title: Why is reduce stuck at 16%?
body: <p>I have a map reduce job I am trying to run on a relatively small data set. I keep running into an issue where the reduce job keeps getting stuck at 16%. My task tracker's log read:</p>
  
  <pre><code>2012-03-21 17:09:23,829 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:09:26,865 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:09:32,902 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:09:38,938 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:09:41,973 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:09:48,010 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:09:51,045 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:09:57,086 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:03,120 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:06,154 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:12,198 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:18,234 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:21,271 INFO org.apache.hadoop.mapred.TaskTracker:&gt; attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:27,310 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:33,342 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:36,374 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:42,403 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:48,435 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:51,462 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:10:57,495 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:11:03,523 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:11:06,545 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:11:12,578 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  2012-03-21 17:11:18,607 INFO org.apache.hadoop.mapred.TaskTracker: attempt_201203211704_0001_r_000000_0 0.16666667% reduce &gt; copy (1 of 2 at 0.16 MB/s)
  </code></pre>