Counting file descriptors used by a process or Go application

file_descriptors.go

package main


func countOpenFiles() int {
	out, err := exec.Command("/bin/sh", "-c", fmt.Sprintf("lsof -p %v | wc -l", os.Getpid())).Output()
	if err != nil {
		// log.Println("count files", err)
		return 0
	}
	n, err := strconv.Atoi(strings.TrimSpace(string(out)))
	if err != nil {
		return 0
	}
	return n
}

file_descriptors.sh

# Process ID's using the most file descriptors
lsof | awk '{ print $2; }' | uniq -c | sort -rn | head

# Name of process + PID
sudo lsof | awk '{ print $1" "$2; }' | uniq -c | sort -rn

# OR

# Find the PID
ps aux | grep yourappname

# Count the file descriptors for this process
lsof -p PIDHERE | wc -l to count

https://oroboro.com/file-handle-leaks-server/