bproc_notifier returns a file descriptor that will become ready for reading whenever a BProc system configuration change takes place. Such changes include node status changes such as going up or down or master daemon configuration reloads.
When a notification takes place, the file descriptor will become ready for reading. Perform a read to acknowledge this clear the ready for read state.
On success, bproc_notifier will return a file descriptor number. On error, bproc_notifier will return -1 and errno will be set appropriately.