-
Jason Madden authored
* Use a higher pickle protocol (2) for serializing objects on Python 2 Previously protocol 1 was used. This is more efficient for new-style classes (all persistent objects are new-style), according to the docs, at the cost of being very slightly less space efficient for old-style classes. In tests of a persistent object with two trivial numeric attributes, the higher protocol was 12 bytes smaller, and serialized and deserialized 1us faster. Introducing a reference to another new-style class for a more realistic test made the higher protocol twice as fast to serialize (20.5 vs 10.3us), almost half the size (215 vs 142 bytes), and it deserialized 30% faster (6.5 vs 4.6us). On Python 2, this will now allow open ``file`` objects to be pickled (loading the object will result in a closed file); previously this would result in a ``TypeError`` (as does under Python 3). We had tests that you couldn't do that with a BlobFile so I had to update it to still make that true. I wouldn't recommend serializing arbitrary open files under Python 2 (for one thing, they can't trivially be deserialized in Python 3), but I didn't take any steps to prevent it either. Since this hasn't been possible, there shouldn't be code in the wild that is trying to do it---and it wouldn't be forward compatible with Python 3 either.
be5a9d54
To find the state of this project's repository at the time of any of these versions, check out
the tags.