When facing a “Too Many Open Files” error, it is normally a result of a process taking up too many file descriptors.
To diagnose this, find out the PID of the process which gave out the error.
You can do this with a:
$ ps auwx | grep <name_of_process>
Verify open file limit per process
📝 Note: Each process that runs have a number of open files limit. By default, most of the time the limit is
$ ulimit -a root@relaye:/home/davidc# ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 15428 max locked memory (kbytes, -l) 65536 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 15428 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited
Key value to look for is open files
📝 A shortcut you could use is
Verify the limit of the process that is running
Sometimes a process could have a different limit as the one that is returned by
ulimit -n. This is because there exist syscalls that can change a running process’s open files limit (citation needed)
To check for a running process' actual limit:
$ cat /proc/<pid>/limits Limit Soft Limit Hard Limit Units Max cpu time unlimited unlimited seconds Max file size unlimited unlimited bytes Max data size unlimited unlimited bytes Max stack size 8388608 unlimited bytes Max core file size 0 unlimited bytes Max resident set unlimited unlimited bytes Max processes 15428 15428 processes Max open files 1024 524288 files Max locked memory 65536 65536 bytes Max address space unlimited unlimited bytes Max file locks unlimited unlimited locks Max pending signals 15428 15428 signals Max msgqueue size 819200 819200 bytes Max nice priority 0 0 Max realtime priority 0 0 Max realtime timeout unlimited unlimited us
Look for the value at Max open files
📝 What is Soft Limit and Hard Limit?
Soft limit is the value that a non-root user can change.
Hard limit is the maximum it can go to. Only root users can change this value.
Verify the number of file descriptors opened
There are two ways to do this.
$ ls /proc/<pid>/fd | wc -l 1024
$ lsof -p <pid> | wc -l 1028
I would recommend using
lsof -p <pid> as it will tell you what exactly is the file being opened, so that you can trace and track.