[HDFS-6300] Prevent multiple balancers from running simultaneously

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 2.8.0, 2.7.1, 3.0.0-alpha1
• Component/s: balancer & mover
• Target Version/s: 2.7.1
• Hadoop Flags: Reviewed
• Assignee: Rakesh Radhakrishnan
• Reporter: Rakesh Radhakrishnan
• Created: 29/Apr/14 12:47
• Updated: 06/Jan/17 00:53
• Resolved: 13/May/15 12:05

Description

Javadoc of "Balancer.java" says, it will not allow to run second balancer if the first one is in progress. But I've noticed multiple can run together and balancer.id implementation is not safe guarding.

 * <li>Another balancer is running. Exiting...

Issue Links

• is broken by: HDFS-3755 Creating an already-open-for-write file with overwrite=true fails
• is related to: HDFS-8897 Balancer should handle fs.defaultFS trailing slash in HA