gh-154139: Document that curses is not thread-safe - #154173
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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 <noreply@anthropic.com>
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GH-155690 is a backport of this pull request to the 3.15 branch. |
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GH-155691 is a backport of this pull request to the 3.14 branch. |
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GH-155692 is a backport of this pull request to the 3.13 branch. |
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…GH-155692) 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. The reference to window.use() and screen.use() is omitted: they were added in 3.16. (cherry picked from commit 1ed6b78) Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
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…GH-155691) 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. The reference to window.use() and screen.use() is omitted: they were added in 3.16. (cherry picked from commit 1ed6b78) Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
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…4173) 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 <noreply@anthropic.com>
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Documents the thread-safety limitation reported in #154139.
_cursesreleases the GIL around the blocking and refresh calls (getch,refresh, …), so with a non-reentrant curses — the default ncurses build on many systems — two threads can race on the shared global screen state and crash the interpreter. Whether curses is usable from multiple threads depends on the library and how it was built, so this is a documentation gap rather than a missing lock in CPython.The note points to serializing the calls or wrapping them in
window.use()/screen.use(), which lock only when the library is built with reentrant support.