Worked on the JeffersonLab/coatjava repository to enhance concurrency safety and runtime efficiency in core data-processing modules. Focused on Java development, the work involved a targeted code refactor that localized internal state within the ModeAHDC extract method, effectively reducing shared mutable state and mitigating race conditions. Additionally, performance optimization was achieved in PreClusterFinder by simplifying the hit list population logic and removing redundant loops, which improved throughput and stability under load. These changes were implemented with minimal surface-area modifications to reduce regression risk, demonstrating a careful approach to code refactoring and performance optimization within a complex Java codebase.