Clean up some locking around hierarchy modification#8849
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headius merged 1 commit intojruby:jruby-9.4from May 29, 2025
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Clean up some locking around hierarchy modification#8849headius merged 1 commit intojruby:jruby-9.4from
headius merged 1 commit intojruby:jruby-9.4from
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There are too many locks in this logic, leading to deadlock potential as reported in jruby#8846. This commit tries to centralize most hierarchy-modifying or hierarchy-walking locks to using the global runtime.getHierarchyLock, and localizes parts of the same code that are only modifying the current class. In the future we should consider the thread-safety of the various structures that make up RubyModule/RubyClass, since currently most of those structures are themselves thread-safe or lock-guarded, so much of the extra locking here may be unnecessary. We also have opportunities to improve some "compute if absent" scenarios and refine the way we lock for hierarchy walking to be more localized. Fixes jruby#8846
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There are too many locks in this logic, leading to deadlock potential as reported in #8846. This commit tries to centralize most hierarchy-modifying or hierarchy-walking locks to using the global runtime.getHierarchyLock, and localizes parts of the same code that are only modifying the current class.
In the future we should consider the thread-safety of the various structures that make up RubyModule/RubyClass, since currently most of those structures are themselves thread-safe or lock-guarded, so much of the extra locking here may be unnecessary. We also have opportunities to improve some "compute if absent" scenarios and refine the way we lock for hierarchy walking to be more localized.
Fixes #8846