title: Unable scale up cassandra using latest datastax python driver
body: <p>We are using multiple cassandra datastax cluster instances(6) to connect to cassandra using python. We are pooling these multiple connections to do some operations. Each operation is independent of other.</p>
  
  <p>It works fine on a small number of operations, but once I try to scale up I get the following errors :</p>
  
  <pre><code>NoHostAvailable: ('Unable to complete the operation against any hosts', {&lt;Host: 127.ption('Pool is shutdown',)})
  </code></pre>
  
  <p>and sometimes the following warning:</p>
  
  <pre><code>WARNING  Heartbeat failed for connection (140414695068880) to 127.0.0.1
  </code></pre>
  
  <p>I tried changing some cluster object parameters but it did not help. </p>
  
  <p>Following is the configuration of key space in cassandra I am using :</p>
  
  <p>'class': 'SimpleStrategy',
  'replication_factor': '1'</p>
  
  <p>I am using lastest versions of cassandra and datastax driver for python. There is only one node is cassandra.</p>
  
  <p>EDIT: More details:</p>
  
  <p>The multiple cluster instances are in different processes (processes are created using the Python multiprocessing module) - one cluster instance per process. Lets call the proccesses Cassandra-Processes (CP). There are a bunch of other process that do some computation and need to look up a Cassandra DB, and write to it, occassionally. The current design is that each of these processes is mapped to one CP, and all DB reads/writes to be done by the process is done via this mapped CP. 'what' exactly is to be read/written is passed into a queue (again from the multiprocessing library) which the mapped CP reads. </p>
  
  <p>We observe that this setup runs for quite sometime - and then suddenly Cassandra begins erroring out.</p>