The picklers do no longer allocate temporary memory when dumping large
bytes and str objects into a file object. Instead the data is
directly streamed into the underlying file object.
Previously the C implementation would buffer all content and issue a
single call to file.write() at the end of the dump. With protocol 4
this behavior has changed to issue one call to file.write() per frame.
The Python pickler with protocol 4 now dumps each frame content as a
memoryview to an IOBytes instance that is never reused and the
memoryview is no longer released after the call to write. This makes it
possible for the file object to delay access to the memoryview of
previous frames without forcing any additional memory copy as was
already possible with the C pickler.
This changes the main documentation, doc strings, source code comments, and a
couple error messages in the test suite. In some cases the word was removed
or edited some other way to fix the grammar.
Fixed ambigious reverse mappings. Added many new mappings. Import mapping
is no longer applied to modules already mapped with full name mapping.
Added tests for compatible pickling and unpickling and for consistency of
_compat_pickle mappings.
Initial patch by Merlijn van Deen.
I've added a few unrelated docstring fixes in the patch while I was at
it, which makes the documentation for pickle a bit more consistent.
