What the default partition assignment strategy for KafkaSourceBuilder

[Lei Wang <le...@gmail.com>]

A simple flink task that consumes a kafka topic message and does some
calculation.
The number of partitions of the topic is 48, I set the parallel also 48 and
expect one parallel consumes one partition.
But after submitting the task I found that there's 5 parallels consuming
two partitions and 5 parallels doing nothing.

Why does this happen? What is the default partition assignment strategy ?

Thanks, Lei