title: Spark Streaming: how to propagate updates to a Broadcast variable to the whole cluster?
body: <p>I have a module in the Spark driver listening to a Kafka Queue and depending on the content of the Queue I need to modify the content of a Broadcast variable (or a closure). In this example this could be a String. </p>
  
  <p>For example if the string "change" arrives on the queue, I need to update the Broadcast variable in every node. </p>
  
  <p>I would like to see a pattern to do this that is clean and performant or at least receive an input on where I can find some material to better understand how to propagate modifications in the Spark Cluster.</p>