I have a job made up of a few FlinkSQL statements using a
statement set. In my job graph viewed through the Flink UI a few of
the tasks/statements are preceded by this task
rowtime field: (#11: event_time TIME ATTRIBUTE(ROWTIME))
that has an upstream Kafka source/sink task.
Occasionally, some of the rowtime tasks appear back pressured
meaning they have high Outpool buffer usage however all of downstream
sql tasks have low InPool and OutPool usage. Also, the CPU and
memory, noo OOM errors, usage is also at acceptable levels as far as I
can tell. Another symptom I notice during these episodes is high
consumer fetch latency with Kafka, but I haven't been able to put my
finger on the direction of the causal arrow. What are some causes of
this behavior and what are the best metrics to look at?
Thank you,
Aeden
