[Dataflow Streaming] Prevent commit threads from sharing commit streams

[arunpandianp]

Since the commit threads were sharing the WindmillStreamPool, the different commit streams can end up sharing commit streams.

This change gives each commit thread its own WindmillStreamPool and avoids the commit stream sharing problem.

[arunpandianp]

R: @scwhittle

[gemini-code-assist]

Summary of Changes

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This pull request resolves a critical concurrency problem in Dataflow Streaming where multiple commit threads were inadvertently sharing commit streams due to a common WindmillStreamPool. By refactoring the stream factory mechanism, each commit thread is now provisioned with its own isolated WindmillStreamPool, thereby eliminating stream contention and enhancing the reliability and stability of commit operations within the streaming pipeline.

Highlights

• Prevented Commit Stream Sharing: Addressed a concurrency issue where commit threads were sharing WindmillStreamPool instances, leading to unintended sharing of commit streams.
• Dedicated Stream Pools: Ensured that each commit thread now receives its own dedicated WindmillStreamPool, isolating commit operations.
• Refactored Stream Factory: Modified the commitWorkStreamFactory to commitWorkStreamFactoryFactory, changing its type from Supplier<CloseableStream<CommitWorkStream>> to Supplier<Supplier<CloseableStream<CommitWorkStream>>> to facilitate per-thread stream pool creation.

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Changelog

• runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/StreamingDataflowWorker.java
  • Updated the StreamingEngineWorkerHarnessFactoryOutput builder to use setCommitWorkStreamFactoryFactory instead of setCommitWorkStreamFactory.
  • Modified the WorkCommitter builder to instantiate WindmillStreamPool with a single stream and provide a factory for it via setCommitWorkStreamFactoryFactory.
• runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/commits/StreamingEngineWorkCommitter.java
  • Changed the constructor parameter commitWorkStreamFactory to commitWorkStreamFactoryFactory with a nested Supplier type.
  • Updated the Builder interface to rename setCommitWorkStreamFactory to setCommitWorkStreamFactoryFactory and adjust its parameter type accordingly.
• runners/google-cloud-dataflow-java/worker/src/test/java/org/apache/beam/runners/dataflow/worker/windmill/client/commits/StreamingEngineWorkCommitterTest.java
  • Refactored the test class field commitWorkStreamFactory to commitWorkStreamFactoryFactory to match the new nested Supplier type.
  • Adjusted the setUp method and various test cases to correctly initialize and utilize the commitWorkStreamFactoryFactory.

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