title: Python Kafka consumer not reading messages as they arrive
body: <p>I am just getting started with Kafka, kafka-python. In the code below, I am trying to read the messages as they arrive. But for some reason, the consumer seems to be waiting till a certain number of messages accrue before fetching them.</p>
  
  <p>I initially thought it was because of the producer which was publishing in batch. When I ran "kafka-console-consumer --bootstrap-servers  --topic ", I could see every message that was being received as soon as it got published ( as seen on the consumer console)</p>
  
  <p>But the python script is not able to receive the messages in the same way. </p>
  
  <pre><code>def run():
      success_consumer = KafkaConsumer('success_logs',
                                       bootstrap_servers=KAFKA_BROKER_URL,
                                       group_id=None,
                                       fetch_min_bytes=1,
                                       fetch_max_bytes=10,
                                       enable_auto_commit=True)
      #dummy poll
      success_consumer.poll()
      for msg in success_consumer:
          print(msg)
  
      success_consumer.close()
  </code></pre>
  
  <p>Can someone point out what configuration changed with KafkaConsumer? Why is it not able to read messages like "kafka-console-consumer" ?</p>