almost 2 years ago


This is a problem I ran into while working on my team, and for some reason the solution was a bit involved. It's possible I didn't find the right resources at first, possibly because there seem to be different solutions depending on which version of OS X you are running.

My problems came in a couple forms, 1 running all of the unit tests in our Ruby of Rails project may have been a lot. Our project includes about 322 unit and functional test files with about 102 gems in the bundle/gemset.

It may have also happened when say, switching rvm gemsets, trying to open the Rails console, especially if it worked before, and then I added/updated gems at all, or running some other form of rails/rvm generic or test command. Any of those things may need to load a lot of files such as the gems, and helped me reach that open file handle limit.

I will attempt to capture my notes here so that if you run into the same type of problem, you can solve it as well.

Help Information

Brief Guide

# Source:

# Paired with:

# Doesn't seem to apply, at least what is viewed through 'sudo launchctl limit'

# Maybe this did successfully change the kernel limit, and I just need to change the [session] limit now?

# Also ran 'sudo launchctl limit maxfiles unlimited unlimited', which defaults to a maximum of 10240.

# But then I tried 'sudo launchctl limit maxfiles 1000000 1000000', and those values 'stuck'.

# Source:

# Paired with:

limit maxfiles 1000000 1000000

No ulimit command use necessary.

More Details

With this current set-up, I thought I had restarted my computer, re-run the problematic task (full unit/functional test suite), and still encountered the same file handle maximum error.

I just looked into the usual terminal environment configuration files (~/.config/fish/ ~/.bashrc ~/.bash_profile ~/.profile /etc/profile /etc/bashrc), and I don't see any ulimit lines in there.

I thought that was required to have the settings take full effect, as I did it with those files set and ran the command in a terminal session to see the eventual success of the task, but I have been running the task after that point, having restarted my computer since then, without re-issuing the ulimit command again, and it works now, so maybe it's not needed?

Resource Dump

  • SuperUser - Increase the maximum number of open file descriptors in Snow Leopard?

    • CLI (temporary)
    • sudo launchctl limit maxfiles 1000000 1000000
      • sudo ulimit -n 12288
      • or ulimit -n 12288 ?
    • Persist
      • /etc/launchd.conf
      • limit maxfiles 1000000 1000000
        • or limit maxfiles 8192 20480
      • limit maxproc 1000 2000
      • /etc/sysctl.conf
      • kern.maxfiles=20480
      • /etc/profile
      • ulimit -n 4096
    • Notes (implicitly quoted) [2]:
      • Alas: "The /etc/launchd.conf file is no longer consulted for subcommands to run during early boot time; this functionality was removed for security considerations."
      • You will need to restart for these changes to take effect.
      • AFAIK you can no longer set limits to 'unlimited' under OS X.
      • launchctl maxfiles is bounded by sysctl maxfiles, and therefore cannot exceed them.
      • sysctl seems to inherit kern.maxfilesperproc from launchctl maxfiles.
      • ulimit seems to inherit it's 'open files' value from launchctl by default.
      • You can set a custom ulimit within /etc/profile, or ~/.profile; while this isn't required, I've provided an example.
      • Be cautious when setting any of these values to a very high number when compared with their default - the features exist stability/security. I've taken these example numbers that I believe to be reasonable, written on other websites.
  • Open files limit does not work as before in OSX Yosemite

    • CLI
      • sysctl -w kern.maxfiles=65000
    • CLI (alternate answer)
      echo 'kern.maxfiles=20480' | sudo tee -a /etc/sysctl.conf
      echo -e 'limit maxfiles 8192 20480\nlimit maxproc 1000 2000' | sudo tee -a /etc/launchd.conf
      echo 'ulimit -n 4096' | sudo tee -a /etc/profile
  • Maximum number of open filehandles per process on OSX (and how to increase)

    • CLI
      • sysctl -w kern.maxfilesperproc=20000
  • How to persist ulimit settings in OSX Mavericks?

    • Persist
      • /Library/LaunchDaemons/limit.maxfiles.plist
        • ....


Right now I don't have any Windows instructions. I wonder if there is a similar problem in a pure-Windows environment, or the exact same problem when running in a *nix-like environment or interpreter such as Cygwin and Bash/Fish respectively.

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