Segfault at exit when calling `sys.activate_stack_trampoline("perf")` after loading a native library

Crash report

What happened?

import sys, ctypes
ctypes.CDLL(None)
sys.activate_stack_trampoline("perf")
sys.activate_stack_trampoline("perf")
sys.activate_stack_trampoline("perf")

100% reproducible on 3.13.12, exits cleanly on 3.13.11.
Same between 3.14.3 and 3.14.2

Things of note:

• The crash occurs during interpreter finalization, not at the point of the call
• No exception is raised; is_stack_trampoline_active() returns True after each call
• Without ctypes.CDLL, 3 calls don't crash (but 10 calls do crash with "no more code watcher IDs available" + segfault)
• 2 calls + ctypes.CDLL doesn't crash; 3 calls is the threshold

Repeated calls to activate_stack_trampoline("perf") when the trampoline is already active should either be a no-op or raise an error.

CPython versions tested on:

3.13, 3.14

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

Python 3.13.12 (main, Mar 10 2026, 18:17:38) [Clang 21.1.4 ]

まず、提供された Python 再現プログラムを CPython 3.13.12 と 3.14.3 で実行し、次に sys.activate_stack_trampoline("perf") の実装をインタープリタの終了処理まで追跡してください。繰り返しの有効化が ctypes.CDLL(None) とどのように相互作用するかを確認し、繰り返し呼び出しが no-op になるかエラーを発生させるかのいずれかで、シャットダウン時のセグフォルトが発生しないことを検証してください。