svn+ssh://pythondev@svn.python.org/python/branches/py3k
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r87834 | antoine.pitrou | 2011-01-07 22:43:59 +0100 (ven., 07 janv. 2011) | 5 lines
Issue #8020: Avoid a crash where the small objects allocator would read
non-Python managed memory while it is being modified by another thread.
Patch by Matt Bandy.
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The debug memory api now keeps track of which external API (PyMem_* or PyObject_*) was used to allocate each block and treats any API violation as an error. Added separate _PyMem_DebugMalloc functions for the Py_Mem API instead of having it use the _PyObject_DebugMalloc functions.
was not always being done properly in some python types and extension
modules. PyMem_MALLOC, PyMem_REALLOC, PyMem_NEW and PyMem_RESIZE have
all been updated to perform better checks and places in the code that
would previously leak memory on the error path when such an allocation
failed have been fixed.
Added checks for integer overflows, contributed by Google. Some are
only available if asserts are left in the code, in cases where they
can't be triggered from Python code.
to each allocated block. This was using 4 bytes for each such
piece of info regardless of platform. This didn't really matter
before (proof: no bug reports, and the debug-build obmalloc would
have assert-failed if it was ever asked for a chunk of memory
>= 2**32 bytes), since container indices were plain ints. But after
the Py_ssize_t changes, it's at least theoretically possible to
allocate a list or string whose guts exceed 2**32 bytes, and the
PYMALLOC_DEBUG routines would fail then (having only 4 bytes
to record the originally requested size).
Now we use sizeof(size_t) bytes for each of a PYMALLOC_DEBUG
build's extra debugging fields. This won't make any difference
on 32-bit boxes, but will add 16 bytes to each allocation in
a debug build on a 64-bit box.
This is a heavily altered derivative of SF patch 1123430, Evan
Jones's heroic effort to make obmalloc return unused arenas to
the system free(), with some heuristic strategies to make it
more likley that arenas eventually _can_ be freed.
