[HBASE-8944] Document workaround for MiniDFSCluster exceptions when running tests

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.94.6, 0.94.6.1
• Fix Version/s: 0.98.0
• Assignee: Andrew Kyle Purtell
• Reporter: David Williams
• Created: 13/Jul/13 18:31
• Updated: 20/Nov/15 11:53
• Resolved: 15/Jul/13 19:13

Description

The HBaseTestingUtility appears to have an unhandled NullPointerException in certain environments. It works on Apache HBase 0.94.6.1 on Mac OSX but not in certain Linux environments such as CentOS.

In Java:

HBaseTestingUtility testingUtility = new HBaseTestingUtility();
testingUtility.startMiniCluster(1);  // blows up on CentOS Linux but not Mac OSX

Creates this exception:

ERROR in (create-table) (MiniDFSCluster.java:426)
Uncaught exception, not in assertion.
expected: nil
  actual: java.lang.NullPointerException: null
 at org.apache.hadoop.hdfs.MiniDFSCluster.startDataNodes (MiniDFSCluster.java:426)
    org.apache.hadoop.hdfs.MiniDFSCluster.<init> (MiniDFSCluster.java:284)
    org.apache.hadoop.hbase.HBaseTestingUtility.startMiniDFSCluster (HBaseTestingUtility.java:444)
    org.apache.hadoop.hbase.HBaseTestingUtility.startMiniCluster (HBaseTestingUtility.java:612)
    org.apache.hadoop.hbase.HBaseTestingUtility.startMiniCluster (HBaseTestingUtility.java:568)
    org.apache.hadoop.hbase.HBaseTestingUtility.startMiniCluster (HBaseTestingUtility.java:555)

I also created a stack overflow ticket here, with more info:

http://stackoverflow.com/questions/17625938/hbase-minidfscluster-java-fails-in-certain-environments

Steps to reproduce:

1. Download a copy of CentOS
2. Install Java
3. Fire up a minicluster as part of the HBaseTestingUtility