Adjusting the File Handle Limits

This topic covers how to adjust file handle limits in Linux and MacOS. It also provides details on ensuring container platforms do not override the file handle limits configured in our Docker images.

Docker Images

The Nexus Repository Docker images are configured with adequate file limits. Some container platforms such as Amazon ECS override the default limits. On these platforms it is recommended that the Docker image be run with the following flags:

--ulimit nofile=65536:65536

Linux Environments

init.d

When using init.d we manage the file handle limit by setting persistent limits for a Linux user.

Add the following to the /etc/security/limits.conf file where the userid is the user running Nexus Repository.
```
<userid> - nofile 65536
<userid> - nproc 65536
```
Optional: Ubuntu ignores the limits.conf file for processes started by the init.d process. Edit the /etc/pam.d/common-session file and uncomment the following line:
```
# session    required   pam_limits.so
```
Restart the service for the change to take effect.

systemd

When using systemd to launch the server, modify the configuration file to add a LimitNOFILE line:

[Unit]
Description=nexus service
After=network.target

[Service]
Type=forking
LimitNPROC=65536
LimitNOFILE=65536
ExecStart=/opt/nexus/bin/nexus start
ExecStop=/opt/nexus/bin/nexus stop
User=nexus
Restart=on-abort

[Install]
WantedBy=multi-user.target

Restart the Nexus Repository for the change to take effect.

MacOS Environments

The method to modify the file descriptor limits on MacOS has changed a few times over the years. Please note your OS version and follow the appropriate instructions.

For OS X Yosemite (10.10) and newer

Create the file: /Library/LaunchDaemons/limit.maxfiles.plist

<!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>65536</string>
          <string>65536</string>
        </array>
      <key>RunAtLoad</key>
        <true/>
      <key>ServiceIPC</key>
        <false/>
    </dict>
  </plist>

If this file already exists, then ensure the value is at least 65536 as shown.

The file must be owned by root:wheel and have permissions -rw-r--r--.

sudo chmod 644 /Library/LaunchDaemons/limit.maxfiles.plist
sudo chown root:wheel /Library/LaunchDaemons/limit.maxfiles.plist

Reboot to activate the change.

Add a new line to $install-dir/bin/nexus.vmoptions containing:
```
-XX:-MaxFDLimit
```
Restart Nexus Repository to activate the change.

For OS X Lion (10.7) up to OS X Mavericks (10.9)

Create and edit the system file /etc/launchd.conf using this command:
```
sudo sh -c 'echo "limit maxfiles 65536 65536" >> /etc/launchd.conf'
```
Reboot to activate the change.
Add a new line to $install-dir/bin/nexus.vmoptions containing:
```
-XX:-MaxFDLimit
```
Restart Nexus Repository to activate the change.