title: Setting parameter in MapReduce Job configuration
body: <p>Is there any way to set a parameter in job configuration from <code>Mapper</code> and is accessible from <code>Reducer</code>.</p>
  
  <p>I tried the below code</p>
  
  <p>In Mapper:  <code>map(..)</code>    : <code>context.getConfiguration().set("Sum","100");</code>
  In reducer: <code>reduce(..)</code> : <code>context.getConfiguration().get("Sum");</code></p>
  
  <p>But in reducer value is returned as <code>null</code>.</p>
  
  <p>Is there any way to implement this or any thing missed out from my side?</p>