Knowledge Base

Setting Max Open File Limits on Mac OSX

This document provides a process for setting soft and hard max open file limits on MAC OSX. Each thread created by a user process will require availability in max open file limits.

Caused by: java.io.IOException: Too many open files

It should be ensured the user running the the neo4j process has the open file limits correctly set. The below process was tested on OSX 10.12.x (Sierra) and Mojave (10.14.x) to change file limits. The same is also reported to work for Yosemite and El Capitan OSX versions, but do note that the process may differ for other OSX versions.

1) In /Library/LaunchDaemons create a file named limit.maxfiles.plist and paste the following in (You can change the two numbers 64000 and 200000 in this case, which are the soft and hard limits, respectively as required). One can check soft limit by ulimit -Sn and hard limit as ulimit -Hn :

<?xml version="1.0" encoding="UTF-8"?>
  <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
          "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
  <plist version="1.0">
    <dict>
      <key>Label</key>
      <string>limit.maxfiles</string>
      <key>ProgramArguments</key>
      <array>
        <string>launchctl</string>
        <string>limit</string>
        <string>maxfiles</string>
        <string>64000</string>
        <string>200000</string>
      </array>
      <key>RunAtLoad</key>
      <true/>
      <key>ServiceIPC</key>
      <false/>
    </dict>
  </plist>

2) Change the owner of your new file:

$ sudo chown root:wheel /Library/LaunchDaemons/limit.maxfiles.plist

3) Load these new settings:

$ sudo launchctl load -w /Library/LaunchDaemons/limit.maxfiles.plist

4) Finally, check that the limits are correct:

$ launchctl limit maxfiles

5) In some cases a machine restart may be required for above to take effect.

References: https://gist.github.com/tombigel/d503800a282fcadbee14b537735d202c