Consistent node execution order by sorting node with Sequentialrunner

RELEASE.md

@@ -25,10 +25,12 @@
 * Reduced number of log lines by changing the logging level from `INFO` to `DEBUG` for low priority messages.
 * Kedro's framework-side logging configuration no longer performs file-based logging. Hence superfluous `info.log`/`errors.log` files are no longer created in your project root, and running Kedro on read-only file systems such as Databricks Repos is now possible.
 * The `root` logger is now set to the Python default level of `WARNING` rather than `INFO`. Kedro's logger is still set to emit `INFO` level messages.
+* Kedro pipeline will have consistent execution order given the same set of nodes when using with `SequentialRunner`.
 * Bumped the upper bound for the Flake8 dependency to <5.0.
 * `kedro jupyter notebook/lab` no longer reuses a Jupyter kernel.
 * Required `cookiecutter>=2.1.1` to address a [known command injection vulnerability](https://security.snyk.io/vuln/SNYK-PYTHON-COOKIECUTTER-2414281).
 
+
 ## Upcoming deprecations for Kedro 0.19.0
 * `kedro.extras.ColorHandler` will be removed in 0.19.0.
 

kedro/pipeline/pipeline.py

@@ -352,7 +352,7 @@ def nodes(self) -> List[Node]:
         return list(chain.from_iterable(self._topo_sorted_nodes))
 
     @property
-    def grouped_nodes(self) -> List[Set[Node]]:
+    def grouped_nodes(self) -> List[List[Node]]:
         """Return a list of the pipeline nodes in topologically ordered groups,
         i.e. if node A needs to be run before node B, it will appear in an
         earlier group.
@@ -870,7 +870,7 @@ def _validate_transcoded_inputs_outputs(nodes: List[Node]) -> None:
         )
 
 
-def _topologically_sorted(node_dependencies) -> List[Set[Node]]:
+def _topologically_sorted(node_dependencies) -> List[List[Node]]:
     """Topologically group and sort (order) nodes such that no node depends on
     a node that appears in the same or a later group.
 
@@ -894,7 +894,9 @@ def _circle_error_message(error_data: Dict[str, str]) -> str:
         return f"Circular dependencies exist among these items: {circular}"
 
     try:
-        return list(toposort(node_dependencies))
+        # Sort it so it has consistent order when run with SequentialRunner
+        result = [sorted(dependencies) for dependencies in toposort(node_dependencies)]
+        return result
     except ToposortCircleError as exc:
         message = _circle_error_message(exc.data)
         raise CircularDependencyError(message) from exc

tests/pipeline/test_pipeline.py

@@ -253,8 +253,9 @@ def test_grouped_nodes(self, input_data):
         grouped = pipeline.grouped_nodes
         # Flatten a list of grouped nodes
         assert pipeline.nodes == list(chain.from_iterable(grouped))
-        # Check each grouped node matches with expected group
-        assert all(g == e for g, e in zip(grouped, expected))
+        # Check each grouped node matches with the expected group, the order is
+        # non-deterministic, so we are only checking they have the same set of nodes.
+        assert all(set(g) == e for g, e in zip(grouped, expected))
 
     def test_free_input(self, input_data):
         nodes = input_data["nodes"]

tests/pipeline/test_pipeline_with_transcoding.py

@@ -121,7 +121,7 @@ def test_grouped_nodes(self, input_data):
         # Flatten a list of grouped nodes
         assert pipeline.nodes == list(chain.from_iterable(grouped))
         # Check each grouped node matches with expected group
-        assert all(g == e for g, e in zip(grouped, expected))
+        assert all(set(g) == e for g, e in zip(grouped, expected))
 
     def test_free_input(self, input_data):
         nodes = input_data["nodes"]