Handling EMFILE: Too Many Open Files Error

Solution

Docker Executor

Docker executors do not allow privileged access, and thus, cannot be used to update the number of open files. In such cases, it is recommended to use the machine executor.

Machine Executor

With kernel-level privileges, users can update the number of open files to a custom value using commands such as ulimit.

Here are the steps to increase the limits at a system-wide level:

sudo sed -i 's/#DefaultLimitNOFILE=1024:524288/DefaultLimitNOFILE=131072:524288/g' /etc/systemd/system.conf
sudo sed -i 's/#DefaultLimitNOFILE=/DefaultLimitNOFILE=131072:524288/g' /etc/systemd/user.conf
sudo systemctl daemon-reexec
echo fs.file-max=131072 | sudo tee -a /etc/sysctl.conf
sudo su - circleci -c 'ulimit -Sn' -s '/bin/bash'

Additionally, changes can be made to the 01-openfiles.conf Ubuntu configuration file located in the /etc/security/limits.d/ directory. This configuration file is shipped with the Ubuntu OS and is not anticipated to change unless deprecated by Canonical.

Conclusion

While the ulimit approach is commonly recommended, making changes to the 01-openfiles.conf within the /etc/security directory is also a safe alternative. 

Additional Resources

• Howtogeek - Too many open files