "\lib\asyncio\selector_events.py", line 55, in __init__
  self._make_self_pipe()
File: "\lib\asyncio\selector_events.py", line 116, in _make_self_pipe
  self._ssock, self._csock = self._socketpair()
File: "\lib\asyncio\windows_events.py", line 295, in _socketpair
  return windows_utils.socketpair()
File: "\lib\socket.py", line 515, in socketpair
  ssock, _ = lsock.accept()
File: "\lib\socket.py", line 195, in accept
  fd, addr = self._accept()

什么ca是在 socket 这样低级的库中引起这种问题的吗？难道我做错了什么？我正在使用Python 3.5.1。

What can be causing such an issue, in a library as low level as socket? Am I doing something wrong? I am using Python 3.5.1.

编辑：我提交了错误报告此处，但Guido建议我继续在StackOverflow上寻求帮助。

I filed a bug report here but Guido recommended me to continue seeking help on StackOverflow.

推荐答案

我正试图了解您要做什么。

I'm trying to understand what you are trying to do.

如果我正确理解它，那么无论输入是协程还是简单的函数调用，您都希望有一个函数可以返回相同的结果。如果我是对的，那么这似乎很好。

If I get it correctly you want a function that will return the same thing whether the input is a coroutine or a simple function call. If I'm correct, then this seems to work fine.

import asyncio
import time

def await_sync(coro, timeout=None):
  if asyncio.iscoroutine(coro):
    f = asyncio.wait_for(coro, timeout)
    loop = asyncio.get_event_loop()
    return loop.run_until_complete(f)
  return coro

async def async_test(x):
    print("x", end="")
    await asyncio.sleep(x)
    print("y", end="")
    return x

def sync_test(x):
    print("x", end="")
    time.sleep(x)
    print("y", end="")
    return x

print(await_sync(sync_test(2)))
print(await_sync(async_test(3)))

这将输出以下结果（我猜是预期的）：

This outputs the following (I guess expected) result:

xy2
xy3

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