[2.7] bpo-35368: Make PyMem_Malloc() thread-safe in debug mode by vstinner · Pull Request #10828 · python/cpython (original) (raw)
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When Python is compiled in debug mode, PyMem_Malloc() uses debug
hooks, but it also uses pymalloc allocator instead of malloc().
Problem: pymalloc is not thread-safe, whereas PyMem_Malloc() is
thread-safe in release mode (it's a thin wrapper to malloc() in this
case).
Modify the debug hook to use malloc() for PyMem_Malloc().
https://bugs.python.org/issue35368
I wrote this PR because I used PyMem_Malloc()/PyMem_Free() in PyThread_start_new_thread() whereas PyMem_Malloc()/PyMem_Free() are not thread safe when Python is build is debug mode and I didn't know that!
https://bugs.python.org/issue33015#msg330806
But I fixed PyThread_start_new_thread() using PR #10829 (commit bc9f53f). So this change is not strictly needed.
@serhiy-storchaka, @benjaminp: Is it too late to fix PyMem_Malloc() to make it thread-safe in Python 2.7?
When Python is compiled in debug mode, PyMem_Malloc() uses debug hooks, but it also uses pymalloc allocator instead of malloc(). Problem: pymalloc is not thread-safe, whereas PyMem_Malloc() is thread-safe in release mode (it's a thin wrapper to malloc() in this case).
Modify the debug hook to use malloc() for PyMem_Malloc().
[2.7] bpo-33015: Make PyMem_Malloc() thread-safe in debug mode [2.7] bpo-35368: Make PyMem_Malloc() thread-safe in debug mode
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Debug mode changes are probably okay.
Thanks for the review @benjaminp! Hopefully, I don't think that anyone uses PyMem_Malloc() without holding the GIL in Python 2 ;-)