15 comment

1. hey thanks for quick n dirty procfs tutorial 🙂

2. thx, that was really useful!quick question: anybody has an idea why the value displayed by ‘lsof -p {procid} | wc -l’ is different to that of ‘ls -l /proc/{procid}/fd | wc -l’. lsof is usually higher…?

   1. Because lsof counts files in /proc//fd and adds the opend shared libs from /proc//maps

3. Thanks man, this was really useful.

4. Thank you. I had a daemon that stopped functioning correctly six hours after I started it. Turns out, I had a file descriptor leak. It had never even crossed my mind until I put 2 and 2 together. This confirmed it. It’s all fixed now, thanks to you!

5. Can’t we use lsof | wc -l for the same

6. you can combine lsof with pidof:

   lsof -p `pidof ruby`

7. I Have a files in /proc//fd which should be in a different pid fd folder! File Descriptor Leak! Closed files from another process are duplicating themselves (random number of duplicate content 5-75 times) into another process’s fd folder! Has anybody seen this before. Solaris 10.

8. Yeah you can combine them all!
   below one gives all type of descriptor opened by “mysqld” process:

   lsof -p `pidof mysqld` |wc -l

   There is a way to set system level “max open file descriptors” and view current count of “open file descriptors” at system-level;
   I’m unable to recollect 🙁
   does anyone know it?

   1. cat /proc/sys/fs/file-nr shows number of open files in the first column, max allowed open files in third column and 0 in the second column.

      It doesn’t update the first column on a single file handle basis, but seems to increase and decrease in steps

9. I have a new unused server here where I’m trying to install/use nginx for php for the first time.

   Strange error for unused server?
   ==
   Firstly, it seems strange to me that I would get “Too many open files” for a new unused server. ulimit -Hn/Sn showed 4096/1024 which seemed adequate whie nginx was using only 9/10 acccording to: ls -l /proc//fd | wc -l

   Anyhow, I followed the instructions and now I get this error:
   ==
   2013/02/15 16:30:39 [alert] 4785#0: 1024 worker_connections are not enough
   2013/02/15 16:30:39 [error] 4785#0: *1021 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 127.0.0.1, server: localhost, request: “GET /info.php HTTP/1.0”, upstream: “http://127.0.0.1:80/info.php”, host: “127.0.0.1”

   Tried:
   ==
   I’ve tried increasing the worker_connections to large numbers e.g. 19999 to no avail.

   Any tips?

10. Just a quick remark: if it’s just for counting, like in

    lsof | wc -l

    then it is much faster not to resolve user ids and network adresses:

    lsof -n -l | wc -l

11. I am quite interested about the subject but I am wondering which is the proper way to monitor these. I am considering adding a metric so I need a current value and a maximum one.

    Kinda strange but I do think that “lsof -n -l | wc -l” is measuring too much, I get ~145.000 on one server and ~10.000 on another one, and these are not under heavy load. After dumping the file I observer measuring TCP connections too, which I would prefer not to count them here.

12. @Sorin

    That’s because it is. Apparently, if a process opens a file handle, then forks, each of the processes will have the same file handle to the opened file, but it only counts as one file handle with respect to file handle limits, so lsof ends up double-counting it.

    Try this:
    lsof | grep / | sort -k9 -u | wc -l
    It will do the same thing, but sort on the name column, and discard duplicates. It means each of protocols, pipes, and sockets count for one, and any duplicate file handles to files are eliminated. It still won’t be accurate, but it will give you a lower bound on how may many file handles are being used.

13. Thanks so much! This page is so useful to find lsof for a particular process!

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