Cannot Change The Maximum Open Files Per Process with Sysctl

Cannot change the maximum open files per process with sysctl

For Ubuntu 17.04. See this solution.

Prior to Ubuntu 17.04:

I don't know why the above settings don't work but it seems you can get the same result by using the /etc/security/limits.conf file.

Set the limit in /etc/security/limits.conf

sudo bash -c "echo '* - nofile 10240' >> /etc/security/limits.conf"

• * means all users. You can replace it by a specific username.
• - means both soft and hard for the type of limit to be enforced. Hard can only be modified by the superuser. Soft can be modified by a non-root user and cannot be superior to hard.
• nofile is the Maximum number of open files parameter.
• 10240 is the new limit.

Reload

Logout and log back in. sudo sysctl -p doesn't seem to be enough to reload.

You can check the new limit with:

ulimit -n

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Tested on Ubuntu 16.04 and CentOS 6. Inspired by this answer.

Max open files for working process

As a system administrator: The /etc/security/limits.conf file controls this on most Linux installations; it allows you to set per-user limits. You'll want a line like myuser - nofile 1000.

Within a process: The getrlimit and setrlimit calls control most per-process resource allocation limits. RLIMIT_NOFILE controls the maximum number of file descriptors. You will need appropriate permissions to call it.

Why redis can not set maximum open file

Redis will never change the maximum open files.

This is a OS configuration and it can be configured on a per user basis also. The error is descriptive and tells you: "increase 'ulimit -n'"

You can refer to this blog post on how to increase the maximum open files descriptors:
http://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/

Maximum number of open filehandles per process on OSX (and how to increase)

found on http://krypted.com/mac-os-x/maximum-files-in-mac-os-x/:

sysctl -w kern.maxfilesperproc=20000

Ruby: Too many open files @ rb_sysopen

• EMFILE is too many files opened in your process.
• ENFILE is too many files opened in the entire system.

So Errno::EMFILE is due to the ruby process opening too many files. This limit is probably set to the default 1024 can be seen with:

$ulimit -n
1024

Instead of:

$ulimit
unlimited

You can raise the limit using this method.

How do I increase the open files limit for a non-root user?

The ulimit command by default changes the HARD limits, which you (a user) can lower, but cannot raise.

Use the -S option to change the SOFT limit, which can range from 0-{HARD}.

I have actually aliased ulimit to ulimit -S, so it defaults to the soft limits all the time.

alias ulimit='ulimit -S'

As for your issue, you're missing a column in your entries in /etc/security/limits.conf.

There should be FOUR columns, but the first is missing in your example.

* soft nofile 4096
* hard nofile 4096

The first column describes WHO the limit is to apply for. '*' is a wildcard, meaning all users. To raise the limits for root, you have to explicitly enter 'root' instead of '*'.

You also need to edit /etc/pam.d/common-session* and add the following line to the end:

session required pam_limits.so

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