public synchronized long expireServer(final ServerName serverName) {
    return expireServer(serverName, false);

  }
Expire the passed server. Add it to list of dead servers and queue a shutdown processing.
@return pid if we queued a ServerCrashProcedure else {@link Procedure#NO_PROC_ID} if we did not
        (could happen for many reasons including the fact that its this server that is going
        down or we already have queued an SCP for this server or SCP processing is currently
        disabled because we are in startup phase).
hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java