Hi, Starting a thread for adding Flink UDF metrics. UDFs are widely used by Flink user, but they introduce significant challenges when it comes to debugging and performance optimization. UDFs often act as black boxes, making it difficult to trace issues or identify the root causes of failures, especially when exceptions occur. The lack of dedicated metrics to quantify critical aspects such as processing time and exception count complicates debugging as well as performance tuning and resource allocation These metrics will be disabled by default to prevent performance downgrade and can be enabled through config. https://docs.google.com/document/d/1V03HJg7hHHcq6npuIO0PSSTDRHEB8ckSP65qJ3YV_10/edit?usp=sharing
Thanks, Shiyuan
