python - pickle 错误 : Can't pickle

Question

我想知道这个错误可能意味着什么:

PicklingError: Can't pickle <type 'function'>: attribute lookup __builtin__.function failed

我理解这与使用多核有关。我在集群上运行我的程序，并在我的这行代码中使用 15 个线程:

gauss2 = PTSampler(ntemps, renwalkers, rendim, lnlike, lnprior, threads=15)

有问题的采样器是在 http://dan.iel.fm/emcee/current/user/pt/ 上为并行回火采样器记录的采样器。

知道这个错误可能意味着什么吗？

Answer 1

该错误意味着您正在尝试 pickle 内置 FunctionType... 而不是函数本身。这很可能是在某处选择函数的类而不是函数本身的编码错误。

>>> import sys
>>> import pickle
>>> import types
>>> types.FunctionType
<type 'function'>
>>> try:
...     pickle.dumps(types.FunctionType)
... except:
...     print sys.exc_info()[1]
... 
Can't pickle <type 'function'>: it's not found as __builtin__.function
>>> def foo(x):
...   return x
... 
>>> try:
...     pickle.dumps(type(foo))
... except:
...     print sys.exc_info()[1]
... 
Can't pickle <type 'function'>: it's not found as __builtin__.function
>>> try:
...     pickle.dumps(foo.__class__)
... except:
...     print sys.exc_info()[1]
... 
Can't pickle <type 'function'>: it's not found as __builtin__.function
>>> pickle.dumps(foo)
'c__main__\nfoo\np0\n.'
>>> pickle.dumps(foo, -1)
'\x80\x02c__main__\nfoo\nq\x00.'

如果您有一个 FunctionType 对象，那么您需要做的就是获取该类的实例之一——即像 foo 这样的函数。