bpo-40521: Make the empty frozenset per interpreter (pythonGH-21068)

vstinner · fasihahmad · commit ab9f8b9c2e78 · 2020-06-29T21:34:50.000+05:30
Each interpreter now has its own empty frozenset singleton.
diff --git a/Include/internal/pycore_interp.h b/Include/internal/pycore_interp.h
@@ -238,6 +238,8 @@ struct _is {
     /* Using a cache is very effective since typically only a single slice is
        created and then deleted again. */
     PySliceObject *slice_cache;
+    // The empty frozenset is a singleton.
+    PyObject *empty_frozenset;
 
     struct _Py_tuple_state tuple;
     struct _Py_list_state list;
diff --git a/Include/internal/pycore_pylifecycle.h b/Include/internal/pycore_pylifecycle.h
@@ -62,7 +62,7 @@ extern void _PyFrame_Fini(PyThreadState *tstate);
 extern void _PyDict_Fini(PyThreadState *tstate);
 extern void _PyTuple_Fini(PyThreadState *tstate);
 extern void _PyList_Fini(PyThreadState *tstate);
-extern void _PySet_Fini(void);
+extern void _PySet_Fini(PyThreadState *tstate);
 extern void _PyBytes_Fini(void);
 extern void _PyFloat_Fini(PyThreadState *tstate);
 extern void _PySlice_Fini(PyThreadState *tstate);
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-05-20-01-17-34.bpo-40521.wvAehI.rst b/Misc/NEWS.d/next/Core and Builtins/2020-05-20-01-17-34.bpo-40521.wvAehI.rst
@@ -1,5 +1,5 @@
-The tuple free lists, the empty tuple singleton, the list free list, the float
-free list, the slice cache, the dict free lists, the frame free list, the
-asynchronous generator free lists, and the context free list are no longer
-shared by all interpreters: each interpreter now its has own free lists and
-caches.
+The tuple free lists, the empty tuple singleton, the list free list, the empty
+frozenset singleton, the float free list, the slice cache, the dict free lists,
+the frame free list, the asynchronous generator free lists, and the context
+free list are no longer shared by all interpreters: each interpreter now its
+has own free lists and caches.
diff --git a/Objects/setobject.c b/Objects/setobject.c
@@ -975,12 +975,11 @@ make_new_set_basetype(PyTypeObject *type, PyObject *iterable)
     return make_new_set(type, iterable);
 }
 
-/* The empty frozenset is a singleton */
-static PyObject *emptyfrozenset = NULL;
-
 static PyObject *
 make_new_frozenset(PyTypeObject *type, PyObject *iterable)
 {
+    PyObject *res;
+
     if (type != &PyFrozenSet_Type) {
         return make_new_set(type, iterable);
     }
@@ -991,7 +990,7 @@ make_new_frozenset(PyTypeObject *type, PyObject *iterable)
             Py_INCREF(iterable);
             return iterable;
         }
-        PyObject *res = make_new_set((PyTypeObject *)type, iterable);
+        res = make_new_set((PyTypeObject *)type, iterable);
         if (res == NULL || PySet_GET_SIZE(res) != 0) {
             return res;
         }
@@ -1000,11 +999,17 @@ make_new_frozenset(PyTypeObject *type, PyObject *iterable)
     }
 
     // The empty frozenset is a singleton
-    if (emptyfrozenset == NULL) {
-        emptyfrozenset = make_new_set((PyTypeObject *)type, NULL);
+    PyInterpreterState *interp = _PyInterpreterState_GET();
+    res = interp->empty_frozenset;
+    if (res == NULL) {
+        interp->empty_frozenset = make_new_set((PyTypeObject *)type, NULL);
+        res = interp->empty_frozenset;
+        if (res == NULL) {
+            return NULL;
+        }
     }
-    Py_XINCREF(emptyfrozenset);
-    return emptyfrozenset;
+    Py_INCREF(res);
+    return res;
 }
 
 static PyObject *
@@ -2300,9 +2305,9 @@ PySet_Add(PyObject *anyset, PyObject *key)
 }
 
 void
-_PySet_Fini(void)
+_PySet_Fini(PyThreadState *tstate)
 {
-    Py_CLEAR(emptyfrozenset);
+    Py_CLEAR(tstate->interp->empty_frozenset);
 }
 
 int
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
@@ -1255,9 +1255,7 @@ finalize_interp_types(PyThreadState *tstate, int is_main_interp)
     _PyAsyncGen_Fini(tstate);
     _PyContext_Fini(tstate);
 
-    if (is_main_interp) {
-        _PySet_Fini();
-    }
+    _PySet_Fini(tstate);
     _PyDict_Fini(tstate);
     _PyList_Fini(tstate);
     _PyTuple_Fini(tstate);

Original file line number	Diff line number	Diff line change
`@@ -975,12 +975,11 @@ make_new_set_basetype(PyTypeObject type, PyObject iterable)`
`975`	`975`	`return make_new_set(type, iterable);`
`976`	`976`	`}`
`977`	`977`
`978`		`-/* The empty frozenset is a singleton */`
`979`		`-static PyObject *emptyfrozenset = NULL;`
`980`		`-`
`981`	`978`	`static PyObject *`
`982`	`979`	`make_new_frozenset(PyTypeObject type, PyObject iterable)`
`983`	`980`	`{`
	`981`	`+ PyObject *res;`
	`982`	`+`
`984`	`983`	`if (type != &PyFrozenSet_Type) {`
`985`	`984`	`return make_new_set(type, iterable);`
`986`	`985`	`}`
`@@ -991,7 +990,7 @@ make_new_frozenset(PyTypeObject type, PyObject iterable)`
`991`	`990`	`Py_INCREF(iterable);`
`992`	`991`	`return iterable;`
`993`	`992`	`}`
`994`		`- PyObject res = make_new_set((PyTypeObject )type, iterable);`
	`993`	`+ res = make_new_set((PyTypeObject *)type, iterable);`
`995`	`994`	`if (res == NULL \|\| PySet_GET_SIZE(res) != 0) {`
`996`	`995`	`return res;`
`997`	`996`	`}`
`@@ -1000,11 +999,17 @@ make_new_frozenset(PyTypeObject type, PyObject iterable)`
`1000`	`999`	`}`
`1001`	`1000`
`1002`	`1001`	`// The empty frozenset is a singleton`
`1003`		`- if (emptyfrozenset == NULL) {`
`1004`		`- emptyfrozenset = make_new_set((PyTypeObject *)type, NULL);`
	`1002`	`+ PyInterpreterState *interp = _PyInterpreterState_GET();`
	`1003`	`+ res = interp->empty_frozenset;`
	`1004`	`+ if (res == NULL) {`
	`1005`	`+ interp->empty_frozenset = make_new_set((PyTypeObject *)type, NULL);`
	`1006`	`+ res = interp->empty_frozenset;`
	`1007`	`+ if (res == NULL) {`
	`1008`	`+ return NULL;`
	`1009`	`+ }`
`1005`	`1010`	`}`
`1006`		`- Py_XINCREF(emptyfrozenset);`
`1007`		`- return emptyfrozenset;`
	`1011`	`+ Py_INCREF(res);`
	`1012`	`+ return res;`
`1008`	`1013`	`}`
`1009`	`1014`
`1010`	`1015`	`static PyObject *`
`@@ -2300,9 +2305,9 @@ PySet_Add(PyObject anyset, PyObject key)`
`2300`	`2305`	`}`
`2301`	`2306`
`2302`	`2307`	`void`
`2303`		`-_PySet_Fini(void)`
	`2308`	`+_PySet_Fini(PyThreadState *tstate)`
`2304`	`2309`	`{`
`2305`		`- Py_CLEAR(emptyfrozenset);`
	`2310`	`+ Py_CLEAR(tstate->interp->empty_frozenset);`
`2306`	`2311`	`}`
`2307`	`2312`
`2308`	`2313`	`int`