gh-144706: Warn against using synchronization primitives within signal handlers (GH-144736)

robsdedude · web-flow · commit 945bf8ce1bf7 · 2026-02-12T18:15:23.000-05:00
diff --git a/Doc/library/signal.rst b/Doc/library/signal.rst
@@ -68,6 +68,11 @@ the synchronization primitives from the :mod:`threading` module instead.
 
 Besides, only the main thread of the main interpreter is allowed to set a new signal handler.
 
+.. warning::
+
+   Synchronization primitives such as :class:`threading.Lock` should not be used
+   within signal handlers.  Doing so can lead to unexpected deadlocks.
+
 
 Module contents
 ---------------
