Kill hadoop DataNode/TaskTracker process using ssh. You can kill all hadoop nodes' zombie processes with this script.

kill-hadoop-slave-processes.php

<?php
$hosts = array('slave_host01', 'slave_host02', 'slave_host03');
foreach ($hosts as $host) {
  exec("ssh $host /usr/java/default/bin/jps | /bin/grep 'DataNode\|TaskTracker' | /bin/sed 's/\([0-9]\) .*/\1/'", $pids);
  foreach ($pids as $pid) {
    exec("ssh $host kill $pid);
  }
}