Only destroy interpreters (by ID refcount) when created by the module.

Author: ericsnowcurrently

Include/cpython/pystate.h

@@ -30,6 +30,9 @@ typedef struct {
     (_PyMainInterpreterConfig){.install_signal_handlers = -1}
 /* Note: _PyMainInterpreterConfig_INIT sets other fields to 0/NULL */
 
+PyAPI_FUNC(int) _PyInterpreterState_RequiresIDRef(PyInterpreterState *);
+PyAPI_FUNC(void) _PyInterpreterState_RequireIDRef(PyInterpreterState *, int);
+
 PyAPI_FUNC(_PyCoreConfig *) _PyInterpreterState_GetCoreConfig(PyInterpreterState *);
 PyAPI_FUNC(_PyMainInterpreterConfig *) _PyInterpreterState_GetMainConfig(PyInterpreterState *);
 

Include/internal/pycore_pystate.h

@@ -30,6 +30,7 @@ struct _is {
 
     int64_t id;
     int64_t id_refcount;
+    int requires_idref;
     PyThread_type_lock id_mutex;
 
     int finalizing;

Modules/_xxsubinterpretersmodule.c

@@ -1997,6 +1997,7 @@ interp_create(PyObject *self, PyObject *args)
         PyThreadState_Swap(save_tstate);
         return NULL;
     }
+    _PyInterpreterState_RequireIDRef(tstate->interp, 1);
     return idobj;
 }
 

Python/pystate.c

@@ -403,7 +403,7 @@ _PyInterpreterState_IDDecref(PyInterpreterState *interp)
     int64_t refcount = interp->id_refcount;
     PyThread_release_lock(interp->id_mutex);
 
-    if (refcount == 0) {
+    if (refcount == 0 && interp->requires_idref) {
         // XXX Using the "head" thread isn't strictly correct.
         PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
         // XXX Possible GILState issues?
@@ -413,6 +413,18 @@ _PyInterpreterState_IDDecref(PyInterpreterState *interp)
     }
 }
 
+int
+_PyInterpreterState_RequiresIDRef(PyInterpreterState *interp)
+{
+    return interp->requires_idref;
+}
+
+void
+_PyInterpreterState_RequireIDRef(PyInterpreterState *interp, int required)
+{
+    interp->requires_idref = required ? 1 : 0;
+}
+
 _PyCoreConfig *
 _PyInterpreterState_GetCoreConfig(PyInterpreterState *interp)
 {