[HDFS-5146] JspHelper#bestNode() doesn't handle bad datanodes correctly

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Cannot Reproduce
• Affects Version/s: 2.1.0-beta, 3.0.0-alpha1
• Assignee: Vinayakumar B
• Reporter: Vinayakumar B
• Created: 30/Aug/13 15:11
• Updated: 12/May/16 18:16
• Resolved: 25/Nov/14 08:03

Description

JspHelper#bestNode() doesn't handle correctly if the chosen datanode is down.

    while (s == null) {
      if (chosenNode == null) {
        do {
          if (doRandom) {
            index = DFSUtil.getRandom().nextInt(nodes.length);
          } else {
            index++;
          }
          chosenNode = nodes[index];
        } while (deadNodes.contains(chosenNode));
      }
      chosenNode = nodes[index];

In this part of the code, choosing the datanode will be done only once.
If the chosen datanode is down, then definitely exception will be thrown instead of re-chosing the available node.