title: Kafka Consumer being Starved because of unbalance
body: <p>I am new to Kafka and think I am missing something on how partition queues get balanced on a topic</p>
  
  <p>We have 5 partitions and 2 consumers on a topic.  The topic has a null key so I assume Kafka randomly picks a new partition to add the new record to in a round robin fashion.</p>
  
  <p>This would mean one consumer would be reading from 3 partitions and the other 2.  If my assumption is right (that the records get evenly distrusted across partitions) the consumer with 3 partitions would be doing more work (1.5x more).  This could lead to one consumer doing nothing while the other keeps working hard.  </p>
  
  <p>I think you should have an even divisible number of partitions to consumers.</p>
  
  <p>Am I missing something?</p>