During January 2025, Ning Zhu developed a partition file size monitoring metric for the apache/celeborn repository, focusing on enhancing observability and operational insight in distributed data pipelines. He implemented the PartitionFileSizeBytes metric using Java and Scala, updating the data writer to report partition file sizes committed by Celeborn workers. This approach enabled proactive detection of unusually large files and facilitated faster troubleshooting of split-message processing delays. By improving metrics instrumentation and monitoring, Ning’s work supported more effective capacity planning and root-cause analysis. The depth of the solution demonstrated strong backend development skills and a clear understanding of distributed systems reliability.