Can you explain how back pressure affect the source in flink? I read the great article https://data-artisans.com/blog/how-flink-handles-backpressure and got the idea but I would like to know more details. Let's consider
org.apache.flink.streaming.api.functions.source.SourceFunction.SourceContext interface and its void collect(T element); method. Is back pressure mechanism going to to block the calling collect method thread for some time? How does it compare what has been written in the mentioned article? I don't quite understand how '*The output side never puts too much data on the wire by a simple watermark mechanism*' is supposed to work. - *Remote exchange*: If task 1 and task 2 run on different worker nodes, the buffer can be recycled as soon as it is on the wire (TCP channel). On the receiving side, the data is copied from the wire to a buffer from the input buffer pool. If no buffer is available, reading from the TCP connection is interrupted. The output side never puts too much data on the wire by a simple watermark mechanism. If enough data is in-flight, we wait before we copy more data to the wire until it is below a threshold. This guarantees that there is never too much data in-flight. If new data is not consumed on the receiving side (because there is no buffer available), this slows down the sender. Thanks, Pawel
