[improve][broker] Ensure metadata session state visibility and improve Unstable observability for ServiceUnitStateChannelImpl #25132
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…bility for ServiceUnitStateChannelImpl
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Pull request overview
This PR addresses a critical visibility issue where metadata session state fields were not properly visible across threads, potentially causing brokers to remain stuck in an "Unstable" state and preventing ownership monitoring. The changes enhance observability by adding volatile modifiers, enriching log messages, and introducing new metrics.
- Marked
lastMetadataSessionEventandlastMetadataSessionEventTimestampas volatile to ensure proper cross-thread visibility - Enhanced warning log message to include session event details for better debugging
- Added four new metrics to track metadata state and session event information
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| ServiceUnitStateChannelImpl.java | Made session event fields volatile, enriched logging with session event details, and added 4 new metrics for metadata state observability |
| ServiceUnitStateChannelTest.java | Added test for verifying metadata state metric values under different session event scenarios |
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...ava/org/apache/pulsar/broker/loadbalance/extensions/channel/ServiceUnitStateChannelTest.java
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Motivation
Long periods of metadata state: Unstable prevent ownership monitoring/cleanup, which can leave orphan service units and stale bundle ownership and trigger massive not served by this instance / Please redo the lookup spam.
The last metadata session event state is updated by one thread and read by another without a visibility guarantee, which can keep the broker stuck in an incorrect “Unstable” view and makes incident debugging difficult.
Modifications
Documentation
docdoc-requireddoc-not-neededdoc-complete