Скачать или смотреть Understanding Why Items Don’t Expire in Your Micronaut/Redis Cache

Discover the reasons behind non-expiring items in your `Micronaut` Redis cache and learn how to properly configure it for expected behavior.
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This video is based on the question https://stackoverflow.com/q/76439158/ asked by the user 'Ole' ( https://stackoverflow.com/u/10816443/ ) and on the answer https://stackoverflow.com/a/76457623/ provided by the user 'Olesia Ilchuk' ( https://stackoverflow.com/u/6273371/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Why Items Don’t Expire in Your Micronaut/Redis Cache

Caching is a powerful technique that enhances application performance by storing data temporarily for fast access. However, sometimes you may encounter issues with caching configurations, particularly when items fail to expire as expected. In this post, we will address the question: Why don't items expire in my Micronaut/Redis cache? Let's break down the problem and explore the solution in detail.

The Problem

When using Micronaut with Redis as your caching mechanism, configuring expiration for cached items is crucial to keep your cache updated and manage memory efficiently. You may encounter a scenario where you have configured a cache, but the items you expect to expire are still lingering in the cache. For example:

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

In the above configuration, the item is set to expire 14 minutes after being written to the cache. However, you notice that after the first call to your method annotated with @ Cacheable(value = "kyc-fenergo-service-token"), the value never expires. So, what could be going wrong?

The Solution

Check Redis Configuration

The first step in solving this problem is to check your Redis server configuration. It’s crucial to ensure that cache key expiration is enabled in your Redis settings. Follow these steps:

Locate the Redis Configuration File: Look for the redis.conf file in your Redis installation directory. This file contains all the configuration settings for your Redis server.

Inspect the notify-keyspace-events Directive: This configuration directive controls how Redis notifies clients about key events, including expiration. You need to make sure it includes the Ex flag. Here’s how to check:

Open redis.conf and locate the line that starts with notify-keyspace-events.

Verify that it is set to include Ex like this:

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

Restart Your Redis Server: If you make any changes to the configuration, don’t forget to restart your Redis server for the changes to take effect.

Understanding Expiration in Redis

In Redis, expiration behaves in a specific way, and it’s important to understand how it works:

Expire After Write: This configuration means that after the item has been written to the cache, it will remain there for the specified duration (e.g., 14 minutes) before it’s eligible for deletion.

Keyspace Notifications: Enabling notifications allows your application to listen for events in Redis, including expiration. If this feature is not enabled, your application may not recognize when items are supposed to expire.

Additional Tips

Validate Connection Settings: Ensure your application is connecting to the correct Redis instance and using the configured cache.

Test Cache Behavior: After configuring the notify-keyspace-events, you can test the expiration by adding a timestamp to the cached values and checking their presence after the expiration time.

Conclusion

Understanding and configuring expiration in a Micronaut/Redis cache is essential for optimal application performance. If your items are not expiring, checking the Redis server configuration should be your first step. By ensuring that key expiration is correctly enabled with the right notification settings, you can maintain an efficient caching strategy.

With this knowledge, you should be able to effectively manage your cache and ensure that it behaves as expected! If you have any more questions or need further assistance, feel free to reach out in the comments below!