运行2天后aio_pika随机连接错误

Question

我有asyncio脚本，每40秒连接到rabbitmq和aio_pika库，并检查是否有任何消息并打印出来然后永远重复。但是，通常，在运行2天后，我将开始接收无限连接异常错误，这只能通过重新启动脚本来解决。也许我的asyncio脚本的逻辑中有一些明显的错误，我错过了？

#!/usr/bin/python3
import time
import async_timeout
import asyncio
import aio_pika

async def got_message(message: aio_pika.IncomingMessage):
    with message.process():
        print(message.body.decode())

async def main(loop):
    try:
        with async_timeout.timeout(10):
            connection = await aio_pika.connect_robust(
                host='#', 
                virtualhost='#', 
                login='#', 
                password='#',
                port=5671,
                loop=loop, 
                ssl=True
            )

            channel = await connection.channel()

            await channel.set_qos(prefetch_count=100)

            queue_name='mm_message'
            queue = await channel.declare_queue(auto_delete=False, name=queue_name)

            routing_key='mm_msg'
            await queue.bind("amq.topic", routing_key)
            que_len = queue.declaration_result.message_count
            if(que_len > 0):
                await queue.consume(got_message)
    except:
        print("connection problems..")

if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    while(True):
        time.sleep(40)
        loop.run_until_complete(main(loop))

这是我在一段时间后无休止地收到的错误：

Traceback (most recent call last):
  File "/usr/lib/python3.5/asyncio/events.py", line 125, in _run
    self._callback(*self._args)
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/adapters/base_connection.py", line 364, in _handle_events
    self._handle_read()
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/adapters/base_connection.py", line 415, in _handle_read
    self._on_data_available(data)
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/connection.py", line 1347, in _on_data_available
    self._process_frame(frame_value)
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/connection.py", line 1414, in _process_frame
    if self._process_callbacks(frame_value):
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/connection.py", line 1384, in _process_callbacks
    frame_value)  # Args
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/callback.py", line 60, in wrapper
    return function(*tuple(args), **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/callback.py", line 92, in wrapper
    return function(*args, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/callback.py", line 236, in process
    callback(*args, **keywords)
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/connection.py", line 1332, in _on_connection_tune
    self._send_connection_open()
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/connection.py", line 1517, in _send_connection_open
    self._on_connection_open, [spec.Connection.OpenOk])
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/connection.py", line 1501, in _rpc
    self._send_method(channel_number, method_frame)
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/connection.py", line 1569, in _send_method
    self._send_frame(frame.Method(channel_number, method_frame))
  File "/usr/local/lib/python3.5/dist-packages/aio_pika/pika/connection.py", line 1548, in _send_frame
    raise exceptions.ConnectionClosed
aio_pika.pika.exceptions.ConnectionClosed

Answer 1

except:
    print("connection problems..")

这将捕获服务异常，如KeyboardInterrupt，SystemExit。你应该never do这样的事情，如果你不打算再加上例外。至少你应该写：

except Exception:
    print("connection problems..")

然而，在上面的asyncio片段的背景下将打破cancellation的机制。为了避免它，如here解释，你应该写：

try:
    await operation
except asyncio.CancelledError:
    raise
except Exception:
    log.log('an error has occurred')

---

同样重要的是要理解连接不仅应该打开，而且也应该关闭（无论打开和关闭之间发生了什么）。为了实现这一点，人们通常使用context managers（以及asyncio - 异步上下文管理器）。

aio_pika似乎并不例外。正如example所示，在处理连接时你应该使用async with：

connection = await aio_pika.connect_robust(
    "amqp://guest:[email protected]/", loop=loop
)

async with connection:
    # ...