During November 2024, Siying Dong focused on enhancing the stability and efficiency of stream processing in the xupefei/spark repository. She addressed a bug in Spark Streaming’s stream-stream join logic by implementing a conditional checkpoint fetch mechanism using Scala and Apache Spark. This approach ensured that checkpoint IDs were retrieved only when supported, reducing unnecessary operations and preventing assertion failures in edge cases. By refining the checkpoint fetch path, Siying improved runtime performance and reliability for streaming workloads. Her work demonstrated a deep understanding of Spark’s internals and contributed targeted, maintainable improvements to the stream processing infrastructure.