Au-Miner opened a new pull request, #28247:
URL: https://github.com/apache/flink/pull/28247
## What is the purpose of the change
Fix a flaky `NullPointerException` raised from Calcite's
`RelMetadataQueryBase.getMetadataHandlerProvider` during Volcano-based query
optimization, surfaced as a PyFlink test failure when planning runs on a thread
that has never initialized `THREAD_PROVIDERS`.
## Brief change log
- Update the metadata query supplier in `FlinkRelOptClusterFactory.create`
to set `RelMetadataQueryBase.THREAD_PROVIDERS` before constructing
`FlinkRelMetadataQuery`, so the parent `RelMetadataQuery` constructor sees a
non-null `JaninoRelMetadataProvider` regardless of which thread invokes the
supplier.
- Cache the `JaninoRelMetadataProvider` instance at object init to avoid
re-wrapping `FlinkDefaultRelMetadataProvider` on every supplier call.
## Verifying this change
Added
`FlinkRelOptClusterFactoryTest#testMetadataQuerySupplierUsableOnFreshThread`,
which spawns a fresh thread, clears `THREAD_PROVIDERS`, invokes the cluster's
supplier, and asserts that the produced `RelMetadataQuery` has a non-null
`metadataHandlerProvider` — the precondition that prevents the NPE in
subsequent metadata calls.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): no
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: no
- The serializers: no
- The runtime per-record code paths (performance sensitive): no
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? no
- If yes, how is the feature documented? not applicable
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