How can I know if python 3 is using cPickle or Pickle?

Question

I saw these two answers about Pickle and cPickle having dealt automatically by python 3, transparent to the user:

How can I know if in python 3, it is using the fast version (cPickle) or not? I want to force it to use cPickle. My main interest is not even on the speed, but on the shorter size of the files, since I am generating files that end up being bigger than 1 GB.

Martijn Pieters · Accepted Answer · 2019-03-29T15:47:35.990

7

Unless you build your Python binary from source, you almost certainly are using the C extension.

However, if you must be certain, check if the _pickle module can be imported:

>>> import _pickle

The pickle module imports _pickle and only if that fails with an ImportError would it be using the pure-Python implementation.

Just to be explicit: what was called cPickle in Python 2 has been renamed to _pickle and is imported transparently, you don't have to do anything explicit to make use of it. That there was a split between pickle and cPickle in Python 2 was just plain confusing.

edited Mar 29 '19 at 15:47

answered Mar 28 '19 at 20:13

Martijn Pieters

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would I know if the import failed? – Homero Esmeraldo Mar 28 '19 at 22:57
Then `ImportError` is raised. It’s just a module, either it is available and so will be used, or the import fails with the usual `ImportError` exception. – Martijn Pieters Mar 28 '19 at 22:58
Wouldn't `ImportError` be treated internally, instead of printing it to me, since it will just import the pure python pickle module instead? – Homero Esmeraldo Mar 28 '19 at 23:02
I never installed cPickle manually, so I just want to make sure it is using that. I will test importing `_pickle` to see if anything changes – Homero Esmeraldo Mar 28 '19 at 23:04
You can still determine if the `_pickle` module can be imported. If it can, then it won’t fail to import when you use the `pickle` module. – Martijn Pieters Mar 28 '19 at 23:06
1

Again, there is no cPickle module in Python 3. That module was replaced with `_pickle` in Python 3. – Martijn Pieters Mar 28 '19 at 23:08

How can I know if python 3 is using cPickle or Pickle?

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