rtthread v5.0.1 , at socket ，使用select函数不能监控多个socket fd的问题。 5.00

/**
 * @brief tcp client mode task entry
 * 
 * @param arg 
 */
void   net_tcpmode_task(void *arg)
{
    fd_set rdset;
    int r, ret;
    int n;
    char *buff_rd;
    int write_sz;
    int max_fd;
    struct timeval tv;
    int size = 0;
    int heartcnt = 0, short_cnt = 0;
    int socketfd,socketfd2;
    int sum= 0;
start:
    socketfd = socket(AF_INET, SOCK_STREAM, 0);
    if(socketfd < 0)
    {
       LOG_E("create socket fail");
        goto start;
    }
    socketfd2 = socket(AF_INET, SOCK_STREAM, 0);
    if(socketfd2 < 0)
    {
       LOG_E("create socket fail");
        goto start;
    }
    r = tcpclient_connect(socketfd,DEFAULT_TCPSERVER_ADDR,DEFAULT_TCPSERVER_PORT);
    if(r < 0 )
    {
        rt_thread_mdelay(1000);
        goto start;
    }
    r = tcpclient_connect(socketfd2,DEFAULT_TCPSERVER_ADDR,32502);
    if(r < 0 )
    {
        rt_thread_mdelay(1000);
        goto start;
    }
    tv.tv_sec  = 1;
    tv.tv_usec = 0;
    buff_rd    = rt_malloc(1024);
    if(buff_rd == NULL)
    {
        LOG_E("alloc buff_rd fail\r\n");
    }
    while(1)
    {
        FD_ZERO(&rdset);
        FD_SET(socketfd, &rdset);
        FD_SET(socketfd2, &rdset);
        max_fd = (socketfd2 > socketfd)?socketfd2:socketfd;
        r = select(max_fd + 1, &rdset, NULL, NULL, &tv);
        if (r < 0)
        {
             LOG_E("select fail,restart");
             break;
        }
        else if (r == 0) 
        {
             ret = send(socketfd,"heart",5,MSG_DONTWAIT);
             if(ret <= 0)
             {
                 break;
             }
             sum = 0;
        }
        if (FD_ISSET(socketfd, &rdset)) //网络接收数据
        {
            ret = recv(socketfd,buff_rd,1024,0);
            if(ret <= 0)
                break;
            LOG_I("fd %d rcv %d bytes",socketfd,ret);
        }
        if (FD_ISSET(socketfd2, &rdset)) //网络接收数据
        {
            ret = recv(socketfd2,buff_rd,1024,0);
            if(ret <= 0)
                break;
            LOG_I("fd %d  rcv %d bytes",socketfd2);
        }  
    }
__end:
    rt_free(buff_rd);
    closesocket(socketfd);
    closesocket(socketfd2);
    rt_thread_mdelay(1000);
    goto start;
}