Caching technology experts share: How to avoid cache penetration problems?

Cache technology experts share: How to avoid cache penetration problems?

Caching technology is an indispensable part of modern software systems and can greatly improve system performance and response speed. However, caching technology itself also has some problems, the most common of which is cache penetration. This article will delve into the cache penetration problem and share some common solutions to help readers better understand and deal with this problem.

1. What is the cache penetration problem?

The cache penetration problem means that a certain query data does not exist in the cache, and this query is frequently requested, resulting in a large number of requests penetrating into the database, causing great damage to the database. The burden and risk may even cause database downtime. The main reason for cache penetration is that some hackers or attackers deliberately use some non-existent keys to frequently access the system, so it is also considered a malicious attack.

2. The harm of cache penetration problem

The main harm of cache penetration problem is that it puts great pressure on the database, thus affecting the stability of the entire system and response speed. If the response is not timely, it will lead to database downtime, system crash, data leakage and other serious consequences. In addition, invalid queries will waste a lot of system resources, affect the normal use of other users, and bring economic losses to the enterprise.

3. How to avoid cache penetration problems?

In order to solve the cache penetration problem, we need to take some effective measures:

(1) Use Bloom filter

The Bloom filter is a An efficient data structure with higher space efficiency than hash table, mainly used to determine whether an element exists in a set. In the cache layer, we can use Bloom filters to filter some requests to avoid penetrating into the database.

(2) Use cache avalanche mechanism

Cache avalanche means that at a certain moment, a large amount of data in the cache fails at the same time, causing a large number of requests to penetrate directly into the database. In order to avoid this situation from happening, we can implement some cache avalanche mechanisms in the cache layer, such as setting different expiration times and using distributed locks to ensure the stability of the cache.

(3) Using asynchronous loading

Asynchronous loading means that when the user requests, a part of the data or the default data will be returned first, and the complete data will be loaded asynchronously in the background and the cache will be updated. Through asynchronous loading, users can avoid frequent requests for non-existent data, thereby reducing cache pressure.

(4) Reasonably set the cache expiration time

The cache expiration time refers to the validity time of the data in the cache. After expiration, you need to query the database again and update the cache. Therefore, it is very important to set the cache expiration time reasonably, neither too long nor too short. Generally speaking, the cache expiration time can be set according to business scenarios and system load conditions.

(5) Use mutex lock

Mutex lock can prevent multiple threads from reading and writing the same resource at the same time, thereby ensuring data consistency and security. If the data corresponding to a certain key in the cache is being loaded by other threads, then we can use a mutex lock to prevent repeated loading and updating of the cache.

4. Summary

Caching technology is becoming more and more widely used in software systems, but there are also some risks and problems, such as cache penetration problems. In order to solve this problem, we can use a variety of technical means, such as Bloom filters, asynchronous loading, cache avalanche mechanism, etc. In addition, properly setting the cache expiration time and using mutex locks can also help us effectively avoid cache penetration problems. I hope this article can help everyone understand and deal with cache penetration problems.

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