aparnasuresh85 opened a new pull request, #2160: URL: https://github.com/apache/solr/pull/2160
https://issues.apache.org/jira/browse/SOLR-17106 <!-- _(If you are a project committer then you may remove some/all of the following template.)_ Before creating a pull request, please file an issue in the ASF Jira system for Solr: * https://issues.apache.org/jira/projects/SOLR For something minor (i.e. that wouldn't be worth putting in release notes), you can skip JIRA. To create a Jira issue, you will need to create an account there first. The title of the PR should reference the Jira issue number in the form: * SOLR-####: <short description of problem or changes> SOLR must be fully capitalized. A short description helps people scanning pull requests for items they can work on. Properly referencing the issue in the title ensures that Jira is correctly updated with code review comments and commits. --> # Description Please provide a short description of the changes you're making with this pull request. The issue involves scalability challenges in SolrJ's LBSolrClient when a pod with numerous cores experiences connectivity problems. The "zombie" ping checking mechanism, operating on a core basis, becomes a bottleneck during distributed search on a massive multi shard collection. Threads attempting to reach unhealthy cores contribute to a high computational load, causing performance issues. LBSolrClient could be configured to disable zombie "ping" checks, but retain zombie tracking. Once a replica/endpoint is identified as a zombie, it could be held in zombie state for X seconds, before being released - hoping that by this timeframe ZK would be updated to mark this endpoint DOWN or the pod is back up and CloudSolrClient would avoid querying it. In any event, only 1 failed query would be needed to send the server back to zombie state. Dev list thread: https://lists.apache.org/thread/f0zfmpg0t48xrtppyfsmfc5ltzsq2qqh # Solution Please provide a short description of the approach taken to implement your solution. Modified the code to make zombie ping checking configurable through a new property named "enableZombiePingChecks." When set to true, the system is designed to periodically send zombie ping requests every zombiePingIntervalMillis. Conversely, setting it to false disables zombie pings and instead monitors the "zombieServers" every zombieStateMonitoringIntervalMillis. This monitoring identifies replicas or endpoints that have spent at least minZombieReleaseTimeMillis as zombies, subsequently releasing them from the zombie state and adding them back to the alive set. The default configuration for zombiePingIntervalMillis remains at 1 minute, while zombieStateMonitoringIntervalMillis is currently set to 5 seconds, and minZombieReleaseTimeMillis is configured at 10 seconds. Corresponding tests in TestLBHttp2SolrClient and TestLBHttpSolrClient have been adjusted accordingly. # Tests Please describe the tests you've developed or run to confirm this patch implements the feature or solves the problem. Slight refactoring in TestLBHttp2SolrClient and TestLBHttpSolrClient, added a new test testReliabilityWithoutZombiePingChecks in TestLBHttp2SolrClient. All tests pass. # Checklist Please review the following and check all that apply: - [x] I have reviewed the guidelines for [How to Contribute](https://wiki.apache.org/solr/HowToContribute) and my code conforms to the standards described there to the best of my ability. - [x] I have created a Jira issue and added the issue ID to my pull request title. - [x] I have given Solr maintainers [access](https://help.github.com/en/articles/allowing-changes-to-a-pull-request-branch-created-from-a-fork) to contribute to my PR branch. (optional but recommended) - [x] I have developed this patch against the `main` branch. - [x] I have run `./gradlew check`. - [x] I have added tests for my changes. - [x] I have added documentation for the [Reference Guide](https://github.com/apache/solr/tree/main/solr/solr-ref-guide) -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
