如何通過cloudpickle腌制python-attrs類函數？

Question

我正在使用 cloudpickle 來傳遞函數，我想通過 cloudpickle 傳遞一個attrs類函數。

import pickle
import attr

@attr.s(auto_attribs=True)
class myclass:
    an_int: int
    a_str: str
    a_float: float

    def myfunc(self):
        return f"{self.an_int} + {self.a_str} + {self.a_float}"

mc = myclass(1, "test", 2.4)
f = pickle.loads(pickle.dumps(mc.myfunc))
print(f())

運行這給了我1 + test + 2.4

而 cloudpickle 的實現

import attr
import cloudpickle

@attr.s(auto_attribs=True)
class myclass:
    an_int: int
    a_str: str
    a_float: float

    def myfunc(self):
        return f"{self.an_int} + {self.a_str} + {self.a_float}"

mc = myclass(1, "test", 2.4)
f = cloudpickle.loads(cloudpickle.dumps(mc.myfunc))
print(f())

給了我錯誤： TypeError: can't pickle _thread._local objects （我將在底部發布完整的錯誤日志）

我相信我需要實現一些__getstate__或__reduce__函數來讓 cloudpickle 對類進行腌制，但我已經嘗試過兩者都沒有任何運氣。

添加功能：

def __reduce__(self):
    return (self.__class__, (self.an_int, self.a_str, self.a_float))

給出同樣的錯誤

為了實現這一目標，我應該實施什么？

蟒蛇錯誤日志：

Traceback (most recent call last):
  File "x.py", line 16, in <module>
    f = cloudpickle.loads(cloudpickle.dumps(mc.myfunc))
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/site-packages/cloudpickle/cloudpickle.py", line 917, in dumps
    cp.dump(obj)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/site-packages/cloudpickle/cloudpickle.py", line 268, in dump
    return Pickler.dump(self, obj)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 437, in dump
    self.save(obj)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 504, in save
    f(self, obj) # Call unbound method with explicit self
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/site-packages/cloudpickle/cloudpickle.py", line 689, in save_instancemethod
    self.save_reduce(types.MethodType, (obj.__func__, obj.__self__), obj=obj)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 638, in save_reduce
    save(args)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 504, in save
    f(self, obj) # Call unbound method with explicit self
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 771, in save_tuple
    save(element)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 549, in save
    self.save_reduce(obj=obj, *rv)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 633, in save_reduce
    save(cls)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 504, in save
    f(self, obj) # Call unbound method with explicit self
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/site-packages/cloudpickle/cloudpickle.py", line 664, in save_global
    return self.save_dynamic_class(obj)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/site-packages/cloudpickle/cloudpickle.py", line 511, in save_dynamic_class
    save(clsdict)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 504, in save
    f(self, obj) # Call unbound method with explicit self
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 856, in save_dict
    self._batch_setitems(obj.items())
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 882, in _batch_setitems
    save(v)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 504, in save
    f(self, obj) # Call unbound method with explicit self
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/site-packages/cloudpickle/cloudpickle.py", line 408, in save_function
    self.save_function_tuple(obj)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/site-packages/cloudpickle/cloudpickle.py", line 573, in save_function_tuple
    save(state)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 504, in save
    f(self, obj) # Call unbound method with explicit self
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 856, in save_dict
    self._batch_setitems(obj.items())
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 882, in _batch_setitems
    save(v)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 504, in save
    f(self, obj) # Call unbound method with explicit self
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 856, in save_dict
    self._batch_setitems(obj.items())
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 882, in _batch_setitems
    save(v)
  File "/home/me/.local/share/pyenv/versions/3.7.0/lib/python3.7/pickle.py", line 524, in save
    rv = reduce(self.proto)
TypeError: can't pickle _thread._local objects

Answer 1

這是由於attrs使用線程__repr__來分解__repr__對象循環，而 cloudpickle 不喜歡這樣。 作為參考，它是在https://github.com/python-attrs/attrs/pull/358中介紹的。

您的快速解決方法是設置@attr.s(repr=False)但隨時在我們的錯誤跟蹤器上打開一個問題，我們可以討論如何繼續。