title: Dont receive message with confluent kafka simple producer/consumer examples?
body: <p>I run <code>kafka_2.11-0.10.1.1</code> with <code>confluent-kafka-0.9.2</code> (master branch) python bindings which uses <code>librdkafka-0.9.2</code>. My machine runs ubuntu-16.04 x86_64. I run <code>zookeeper-3.4.8-1</code> on port <code>2181</code>. I run confluent <strong>producer</strong> example like so:</p>
  
  <pre><code>$ cd confluent-kafka-python/examples
  $ python producer.py localhost:9095 confluent-01
  first message
  2nd msg
  </code></pre>
  
  <p>and the <strong>consumer</strong>:</p>
  
  <pre><code>$ python consumer.py localhost:9095 confluentgroup confluent-01
  </code></pre>
  
  <p>Everything runs locally on my machine, which does not run any firewall.</p>
  
  <p><strong>Remarks</strong>:</p>
  
  <ul>
  <li>the topic is successfully created on Zookeeper</li>
  <li>the broker successfully receives the producer messages:</li>
  <li>the consumer sets following conf <code>{'bootstrap.servers': broker, 'group.id': group, 'session.timeout.ms': 6000, 'default.topic.config': {'auto.offset.reset': 'smallest'}, 'api.version.request': True }</code></li>
  <li>in the beginning <code>producer/consumer</code> work fine for some time, until I get <code>Receive failed: Disconnected</code> on the producer side. Exerpt:</li>
  </ul>
  
  <hr>
  
  <pre><code>$ python producer.py  localhost:9095 confluent-02
  asd
  % Message delivered to confluent-02 [0]
  1234123
  890890
  % Message delivered to confluent-02 [0]
  %3|1485791262.420|FAIL|rdkafka#producer-1| [thrd:obscura.ax.example.com:9095/3]: obscura.ax.example.com:9095/3: Receive failed: Disconnected
  </code></pre>
  
  <p><strong>Problem</strong>: I don't get anything on the consumer side after a while</p>
  
  <p>Questions:</p>
  
  <ol>
  <li>What am i doing wrong?</li>
  <li><strong>How can I verify the producer messages have been received on the broker side?</strong>
  The producer messages are properly received on the broker side. </li>
  <li><strong>How can I debug the consumer side?</strong>
  I added <code>'debug': "cgrp, topic, fetch"</code> to consumer conf. Where can I read the logs?</li>
  </ol>