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gh-143057: avoid locking in tracemalloc C-APIs when it is not enabled (#143065)

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Kumar Aditya 2025-12-22 21:08:07 +05:30 • committed by GitHub
parent 9ded3dd4e9
commit e728b006de
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3 changed files with 16 additions and 3 deletions
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5
Include/internal/pycore_tracemalloc.h
View file

@ -21,7 +21,10 @@ struct _PyTraceMalloc_Config {
} initialized;
/* Is tracemalloc tracing memory allocations?
Variable protected by the TABLES_LOCK(). */
Variable protected by the TABLES_LOCK() and stored atomically.
Atomic store is used so that it can read without locking for the
general case of checking if tracemalloc is enabled.
*/
int tracing;
/* limit of the number of frames in a traceback, 1 by default.

1
Misc/NEWS.d/next/Core_and_Builtins/2025-12-22-12-03-09.gh-issue-143057.Majsre.rst Normal file
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@ -0,0 +1 @@
Avoid locking in :c:func:`PyTraceMalloc_Track` and :c:func:`PyTraceMalloc_Untrack` when :mod:`tracemalloc` is not enabled.

13
Python/tracemalloc.c
View file

@ -850,7 +850,7 @@ _PyTraceMalloc_Start(int max_nframe)
/* everything is ready: start tracing Python memory allocations */
TABLES_LOCK();
tracemalloc_config.tracing = 1;
_Py_atomic_store_int_relaxed(&tracemalloc_config.tracing, 1);
TABLES_UNLOCK();
return 0;
@ -867,7 +867,7 @@ _PyTraceMalloc_Stop(void)
}
/* stop tracing Python memory allocations */
tracemalloc_config.tracing = 0;
_Py_atomic_store_int_relaxed(&tracemalloc_config.tracing, 0);
/* unregister the hook on memory allocators */
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &allocators.raw);
@ -1207,6 +1207,10 @@ int
PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr,
size_t size)
{
if (_Py_atomic_load_int_relaxed(&tracemalloc_config.tracing) == 0) {
/* tracemalloc is not tracing: do nothing */
return -2;
}
PyGILState_STATE gil_state = PyGILState_Ensure();
TABLES_LOCK();
@ -1228,6 +1232,11 @@ PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr,
int
PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr)
{
if (_Py_atomic_load_int_relaxed(&tracemalloc_config.tracing) == 0) {
/* tracemalloc is not tracing: do nothing */
return -2;
}
TABLES_LOCK();
int result;