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| -rw-r--r-- | Doc/whatsnew/whatsnew25.tex | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/Doc/whatsnew/whatsnew25.tex b/Doc/whatsnew/whatsnew25.tex index 958b3be..4733b38 100644 --- a/Doc/whatsnew/whatsnew25.tex +++ b/Doc/whatsnew/whatsnew25.tex @@ -1453,6 +1453,23 @@ actually drop when you delete them, and the memory may be returned to the operating system. (Implemented by Evan Jones, and reworked by Tim Peters.) +Note that this change means extension modules need to be more careful +with how they allocate memory. Python's API has a number of different +functions for allocating memory that are grouped into families. For +example, \cfunction{PyMem_Malloc()}, \cfunction{PyMem_Realloc()}, and +\cfunction{PyMem_Free()} are one family that allocates raw memory, +while \cfunction{PyObject_Malloc()}, \cfunction{PyObject_Realloc()}, +and \cfunction{PyObject_Free()} are another family that's supposed to +be used for creating Python objects. + +Previously these different families all reduced to the platform's +\cfunction{malloc()} and \cfunction{free()} functions. This meant +it didn't matter if you got things wrong and allocated memory with the +\cfunction{PyMem} function but freed it with the \cfunction{PyObject} +function. With the obmalloc change, these families now do different +things, and mismatches will probably result in a segfault. You should +carefully test your C extension modules with Python 2.5. + \item Coverity, a company that markets a source code analysis tool called Prevent, provided the results of their examination of the Python source code. The analysis found a number of refcounting bugs, often @@ -1472,6 +1489,21 @@ changes to your code: \item The \module{pickle} module no longer uses the deprecated \var{bin} parameter. +\item C API: Many functions now use \ctype{Py_ssize_t} +instead of \ctype{int} to allow processing more data +on 64-bit machines. Extension code may need to make +the same change to avoid warnings and to support 64-bit machines. +See the earlier +section~ref{section-353} for a discussion of this change. + +\item C API: +The obmalloc changes mean that +you must be careful to not mix usage +of the \cfunction{PyMem_*()} and \cfunction{PyObject_*()} +families of functions. Memory allocated with +one family's \cfunction{*_Malloc()} must be +freed with the corresponding family's \cfunction{*_Free()} function. + \end{itemize} |