We have several Java Spring Boot applications that access DB2 on AS400. We’re seeing an unexplained 40 ms delay on every interaction (PREPARE, OPEN, FETCH, CLOSE, COMMIT, etc.) with the database. We only see this delay when running it in Kubernetes with Istio enabled. We don’t see it when we run it as a standalone container with Podman nor as fat jar from a command line. And, we don’t see anything similar with other databases, i.e. PostgreSQL, MySQL, etc. When we use an annotation of traffic.sidecar.istio.io/excludeOutboundPorts: "449,8471,8476,9471,9476" on the pods, the delay goes away.
I have two questions.
- How can I figure out where this delay is coming from?
- Has anyone else seen something similar before?
Environment:
- Kubernetes version 1.20.9
- Istio version 1.10