[HADOOP-137] Different TaskTrackers may get the same task tracker id, thus cause many problems.

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 0.2.0
• Fix Version/s: 0.2.0
• Assignee: Owen O'Malley
• Reporter: Runping Qi
• Created: 15/Apr/06 07:10
• Updated: 08/Jul/09 16:51
• Resolved: 02/May/06 03:05

Description

In the TaskTracker#Initialize method, the following line assigns task tracker name (id):

this.taskTrackerName = "tracker_" + (Math.abs(r.nextInt()) % 100000);

For a fair size cluster, it is possible that different task trackers to get the same id, causing name conflict.
I encountered this problem with a cluster of 274 nodes. Once such conflict happens, a lot of strange things may happen.
For example, a reducer task tried to copy from a machine (task tracker) a map output file that was actually produced
on another machine.

Issue Links

• is related to: HADOOP-134 JobTracker trapped in a loop if it fails to localize a task