How to use Memcached caching technology in PHP to improve image loading speed

With the development of the Internet, the number of visits to the website is increasing. In order to improve the performance and user experience of the website, caching technology has become an indispensable part. Among them, Memcached is a high-performance distributed cache system that is widely used in the Internet field and is especially suitable for caching a large number of read operations. This article will introduce how to use Memcached caching technology in PHP to improve the loading speed of images.

1. Introduction to Memcached

1.1 What is Memcached

Memcached is a high-performance distributed memory object caching system used to reduce database load in dynamic web applications. . It improves application responsiveness and scalability by caching data and objects in memory to reduce the need for disk IO. Memcached was originally created by Brad Fitzpatrick in 2003 and became an Apache Foundation top-level project in 2007.

1.2 Advantages of Memcached

• Memory cache: Memcached cache data is not written to disk, but stored in memory, so the read and write speed is very fast, which can greatly improve system performance.
• Distributed system: Memcached is a distributed cache system that can increase the number of nodes and improve cache capacity and performance through simple configuration.
• Easy to use: Memcached provides a simple API interface and is easy to use.

2. Use Memcached to cache images

2.1 Idea

In a typical Web application, images are one of the frequently requested resources, so we You can reduce the load on the database and improve loading speed by caching images in Memcached. The specific implementation ideas are as follows:

• When the client page requests an image, the background first checks whether there is a corresponding Memcached cache.
• If it exists, read the image data directly from the cache and return it to the client.
• If it does not exist, read the image data, cache it in Memcached, and return it to the client.

In this way, we can increase the loading speed of images to a new level, while reducing the load on the database and improving system performance.

2.2 Code Implementation

Using Memcached to cache images requires installing the Memcached extension first. Here we take Mac OS as an example.

The installation steps are as follows:

• First install the libmemcached software package:

$ brew install libmemcached

• Then install the php-memcached extension:

$ pecl install memcached

Note: If dependency problems occur during the installation process, please install accordingly according to the prompts Dependent libraries.

After installing the extension, we can start using it. The following is the sample code:

<?php
$memcached = new Memcached(); //创建一个Memcached对象
//添加服务器节点，可以是多个
$memcached->addServer('localhost', 11211);
//从缓存中获取图片数据
$img = $memcached->get('test.jpg');
if (!$img) {
    //如果缓存中没有图片数据，从磁盘中读取
    $img = file_get_contents('test.jpg');
    //将图片数据缓存到Memcached中，过期时间为1小时
    $memcached->set('test.jpg', $img, 3600);
}
//设置HTTP响应头，返回图片
header("Content-type: image/jpeg");
echo $img;
?>

In this example, we first create a Memcached object and add a server node. Then use the get method to find whether the corresponding image data exists in the cache. If it exists, it will be returned directly. Otherwise, the image data will be read from the disk, then cached in Memcached and returned to the client.

3. Summary

By using Memcached caching technology, we can increase the loading speed of images to a new level, while reducing the load on the database and improving system performance. In practical applications, we can cache more data as needed to improve system performance and scalability. Of course, when using Memcached caching technology, you also need to pay attention to avoid problems such as cache invalidation and cache penetration. These problems can be further understood and solved in the following studies.

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