https://github.com/python/cpython/commit/c749534b06fd4b4bf99fed1b0cc3e6e5596744e7
commit: c749534b06fd4b4bf99fed1b0cc3e6e5596744e7
branch: 3.14
author: Donghee Na <[email protected]>
committer: corona10 <[email protected]>
date: 2026-08-13T15:20:04Z
summary:
[3.14] gh-129752: Don't update adaptive counters when TLBC=0 in free-threading.
(gh-155497) (gh-155715)
(cherry picked from commit ee4fe00a8f72ea84a421bb626d7c78335c5c9ea1)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2026-08-11-01-45-24.gh-issue-129752.Zo3OUx.rst
M Lib/test/test_thread_local_bytecode.py
M Python/ceval_macros.h
diff --git a/Lib/test/test_thread_local_bytecode.py
b/Lib/test/test_thread_local_bytecode.py
index d5c56db8d5da58..6ea0e777e02605 100644
--- a/Lib/test/test_thread_local_bytecode.py
+++ b/Lib/test/test_thread_local_bytecode.py
@@ -108,7 +108,6 @@ def f(a, b, q=None):
""")
assert_python_ok("-X", "tlbc=1", "-c", code)
- @support.skip_if_sanitizer("gh-129752: data race on adaptive counter",
thread=True)
def test_no_copies_if_tlbc_disabled(self):
code = textwrap.dedent("""
import queue
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2026-08-11-01-45-24.gh-issue-129752.Zo3OUx.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2026-08-11-01-45-24.gh-issue-129752.Zo3OUx.rst
new file mode 100644
index 00000000000000..aad13dc0adef34
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2026-08-11-01-45-24.gh-issue-129752.Zo3OUx.rst
@@ -0,0 +1,2 @@
+Don't update adaptive counters in the free-threaded build when thread-local
+bytecode is disabled (``-X tlbc=0``). Patch by Donghee Na.
diff --git a/Python/ceval_macros.h b/Python/ceval_macros.h
index 95a8e719d4d0d1..c75c0b2410c677 100644
--- a/Python/ceval_macros.h
+++ b/Python/ceval_macros.h
@@ -285,6 +285,25 @@ GETITEM(PyObject *v, Py_ssize_t i) {
#define ADAPTIVE_COUNTER_TRIGGERS(COUNTER) \
backoff_counter_triggers(forge_backoff_counter((COUNTER)))
+#ifdef Py_GIL_DISABLED
+/* Counters are unreachable when thread-local bytecode is disabled,
+ * so there is no need to update them. */
+#define ADVANCE_ADAPTIVE_COUNTER(COUNTER) \
+ do { \
+ _Py_BackoffCounter cnt = (COUNTER); \
+ if (!is_unreachable_backoff_counter(cnt)) { \
+ (COUNTER) = advance_backoff_counter(cnt); \
+ } \
+ } while (0);
+
+#define PAUSE_ADAPTIVE_COUNTER(COUNTER) \
+ do { \
+ _Py_BackoffCounter cnt = (COUNTER); \
+ if (!is_unreachable_backoff_counter(cnt)) { \
+ (COUNTER) = pause_backoff_counter(cnt); \
+ } \
+ } while (0);
+#else
#define ADVANCE_ADAPTIVE_COUNTER(COUNTER) \
do { \
(COUNTER) = advance_backoff_counter((COUNTER)); \
@@ -294,6 +313,7 @@ GETITEM(PyObject *v, Py_ssize_t i) {
do { \
(COUNTER) = pause_backoff_counter((COUNTER)); \
} while (0);
+#endif
#ifdef ENABLE_SPECIALIZATION_FT
/* Multiple threads may execute these concurrently if thread-local bytecode is
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