https://github.com/python/cpython/commit/e728b006de984ab11532f5c9cf60c57671ec37ab
commit: e728b006de984ab11532f5c9cf60c57671ec37ab
branch: main
author: Kumar Aditya <[email protected]>
committer: kumaraditya303 <[email protected]>
date: 2025-12-22T21:08:07+05:30
summary:
gh-143057: avoid locking in `tracemalloc` C-APIs when it is not enabled
(#143065)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2025-12-22-12-03-09.gh-issue-143057.Majsre.rst
M Include/internal/pycore_tracemalloc.h
M Python/tracemalloc.c
diff --git a/Include/internal/pycore_tracemalloc.h
b/Include/internal/pycore_tracemalloc.h
index 693385f9a46d12..9974ea3c4143fa 100644
--- a/Include/internal/pycore_tracemalloc.h
+++ b/Include/internal/pycore_tracemalloc.h
@@ -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.
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2025-12-22-12-03-09.gh-issue-143057.Majsre.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-22-12-03-09.gh-issue-143057.Majsre.rst
new file mode 100644
index 00000000000000..2eac8c1cfdc10c
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-22-12-03-09.gh-issue-143057.Majsre.rst
@@ -0,0 +1 @@
+Avoid locking in :c:func:`PyTraceMalloc_Track` and
:c:func:`PyTraceMalloc_Untrack` when :mod:`tracemalloc` is not enabled.
diff --git a/Python/tracemalloc.c b/Python/tracemalloc.c
index 20351618721c3b..cdd96925d1f27a 100644
--- a/Python/tracemalloc.c
+++ b/Python/tracemalloc.c
@@ -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;
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