- fix for python refcounting crashes, remember PyDict_GetItem and PyDict_GetItemString borrow a ref.

- the namespace dictionary wasn't being de-allocated for each run.
- clear every error after printing it to avoid stale PyObjects hanging about.

source/blender/python/intern/bpy_interface.c

@@ -179,7 +179,7 @@ int BPY_run_python_script( bContext *C, const char *fn, struct Text *text )
 			MEM_freeN( buf );
 
 			if( PyErr_Occurred(  ) ) {
-				PyErr_Print();
+				PyErr_Print(); PyErr_Clear();
 				BPY_free_compiled_text( text );
 				PyGILState_Release(gilstate);
 				return 0;
@@ -195,10 +195,12 @@ int BPY_run_python_script( bContext *C, const char *fn, struct Text *text )
 	}
 	
 	if (!py_result) {
-		PyErr_Print();
+		PyErr_Print(); PyErr_Clear();
 	} else {
 		Py_DECREF( py_result );
 	}
+	
+	Py_DECREF(py_dict);
 	PyGILState_Release(gilstate);
 	
 	//BPY_end_python();
@@ -220,7 +222,7 @@ static void exit_pydraw( SpaceScript * sc, short err )
 	script = sc->script;
 
 	if( err ) {
-		PyErr_Print(  );
+		PyErr_Print(); PyErr_Clear();
 		script->flags = 0;	/* mark script struct for deletion */
 		SCRIPT_SET_NULL(script);
 		script->scriptname[0] = '\0';
@@ -327,13 +329,14 @@ int BPY_run_python_script_space(const char *modulename, const char *func)
 		}
 	}
 	
-	if (!py_result)
-		PyErr_Print();
-	else
+	if (!py_result) {
+		PyErr_Print(); PyErr_Clear();
+	} else
 		Py_DECREF( py_result );
 	
 	Py_XDECREF(module);
 	
+	Py_DECREF(py_dict);
 	
 	PyGILState_Release(gilstate);
 	return 1;
@@ -406,7 +409,7 @@ void BPY_run_ui_scripts(bContext *C, int reload)
 			if(mod) {
 				Py_DECREF(mod); /* could be NULL from reloading */
 			} else {
-				PyErr_Print();
+				PyErr_Print(); PyErr_Clear();
 				fprintf(stderr, "unable to import \"%s\"  %s/%s\n", path, dirname, de->d_name);
 			}
 		}
@@ -527,7 +530,7 @@ static float pydriver_error(ChannelDriver *driver)
 	driver->flag |= DRIVER_FLAG_INVALID; /* py expression failed */
 	fprintf(stderr, "\nError in Driver: The following Python expression failed:\n\t'%s'\n\n", driver->expression);
 	
-	PyErr_Print();
+	PyErr_Print(); PyErr_Clear();
 
 	return 0.0f;
 }
@@ -586,7 +589,7 @@ float BPY_pydriver_eval (ChannelDriver *driver)
 			}
 			
 			fprintf(stderr, "\tBPY_pydriver_eval() - couldn't add variable '%s' to namespace \n", dtar->name);
-			PyErr_Print();
+			PyErr_Print(); PyErr_Clear();
 		}
 	}
 	

source/blender/python/intern/bpy_rna.c

@@ -1144,7 +1144,7 @@ static PyObject * pyrna_func_call(PyObject * self, PyObject *args, PyObject *kw)
 			i++;
 		}
 		else if (kw != NULL)
-			item= PyDict_GetItemString(kw, pid);
+			item= PyDict_GetItemString(kw, pid);  /* borrow ref */
 
 		if (item==NULL) {
 			if(flag & PROP_REQUIRED) {
@@ -1957,12 +1957,10 @@ PyObject *pyrna_basetype_register(PyObject *self, PyObject *args)
 	}
 	
 	/* get the context, so register callback can do necessary refreshes */
-	item= PyDict_GetItemString(PyEval_GetGlobals(), "__bpy_context__");
+	item= PyDict_GetItemString(PyEval_GetGlobals(), "__bpy_context__");  /* borrow ref */
 
-	if(item) {
+	if(item)
 		C= (bContext*)PyCObject_AsVoidPtr(item);
-		Py_DECREF(item);
-	}
 
 	/* call the register callback */
 	BKE_reports_init(&reports, RPT_PRINT);
@@ -1998,18 +1996,14 @@ PyObject *pyrna_basetype_unregister(PyObject *self, PyObject *args)
 	}
 
 	/* check we got an __rna__ attribute */
-	item= PyDict_GetItemString(((PyTypeObject*)py_class)->tp_dict, "__rna__");
+	item= PyDict_GetItemString(((PyTypeObject*)py_class)->tp_dict, "__rna__");  /* borrow ref */
 
 	if(!item || !BPy_StructRNA_Check(item)) {
-		if(item) {
-			Py_DECREF(item);
-		}
 		PyErr_SetString(PyExc_AttributeError, "expected a Type subclassed from a registerable rna type (no __rna__ property).");
 		return NULL;
 	}
 
 	/* check the __rna__ attribute has the right type */
-	Py_DECREF(item);
 	py_srna= (BPy_StructRNA*)item;
 
 	if(py_srna->ptr.type != &RNA_Struct) {
@@ -2026,12 +2020,10 @@ PyObject *pyrna_basetype_unregister(PyObject *self, PyObject *args)
 	}
 	
 	/* get the context, so register callback can do necessary refreshes */
-	item= PyDict_GetItemString(PyEval_GetGlobals(), "__bpy_context__");
+	item= PyDict_GetItemString(PyEval_GetGlobals(), "__bpy_context__");  /* borrow ref */
 
-	if(item) {
+	if(item)
 		C= (bContext*)PyCObject_AsVoidPtr(item);
-		Py_DECREF(item);
-	}
 
 	/* call unregister */
 	unreg(C, py_srna->ptr.data);

source/blender/python/intern/bpy_ui.c

@@ -344,7 +344,7 @@ static PyObject *Method_registerKey( PyObject * self, PyObject * args )
 static bContext *get_py_context__internal(void)
 {
 	PyObject *globals = PyEval_GetGlobals();
-	PyObject *val= PyDict_GetItemString(globals, "__bpy_context__");
+	PyObject *val= PyDict_GetItemString(globals, "__bpy_context__"); /* borrow ref */
 	return PyCObject_AsVoidPtr(val);
 }