[HBASE-16816] HMaster.move() should throw exception if region to move is not online

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.1.2
• Fix Version/s: 1.4.0, 0.98.24
• Component/s: Admin
• Hadoop Flags: Reviewed
• Assignee: Allan Yang
• Reporter: Allan Yang
• Created: 12/Oct/16 11:44
• Updated: 14/Nov/16 22:03
• Resolved: 13/Oct/16 18:11

Description

The move region function in HMaster only checks whether the region to move exists

if (regionState == null) {
      throw new UnknownRegionException(Bytes.toStringBinary(encodedRegionName));
    }

It will not return anything if the region is split or in transition which is not movable. So the caller has no way to know if the move region operation is failed.
It is a problem for "region_move.rb". It only gives up moving a region if a exception is thrown.Otherwise, it will wait until a timeout and retry. Without a exception, it have no idea the region is not movable.

begin
      admin.move(Bytes.toBytes(r.getEncodedName()), Bytes.toBytes(newServer))
    rescue java.lang.reflect.UndeclaredThrowableException,
        org.apache.hadoop.hbase.UnknownRegionException => e
      $LOG.info("Exception moving "  + r.getEncodedName() +
        "; split/moved? Continuing: " + e)
      return
    end
 # Wait till its up on new server before moving on
    maxWaitInSeconds = admin.getConfiguration.getInt("hbase.move.wait.max", 60)
    maxWait = Time.now + maxWaitInSeconds
    while Time.now < maxWait
      same = isSameServer(admin, r, original)
      break unless same
      sleep 0.1
    end
  end