Make sure datastack memory is freed after fork.

Author: markshannon

Objects/frameobject.c

@@ -630,16 +630,18 @@ frame_dealloc(PyFrameObject *f)
     PyCodeObject *co = f->f_code;
 
     /* Kill all local variables */
-    if (f->f_own_locals_memory) {
+    if (f->f_localsptr) {
         for (int i = 0; i < co->co_nlocalsplus+FRAME_SPECIALS_SIZE; i++) {
             Py_CLEAR(f->f_localsptr[i]);
         }
         /* Free items on stack */
         for (int i = 0; i < f->f_stackdepth; i++) {
             Py_XDECREF(f->f_valuestack[i]);
         }
-        PyMem_Free(f->f_localsptr);
-        f->f_own_locals_memory = 0;
+        if (f->f_own_locals_memory) {
+            PyMem_Free(f->f_localsptr);
+            f->f_own_locals_memory = 0;
+        }
     }
     f->f_stackdepth = 0;
     Py_XDECREF(f->f_back);

Python/ceval.c

@@ -5179,7 +5179,6 @@ _PyEval_Vector(PyThreadState *tstate, PyFrameConstructor *con,
     */
     assert (!is_coro);
     assert(f->f_own_locals_memory == 0);
-    assert(f->f_stackdepth == 0);
     if (Py_REFCNT(f) > 1) {
         Py_DECREF(f);
         _PyObject_GC_TRACK(f);
@@ -5188,10 +5187,11 @@ _PyEval_Vector(PyThreadState *tstate, PyFrameConstructor *con,
         }
     }
     else {
+        ++tstate->recursion_depth;
+        f->f_localsptr = NULL;
         for (int i = 0; i < code->co_nlocalsplus + FRAME_SPECIALS_SIZE; i++) {
             Py_XDECREF(localsarray[i]);
         }
-        ++tstate->recursion_depth;
         Py_DECREF(f);
         --tstate->recursion_depth;
     }

Python/pystate.c

@@ -897,6 +897,13 @@ PyThreadState_Clear(PyThreadState *tstate)
     if (tstate->on_delete != NULL) {
         tstate->on_delete(tstate->on_delete_data);
     }
+    _PyStackChunk *chunk = tstate->datastack_chunk;
+    tstate->datastack_chunk = NULL;
+    while (chunk != NULL) {
+        _PyStackChunk *prev = chunk->previous;
+        _PyObject_VirtualFree(chunk, chunk->size);
+        chunk = prev;
+    }
 }
 
 
@@ -941,7 +948,6 @@ _PyThreadState_Delete(PyThreadState *tstate, int check_current)
         }
     }
     tstate_delete_common(tstate, gilstate);
-    _PyObject_VirtualFree(tstate->datastack_chunk, tstate->datastack_chunk->size);
     PyMem_RawFree(tstate);
 }