Data caching technology and solutions to common problems in PHP

As people continue to pursue website access speed, data caching technology has gradually become a commonly used solution during the development process. PHP is one of the most widely used server-side scripting languages ​​today, and its data caching technology is also becoming increasingly mature. This article will introduce data caching technology in PHP and solutions to common problems.

1. Data caching technology

1. APC: It is the earliest PHP-specific data cache. Its main purpose is to accelerate by minimizing PHP files, thereby reducing Reduce server resource consumption. The disadvantage of APC is that it is not well integrated with the core of PHP. It only supports normal data types and array types, and you may encounter some security issues if you use a shared server.
2. Memcached: Currently the most widely used PHP cache, it has become one of the most useful high-performance distributed caching systems in large-scale web applications. It is the main cache used by websites such as Facebook. Memcached can handle a wide range of data types, including text, object, and binary data, and it can be used across individual servers and cluster connections.
3. Redis: In addition to Memcached, Redis is also a very popular caching system. Unlike Memcached, Redis is not only a caching system, but also a data structure server that performs data storage directly in memory. It supports 5 different data types: strings, lists, sets, ordered sets, and hashes. Hope expressed.
4. Xcache: It is an efficient PHP accelerator that can accelerate in-process variables up to 50 times. Its biggest advantage is that it supports the latest binary bytecode file format provided by Zend, which is very suitable for the acceleration of PHP code execution.
5. APCu: It is a streamlined version developed on the basis of APC. It removes many functions that have nothing to do with caching, but focuses more on speed and performance.

2. Solutions to common problems

In the actual application process, we often encounter some problems, such as cache variable values ​​expiration, cache occupying too many system resources, etc. The following are some common problem solutions:

1. Cache variable value expires

When using caching technology, the cache time is too long or the cache variable content changes but Failure to update the cache in a timely manner may result in inconsistent cache data content. There are two ways to solve this problem: scheduled updates and monitoring updates.

2. The cache occupies too many system resources

The cache occupies too many system resources is a common problem. The solution to this problem requires comprehensive consideration of system performance, cache storage space and Cache update frequency and other factors. Some of these implementation methods include: using cache middleware, automatically clearing data when cached data expires, sharding cached data, etc.

3. Loss of cached data

In applications, cached data may be accidentally deleted or cached data may be stored incorrectly. The way to solve this problem is to use the backup method, that is, to store the backup data in the cache data copy of the master node. When the master node data is lost, the backup data can be used to restore it.

4. Cache penetration

Cache penetration means that an attacker uses a non-existent key or a deliberately disrupted key to access the cache, which is prone to occur in high-concurrency systems. . The way to solve this problem is to use Bloom filters, which can quickly perform key lookups in memory and can predict non-existence.

Conclusion

Data caching technology can improve the efficiency and performance of Web applications, but it also needs to face some practical problems. Developers need to comprehensively consider factors such as application scenarios, system performance, and maintenance costs to select appropriate caching technologies and solutions. Only by optimizing step by step can you obtain the best results.

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