Why flink container vcore size is always 1

Question

I am running flink on yarn(more precisely in AWS EMR yarn cluster).

I read flink document and source code that by default for each task manager container, flink will

Answer 1

I get the answer finally. It's because yarn is use "DefaultResourceCalculator" allocation strategy, so only memory is counted for yarn RM, even if flink requested 3 vcores, but yarn simply ignore the cpu core number.