From 5f57f6970bdea45cc2b192d612bfd8199f51491e Mon Sep 17 00:00:00 2001
From: Divyanshu Choudhury <divyanshuchoudhury3@gmail.com>
Date: Fri, 30 Jan 2026 06:05:30 +0530
Subject: [PATCH] gh-143423: Fix free-threaded build detection in sampling
 profiler (#143426)

---
 Lib/profiling/sampling/sample.py              | 29 +++++++++++--------
 ...-01-05-05-31-05.gh-issue-143423.X7YdnR.rst |  1 +
 2 files changed, 18 insertions(+), 12 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2026-01-05-05-31-05.gh-issue-143423.X7YdnR.rst

diff --git a/Lib/profiling/sampling/sample.py b/Lib/profiling/sampling/sample.py
index e73306ebf290..f657849e72bb 100644
--- a/Lib/profiling/sampling/sample.py
+++ b/Lib/profiling/sampling/sample.py
@@ -42,6 +42,7 @@ except ImportError:
     LiveStatsCollector = None
 
 _FREE_THREADED_BUILD = sysconfig.get_config_var("Py_GIL_DISABLED") is not None
+
 # Minimum number of samples required before showing the TUI
 # If fewer samples are collected, we skip the TUI and just print a message
 MIN_SAMPLES_FOR_TUI = 200
@@ -64,19 +65,23 @@ class SampleProfiler:
         self.realtime_stats = False
 
     def _new_unwinder(self, native, gc, opcodes, skip_non_matching_threads):
-        if _FREE_THREADED_BUILD:
-            unwinder = _remote_debugging.RemoteUnwinder(
-                self.pid, all_threads=self.all_threads, mode=self.mode, native=native, gc=gc,
-                opcodes=opcodes, skip_non_matching_threads=skip_non_matching_threads,
-                cache_frames=True, stats=self.collect_stats
-            )
+        kwargs = {}
+        if _FREE_THREADED_BUILD or self.all_threads:
+            kwargs['all_threads'] = self.all_threads
         else:
-            unwinder = _remote_debugging.RemoteUnwinder(
-                self.pid, only_active_thread=bool(self.all_threads), mode=self.mode, native=native, gc=gc,
-                opcodes=opcodes, skip_non_matching_threads=skip_non_matching_threads,
-                cache_frames=True, stats=self.collect_stats
-            )
-        return unwinder
+            kwargs['only_active_thread'] = bool(self.all_threads)
+
+        return _remote_debugging.RemoteUnwinder(
+            self.pid,
+            mode=self.mode,
+            native=native,
+            gc=gc,
+            opcodes=opcodes,
+            skip_non_matching_threads=skip_non_matching_threads,
+            cache_frames=True,
+            stats=self.collect_stats,
+            **kwargs
+        )
 
     def sample(self, collector, duration_sec=None, *, async_aware=False):
         sample_interval_sec = self.sample_interval_usec / 1_000_000
diff --git a/Misc/NEWS.d/next/Library/2026-01-05-05-31-05.gh-issue-143423.X7YdnR.rst b/Misc/NEWS.d/next/Library/2026-01-05-05-31-05.gh-issue-143423.X7YdnR.rst
new file mode 100644
index 000000000000..d9276dfd400a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-01-05-05-31-05.gh-issue-143423.X7YdnR.rst
@@ -0,0 +1 @@
+Fix free-threaded build detection in the sampling profiler when Py_GIL_DISABLED is set to 0.
-- 
2.47.3