https://github.com/python/cpython/commit/1ed6b78232a8739aa3b1ee1ce7ce2e1d998e3607
commit: 1ed6b78232a8739aa3b1ee1ce7ce2e1d998e3607
branch: main
author: Serhiy Storchaka <[email protected]>
committer: serhiy-storchaka <[email protected]>
date: 2026-08-13T13:15:29+03:00
summary:

gh-154139: Document that curses is not thread-safe (GH-154173)

Whether curses is thread-safe depends on the library and how it was built.
The blocking and refresh methods release the GIL, so with a non-reentrant
curses, unsynchronized use from several threads can crash.

Co-authored-by: Claude Opus 4.8 <[email protected]>

files:
M Doc/library/curses.rst

diff --git a/Doc/library/curses.rst b/Doc/library/curses.rst
index a833914a5d56d4..04cf2e17d538fc 100644
--- a/Doc/library/curses.rst
+++ b/Doc/library/curses.rst
@@ -31,6 +31,19 @@ Linux and the BSD variants of Unix.
    Whenever the documentation mentions a *character string* it can be specified
    as a Unicode string or a byte string.
 
+.. note::
+
+   Whether curses may be used from several threads
+   depends on the underlying library and how it was built.
+   In many implementations, including the default build of ncurses,
+   the screen state is shared and not thread-safe;
+   since the blocking and refresh methods
+   (such as :meth:`~window.getch` and :meth:`~window.refresh`)
+   release the :term:`GIL`,
+   unsynchronized use from several threads can then crash the interpreter.
+   Serialize the calls,
+   or wrap them in :meth:`window.use` and :meth:`screen.use`.
+
 .. seealso::
 
    Module :mod:`curses.ascii`

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