Github user NicoK commented on a diff in the pull request:
https://github.com/apache/flink/pull/5583#discussion_r170988543
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/consumer/UnionInputGate.java
---
@@ -61,7 +61,7 @@
* +--------------------+
* </pre>
*
- * It is possible to recursively union union input gates.
+ * <strong>It is NOT possible to recursively union union input
gates.</strong>
--- End diff --
That would be a more invasive change in several places using `InputGate`s
and we actually are able to use any other input gate types (if there were some)
- just the recursive union does not make sense. So I guess, excluding ourself
is the better approach here in terms of extensibility. Think of it as we're
excluding this use not because we did not implement `pollNextBuffer` but
because it does not make sense and we do not want this recursion.
---
