Education Ecosystem Blog

Why Python Django freeze

If you are into web development, you probably have used or heard of Django before. It is a python framework used for building websites. However, using Django to build websites has its own challenges. For example, one common issue that occurs when using this framework is that it sometimes freezes on the server. There are many reasons why this can occur. To determine what causes this issue, you can check the CPU usage of the server or check on the logs. The most likely reason why this occurs is because of overloading of the server. This might be a server issue, but if you are already using a reliable server, like AWS, then the root cause might be something else. In the following section, we will go through why this problem occurs and how to solve Django freezing issue.

What can you do as a developer

As mentioned earlier, the most likely cause is because of the overloading the server due to traffic spikes. If there’s too much traffic coming in, and the load is not distributed equally among the servers, it will eventually freeze. The easiest way to fix this issue is to use a load balancer like Gunicorn or Nginx. A load balancer aims to distribute the tasks (traffic) over a set of resources (computing unit), with the aim of making the processing more efficient. When the load is not balanced, some of the processing unit will handle more tasks than others, causing a higher response time and ultimately freezing. Installing Gunicorn will solve this issue by employing Workers to optimize the process of handling the traffic. As a result, this will remove the bottleneck and users can now navigate through the website smoothly. 

What is Gunicorn?

Gunicorn works by creating clones of the master process, resulting in child processes known as Workers. By default, the role of the master is to manage the workers and create them as needed. While the role of the workers is to handle the HTTP requests made by clients. Furthermore, each worker is allowed to create threads and pseudo-threads, which enables them to work on different processes. As a result, the performance of the server is improved due to workers concurrently handling requests. Now that you understand how it works, we will see how to deploy Gunicorn in the following section.

How to use Gunicorn

Step 1: Installing Gunicorn

Installing Gunicorn is straightforward, use the following command in your terminal `pip install gunicorn`.

You can also install:

• from the source, using `pip install git+https://github.com/benoitc/gunicorn.git`
• using Async Workers, with `greenlet` and `evenlet`. First install them using `pip install greentlet` and `pip install eventlet`, then use `pip install gunicorn[eventlet]`.
• using Debian GNU/LINUX, with ` sudo apt-get install gunicorn3` command.
• in ubuntu, using `sudo apt-get update` then `sudo apt-get install gunicorn`

Step 2: Running Gunicorn

After installation, you can run Gunicorn by using the `gunicorn` command. This command takes the following syntax:

` gunicorn [OPTIONS] [WSGI_APP]`

OPTIONS: Insert the command from the list of available options.
WSGI_APP: Takes the pattern of $(MODULE_NAME):$(VARIABLE_NAME)

Step 3: Configuration settings

Gunicorn uses configuration settings provided from 5 places:

• Environmental variables
• Framework specific configuration file
• From the `gunicorn.conf.py` configuration file import. This is optional.
• From the command line arguments in the `GUNICORN_CMD_ARGS` environment variable.
• From the command line used to call Gunicorn

To see the full list of settings, you can type ` gunicorn -h`. Visit this page for a list of available settings.

Step 4: Deploying Gunicorn

Once you have configured Gunicorn, you can deploy it. You should use Gunicorn behind a proxy server, like Nginx. This will increase security by buffering up against DoS attacks, and makes the server process run more efficiently by balancing the load. You can also use Virtualenv. Visit this page for more information on how you can deploy Gunicorn.

How to fix this error

Gunicorn is the go-to solution if your web app freezes constantly on the server. It can balance out the incoming load, which is great during traffic spikes. Gunicorn works by dividing the tasks among workers, and improves the process by increasing efficiency. It is typically used in conjunction with Nginx, a reverse proxy. By using these 2 tools, your web application will run more smoothly and securely.