[HADOOP-7424] Log an error if the topology script doesn't handle multiple args

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.23.1
• Labels: newbie
• Hadoop Flags: Reviewed
• Assignee: Uma Maheswara Rao G
• Reporter: Eli Collins
• Created: 23/Jun/11 23:22
• Updated: 02/May/13 02:29
• Resolved: 28/Oct/11 02:26

Description

ScriptBasedMapping#resolve currently warns and returns null if it passes n arguments to the topology script and gets back a different number of resolutions. This indicates a bug in the topology script (or it's input) and therefore should be an error.

// invalid number of entries returned by the script
LOG.warn("Script " + scriptName + " returned "
   + Integer.toString(m.size()) + " values when "
   + Integer.toString(names.size()) + " were expected.");
return null;

There's only one place in Hadoop (FSNamesystem init) where we pass multiple arguments to the topology script, and it only done for performance (to trigger resolution/caching of all the hosts in the includes file on startup). So currently a topology script that doesn't handle multiple arguments just means the initial cache population doesn't work.

Issue Links

• is depended upon by: HADOOP-7863 Apply HADOOP-7424 "Log an error if the topology script doesn't handle multiple args" to 0.23 branch