Merge pull request #81 from lsst/tickets/DM-17398

DM-17398: Allow graph traversal for "split graphs"
lsst · Jan 23, 2019 · 79c42fc · 79c42fc
2 parents 0a7b887 + cc44b0d
commit 79c42fc
Showing 1 changed file with 11 additions and 1 deletion.
diff --git a/python/lsst/pipe/base/graph.py b/python/lsst/pipe/base/graph.py
@@ -195,7 +195,17 @@ def orderedTaskNodes(graph):
                     # if data exists in butler then `id` is not None
                     if dataRef.id is None:
                         key = (dataRef.datasetType.name, DataId(dataRef.dataId))
-                        prereq.append(outputs[key])
+                        try:
+                            prereq.append(outputs[key])
+                        except KeyError:
+                            # The Quantum that makes our inputs is not in the graph,
+                            # this could happen if we run on a "split graph" which is
+                            # usually just one quantum. Check for number of Quanta
+                            # in a graph and ignore error if it's just one.
+                            # TODO: This code has to be removed or replaced with
+                            # something more generic
+                            if not (len(self) == 1 and len(self[0].quanta) == 1):
+                                raise
 
                 # Update `outputs` with this quantum outputs
                 for dataRef in chain.from_iterable(quantum.outputs.values()):