Don't lock on the GIL-ful build.

Author: ZeroIntensity

Include/internal/pycore_atexit.h

@@ -52,8 +52,9 @@ struct atexit_state {
     atexit_py_callback **callbacks;
     int ncallbacks;
     int callback_len;
-
+#ifdef Py_GIL_DISABLED
     PyMutex lock;
+#endif
 };
 
 // Export for '_interpchannels' shared extension

Modules/atexitmodule.c

@@ -12,10 +12,15 @@
 #include "pycore_interp.h"        // PyInterpreterState.atexit
 #include "pycore_pystate.h"       // _PyInterpreterState_GET
 
+#ifdef Py_GIL_DISABLED
 /* Note: anything declared as static in this file assumes the lock is held
  * (except for the Python-level functions) */
 #define _PyAtExit_LOCK(state) PyMutex_Lock(&state->lock);
 #define _PyAtExit_UNLOCK(state) PyMutex_Unlock(&state->lock);
+#else
+#define _PyAtExit_LOCK(state)
+#define _PyAtExit_UNLOCK(state)
+#endif
 
 /* ===================================================================== */
 /* Callback machinery. */