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Pickling objects with __slots__ fails #225

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sk1p opened this issue Jan 2, 2019 · 5 comments · Fixed by #228
Closed

Pickling objects with __slots__ fails #225

sk1p opened this issue Jan 2, 2019 · 5 comments · Fixed by #228

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@sk1p
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sk1p commented Jan 2, 2019

The following minimal test case:

diff --git a/tests/cloudpickle_test.py b/tests/cloudpickle_test.py
index d318da7..fec779c 100644
--- a/tests/cloudpickle_test.py
+++ b/tests/cloudpickle_test.py
@@ -1310,6 +1310,17 @@ class CloudPickleTest(unittest.TestCase):
 
         self.assertEqual(f2.__annotations__, f.__annotations__)
 
+    def test_slots(self):
+        class WithSlots(object):
+            __slots__ = ["a"]
+
+            def __init__(self):
+                self.a = 42
+
+        obj = WithSlots()
+        obj2 = pickle_depickle(obj, protocol=self.protocol)
+        self.assertEqual(obj2.a, 42)
+
 
 class Protocol2CloudPickleTest(CloudPickleTest):

Fails with this exception:

obj = <tests.cloudpickle_test.CloudPickleTest.test_slots.<locals>.WithSlots object at 0x7f5cdc8f94c8>, protocol = 4

    def pickle_depickle(obj, protocol=cloudpickle.DEFAULT_PROTOCOL):
        """Helper function to test whether object pickled with cloudpickle can be
        depickled with pickle
        """
>       return pickle.loads(cloudpickle.dumps(obj, protocol=protocol))
E       AttributeError: type object 'WithSlots' has no attribute 'a'

obj        = <tests.cloudpickle_test.CloudPickleTest.test_slots.<locals>.WithSlots object at 0x7f5cdc8f94c8>
protocol   = 4

Pickling with pickle from the standard library works.

@pwais
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pwais commented Jan 12, 2019

Similarly, pickle can pickle a slotted object with highest protocol, but cloudpickle cannot:

# python
Python 2.7.12 (default, Dec  4 2017, 14:50:18) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> class WithSlots(object):
...   __slots__ = ["a"]
...   def __init__(self):
...     self.a = 42
... 
>>> import pickle
>>> pickle.dumps(WithSlots())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/pickle.py", line 1380, in dumps
    Pickler(file, protocol).dump(obj)
  File "/usr/lib/python2.7/pickle.py", line 224, in dump
    self.save(obj)
  File "/usr/lib/python2.7/pickle.py", line 306, in save
    rv = reduce(self.proto)
  File "/usr/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
>>> pickle.dumps(WithSlots(), -1)
'\x80\x02c__main__\nWithSlots\nq\x00)\x81q\x01N}q\x02U\x01aq\x03K*s\x86q\x04b.'

>>> import cloudpickle
>>> cloudpickle.__version__
'0.6.1'
>>> cloudpickle.dumps(WithSlots())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/cloudpickle/cloudpickle.py", line 931, in dumps
    cp.dump(obj)
  File "/usr/local/lib/python2.7/dist-packages/cloudpickle/cloudpickle.py", line 284, in dump
    return Pickler.dump(self, obj)
  File "/usr/lib/python2.7/pickle.py", line 224, in dump
    self.save(obj)
  File "/usr/lib/python2.7/pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "/usr/lib/python2.7/pickle.py", line 396, in save_reduce
    save(cls)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/local/lib/python2.7/dist-packages/cloudpickle/cloudpickle.py", line 678, in save_global
    return self.save_dynamic_class(obj)
  File "/usr/local/lib/python2.7/dist-packages/cloudpickle/cloudpickle.py", line 517, in save_dynamic_class
    save(clsdict)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 655, in save_dict
    self._batch_setitems(obj.iteritems())
  File "/usr/lib/python2.7/pickle.py", line 687, in _batch_setitems
    save(v)
  File "/usr/lib/python2.7/pickle.py", line 306, in save
    rv = reduce(self.proto)
TypeError: can't pickle member_descriptor objects

@pwais
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pwais commented Jan 12, 2019

Ah! this only occurs when the object is in the __main__ module. It also happens for older cloudpickle (I tried 0.3.1) so I don't think it's a regression.

This works:

$ cat foo.py 
class Bar(object):
  __slots__ = ('x',)
  def __init__(self):
    self.x = 5

$ python
Python 2.7.12 (default, Dec  4 2017, 14:50:18) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from foo import Bar
>>> import cloudpickle
>>> cloudpickle.dumps(Bar())
'\x80\x02cfoo\nBar\nq\x00)\x81q\x01N}q\x02U\x01xq\x03K\x05s\x86q\x04b.'

My guess is the test and/or demo don't work due to this __main__ module issue.

@ogrisel
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Contributor

ogrisel commented Jan 14, 2019

Thanks for the report @sk1p and @pwais. Is any of you interested in working on a pull request to implement support for slots in cloudpickle?

@pierreglaser you might be interested in this as well.

@pierreglaser
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Member

Indeed this should be implemented. I'll work on this.

@ogrisel
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Contributor

ogrisel commented Jan 23, 2019

@pwais @sk1p I just released cloudpickle 0.7.0 to PyPI for this new feature.

wip-sync pushed a commit to NetBSD/pkgsrc-wip that referenced this issue Apr 4, 2022
2.0.0
=====

- Python 3.5 is no longer supported.

- Support for registering modules to be serialised by value. This allows code
  defined in local modules to be serialised and executed remotely without those
  local modules installed on the remote machine.
  ([PR #417](cloudpipe/cloudpickle#417))

- Fix a side effect altering dynamic modules at pickling time.
  ([PR #426](cloudpipe/cloudpickle#426))

- Support for pickling type annotations on Python 3.10 as per [PEP 563](
  https://www.python.org/dev/peps/pep-0563/)
  ([PR #400](cloudpipe/cloudpickle#400))

- Stricter parametrized type detection heuristics in
  _is_parametrized_type_hint to limit false positives.
  ([PR #409](cloudpipe/cloudpickle#409))

- Support pickling / depickling of OrderedDict KeysView, ValuesView, and
  ItemsView, following similar strategy for vanilla Python dictionaries.
  ([PR #423](cloudpipe/cloudpickle#423))

- Suppressed a source of non-determinism when pickling dynamically defined
  functions and handles the deprecation of co_lnotab in Python 3.10+.
  ([PR #428](cloudpipe/cloudpickle#428))

1.6.0
=====

- `cloudpickle`'s pickle.Pickler subclass (currently defined as
  `cloudpickle.cloudpickle_fast.CloudPickler`) can and should now be accessed
  as `cloudpickle.Pickler`. This is the only officially supported way of
  accessing it.
  ([issue #366](cloudpipe/cloudpickle#366))

- `cloudpickle` now supports pickling `dict_keys`, `dict_items` and
  `dict_values`.
  ([PR #384](cloudpipe/cloudpickle#384))

1.5.0
=====

- Fix a bug causing cloudpickle to crash when pickling dynamically created,
  importable modules.
  ([issue #360](cloudpipe/cloudpickle#354))

- Add optional dependency on `pickle5` to get improved performance on
  Python 3.6 and 3.7.
  ([PR #370](cloudpipe/cloudpickle#370))

- Internal refactoring to ease the use of `pickle5` in cloudpickle
  for Python 3.6 and 3.7.
  ([PR #368](cloudpipe/cloudpickle#368))

1.4.1
=====

- Fix incompatibilities between cloudpickle 1.4.0 and Python 3.5.0/1/2
  introduced by the new support of cloudpickle for pickling typing constructs.
  ([issue #360](cloudpipe/cloudpickle#360))

- Restore compat with loading dynamic classes pickled with cloudpickle
  version 1.2.1 that would reference the `types.ClassType` attribute.
  ([PR #359](cloudpipe/cloudpickle#359))

1.4.0
=====

**This version requires Python 3.5 or later**

- cloudpickle can now all pickle all constructs from the ``typing`` module
  and the ``typing_extensions`` library in Python 3.5+
  ([PR #318](cloudpipe/cloudpickle#318))

- Stop pickling the annotations of a dynamic class for Python < 3.6
  (follow up on #276)
  ([issue #347](cloudpipe/cloudpickle#347))

- Fix a bug affecting the pickling of dynamic `TypeVar` instances on Python 3.7+,
  and expand the support for pickling `TypeVar` instances (dynamic or non-dynamic)
  to Python 3.5-3.6 ([PR #350](cloudpipe/cloudpickle#350))

- Add support for pickling dynamic classes subclassing `typing.Generic`
  instances on Python 3.7+
  ([PR #351](cloudpipe/cloudpickle#351))

1.3.0
=====

- Fix a bug affecting dynamic modules occuring with modified builtins
  ([issue #316](cloudpipe/cloudpickle#316))

- Fix a bug affecting cloudpickle when non-modules objects are added into
  sys.modules
  ([PR #326](cloudpipe/cloudpickle#326)).

- Fix a regression in cloudpickle and python3.8 causing an error when trying to
  pickle property objects.
  ([PR #329](cloudpipe/cloudpickle#329)).

- Fix a bug when a thread imports a module while cloudpickle iterates
  over the module list
  ([PR #322](cloudpipe/cloudpickle#322)).

- Add support for out-of-band pickling (Python 3.8 and later).
  https://docs.python.org/3/library/pickle.html#example
  ([issue #308](cloudpipe/cloudpickle#308))

- Fix a side effect that would redefine `types.ClassTypes` as `type`
  when importing cloudpickle.
  ([issue #337](cloudpipe/cloudpickle#337))

- Fix a bug affecting subclasses of slotted classes.
  ([issue #311](cloudpipe/cloudpickle#311))

- Dont pickle the abc cache of dynamically defined classes for Python 3.6-
  (This was already the case for python3.7+)
  ([issue #302](cloudpipe/cloudpickle#302))

1.2.2
=====

- Revert the change introduced in
  ([issue #276](cloudpipe/cloudpickle#276))
  attempting to pickle functions annotations for Python 3.4 to 3.6. It is not
  possible to pickle complex typing constructs for those versions (see
  [issue #193]( cloudpipe/cloudpickle#193))

- Fix a bug affecting bound classmethod saving on Python 2.
  ([issue #288](cloudpipe/cloudpickle#288))

- Add support for pickling "getset" descriptors
  ([issue #290](cloudpipe/cloudpickle#290))

1.2.1
=====

- Restore (partial) support for Python 3.4 for downstream projects that have
  LTS versions that would benefit from cloudpickle bug fixes.

1.2.0
=====

- Leverage the C-accelerated Pickler new subclassing API (available in Python
  3.8) in cloudpickle. This allows cloudpickle to pickle Python objects up to
  30 times faster.
  ([issue #253](cloudpipe/cloudpickle#253))

- Support pickling of classmethod and staticmethod objects in python2.
  arguments. ([issue #262](cloudpipe/cloudpickle#262))

- Add support to pickle type annotations for Python 3.5 and 3.6 (pickling type
  annotations was already supported for Python 3.7, Python 3.4 might also work
  but is no longer officially supported by cloudpickle)
  ([issue #276](cloudpipe/cloudpickle#276))

- Internal refactoring to proactively detect dynamic functions and classes when
  pickling them.  This refactoring also yields small performance improvements
  when pickling dynamic classes (~10%)
  ([issue #273](cloudpipe/cloudpickle#273))

1.1.1
=====

- Minor release to fix a packaging issue (Markdown formatting of the long
  description rendered on pypi.org). The code itself is the same as 1.1.0.

1.1.0
=====

- Support the pickling of interactively-defined functions with positional-only
  arguments. ([issue #266](cloudpipe/cloudpickle#266))

- Track the provenance of dynamic classes and enums so as to preseve the
  usual `isinstance` relationship between pickled objects and their
  original class defintions.
  ([issue #246](cloudpipe/cloudpickle#246))

1.0.0
=====

- Fix a bug making functions with keyword-only arguments forget the default
  values of these arguments after being pickled.
  ([issue #264](cloudpipe/cloudpickle#264))

0.8.1
=====

- Fix a bug (already present before 0.5.3 and re-introduced in 0.8.0)
  affecting relative import instructions inside depickled functions
  ([issue #254](cloudpipe/cloudpickle#254))

0.8.0
=====

- Add support for pickling interactively defined dataclasses.
  ([issue #245](cloudpipe/cloudpickle#245))

- Global variables referenced by functions pickled by cloudpickle are now
  unpickled in a new and isolated namespace scoped by the CloudPickler
  instance. This restores the (previously untested) behavior of cloudpickle
  prior to changes done in 0.5.4 for functions defined in the `__main__`
  module, and 0.6.0/1 for other dynamic functions.

0.7.0
=====

- Correctly serialize dynamically defined classes that have a `__slots__`
  attribute.
  ([issue #225](cloudpipe/cloudpickle#225))

0.6.1
=====

- Fix regression in 0.6.0 which breaks the pickling of local function defined
  in a module, making it impossible to access builtins.
  ([issue #211](cloudpipe/cloudpickle#211))

0.6.0
=====

- Ensure that unpickling a function defined in a dynamic module several times
  sequentially does not reset the values of global variables.
  ([issue #187](cloudpipe/cloudpickle#205))

- Restrict the ability to pickle annotations to python3.7+ ([issue #193](
  cloudpipe/cloudpickle#193) and [issue #196](
  cloudpipe/cloudpickle#196))

- Stop using the deprecated `imp` module under Python 3.
  ([issue #207](cloudpipe/cloudpickle#207))

- Fixed pickling issue with singleton types `NoneType`, `type(...)` and
  `type(NotImplemented)` ([issue #209](cloudpipe/cloudpickle#209))

0.5.6
=====

- Ensure that unpickling a locally defined function that accesses the global
  variables of a module does not reset the values of the global variables if
  they are already initialized.
  ([issue #187](cloudpipe/cloudpickle#187))

0.5.5
=====

- Fixed inconsistent version in `cloudpickle.__version__`.

0.5.4
=====

- Fixed a pickling issue for ABC in python3.7+ ([issue #180](
  cloudpipe/cloudpickle#180)).

- Fixed a bug when pickling functions in `__main__` that access global
  variables ([issue #187](
  cloudpipe/cloudpickle#187)).

0.5.3
=====
- Fixed a crash in Python 2 when serializing non-hashable instancemethods of built-in
  types ([issue #144](cloudpipe/cloudpickle#144)).

- itertools objects can also pickled
  ([PR #156](cloudpipe/cloudpickle#156)).

- `logging.RootLogger` can be also pickled
  ([PR #160](cloudpipe/cloudpickle#160)).

0.5.2
=====

- Fixed a regression: `AttributeError` when loading pickles that hold a
  reference to a dynamically defined class from the `__main__` module.
  ([issue #131]( cloudpipe/cloudpickle#131)).

- Make it possible to pickle classes and functions defined in faulty
  modules that raise an exception when trying to look-up their attributes
  by name.

0.5.1
=====

- Fixed `cloudpickle.__version__`.

0.5.0
=====

- Use `pickle.HIGHEST_PROTOCOL` by default.

0.4.4
=====

- `logging.RootLogger` can be also pickled
  ([PR #160](cloudpipe/cloudpickle#160)).

0.4.3
=====

- Fixed a regression: `AttributeError` when loading pickles that hold a
  reference to a dynamically defined class from the `__main__` module.
  ([issue #131]( cloudpipe/cloudpickle#131)).

- Fixed a crash in Python 2 when serializing non-hashable instancemethods of built-in
  types. ([issue #144](cloudpipe/cloudpickle#144))

0.4.2
=====

- Restored compatibility with pickles from 0.4.0.
- Handle the `func.__qualname__` attribute.

0.4.1
=====

- Fixed a crash when pickling dynamic classes whose `__dict__` attribute was
  defined as a [`property`](https://docs.python.org/3/library/functions.html#property).
  Most notably, this affected dynamic [namedtuples](https://docs.python.org/2/library/collections.html#namedtuple-factory-function-for-tuples-with-named-fields)
  in Python 2. (cloudpipe/cloudpickle#113)
- Cloudpickle now preserves the `__module__` attribute of functions (cloudpipe/cloudpickle#118).
- Fixed a crash when pickling modules that don't have a `__package__` attribute (cloudpipe/cloudpickle#116).

0.4.0
=====

* Fix functions with empty cells
* Allow pickling Logger objects
* Fix crash when pickling dynamic class cycles
* Ignore "None" mdoules added to sys.modules
* Support WeakSets and ABCMeta instances
* Remove non-standard `__transient__` support
* Catch exception from `pickle.whichmodule()`

0.3.1
=====

* Fix version information and ship a changelog

 0.3.0
=====

* Import submodules accessed by pickled functions
* Support recursive functions inside closures
* Fix `ResourceWarnings` and `DeprecationWarnings`
* Assume modules with `__file__` attribute are not dynamic

0.2.2
=====

* Support Python 3.6
* Support Tornado Coroutines
* Support builtin methods
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