private boolean remove(SimpleServerRpcConnection connection) {
      boolean removed = connections.remove(connection);
      if (removed) {
        count.getAndDecrement();
      }
      return removed;
    }
The number of open RPC conections
@return the number of open rpc connections
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/SimpleRpcServer.java