Minor Description
Based on my work with HDFS-14258, I noticed that when a user calls the kill() method in DataXceiverServer, it closes the PeerServer. This causes the thread responsible for receiving connections from the PeerServer to interrupt and then exit. On the way out, this thread also closes the PeerServer for good measure. I'm not sure what the affects of closing the PeerServer are twice, but it should be avoided.
To be clear, this is not a regressions caused by HDFS-14258, if anything, HDFS-14258 makes it easier to fix. 