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【无法解决】Flask中用pickle去保存Websocket对象出错:TypeError a class that defines __slots__ without defining __getstate__ cannot be pickled

Flask crifan 933浏览 0评论

折腾:

【规避解决】Flask中开了多个worker时如何使用全局变量

期间,再去试试:

用Pickle+redis的方式保存对象

结果,用代码:

    gLog.debug(“gWsDict=%s”, gWsDict)
    pickledGWsDict = pickle.dumps(gWsDict)
    gLog.debug(“pickledGWsDict=%s”, pickledGWsDict)
    savePickledGWsDictResult = redis_store.set(‘gWsDict’, pickledGWsDict)
    gLog.debug(“savePickledGWsDictResult=%s”, savePickledGWsDictResult)

无法用redis+pickle去保存对象:

DEBUG in Websocket [/root/RunningFast/staging/runningfast/resources/Websocket.py:356]:
added new ws for user user-cc680b0a-8d04-4f2b-8ad9-c6fefb527861 , gWsDict={u’user-cc680b0a-8d04-4f2b-8ad9-c6fefb527861′: <geventwebsocket.websocket.WebSocket object at 0x7f9934f53de0>}

<div–<——————————————————————————

<div–<——————————————————————————

DEBUG in Websocket [/root/RunningFast/staging/runningfast/resources/Websocket.py:358]:
gWsDict={u’user-cc680b0a-8d04-4f2b-8ad9-c6fefb527861′: <geventwebsocket.websocket.WebSocket object at 0x7f9934f53de0>}

<div–<——————————————————————————

Traceback (most recent call last):
  File “/root/Envs/RunningFast/lib/python2.7/site-packages/gevent/pywsgi.py”, line 884, in handle_one_response
    self.run_application()
  File “/root/Envs/RunningFast/lib/python2.7/site-packages/geventwebsocket/handler.py”, line 76, in run_application
    self.run_websocket()
  File “/root/Envs/RunningFast/lib/python2.7/site-packages/geventwebsocket/handler.py”, line 52, in run_websocket
    self.application(self.environ, lambda s, h, e=None: [])
  File “/root/Envs/RunningFast/lib/python2.7/site-packages/flask/app.py”, line 2000, in __call__
    return self.wsgi_app(environ, start_response)
  File “/root/Envs/RunningFast/lib/python2.7/site-packages/flask_sockets.py”, line 45, in __call__
    handler(environment, **values)
  File “/root/RunningFast/staging/runningfast/resources/Websocket.py”, line 359, in userWebsocket
    pickledGWsDict = pickle.dumps(gWsDict)
  File “/usr/local/lib/python2.7/pickle.py”, line 1380, in dumps
    Pickler(file, protocol).dump(obj)
  File “/usr/local/lib/python2.7/pickle.py”, line 224, in dump
    self.save(obj)
  File “/usr/local/lib/python2.7/pickle.py”, line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File “/usr/local/lib/python2.7/pickle.py”, line 655, in save_dict
    self._batch_setitems(obj.iteritems())
  File “/usr/local/lib/python2.7/pickle.py”, line 669, in _batch_setitems
    save(v)
  File “/usr/local/lib/python2.7/pickle.py”, line 306, in save
    rv = reduce(self.proto)
  File “/root/Envs/RunningFast/lib/python2.7/copy_reg.py”, line 77, in _reduce_ex
    raise TypeError(“a class that defines __slots__ without “
TypeError: a class that defines __slots__ without defining __getstate__ cannot be pickled

看起来是此处的字典变量gWsDict保存了

geventwebsocket.websocket.WebSocket

的示例

但是

geventwebsocket.websocket.WebSocket

本身无法被pickle

因为是:

websocket TypeError  __getstate__ cannot be pickled

geventwebsocket TypeError  __getstate__ cannot be pickled

geventwebsocket global

flask global websocket object

flask-sockets active socket

Recently Active ‘flask-sockets’ Questions – Stack Overflow

python – Using gevent and Flask to implement websocket, how to achieve concurrency? – Stack Overflow

和我的问题类似:

ws可以被打开

但是别的地方,无法访问到。。。

无法用有效的办法,把当前active的ws保存起来,供别处调用。

暂时还是没有找到有效的办法,解决:

当别处需要通过ws给某个用户发送信息时

此时却无法获得对应用户的ws

因为:

无法直接有效的,把已打开的ws,加入到全局变量中

-》全局变量的话,此处由于gunicorn开了多个worker,导致不同woker中的全局变量是独立的

想要把全局变量保存到redis中,结果此处的ws的对象:

geventwebsocket.websocket.WebSocket

无法被pickle

搜:

geventwebsocket pickle

pickle geventwebsocket

geventwebsocket cannot be pickled

geventwebsocket __getstate__ cannot be pickled

pickle – Python Pickling Slots Error – Stack Overflow

python – Pickle all attributes except one – Stack Overflow

python – Why am I getting an error about my class defining __slots__ when trying to pickle an object? – Stack Overflow

gevent WebSocket __getstate__ cannot be pickled

WebSocket __getstate__ cannot be pickled

WebSocket  cannot be pickled

python – Sharing websockets object between tornado processes – Stack Overflow

也是遇到:

实时的,在线的连接,是无法被pickle序列化,保存到数据库的。

-》每个ws是被一个线程打开的

-》找到对应的线程,线程里面,或许就可以获得对应的ws了?

那人尝试了:

multiprocessing.Manager()

这个库,但是太复杂了。

-》可以考虑进程间通信,这种库,相对还是很多的。

其中redis是相对来说比较好的选择

-》那就去试试:

用redis实现进程间通信

handler exception: can’t pickle <type ‘thread.lock> · Issue #203 · kanaka/websockify

【已解决】Flask中的线程或进程间通信

【总结】

注:

如果是一般的数据(可以(通过pickel等)序列化和反序列化的),可以通过其他方式去存储。比如用redis,memchached等等。

而此处的ws,即geventwebsocket.websocket.WebSocket对象,是个实时的对象,不能用序列化的办法去保存(到redis中),因为即使可以被序列化为字符串,但是反序列化后得到的对象,也不是原先的对象了(内部的ws也就失效了,无法用ws去send消息了)

(注:且此WebSocket本身就不支持,无法被pickle序列化为字符串)

而解决的思路是:

只能去想办法拿到,实时的ws,然后去处理

-》可以通过线程间的通信,把ws传递出去,进行处理

-》而线程间通信,有多种凡事,redis是其中一种用的比较多的。

-》所以最后去通过:

【已解决】Flask中的线程或进程间通信

而通过线程间通信,解决了如何获取实时的ws对象,然后继续去处理。

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