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Posted to issues@solr.apache.org by "aparnasuresh85 (via GitHub)" <gi...@apache.org> on 2025/04/02 15:51:23 UTC
[PR] SOLR-17720: Fix deadlock possibility in CollectionPropertiesZkStateReader [solr]
aparnasuresh85 opened a new pull request, #3304:
URL: https://github.com/apache/solr/pull/3304
https://issues.apache.org/jira/browse/SOLR-17720
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# Description
Please provide a short description of the changes you're making with this pull request.
Fix deadlock possibility in CollectionPropertiesZkStateReader
Please provide a short description of the approach taken to implement your solution.
The deadlock occurs due to conflicting lock acquisition orders between removeCollectionPropsWatcher() and refreshAndWatch():
removeCollectionPropsWatcher() first locks collectionPropsObservers via compute(collection, <function>), then waits on getCollectionLock(collection).
refreshAndWatch() first locks getCollectionLock(coll), then waits on collectionPropsObservers.remove(coll).
To resolve this, the fix moves the synchronized (getCollectionLock(collection)) block outside the compute() call in removeCollectionPropsWatcher(), ensuring a consistent lock order and preventing deadlock. While the overall locking logic could be simplified further, this change specifically addresses the deadlock scenario.
# Tests
No new tests introduced. Ensure existing tests pass.
# Checklist
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- [ ] I have developed this patch against the `main` branch.
- [ ] I have run `./gradlew check`.
- [ ] I have added tests for my changes.
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Re: [PR] SOLR-17720: Fix deadlock possibility in CollectionPropertiesZkStateReader [solr]
Posted by "dsmiley (via GitHub)" <gi...@apache.org>.
dsmiley merged PR #3304:
URL: https://github.com/apache/solr/pull/3304
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Re: [PR] SOLR-17720: Fix deadlock possibility in CollectionPropertiesZkStateReader [solr]
Posted by "dsmiley (via GitHub)" <gi...@apache.org>.
dsmiley commented on PR #3304:
URL: https://github.com/apache/solr/pull/3304#issuecomment-2795103123
Once those things are done, I'll merge!
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Re: [PR] SOLR-17720: Fix deadlock possibility in CollectionPropertiesZkStateReader [solr]
Posted by "aparnasuresh85 (via GitHub)" <gi...@apache.org>.
aparnasuresh85 commented on PR #3304:
URL: https://github.com/apache/solr/pull/3304#issuecomment-2822049056
> Once those things are done, I'll merge!
Done!
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