pawel-bugalski-dynatrace opened a new pull request #2429: URL: https://github.com/apache/lucene-solr/pull/2429
# Description Replaces `scratch1` field in `BytesRefHash` with `scratch` local variable. As a result it is now possible to call `BytesRefHash#find` concurrently as long as there are no concurrent modifications to BytesRefHash instance and it is correctly published. This addresses the concurrency issue with Monitor (aka Luwak) since it is using `BytesRefHash#find` concurrently without additional synchronization. While in theory creating a new `BytesRef` in `equals` method means additional allocation, in practice this allocation is removed by C2 compiler when inlining find method. # Solution Remove unnecessary state from `BytesRefHash` so that non-mutating find method behaves similar to `HashMap`'s get/containsKey. # Tests Added a new unit test that reproduces a problem. Checked that C2 compiler correctly removes the new allocation. # 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 `master` branch. - [x] I have run `./gradlew check`. - [x] I have added tests for my changes. - [ ] I have added documentation for the [Ref Guide](https://github.com/apache/lucene-solr/tree/master/solr/solr-ref-guide) (for Solr changes only). ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
