Fllink Web UI not displaying records received in a Custom Source implementation

Question

I have build a custom source to process a log stream in Flink. The program is running fine and giving me the desired results after processing the records.

But, when I check the Web UI, I do not see the counts. Below is the screenshot: Records/Bytes Count

Answer 1

Flink chained all the operators of your pipeline into one operator: Source -> FlatMap -> ProcessLog -> Sink. Thus, this single operator contains the source and the sink. Additionally, Flink can neither measure the amount of bytes read by a source nor the number of bytes written by a sink. It can only measure the bytes sent between operators. Since the source and sink are executed in the same operator, the web UI does not show you any bytes sent/received.