Increasing the File Descriptor Limit

To resolve the warning, we need to increase the file descriptor limit. Let’s understand in the below order:

1. Edit the System Configuration File

macOS uses a configuration file to set limits for user processes. Open this file in a text editor with administrative privileges:

sudo nano /etc/sysctl.conf

Explanation: If the file doesn’t exist then create it.

2. Add the Limit Settings

Add the following lines to increase the maximum number of open files:

kern.maxfiles=65536
kern.maxfilesperproc=65536
3.Save the file and exit the editor.

Explanation: These commands set the maximum number of open files for the system and per process, respectively, to 65536, helping resolve the “soft rlimits” warning on macOS

3. Apply the Changes

Apply the changes by running the following commands.

sudo sysctl -w kern.maxfiles=65536
sudo sysctl -w kern.maxfilesperproc=65536

Explanation: These commands dynamically update the system’s maximum number of open files and the maximum number of open files per process to 65536, respectively, resolving the “soft rlimits” warning on macOS

4. Update the User Limits

We also need to update the user limits. Edit or create the file /etc/launchd.conf:

sudo nano /etc/launchd.conf

Explanation: This command opens the launchd.conf file for editing using the nano text editor with superuser (sudo) privileges

Add the following line to set the soft limit for all user processes:

limit maxfiles 65536 65536

Explanation: This command sets the soft limit for the maximum number of open files to 65536 for all user processes.

5. Reboot the System:

To apply the changes, reboot your macOS:

sudo reboot

Explanation: This command reboots the macOS system, applying the changes made to the file descriptor limits.

Verifying the Changes After rebooting, verify the new limits by running the ulimit command again:

ulimit -n
ulimit -Hn

Explanation: These commands are used to check the current “soft” limit (ulimit -n) and the “hard” limit (ulimit -Hn) for the maximum number of file descriptors a user can open in a single session

MongoDB users on macOS computers might face a “soft Rlimits warning” during startup which refers to the system limit is not correctly set. This irregular warning may be a tripping block to the proper operation of MongoDB and also its stability in particular under the huge data processing.

In this article, We will learn about How to Fix MongoDB “soft rlimits” Warning On MacOS by providing a step-by-step guide.