Bash running out of File Descriptors - bash

Question

I was working on a project, and I want to contribute with the solution I found:
The code is of the kind:
while true
do
while read VAR
do
......
done < <(find ........ | sort)
sleep 3
done
The errors in the log where:
/dir/script.bin: redirection error: cannot duplicate fd: Too many open files
/dir/script.bin: cannot make pipe for process substitution: Too many open files
/dir/script.bin: line 26: <(find "${DIRVAR}" -type f -name '*.pdf' | sort): Too many open files
find: `/somedirtofind': Too many open files
/dir/script.bin: cannot make pipe for process substitution: Too many open files
/dir/script.bin: cannot make pipe for process substitution: Too many open files
/dir/script.bin: line 26: <(find "${DIRVAR}" -type f -name '*.pdf' | sort): ambiguous redirect
I noticed with command:
ls -l /proc/3657(pid here)/fd that the file descriptors were constantly increasing.
Using Debian 7, GNU bash, version 4.2.37(1)-release (i486-pc-linux-gnu)

Answer 1

The solution that worked for me is:
while true
do
find ........ | sort | while read VAR
do
done
sleep 3
done
Which is, avoiding the subshell at the end, there must be some kind of leak.
Now I don't see file descriptors in the process directory when doing ls
Mail to bugtracker:
The minimum reproduceable code is:
#!/bin/bash
function something() {
while true
do
while read VAR
do
dummyvar="a"
done < <(find "/run/shm/directory" -type f | sort)
sleep 3
done
}
something &
Which fails with many pipes fd open.
Changing the While feed to this:
#!/bin/bash
function something() {
find "/run/shm/directory" -type f | sort | while true
do
while read VAR
do
dummyvar="a"
done
sleep 3
done
}
something &
Works completely normal.
However, removing the call as function in background:
#!/bin/bash
while true
do
while read VAR
do
dummyvar="a"
done < <(find "/run/shm/debora" -type f | sort)
sleep 3
done
But executing the script with ./test.sh & (in background), works
without problems too.

Answer 2

I was having the same issue and played around with the things you suggested. You said:
But executing the script with ./test.sh & (in background), works
without problems too.
So what worked for me is to run in the background and just wait for it to finish each time:
while true
do
while read VAR
do
......
done < <(find ........ | sort) &
wait
done
Another thing that worked was to put the code creating the descriptor into a function without running on background:
function fd_code(){
while read VAR
do
......
done < <(find ........ | sort)
}
while true
do
fd_code
done