posixmodule ignores signals in os_openpty_impl and os_grantpt_impl by wrapping them in two PyOS_setsig calls:

   sig_saved = PyOS_setsig(SIGCHLD, SIG_DFL);
    ...
    PyOS_setsig(SIGCHLD, sig_saved);

This relies on the GIL being held, so it probably needs a dedicated lock in free-threading builds.

Linked PRs

• gh-114727: Update os_{openpty|grantpt}_impl to use per module lock. #117017