我在Tornado WebSocket服务器中遇到了一个异常,但它在跟踪中没有提供任何信息来知道它是从程序中的哪一行代码或哪一步产生的。我想找出原因,以便尝试捕获异常的起源
错误跟踪:(未提及我的文件的任何部分)
[E 200527 21:07:19 base_events:1608] Task exception was never retrieved
future: <Task finished coro=<WebSocketProtocol13.write_message.<locals>.wrapper() done, defined at /usr/local/lib/python3.7/site-packages/tornado/websocket.py:1102> exception=WebSocketClosedError()>
Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/tornado/websocket.py", line 1104, in wrapper
await fut
tornado.iostream.StreamClosedError: Stream is closed
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/tornado/websocket.py", line 1106, in wrapper
raise WebSocketClosedError()
tornado.websocket.WebSocketClosedError
[E 200527 21:07:19 base_events:1608] Task exception was never retrieved
同一组回溯重复了16次以上
这是我的密码:
import tornado.iostream
import tornado.web
import tornado.gen
import tornado.websocket
import asyncio
class SocketHandler(tornado.websocket.WebSocketHandler):
waiters = set()
def initialize(self):
self.client_name = "newly_connected"
def get_compression_options(self):
# Non-None enables compression with default options.
return {}
def open(self):
print('connection opened')
# SocketHandler.waiters.add(self)
def on_close(self):
print("CLOSED!", self.client_name)
try:
SocketHandler.waiters.remove(self)
except KeyError:
print('tried removing new client')
def check_origin(self, origin):
# Override the origin check if needed
return True
@classmethod
async def send_updates(cls, message):
if len(cls.waiters) < 2:
while True:
chat = {}
# Prevent RuntimeError: Set changed size during iteration
waiters_copy = cls.waiters.copy()
for waiter in waiters_copy:
try:
await waiter.write_message(chat)
except tornado.websocket.WebSocketClosedError:
pass
except tornado.iostream.StreamClosedError:
pass
except Exception as e:
print('Exception e:', waiter.client_name)
pass
# sleep a bit
await asyncio.sleep(0.05)
else:
print('broadcast loop already running')
async def on_message(self, message):
print("RECEIVED :", message)
self.client_name = message
self.first_serve_cache_on_connnect()
SocketHandler.waiters.add(self)
await SocketHandler.send_updates(message)
def first_serve_cache_on_connnect(self):
print('serving cache on connect')
temp_calc_results = self.namespace.results
try:
self.write_message(temp_calc_results)
except Exception as e:
pass
我已经尝试捕获在向websocket客户端发送消息时可能导致任何错误的异常,但当客户端连接到服务器时,仍然会发生此错误
消息“TaskException was never retrieve”(任务异常从未检索)不是关于缺少的
try/except
块,而是关于缺少的await
。在first_serve_cache_on_connect
中,在不调用await
的情况下调用write_message
,因此first_serve_cache_on_connect
在引发异常时不再运行,它除了日志之外无处可去这基本上是无害的,但是如果你想清理你的日志,你需要使
first_serve_cache_on_connect
成为一个async def
协同程序,用on_message
中的await
调用它,用await
调用write_message
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