Ubuntu – Too many open files – how to find the culprit


When running tail -f filename, I got the following message:

tail: inotify cannot be used, reverting to polling: Too many open files

Is that a potential problem?

How do I diagnose what's responsible for all the open files? I have a list of suspect processes, but if they don't turn out to be the culprits, instructions that don't rely on knowing which process to check would be useful.

Best Answer

You can use lsof to understand who's opening so many files. Usually it's a (web)server that opens so many files, but lsof will surely help you identify the cause.

Once you understand who's the bad guy you can

  • kill the process/stop the program
  • raise the ulimit

If output from lsof is quite huge try redirecting it to a file and then open the file

Example (you might have to Ctrl+C the first command)

lsof > ~/Desktop/lsof.log
cat ~/Desktop/lsof.log | awk '{ print $2 " " $1; }' | sort -rn | uniq -c | sort -rn | head -20
vim ~/Desktop/lsof.log
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