Application practice of Redis caching technology to solve cache avalanche in PHP applications

As the scale of web applications continues to expand, more applications store data in the cache to improve response speed. In high-concurrency scenarios, cache avalanche is a common problem. It will cause application performance to decrease and may cause system downtime. For this problem, Redis caching technology can provide some solutions. This article will introduce how to use Redis caching technology to solve the cache avalanche problem in PHP applications.

What is cache avalanche?

Cache avalanche refers to a situation where a large number of cache keys in the cache system expire at the same time at a certain moment, causing a large number of requests to fall on the database, causing the database to crash. Cache avalanches are difficult to deal with because they cause a ripple effect across multiple components. For example, when our Redis server goes down, the application will send a large number of requests to the database server, causing the database server to be unable to handle the requests normally.

Solution

Using Redis caching technology can effectively solve the cache avalanche problem. Redis is a high-performance, non-relational, in-memory storage database that supports persistence and allows storage of a variety of data structures such as key-value pairs, lists, sets, ordered sets, and hash tables. Redis provides many advanced features, such as publish and subscribe, Lua scripts, and automatic failover, which can be used to build a reliable caching system.

Advantages

The biggest advantage of using Redis caching technology is to improve the system's timely response to requests and fast reading and writing speed, and to be able to store and read data stably and reliably, while providing High concurrent processing capabilities. All this can effectively avoid cache avalanche problems.

Application Practice

Using Redis caching technology to solve the cache avalanche problem is not an easy task and requires us to make some improvements in the system architecture.

1. Solving the avalanche problem

There are many ways to solve the cache avalanche problem, the most commonly used of which are locking and distributed locking. The locking method is to randomly add some time to the expiration time of the cache object so that the cache object's failure does not occur at the same time. Distributed locks allocate a lock on multiple nodes, and use distributed locks to ensure the consistency and reliability of data when writing data.

2. Cache preheating

Cache preheating is to load hot data (data that may be accessed in large quantities in the future) into Redis in advance. The cache has been generated during large-scale queries, so that It can effectively prevent high-concurrency query requests due to cache failure from falling directly to lower-layer storage such as databases, thereby avoiding excessive server pressure and resulting system unavailability.

3.Redis Cluster

In order to improve the high availability and reliability of the Redis system, we can use Redis Cluster. Redis cluster can divide a Redis database into multiple nodes, and each node can perform separate operation functions. Redis cluster provides distributed database management and maintenance functions, including data sharding, data backup, data recovery, data failover, system monitoring and alarms, etc., which can ensure the stability of the system.

Summary

Redis caching technology is an effective way to solve the cache avalanche problem and has also been widely used in PHP applications. Using Redis caching technology can effectively guarantee the performance and stability of the system. However, in the actual application process, targeted optimization and adjustments need to be made for different business scenarios to adapt to specific application scenarios.

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