gh-109860: Use a New Thread State When Switching Interpreters, When Necessary (gh-110245)

In a few places we switch to another interpreter without knowing if it has a thread state associated with the current thread.  For the main interpreter there wasn't much of a problem, but for subinterpreters we were *mostly* okay re-using the tstate created with the interpreter (located via PyInterpreterState_ThreadHead()).  There was a good chance that tstate wasn't actually in use by another thread.

However, there are no guarantees of that.  Furthermore, re-using an already used tstate is currently fragile.  To address this, now we create a new thread state in each of those places and use it.

One consequence of this change is that PyInterpreterState_ThreadHead() may not return NULL (though that won't happen for the main interpreter).
This commit is contained in:
Eric Snow 2023-10-03 09:20:48 -06:00 committed by GitHub
parent 4227bfa8b2
commit f5198b09e1
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8 changed files with 151 additions and 68 deletions

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@ -655,7 +655,8 @@ pycore_create_interpreter(_PyRuntimeState *runtime,
return status;
}
PyThreadState *tstate = _PyThreadState_New(interp);
PyThreadState *tstate = _PyThreadState_New(interp,
_PyThreadState_WHENCE_INTERP);
if (tstate == NULL) {
return _PyStatus_ERR("can't make first thread");
}
@ -2050,7 +2051,8 @@ new_interpreter(PyThreadState **tstate_p, const PyInterpreterConfig *config)
return _PyStatus_OK();
}
PyThreadState *tstate = _PyThreadState_New(interp);
PyThreadState *tstate = _PyThreadState_New(interp,
_PyThreadState_WHENCE_INTERP);
if (tstate == NULL) {
PyInterpreterState_Delete(interp);
*tstate_p = NULL;