title: Automatically set maximum number of map tasks per node to the number of cores?
body: <p>I'm working on setting up a hadoop cluster where the nodes are all fairly heterogeneous, i.e. they each have a different number of cores. Currently I have to manually edit the <code>mapred-site.xml</code> on each node to fill in <code>{cores}</code>:</p>
  
  <pre><code>&lt;property&gt;
      &lt;name&gt;mapred.tasktracker.map.tasks.maximum&lt;/name&gt;
      &lt;value&gt;{cores}&lt;/value&gt;
  &lt;/property&gt;
  </code></pre>
  
  <p>Is there an easier way to to this when I add new nodes? Most of the other values are some default and the maximum map tasks is the only thing that changes from node to node.</p>