[KAFKA-9739] StreamsBuilder.build fails with StreamsException "Found a null keyChangingChild node for OptimizableRepartitionNode"

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.2.0, 2.3.0, 2.2.1, 2.2.2, 2.4.0, 2.3.1, 2.4.1
• Fix Version/s: 2.2.3, 2.3.2, 2.6.0, 2.4.2, 2.5.1
• Component/s: streams
• Assignee: Bill Bejeck
• Reporter: Artur Poliachenko
• Created: 20/Mar/20 14:45
• Updated: 15/Apr/20 19:51
• Resolved: 03/Apr/20 16:06

Description

We created a topology using Streams DSL (topology description is available in the attached topology-description.txt, no optimization).

Topology works fine with topology.optimization=none, however it fails to build with StreamsException "Found a null keyChangingChild node for OptimizableRepartitionNode" if we set topology.optimization=all (exception stack trace is attached streams-exception-log.txt).

We used https://zz85.github.io/kafka-streams-viz/ to visualize topology and try to guess what might be upsetting optimizer, yet did not manage to figure it out ourselves.

Issue Links

• links to: GitHub Pull Request #8400
• links to: GitHub Pull Request #8416
• links to: GitHub Pull Request #8419
• links to: GitHub Pull Request #8492