Node.Js and Open Files Limit in Linux

Nodemon Error: System limit for number of file watchers reached

If you are using Linux, your project is hitting your system's file watchers limit

To fix this, on your terminal, try:

echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p

Error: EMFILE: too many open files, watch, unless I use sudo

I think I've found a solution:

• Set limits in /etc/sysctl.conf by adding:

fs.inotify.max_user_watches=524288
fs.inotify.max_user_instances=512

• Open a new terminal or reload sysctl.conf variables with

  sudo sysctl --system
  

• Run yarn start

Everything should work fine now, hopefully. If it doesn't work try setting the limits higher.

Node.js and ulimit

I received this answer back from AWS support, and it works:

As for the container, every beanstalk instance, is a container with beanstalk software that will download your application upon startup, and modify system parameters depending on the environment type, and on your .ebextensions folder on your application.

So in order to achieve my suggestion, you will need to create a .ebextensions on your application, with the contents I have mentioned.

Just as a recap, please create a file named app.config inside your .ebextensions folder on your application, with the following (updated) content:

files:
 "/etc/security/limits.conf":
     mode: "00644"
     owner: "root"
     group: "root"
     content: |
         *                soft    nofile          20000
         *                hard    nofile          20000

commands:
 container_commands:
      command: "ulimit -HSn 20000; service httpd restart;"

After you added this file, save the project and make a new deployment.

As for ssh, if you want to run a user with more limits, you can run the following command after you are logged in:
sudo su -c "ulimit -HSn 20000; su - ec2-user"

And that current session will have the limits you so desire.

For reference:
http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/customize-containers-ec2.html#customize-containers-format-services
https://unix.stackexchange.com/questions/29577/ulimit-difference-between-hard-and-soft-limits
http://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/

How do I change the number of open files limit in Linux?

You could always try doing a ulimit -n 2048. This will only reset the limit for your current shell and the number you specify must not exceed the hard limit

Each operating system has a different hard limit setup in a configuration file. For instance, the hard open file limit on Solaris can be set on boot from /etc/system.

set rlim_fd_max = 166384
set rlim_fd_cur = 8192

On OS X, this same data must be set in /etc/sysctl.conf.

kern.maxfilesperproc=166384
kern.maxfiles=8192

Under Linux, these settings are often in /etc/security/limits.conf.

There are two kinds of limits:

• soft limits are simply the currently enforced limits
• hard limits mark the maximum value which cannot be exceeded by setting a soft limit

Soft limits could be set by any user while hard limits are changeable only by root.
Limits are a property of a process. They are inherited when a child process is created so system-wide limits should be set during the system initialization in init scripts and user limits should be set during user login for example by using pam_limits.

There are often defaults set when the machine boots. So, even though you may reset your ulimit in an individual shell, you may find that it resets back to the previous value on reboot. You may want to grep your boot scripts for the existence ulimit commands if you want to change the default.

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