Скачать или смотреть Exploring the Difference Between request.session.modified and SESSION_SAVE_EVERY_REQUEST in Django

Understand the impact of `request.session.modified` and `SESSION_SAVE_EVERY_REQUEST` on Django session management and performance.
---
This video is based on the question https://stackoverflow.com/q/64032661/ asked by the user 'dev-jeff' ( https://stackoverflow.com/u/9737374/ ) and on the answer https://stackoverflow.com/a/64032802/ provided by the user 'willeM_ Van Onsem' ( https://stackoverflow.com/u/67579/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: request.session.modified vs SESSION_SAVE_EVERY_REQUEST

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding Django Session Management

Managing user sessions is a crucial aspect of web development, especially when building applications with Django. Two important concepts in this area are request.session.modified and SESSION_SAVE_EVERY_REQUEST. Though they may seem similar, they serve different purposes and can impact the performance of your application. In this post, we will break down how each of these functions works and weigh the pros and cons of using SESSION_SAVE_EVERY_REQUEST.

What is request.session.modified?

In Django, the request.session object is a mapping that stores user-specific data, such as shopping cart items, user preferences, and authentication information. When changes are made to the session, Django does not automatically mark the session as modified. This means that the session data will not be saved unless you explicitly indicate that it has changed. You can do this by setting:

[[See Video to Reveal this Text or Code Snippet]]

When you use this method, Django recognizes that something in the session has changed and ensures that the new session data is saved at the end of the request.

What is SESSION_SAVE_EVERY_REQUEST?

SESSION_SAVE_EVERY_REQUEST is a setting in your Django project that, when set to True, tells Django to save the session data at the end of every request, regardless of whether any changes were made. This means that every time a user makes a request, Django will serialize and save the session to server storage. To configure this, add the following line in your settings.py:

[[See Video to Reveal this Text or Code Snippet]]

Advantages of SESSION_SAVE_EVERY_REQUEST

Simplicity: By enabling this setting, you eliminate the need to manually set request.session.modified. This can help reduce errors in your code and keep it cleaner.

Data Consistency: If you're frequently updating session data, saving it on every request ensures that the latest changes are always recorded.

Disadvantages and Performance Concerns

While SESSION_SAVE_EVERY_REQUEST may seem advantageous, it does come with some drawbacks:

Performance Overhead: Saving a session every time will serialize the session data regardless of changes. This results in additional processing for every request, which can lead to performance degradation, especially in high-traffic applications.

Increased I/O Operations: When session data is saved, it can generate extra filesystem I/O or database queries. If sessions are stored on disk or in a database, you may see increased latency in response times due to additional operations.

Unintentional Consequences: If you're debugging or testing, having SESSION_SAVE_EVERY_REQUEST set to True might mask issues related to session handling since it saves the session on every request even if unintentional data changes occurred.

Optimizing Session Management

Recommendations

When working with sessions in Django, evaluate your application's usage patterns first. If sessions are modified frequently, or if data consistency is critical, SESSION_SAVE_EVERY_REQUEST may be beneficial.

For applications with fewer session changes, manually using request.session.modified can minimize performance hits while managing resource use efficiently.

Alternative Approach

If you prefer not to use either of the previous options, here is a common pattern that can be employed to safely manipulate session data:

[[See Video to Reveal this Text or Code Snippet]]

This ensures that changes are recorded properly while giving you full control over when the session is modified without any unnecessary performance hits.

Conclusion

In conclusion, while both request.session.modified and SESSION_SAVE_EVERY_REQUEST serve to help manage session data in Django, they have distinct applica