我设计了一段python代码，它基本上可以作为更大的方案中的微服务。
我在循环中安排了两个任务，并设置了两个在执行程序中运行的任务。
奇怪的部分是代码运行良好。我期待的一切。但是当我用KeyboardInterrupt（ Ctrl + C ）结束它时，我会看到错误和异常。这让我觉得我肯定在这里滥用asyncio模式。我将尝试提供代码的简要概述，而不必立即进入冗长的细节：
class Prototype:
def _redis_subscriber(self):
self._p = self._redis_itx.pubsub(ignore_subscribe_messages=True)
self._p.subscribe("channel1")
while True:
pubbed_msg = self._p.get_message()
if pubbed_msg is not None:
#process process process
time.sleep(0.01)
def _generic_worker_on_internal_q(self):
while True:
item = self.q.get() #blocking call
#process item
async def task1(self):
#network I/O bound code
async def task2(self):
#network I/O bound code. also fills with self.q.put()
def run(self):
asyncio.ensure_future(self.task1(), loop=self._event_loop)
asyncio.ensure_future(self.task2(), loop=self._event_loop)
asyncio.ensure_future(self._event_loop.run_in_executor(None, self._redis_subscriber))
asyncio.ensure_future(self._event_loop.run_in_executor(None, self._generic_worker_on_internal_q))
self._event_loop.run_forever()
if __name__ == '__main__':
p = Prototype()
p.run()
另外，我尝试在Protoype.run（）方法中尝试另一种方法：
def __init__(self):
self._tasks = []
def run(self):
self._tasks.append(asyncio.ensure_future(self._task1()))
self._tasks.append(asyncio.ensure_future(self._task2()))
self._tasks.append(asyncio.ensure_future(self._event_loop.run_in_executor(None, self._redis_subscriber)))
self._tasks.append(asyncio.ensure_future(self._event_loop.run_in_executor(None, self._generic_worker_on_internal_q)))
self._event_loop.run_until_complete(self._tasks)
无论如何，当我尝试使用 Ctrl + C 结束正在运行的脚本时，它在第一次尝试时不会退出。我要按两次。这就是出现的问题：
KeyboardInterrupt
^CError in atexit._run_exitfuncs:
Traceback (most recent call last):
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/concurrent/futures/thread.py", line 40, in _python_exit
t.join()
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 1056, in join
self._wait_for_tstate_lock()
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 1072, in _wait_for_tstate_lock
elif lock.acquire(block, timeout):
KeyboardInterrupt
Exception ignored in: <bound method BaseEventLoop.call_exception_handler of <_UnixSelectorEventLoop running=False closed=False debug=False>>
Traceback (most recent call last):
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncio/base_events.py", line 1296, in call_exception_handler
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/logging/__init__.py", line 1335, in error
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/logging/__init__.py", line 1442, in _log
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/logging/__init__.py", line 1452, in handle
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/logging/__init__.py", line 1514, in callHandlers
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/logging/__init__.py", line 863, in handle
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/logging/__init__.py", line 1069, in emit
File "/usr/local/Cellar/python3/3.6.4/Frameworks/Python.framework/Versions/3.6/lib/python3.6/logging/__init__.py", line 1059, in _open
NameError: name 'open' is not defined
我哪里错了？
答案 0 :(得分：1)
您在执行程序中安排了两个无限任务。这些任务阻止了退出。
默认任务执行程序将它们放入由队列管理的线程中，并在退出时，发出队列信号以停止执行任务。但是，如果您的任务永远不会返回，则队列管理器永远不会检查此状态。
您可以通过不运行无限循环来避免此状态。相反，每次到达结束时重新安排您的任务，并且不会阻止获取消息：
def _redis_subscriber(self):
self._p = self._redis_itx.pubsub(ignore_subscribe_messages=True)
self._p.subscribe("channel1")
def process_message():
# non-blocking task to repeatedly run in the executor
pubbed_msg = self._p.get_message(False)
if pubbed_msg is not None:
# process process process
time.sleep(0.01)
# reschedule function for next message
asyncio.ensure_future(self._event_loop.run_in_executor(None, process_message))
# kick of first handler
process_message()
您仍然可以在执行程序中运行此功能以启动它：
def run(self):
# ...
asyncio.ensure_future(self._event_loop.run_in_executor(None, self._redis_subscriber))
对_generic_worker_on_internal_q()执行相同的操作，并确保您避免使用对Queue.get()的屏蔽调用，因此请使用self.q.get(False)。
你甚至可以使用装饰器：
import asyncio
from functools import partial, wraps
def auto_reschedule(loop=None, executor=None):
"""Repeatedly re-schedule function in the given executor"""
def decorator(f):
@wraps(f)
def wrapper(*args, **kwargs):
result = f(*args, **kwargs)
callable = wrapper
if args or kwargs:
callable = partial(callable, *args, **kwargs)
current_loop = loop
if current_loop is None:
current_loop = asyncio.get_event_loop()
current_loop.run_in_executor(executor, callable)
return result
return wrapper
return decorator
并在内部函数上使用此装饰器，您可以访问引用循环的实例属性：
def _redis_subscriber(self):
self._p = self._redis_itx.pubsub(ignore_subscribe_messages=True)
self._p.subscribe("channel1")
@auto_reschedule(self._event_loop)
def process_message():
# non-blocking task to repeatedly run in the executor
pubbed_msg = self._p.get_message(False)
if pubbed_msg is not None:
# process process process
time.sleep(0.01)
# kick of first handler
process_message()
后者的快速演示：
import asyncio
import time
import random
# auto_reschedule imported or defined
def create_thread_task(i, loop):
@auto_reschedule(loop)
def thread_task():
print(f'Task #{i} running in worker')
time.sleep(random.uniform(1, 3))
return thread_task
def main():
loop = asyncio.get_event_loop()
for i in range(5):
asyncio.ensure_future(
loop.run_in_executor(None, create_thread_task(i, loop)))
loop.run_forever()
if __name__ == '__main__':
main()