aiohttp使response.json（）失败，状态为500

Question

服务器代理请求。

@asyncio.coroutine
def send_async_request(method, url, data, timeout):
    with ClientSession() as session:
        response = yield from asyncio.wait_for(
            session.request(method, url, data=data), timeout=timeout
        )
        return response

一切都在响应代码200上工作。当涉及到500响应代码时，无法从响应中读取json。 异常ServerDisconnectedError：

response = yield from send_async_request(request.method, url)
response_json = yield from response.json()

Traceback (most recent call last):  

File "C:\Python34\lib\site-packages\aiohttp\server.py", line 285, in start
    yield from self.handle_request(message, payload)
  File "C:\Python34\lib\site-packages\aiohttp\web.py", line 90, in handle_request
    resp = yield from handler(request)
  File "D:/projects/SeleniumGridDispatcher/trunk/application.py", line 122, in proxy_wd
    response_json = yield from response.json()
  File "C:\Python34\lib\site-packages\aiohttp\client_reqrep.py", line 764, in json
    yield from self.read()
  File "C:\Python34\lib\site-packages\aiohttp\client_reqrep.py", line 720, in read
    self._content = yield from self.content.read()
  File "C:\Python34\lib\site-packages\aiohttp\streams.py", line 486, in wrapper
    result = yield from func(self, *args, **kw)
  File "C:\Python34\lib\site-packages\aiohttp\streams.py", line 541, in read
    return (yield from super().read(n))
  File "C:\Python34\lib\site-packages\aiohttp\streams.py", line 261, in read
    block = yield from self.readany()
  File "C:\Python34\lib\site-packages\aiohttp\streams.py", line 486, in wrapper
    result = yield from func(self, *args, **kw)
  File "C:\Python34\lib\site-packages\aiohttp\streams.py", line 549, in readany
    return (yield from super().readany())
  File "C:\Python34\lib\site-packages\aiohttp\streams.py", line 284, in readany
    yield from self._waiter
  File "C:\Python34\lib\asyncio\futures.py", line 358, in __iter__
    yield self  # This tells Task to wait for completion.
  File "C:\Python34\lib\asyncio\tasks.py", line 290, in _wakeup
    future.result()
  File "C:\Python34\lib\asyncio\futures.py", line 274, in result
    raise self._exception
aiohttp.errors.ServerDisconnectedError

帮助了解发生了什么。 Python：3.4.4 aiohttp：0.22.5

Answer 1

任何时候都可能发生500个错误，尤其是服务器处于高负载或不稳定状态时。 通过捕获异常使代码更具弹性。 然后你可能会重试或只是返回响应。

@asyncio.coroutine
def send_async_request(method, url, data, timeout):
    with ClientSession() as session:
        try:             
            response = yield from asyncio.wait_for(
                session.request(method, url, data=data), timeout=timeout
            )
        except  Exception as e:
            print("%s has error '%s: %s'" % (url, response.status, response.reason))
            # now you can decide what you want to do
            # either return the response anyways or do some handling right here
        return response

Answer 2

请检查Content-Length以获得500响应。 看起来像aiohttp尝试读取json体，但是身体比标头中指定的短。