Performance and Scalability Analysis of Cache_Lite Library's Cache Implementation in PHP Applications

As Internet applications become more and more popular, almost all websites need to involve data access and storage. For websites with high traffic volume, database reading and writing operations will be performed frequently, which will obviously affect the performance of the website. In order to improve the access speed and response time of the website, using caching technology is a good choice.

In PHP applications, caching technology can be implemented using the Cache_Lite library. It is a PHP-based caching library that can cache various types of data structures, such as text, arrays, etc. Here we will discuss the performance and scalability analysis of the cache implementation of the Cache_Lite library in PHP applications.

1. Performance Analysis

Before conducting performance testing, we need to clarify several concepts:

1. hit: hit. Represents the operation of getting data from the cache.
2. miss: Missed. Represents operations that require obtaining data from the database.
3. ttl: Cache time. Indicates the validity period of cached data. After the validity period, the data needs to be retrieved from the database again.

Before conducting performance testing, we need to prepare a simple data table and insert several pieces of test data.

The test code is as follows:

require_once 'Cache/Lite.php';

$options = array(
    'lifeTime' => 3600,
    'cacheDir' => './cache/',
    'automaticSerialization' => true
);

$cache = new Cache_Lite($options);

$id = $_GET['id'];

if ($cache->get('article_'.$id)) {
    $row = $cache->get('article_'.$id);
    echo 'hit: article_'.$id.'<br/>';
} else {
    $db = new mysqli('localhost', 'root', '', 'test');
    $res = $db->query("select * from articles where id=$id");
    $row = $res->fetch_assoc();
    $cache->save($row, 'article_'.$id);
    echo 'miss: article_'.$id.'<br/>';
}

echo $row['title'].'<br/>';
echo $row['content'].'<br/>';

The code uses an instance of Cache_Lite to obtain the data in the cache through the get method. If the cache is not hit, then Get data from database and save it into cache. During the test, we can set the lifeTime parameter to different values ​​to observe the effect of caching.

In order to get the results of the performance test, we need to use Apache's Bench command to test. The test command is as follows:

ab -c 10 -n 100 http://localhost/article.php?id=1

Among them, -c represents the number of concurrent requests, and -n represents the total number of requests. We can set different number of concurrent requests and number of requests for testing and observe the performance of the Cache_Lite library under different pressures.

The following table is my test results:

##1010010195201006544##50As can be seen from the table, we tested with two different

Number of concurrent requests	Number of requests	ttl=60 seconds	ttl=300 seconds
1	100	410	437
5	100	197	194
100	60	29

ttl

parameters under different numbers of concurrent requests and requests. The more the total number of requests, the higher the cache hit rate. The difference in test results will be smaller. When the ttl parameter is small, the performance is relatively stable and basically has nothing to do with changes in the number of requests and the number of concurrent requests. This is because the expiration time of cached data is shorter, resulting in a higher number of cached data misses. many. When the ttl parameter is larger, as the number of concurrent requests and the number of requests increases, the cache hit rate gradually increases, and the performance is better. 2. Scalability analysis

The Cache_Lite library can not only be used as an excellent cache library, but also has good scalability. It is based on file storage and PHP serialization methods, supports different storage engines and different serialization methods, and can be freely expanded as needed.

Storage engine extension

1. The Cache_Lite library uses the file storage engine by default, and the cached data is stored on the local hard disk. Although the file storage engine has high reliability and stability, it is only suitable for a single server environment. When facing a high-concurrency, multi-server environment, you need to use distributed caching solutions, such as Redis, Memcached, etc.

The Cache_Lite library also provides an implementation of using Redis as a storage engine. We only need to adjust its configuration.

Extension of serialization method

2. The Cache_Lite library uses PHP's serialization method by default, which can support the caching of complex data structures such as arrays and objects. But in some scenarios, we need to encrypt and compress the cached data, which can be achieved using a custom serialization method.

We can use the

setOption

method provided by the Cache_Lite library to implement the extension of the serialization method. The specific code is as follows: <pre class='brush:php;toolbar:false;'>class MySerial { public static function encode($data) { return strrev($data); } public static function decode($data) { return strrev($data); } } $options = array( 'lifeTime' =&gt; 3600, 'cacheDir' =&gt; './cache/', 'automaticSerialization' =&gt; true, 'automaticCleaningFactor' =&gt; 50, 'serializer' =&gt; array('MySerial', 'encode', 'decode') ); $cache = new Cache_Lite($options);</pre>In the code, we manually specify the serialization method of the cache library through the

setOption

method, and then pass the encode and decode methods in the custom MySerial class to The setOption method. To sum up, the Cache_Lite library can not only improve application performance, but also has good scalability. Using the Cache_Lite library can bring a lot of convenience and benefits to our PHP applications.

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