Meet0861 opened a new pull request, #24759: URL: https://github.com/apache/pulsar/pull/24759
Fixes: [#24754](https://github.com/apache/pulsar/issues/24754) ### Motivation The topK bundle selection fails due to the sorting failure in the partition sort algo being used [here](https://github.com/apache/pulsar/blob/437d9f6a3ccfdfd327ac032c298728fcc43fc263/pulsar-broker/src/main/java/org/apache/pulsar/broker/loadbalance/extensions/models/TopKBundles.java#L115). Partition sort uses, NamespaceBundleStats' + BundleData's custom ccompararable implementations where it checks throughput, connections, cache size etc against the defined threshold and when values are within the defined thresholds, they are considered "equal" (return 0), but this creates transitivity violations. It violates the transitivity property required by Java's Comparable interface, causing [Collections.sort()](https://github.com/apache/pulsar/blob/437d9f6a3ccfdfd327ac032c298728fcc43fc263/pulsar-broker/src/main/java/org/apache/pulsar/broker/loadbalance/extensions/models/TopKBundles.java#L148) to potentially throw IllegalArgumentException with "Comparison method violates its general contract" error. Error Log: `2025-09-12T22:29:58.832386492+05:30 16:59:58.832 [pulsar-load-manager-1-1] WARN org.apache.pulsar.broker.loadbalance.LoadResourceQuotaUpdaterTask - Error write resource quota - java.lang.IllegalArgumentException: Comparison method violates its general contract` Due to this failure, the job - writeBundleDataOnZooKeeper(leader broker writes bundle data aggregated from all brokers to metadata store) in modularLoadManager may fail [link](https://github.com/apache/pulsar/blob/437d9f6a3ccfdfd327ac032c298728fcc43fc263/pulsar-broker/src/main/java/org/apache/pulsar/broker/loadbalance/impl/ModularLoadManagerImpl.java#L1173) and can cause degradation in productions due to failure/inconsistencies in LB decisions ### Modifications added strict NamespaceBundleStats comparator and BundleData comparator to be used for sorting for topk bundle comparison which is being used by ModularLoadManager and ExtensibleLoadManager ### Verifying this change - [ ] Make sure that the change passes the CI checks. This change added tests and can be verified as follows: - *Added unit tests to validate the fix* ### Does this pull request potentially affect one of the following parts: <!-- DO NOT REMOVE THIS SECTION. CHECK THE PROPER BOX ONLY. --> *If the box was checked, please highlight the changes* - [ ] Dependencies (add or upgrade a dependency) - [ ] The public API - [ ] The schema - [ ] The default values of configurations - [ ] The threading model - [ ] The binary protocol - [ ] The REST endpoints - [ ] The admin CLI options - [ ] The metrics - [ ] Anything that affects deployment ### Documentation <!-- DO NOT REMOVE THIS SECTION. CHECK THE PROPER BOX ONLY. --> - [ ] `doc` <!-- Your PR contains doc changes. --> - [ ] `doc-required` <!-- Your PR changes impact docs and you will update later --> - [ *] `doc-not-needed` <!-- Your PR changes do not impact docs --> - [ ] `doc-complete` <!-- Docs have been already added --> ### Matching PR in forked repository PR in forked repository: https://github.com/Meet0861/pulsar/tree/fix-transitivityViolationInNamespaceBundleStatsAndBundledataComparator <!-- After opening this PR, the build in apache/pulsar will fail and instructions will be provided for opening a PR in the PR author's forked repository. apache/pulsar pull requests should be first tested in your own fork since the apache/pulsar CI based on GitHub Actions has constrained resources and quota. GitHub Actions provides separate quota for pull requests that are executed in a forked repository. The tests will be run in the forked repository until all PR review comments have been handled, the tests pass and the PR is approved by a reviewer. --> -- 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: commits-unsubscr...@pulsar.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
