Cleanup executor resources after execution

voila/handler.py

@@ -200,6 +200,8 @@ async def _jinja_notebook_execute(self, nb, kernel_id):
         # see the updated variable (it seems to be local to our block)
         nb.cells = result.cells
 
+        await self._cleanup_resources()
+
     async def _jinja_cell_generator(self, nb, kernel_id):
         """Generator that will execute a single notebook cell at a time"""
         nb, resources = ClearOutputPreprocessor().preprocess(nb, {'metadata': {'path': self.cwd}})
@@ -250,6 +252,12 @@ async def _jinja_cell_generator(self, nb, kernel_id):
             finally:
                 yield output_cell
 
+        await self._cleanup_resources()
+
+    async def _cleanup_resources(self):
+        await ensure_async(self.executor.km.cleanup_resources())
+        await ensure_async(self.executor.kc.stop_channels())
+
     async def load_notebook(self, path):
         model = await ensure_async(self.contents_manager.get(path=path))
         if 'content' not in model: