@Override
  @QosPriority(priority = HConstants.ADMIN_QOS)
  public RollWALWriterResponse rollWALWriter(final RpcController controller,
    final RollWALWriterRequest request) throws ServiceException {
    try {
      checkOpen();
      requestCount.increment();
      server.getRegionServerCoprocessorHost().preRollWALWriterRequest();
      server.getWalRoller().requestRollAll();
      server.getRegionServerCoprocessorHost().postRollWALWriterRequest();
      RollWALWriterResponse.Builder builder = RollWALWriterResponse.newBuilder();
      return builder.build();
    } catch (IOException ie) {
      throw new ServiceException(ie);
    }
  }
Roll the WAL writer of the region server.
@param controller the RPC controller
@param request    the request
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java