title: Partition are not getting assigned to Kafka consumer instance
body: <p>When I start consumer with single instance it is show in consumer group but it is not consuming data from topic. After that if I start another consumer and my first consumer start consuming data but latest consumer instance doesn't have any partition assigned to it.</p>
  
  <p>below is the info log when first consumer instance starts.</p>
  
  <blockquote>
    <p>INFO:kafka.client:Bootstrapping cluster metadata from [(u'kafka-broker1.ap-south-1.staging.internal', 9092, 0)]
    INFO:kafka.conn:: connecting to 172.31.1.66:9092
    INFO:kafka.client:Bootstrap succeeded: found 3 brokers and 19 topics.
    INFO:kafka.conn:: Closing connection. 
    INFO:kafka.conn:: connecting to 172.31.1.148:9092
    INFO:kafka.conn:Broker version identifed as 0.11.0
    INFO:kafka.conn:Set configuration api_version=(0, 11, 0) to skip auto check_version requests on startup
    INFO:kafka.consumer.subscription_state:Subscribing to pattern: /events/
    INFO:kafka.conn:: connecting to 172.31.1.70:9092
    INFO:kafka.cluster:Group coordinator for datadog is BrokerMetadata(nodeId=1, host=u'kafka-broker1.ap-south-1.staging.internal', port=9092, rack=None)
    INFO:kafka.coordinator:Discovered coordinator 1 for group datadog
    INFO:kafka.conn:: connecting to 172.31.1.66:9092
    INFO:kafka.coordinator.consumer:Revoking previously assigned partitions set([]) for group datadog
    INFO:kafka.coordinator:(Re-)joining group datadog
    INFO:kafka.consumer.subscription_state:Updating subscribed topics to: [u'events']
    INFO:kafka.coordinator:Joined group 'datadog' (generation 843) with member_id kafka-python-1.3.5-e3c25fb3-39ea-4550-845f-9b663355b4f5
    INFO:kafka.coordinator:Successfully joined group datadog with generation 843
    INFO:kafka.consumer.subscription_state:Updated partition assignment: []
    INFO:kafka.coordinator.consumer:Setting newly assigned partitions set([]) for group datadog</p>
  </blockquote>
  
  <p>When I start second instance first instance get partition assigned and second instance have 0 partition assigned and have same info log as first instance before starting second instance.</p>
  
  <p>below is the info log of first instance after second instance started.</p>
  
  <blockquote>
    <p>INFO:kafka.coordinator.consumer:Setting newly assigned partitions set([]) for group datadog
    WARNING:kafka.coordinator:Heartbeat failed for group datadog because it is rebalancing
    WARNING:kafka.coordinator:Heartbeat failed ([Error 27] RebalanceInProgressError); retrying
    INFO:kafka.coordinator.consumer:Revoking previously assigned partitions set([]) for group datadog
    INFO:kafka.coordinator:(Re-)joining group datadog
    INFO:kafka.coordinator:Skipping heartbeat: no auto-assignment or waiting on rebalance
    INFO:kafka.coordinator:Joined group 'datadog' (generation 843) with member_id kafka-python-1.3.5-ddb66185-c615-4f31-9729-9384131f24c9
    INFO:kafka.coordinator:Elected group leader -- performing partition assignments using range
    INFO:kafka.coordinator:Successfully joined group datadog with generation 843
    INFO:kafka.consumer.subscription_state:Updated partition assignment: [TopicPartition(topic=u'events', partition=0), TopicPartition(topic=u'events', partition=1), TopicPartition(topic=u'events', partition=2), TopicPartition(topic=u'events', partition=3), TopicPartition(topic=u'events', partition=4), TopicPartition(topic=u'events', partition=5), TopicPartition(topic=u'events', partition=6), TopicPartition(topic=u'events', partition=7), TopicPartition(topic=u'events', partition=8), TopicPartition(topic=u'events', partition=9)]
    INFO:kafka.coordinator.consumer:Setting newly assigned partitions set([TopicPartition(topic=u'events', partition=6), TopicPartition(topic=u'events', partition=7), TopicPartition(topic=u'events', partition=8), TopicPartition(topic=u'events', partition=9), TopicPartition(topic=u'events', partition=0), TopicPartition(topic=u'events', partition=1), TopicPartition(topic=u'events', partition=2), TopicPartition(topic=u'events', partition=3), TopicPartition(topic=u'events', partition=4), TopicPartition(topic=u'events', partition=5)]) for group datadog</p>
  </blockquote>
  
  <p><strong>We always have 1 consumer instance with unassigned partitions on all the cases,  last consumer instance always have 0 partition assigned</strong></p>
  
  <p>**Below are the screenshot for the same ** </p>
  
  <p><a href="https://i.stack.imgur.com/1zzrW.png" rel="nofollow noreferrer">No partitions assigned to first consumer instance</a></p>
  
  <p><a href="https://i.stack.imgur.com/NxxxO.png" rel="nofollow noreferrer">No partitions assigned to last consumer instance</a></p>
  
  <p><strong>We also suspect clustering of kafka. When we had only 1 kafka node partition assignment to consumer instance and re-balancing was working fine. But after going into multi-node cluster we are facing this issue</strong></p>