@Override
      public void run(Object parameter) {
        setCancelled(call);
        synchronized (BlockingRpcConnection.this) {
          if (callSender != null) {
            callSender.remove(call);
          } else {
            calls.remove(call.id);
          }
        }
      }
Initiates a call by sending the parameter to the remote server. Note: this is not called from
the Connection thread, but by other threads.
@see #readResponse()
hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BlockingRpcConnection.java