msn-tldr opened a new pull request, #15493: URL: https://github.com/apache/kafka/pull/15493
NOTE this cherry-picks https://github.com/apache/kafka/pull/14522 into 3.7 As this [JIRA](https://issues.apache.org/jira/browse/KAFKA-16226) explains, there is increased synchronization between application-thread, and the background thread as the background thread started to synchronized methods Metadata.currentLeader() in [original PR](https://github.com/apache/kafka/pull/14384). So this PR does the following changes 1. Changes background thread, i.e. RecordAccumulator's partitionReady(), and drainBatchesForOneNode(), to not use `Metadata.currentLeader()`. Instead rely on `MetadataCache` that is immutable. So access to it is unsynchronized. 2. This PR repurposes `MetadataCache` as an immutable snapshot of Metadata. This is a wrapper around public `Cluster`. `MetadataCache`'s API/functionality should be extended for internal client usage Vs public `Cluster`. For example, this PR adds `MetadataCache.leaderEpochFor()` 3. Rename `MetadataCache` to `MetadataSnapshot` to make it explicit its immutable. **Note both `Cluster` and `MetadataCache` are not syncronized, hence reduce synchronization from the hot path for high partition counts.** Reviewers: Jason Gustafson <ja...@confluent.io> *More detailed description of your change, if necessary. The PR title and PR message become the squashed commit message, so use a separate comment to ping reviewers.* *Summary of testing strategy (including rationale) for the feature or bug fix. Unit and/or integration tests are expected for any behaviour change and system tests should be considered for larger changes.* ### Committer Checklist (excluded from commit message) - [ ] Verify design and implementation - [ ] Verify test coverage and CI build status - [ ] Verify documentation (including upgrade notes) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
