title: Kafka consumer logic for reading records from partitions
body: <p>When a Kafka consumer reads from a its assigned partitions, is there any particular logic that is used by the consumer fetcher thread(s) to get the data out of the partitions? For example, does the fetcher thread make any logic/effort to read equally/uniformly out of the assigned partitions? does it fetch more records from the most lagging partition? or it is just a simple round robin-like logic?</p>
  <p>Any detailled documentation on the consumer fecthing logic?</p>
  <p>Thank you.</p>