How to check ulimit usage

Question

Is there any way to check the usage of the ulimits for a given user? I know that you can change ulimits for a single process when you start it up or for a single shell when running but I want to be able to "monitor" how close a user is to hitting their limits. I am planning on writing a bash script that will report back to statsd the current usage percentage. Specifically, I want to track:

open files (ulimit -n)
max user processes (ulimit -u)
pending signals (ulimit -i)

What I want out is the percentage of usage (0-100).

if you have process accounting turned on in your kernel you can collect detailed usage statistics about your users. — casey, Sep 17 '15 at 20:37

m13r · Answer 1 · 2018-01-26T07:41:39.003

38

Maybe this helps for the first question:

If you know the process IDs (PID) of the specific user you can get the limits for each process with:

cat /proc/<PID>/limits

You can get the number of opened files for each PID with:

ls -1 /proc/<PID>/fd | wc -l

And then just compare the value of Max open files with the number of open file descriptors from the second command to get a percentage.

edited Jan 26 '18 at 07:41

answered Jun 08 '16 at 09:02

m13r

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agc · Answer 2 · 2021-08-26T04:10:56.737

Output the current user's percentage of open files, proc, and pending signals, by several inconvenient methods and standard tools:

paste <(grep 'open files\|processes\|pending signals' \
              /proc/self/limits | cut -c27-38)        \
      <(i=`whoami`
        lsof -n -u $i 2> /dev/null | 
             tail -n +2 | 
             awk {'print $9'} | 
             wc -l
        ps --no-headers -U $i -u $i u | wc -l
        ps -u $i -o pid= | 
             xargs printf "/proc/%s/status\n" |
             xargs grep -s 'SigPnd' |
             sed 's/.*\t//' | 
             paste -sd+ | 
             bc ; ) \
      <(grep 'open files\|processes\|pending signals' \
             /proc/self/limits | 
                   cut -c1-19) | 
while read a b name ; do 
    printf '%3i%%  %s\n' $((${b}00/a)) "$name"
done

Output on my system:

 16%  Max processes
 12%  Max open files
  0%  Max pending signals

Assuming those numbers are good, what this answer shows is that it can be done in shell, but probably shouldn't, unless there are much better shell methods. Rather, this Q would be better done with gcc, or python, etc.

Thank, I expanded on this by printing the label on each line in https://gitlab.com/-/snippets/2079836 — Herman van Rink, Feb 20 '21 at 19:51

score -8 · Answer 3 · answered Sep 17 '15 at 20:32

-8

Ulimits are properties of processes and are inherited to child processes.

You cannot get the limits for another process.

answered Sep 17 '15 at 20:32

schily

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5

Nonsense. `man lsof`, `man ps`, … – Gilles 'SO- stop being evil' Sep 17 '15 at 23:43
1

You seem to missunderstand how UNIX works and how lsof gets it's results. lsof reads kernel memory to get values, there is no documented interface that is used by lsof, so lsof will fail in case even minor changes have been made to internal kernel data structures. – schily Sep 18 '15 at 09:05
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That's a headache for the `lsof` maintainer, sure. But not relevant for the end-user. Also incorrect in the context of this question, since it's asking specifically about Linux, which has documented interfaces (`man proc`). – Gilles 'SO- stop being evil' Sep 18 '15 at 09:44
You are talking about undocumented interfaces that are subject to changes without notice in this case. – schily Sep 18 '15 at 09:56

How to check ulimit usage

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