title: kafka consumer group id does not work as expected
body: <p>I am new people on apache Kafka. When I go through quick start instruction via <a href="http://kafka.apache.org/quickstart" rel="nofollow noreferrer">http://kafka.apache.org/quickstart</a> with latest version kafka_2.12-2.2.0.  I got a problem and can't figure it out by myself.</p>
  
  <p>The issue is, on my laptop, I created 3 brokers to simulate cluster situation.</p>
  
  <p>Each broker has its owned server property file.  I made below change for each server property file and leave other default value as what it is.</p>
  
  <pre><code>broker.id=1      (server2: broker.id=2;  server3: broker.id=3)
  
  listeners=PLAINTEXT://127.0.0.1:9092   (server2: 127.0.0.1:9023;  server3: 127.0.0.1:9004) 
  
  log.dirs=/tmp/kafka-logs   (server2: /tmp/kafka-logs-2; server3: /tmp/kafka-logs-3)
  
  num.partitions=3   (for all servers)
  
  offsets.topic.replication.factor=3  (for all servers)
  </code></pre>
  
  <p>After I started ZK and those 3 brokers, I (can) create a topic 'TestTopic' with 3 partitions on any broker </p>
  
  <pre><code>bin/kafka-topics.sh --create --bootstrap-server localhost:9092 --replication-factor 1 --partitions 3 --topic TestTopic
  </code></pre>
  
  <p>And then I use below command to start 3 consumers in the same group 'rickygroup'.</p>
  
  <p>//consumer one</p>
  
  <pre><code>bin/kafka-console-consumer.sh --bootstrap-server 127.0.0.1:9092 --from-beginning --topic TestTopic —group.id rickygroup —group.name rickygroup
  </code></pre>
  
  <p>//consumer two</p>
  
  <pre><code>bin/kafka-console-consumer.sh --bootstrap-server 127.0.0.1:9093 --from-beginning --topic TestTopic —group.id rickygroup —group.name rickygroup
  </code></pre>
  
  <p>//consumer three</p>
  
  <pre><code>bin/kafka-console-consumer.sh --bootstrap-server 127.0.0.1:9094 --from-beginning --topic TestTopic —group.id rickygroup —group.name rickygroup
  </code></pre>
  
  <p>Now, I use another terminal to publish some messages on Topic 'TestTopic'. The issue is, all of the above 3 consumers will get all and exactly the same messages.  My understanding is 3 consumers should consume all messages indifference instead of the same.  Otherwise, the consumer group shows repeated consuming instead of balance consuming.</p>
  
  <p>Is there any misunderstanding on consumer group concept by me? or anything I did wrong here?</p>