how to count the open files without lsof

Question

we have in our cluster more then 800 rhel machines - version 7.2

since lsof | wc -l

take too much time ( sometimes 3-4 min ) , in order to get the current open files

we want to know if there are other approach that can give the total current open files in short time

note - in our case , we have 835 linux machines , so it will be very bad to use lsof | wc -l on all machines , according to our calculation it will take 40~hours

Answer 1

As root:

find /proc/[1-9]*/fd/ -mindepth 1 -printf . 2>/dev/null | wc -c