Worked on the xupefei/spark repository to enhance the performance and stability of Spark Streaming workloads by addressing a specific bug related to stream-stream join checkpoint fetching. Focused on optimizing the checkpoint fetch path, the developer implemented logic in Scala to ensure checkpoint IDs are retrieved only when supported, thereby reducing unnecessary operations and preventing assertion failures in edge cases. This targeted fix, aligned with SPARK-50253, improved runtime efficiency for streaming applications by limiting checkpoint fetches to valid scenarios. The work demonstrated a strong understanding of Apache Spark internals, stream processing, and effective bug resolution within a complex distributed data processing environment.