Worked on enhancing reliability in Spark’s backend by addressing a critical issue in exception handling within the xupefei/spark repository. Focused on SparkUncaughtExceptionHandler, the developer implemented logic in Scala to traverse exception chains and accurately identify fatal errors, such as OutOfMemoryError, which were previously misreported as uncaught exceptions. This fix ensured that Spark applications now report precise exit codes, improving shutdown semantics and error observability in production environments. The work demonstrated a strong grasp of Spark internals, backend development, and exception handling, contributing to more robust error reporting and greater operational stability for Spark deployments in real-world scenarios.