Linux file limit increase

How to Increase the Maximum Open File Limit in Linux

Linux systems come with a default configuration that optimizes system performance based on average user workloads. However, specific tasks require more resources than others. For instance, running a large database server or a high-traffic web server necessitates a higher number of open files than usual. If the maximum open file limit isn’t increased to accommodate these demanding tasks, it may result in system errors or inefficiencies. This article will provide a comprehensive guide to increasing the open file limit in Linux, thereby optimizing system performance and maximizing productivity.

What is the Open File Limit in Linux?

In Linux, the ‘open file limit’ refers to the maximum number of file descriptors that a single process can open concurrently. A file descriptor is a unique integer that the system uses to access and manage open files and network sockets.

By default, most Linux systems limit this number to prevent system resources from being overwhelmed. However, this limit may become a bottleneck for certain applications that need to handle many files simultaneously.

Understanding the Need for an Increase

When operating a system with intensive workloads, such as large-scale data processing applications, high-traffic web servers, or extensive database systems, the default open file limit may not suffice. The system might return an error like “Too many open files”, suggesting that you need to increase the open file limit.

How to Check the Current Limit

Before changing anything, it’s prudent to check the current limit settings. In Linux, you can check the limit for the current session by running the following command:

This will return an integer, representing the current limit of open file descriptors for the current shell session.

How to Increase the Open File Limit

Now let’s dive into the steps to increase the open file limit in Linux:

To increase the limit for all users, you need to edit the /etc/sysctl.conf file. Append or modify the following lines:

The above command increases the system-wide limit to 100,000. Save and exit the file. To apply the changes, use the following command:

Edit the /etc/security/limits.conf file and append the following lines to increase the limit for a specific user (replace ‘username’ with the actual username):

The ‘soft’ limit is the actual limit enforced for sessions, while the ‘hard’ limit acts as the ceiling for the soft limit. An unprivileged process may only set its soft limit to a value in the range from 0 up to the hard limit.

Increase Limit In Docker Container

If you are running your application in a containerized environment, you can increase the max open file limit by passing the appropriate flag to the container runtime. For example, when running a container with Docker, you can pass the —ulimit flag to set the limit:

docker run --ulimit nofile=1000000:1000000 my_image 

It’s also possible to increase the limit for a specific user by editing the user’s shell profile file. For example, if you are using the bash shell, you can edit the “.bashrc” file located in the user’s home directory. To increase the limit, you can add the following line to the file:

It’s important to note that increasing the maximum open file limit is not a solution for all performance issues. It’s a way to address specific problems caused by running out of file handles, but if your system is experiencing performance issues, it’s important to identify the root cause before increasing the limit.

Conclusion

Increasing the open file limit in Linux is a vital process to maximize system productivity and performance, especially in resource-intensive environments. While the default configuration may work for most users, understanding how to adjust these limits gives you more control over your Linux system, ensuring optimal system performance regardless of the workload. Remember, it’s crucial to monitor your system’s performance and make appropriate adjustments as your needs evolve.

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How to increase the open file limits on Ubuntu

On a Linux-based system such as Ubuntu, we occasionally face problems such as “too many open files,” especially when you install and work in platforms like Apache web server and Oracle database. The encountered error signifies that our server has opened the files up to the default maximum number. This issue occurs when the system imposes resource constraints on any user or session. For instance, the maximum size that can be locked into memory, the maximum size of created file, the maximum CPU time that can be utilized, the maximum number of processes that are allowed to execute, and the maximum virtual memory size that can be used; these are all examples of resource limitations in an Ubuntu system.

What are the limits types in Ubuntu

Limits in an Ubuntu system are of two types:

• Soft limit: This type of limit indicates the current value of the session or user.. An Ubuntu user has the option to increase its value to the hard limit.
• Hard Limit: The superuser/root sets the maximum allowable limit for a user or session, known as the hard limit.

Now, we will explain the procedure to increase the open file limits on Ubuntu. So let’s start!

How to increase the open file limits on Ubuntu

First of all, open your Ubuntu terminal by pressing “CTRL+ALT+T”. Now, we will check out the current limits of the resources. For this, we will execute the “unlimit” command.

What is unlimit command in Ubuntu

The “unlimit” is a Linux shell command utilized to set, view, or limit the current user’s resources. It also extracts information about how many open file descriptors each process has. Many Ubuntu users execute this command to limit the resources which are in the use of a process.

How to check current limits in Ubuntu

To view the current limits set, add the “-a” option in the “unlimit” command:

Execution of the above-given command will show you the following output:

How to check the soft and hard open file limits in Ubuntu

To view the current soft limit, execute the unlimit command with the “-Sn” option:

From the below-given output, you can see that “1024” is the soft limits of the open files in our Ubuntu system:

The “-Hn” option is added to the “unlimit” command for retrieving the hard limit of the open files:

How to increase the open file limits for the current session in Ubuntu

As mentioned earlier, you can utilize the “unlimit” command for setting the current session limits. If you want to increase the open file limits for your current Ubuntu session, choose a value between the soft and hard limits and add that specific numerical value with the “-n” option. Adding the “-n” option to the “unlimit” command lets you increase the open file limits:

How to increase per-user open file limits in Ubuntu

You can also increase the open file limits for a specific user. To do so, open the limits configuration file “/etc/security/limits.conf” in the “nano” editor:

In the “nano” editor, the limit configuration file will look like this:

Now, add the following content in the “/etc/security/limits.conf” file:

linuxhint soft nproc 100000

linuxhint hard nproc 100000

linuxhint soft nofile 100000

linuxhint hard nofile 100000

Press “CTRL+O” and save the changes we made in the “/etc/security/limits.conf”:

In the next step, we will restrict the number of system resources a user can get in a single session by enabling the pam_limits. For this, you have to edit the “/etc/pam.d/common-session” file in your “nano” editor:

Now, add this line to enable the pam_limits for the current session:

Press “CTRL+O” to save the added content of “ /etc/pam.d/common-session” file:

How to increase system-wide open file limits in Ubuntu

Ubuntu also provides you the option to increase system-wide open file limits. For this purpose, we will edit the “/etc/sysctl.conf” file:

You can set the maximum number of file handles that the Linux kernel will allocate by using the “fs.file-max” parameter. Now, add the below-given line in the “sysctl.conf” file:

Setting the value “2097152” for “fs.file-max” parameter will set this value as maximum number of file handles:

Again, press “CTRL+O” to save the “sysctl.conf” file:

The “sysctl” command with the “-p” option will load the kernel settings from the “sysctl.conf” file. For applying the changes we have made, execute the below-given “sysctl” command in your terminal:

The execution of the above-given command will increase the maximum number of open files across the entire system:

Conclusion

In Ubuntu, many applications, such as the Apache web server or the Oracle databases, require a higher open file limit, resulting in an excessive number of open files, file descriptors, etc. If the number of open files exceeds the default limit, file opening difficulties and access control issues may arise. This article showed you how you can increase the open file limits in your Ubuntu system. Moreover, you have also seen how to check and increase the system-wide and per-user limits of opened files.

About the author

Sharqa Hameed

I am a Linux enthusiast, I love to read Every Linux blog on the internet. I hold masters degree in computer science and am passionate about learning and teaching.

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How to increase the ulimit and file descriptors limit in linux.

If you get the error “too many open files” , please check below steps :

The file-max is the maximum File Descriptors (FD). It is a kernel setting enforced at the system level. The ulimit is enforced at the user level. It should be configured to be less than file-max.

The default settings are very low , for high performance servers it should be increased. The default settings assume that the several user share the same system and limit is sufficient.

To change the file descriptor setting, edit the kernel parameter file /etc/sysctl.conf. Add line fs.file-max=[new value] to it.

for eg. # vi /etc/sysctl.conf and enter fs.file-max = 400000

To apply the changes :
#sysctl -p

To change the ulimit setting, edit the file /etc/security/limits.conf and set the hard and soft limits in it :
for eg. # vi /etc/security/limits.conf
* soft nofile 40000
* hard nofile 40000

After changed reboot the server.
# reboot

Now,test system settings using the below commands:

To check the current open file descriptor limit:
# more /proc/sys/fs/file-max

OR sysctl -a | grep fs.file-max

To find out how many file descriptors are currently being used:

To find out how many files are currently open:

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