title: Why Hadoop Mapreduce distributed processing takes longer than normal sequential processing?
body: <p>I wrote a simple code in Java to read csv file, make slight changes in the lines (using hashes), and then write to the output file.</p>
  
  <p>I wanted to compare sequential version (plain java) and MapReduce version of the code. (Codes doesn't have much difference).</p>
  
  <p>I tried codes both in pseudo-distributed hadoop (single node) and fully-distributed hadoop (3 nodes), but to my surprise, the time of execution of MapReduce version is always higher than that of sequential (Approx twice or thrice).</p>
  
  <p>I don't have much experience in Hadoop, but at least distributed processing should take less time than serial processing (because that's why we have distributed processing). I even tried on varying dataset size.</p>