Boosting AWS Lightsail Performance with Swapon to Save Your Low-RAM Instance

Adrian Rubico

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Jul 24, 2024

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09:55 PM GMT+8

Have you ever experienced reaching high CPU burst loads on your AWS Lightsail instance, causing it to become unresponsive? I'm here to guide you on how to improve your instance with a tweak on your server configuration.

Managing server performance on AWS Lightsail can be challenging, especially when working with instances that have limited resources. In my case, the specifications on my server are

  • 1GB Ram
  • 2vCPUs
  • 40 GB SSD Disk
  • 2 TB Transfer

I recently encountered high CPU utilization, primarily caused by memory spikes during remote development sessions. This issue led to frequent server unresponsiveness, impacting the downtime of my web application. Instead of purchasing costly memory upgrades, I discovered an effective solution using Swapon to manage memory more efficiently. In this post, I will share how I resolved memory spikes, maintained optimal CPU burst capacity, and improved performance without incurring additional costs.

The Problem

As shown in the graphic below, the metrics of my server instance indicate spikes in usage. When these spikes occur, the server may become unresponsive, and your web application might become inaccessible.

Previously, I would restart the instance because I could not access it during these times. The reason for these spikes was that I used Visual Studio Code's remote development feature to review and develop my blog site. I noticed that these spikes occurred every time I engaged in remote development.

The Solution

Exploring Options

Upgrading the server's memory will incur additional costs, approximately $5 for 2GB of RAM and $24 for 4GB of RAM. Please refer to this link for pricing details. Since the only application running is a web application that mainly retrieves and displays information, I have decided to use Swapon as an alternative solution instead of upgrading the memory.

What is Swapon?

Swapon is a Linux command that activates swap space, allowing the system to utilize disk space as additional memory. Using Swapon can optimize memory performance without the need for a costly memory upgrade.

Setting up Swapon on your AWS Lightsail instance

Step 1 - Ensure there is no swap space created

bash 
sudo swapon --show

We can also verify that there is no active swap by using the free command.

bash 
free -h
bash 
# Output
               total        used        free      shared   buff/cache  available
Mem:           924Mi       333Mi       115Mi       0.0Ki       474Mi       426Mi
Swap:             0B          0B          0B

Step 2 - Create a swap file

bash 
CMD ["executable", "param1", "param2"]

To create a 2GB swap file, use the following command. The swap space should be twice the size of RAM if the RAM is less than 2GB. If the RAM is 2GB or more, the swap space should be the same size as the RAM plus an additional 2GB.

Step 3 - Secure the swap file

Set the correct permissions to ensure that only the root can access the swap file.

bash 
sudo fallocate -l 2G /swapfile

Step 4 - Enable the swap file

Enable the swap file so the system start using it.

bash 
sudo chmod 600 /swapfile

Step 5 - Make the swap file permanent

To ensure the swap file is used after a reboot, add it to the /etc/fstab file

bash 
sudo swapon /swapfile

Step 6 - Verify the created swap file

bash 
sudo swapon --show
bash 
# Output
NAME      TYPE SIZE   USED PRIO
/swapfile file   2G     0B   -2

We can also verify that in memory usage system by using the free command.

bash 
free -h
bash 
# Output
               total        used        free      shared   buff/cache  available
Mem:           924Mi       333Mi       115Mi       0.0Ki       474Mi       426Mi
Swap:          2.0Gi          0B       2.0Gi

Step 7 - Adjust swappiness to optimize performance

Swappiness dictates how aggressively the system utilizes swap space. By default, it is set to 60, but you can reduce it to minimize swap space usage.

bash 
sudo sysctl vm.swappiness=10

To make this change permanent, add vm.swappiness=10 to the /etc/sysctl.conf file.

Conclusion

Implementing Swapon on my AWS Lightsail instance proved to be an effective and cost-efficient solution for managing memory spikes and maintaining optimal burst capacity. This approach not only maintains instances during high-demand tasks but also provides a sustainable way to handle memory management. The metrics clearly show no spikes, as illustrated in the graphic below. 

Additionally, this experience has highlighted that heavily relying on remote development can be problematic. It is not a good practice for deploying production web applications. As a result, I am transitioning towards a DevOps approach, which will optimize development and deployment processes. I am excited about this transition and share my experience in my next blog post.

This guide can help you resolve similar challenges by exploring Swapon as an alternative to upgrading hardware. This approach can offer substantial benefits and cost savings. Regular monitoring is crucial for maintaining optimal server performance. Implementing DevOps practices can improve your infrastructure by automating processes and making them more efficient. Don't forget to keep an eye out for more updates on my progress toward implementing a DevOps workflow.

TAGS:

linux aws linux-administration monitoring aws-lightsail

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