Worked on the apache/spark repository to enhance the reliability of Spark SQL workloads by addressing a critical issue in job group cancellation. Focused on backend development using Scala and Apache Spark, the developer delivered a targeted bug fix that prevents IllegalStateException and incorrect state reporting by ensuring SparkContext is not stopped before cancelling a job group. This change, aligned with SPARK-52546, improved the stability of long-running and interactive jobs by reducing misreporting during cancellations. The work demonstrated careful defensive programming and a strong understanding of distributed state management, contributing to more predictable and trustworthy Spark job cancellation semantics.