public void startSelectMasterTask(final String host, final String port, final String contextPath) {
        LOG.info("starting select master task");
        // schedule task selectPeriod seconds
        executorService.scheduleAtFixedRate(() -> doSelectMaster(host, port, contextPath),
                0,
                clusterProperties.getSelectPeriod(),
                TimeUnit.SECONDS);
    }
start master select task.

@param host host
@param port port
@param contextPath contextPath
shenyu-admin/src/main/java/org/apache/shenyu/admin/mode/cluster/service/ShenyuClusterService.java