What is using up file descriptors?

Question

I have a problem where my application is crashing saying that there are too many open files. running lsof | wc -l it says that there are 3447067 open file descriptors however I can't find out what is using that many file descriptors.

I ran cat /etc/passwd to find all users on the system followed by lsof -u <user> | wc -l for all those users, but I didn't even come near the amount of used descriptors.

Is there any reasonable way of determining what is using up so many file descriptors?

Answer 1

for dir in /proc/[1-9]*/fd; do
    echo "$dir"
    cd "$dir" &>/dev/null || continue
    set -- *
    echo $#
    echo
done

This is the output of lsof. I do not know why it differs.

lsof -F p | sort | uniq -c | sort -n