nginx worker spawn failed when configured thousands of virtual servers

I tested the qat engine in my own nginx server, which the number virtual servers is larger than 2000, the nginx worker failed to getting start, the driver version is QAT-1.7.0-470b06. the "qat_notify_mode " in nginx config is poll. I follow the stack of coredump file, and find the func adf_proxy_poll_event() in the source file adf_process_proxy.c use select() to monitor the heartbeat of the accel devices ,the fd returned by the udev_monitor_get_fd() may easily out of range. suggested to use poll()..