The difference and effect of acceleration, cache extension in PHP (Eaccelerator, memcached, XCache, APC) _php instance

PHP has Eaccelerator, memcached, XCache, APC 4 acceleration, cache expansion, below to introduce their differences, look at it!

Toss the VPS friends, in the installation of a good lnmp and other Web running environment will choose some cache expansion installation to improve the speed of PHP, is often introduced by the eaccelerator, memcached, XCache, alternative PHP Cache These caching extensions, what is the difference between them? What are the functions of the difference? This is the answer that this article gives everybody.

　　1, Eaccelerator

Eaccelerator is a free and open source PHP accelerator, optimized and dynamic content caching, improve the caching performance of PHP scripts, so that PHP script in the state of compilation, the cost of the server almost completely eliminated. It also optimizes the script to accelerate its execution efficiency. So that the PHP program code efficiency can be increased 1-10 times. The text can be understood as: Eaccelerator is the PHP accelerator extension.

　　2, memcached

Memcached is a high-performance distributed memory object caching system for dynamic Web applications to reduce database load. It reduces the number of read databases by caching data and objects in memory, providing the speed of dynamic, database-driven Web sites. From the text can be understood as: Memory cache expansion, and for the cluster server more use, mainly for distributed caching, is a database cache.

　　3, Alternative PHP cache (APC caching)

Alternative PHP cache (APC caching) is a valid open source Cache tool for PHP, he can cache opcode (target file) of the PHP intermediate code. The APC cache is divided into two parts: the system cache and the user data cache. The system cache is automatically used, which means that the APC caches the compiled results of the PHP file source code, and then compares the time markers before calling again. If it does not expire, it is run using cached code. The default cache is 3600s (one hour). But it still wastes a lot of CPU time. Therefore, you can set the system cache to never expire (apc.ttl=0) in php.ini. But if you do this, you need to restart your Web server after you change the PHP code ( Like Apache ...). Current performance testing of APC generally refers to this layer of cache; from text to: Alternative PHP cache (APC caching) is also a kind of memory cache expansion, is a database cache extension.

　4, Xcache

is an open source opcode buffer/optimizer, he can improve the PHP performance on the server, he by the data compiled PHP buffer to the shared memory to avoid duplication of the compilation process, can directly use the buffer compiled code to improve speed. Typically, you can increase your page generation rate by 2 to 5 times times and reduce server load. In fact, it is the same as eaccelerator PHP accelerator extension.

The above is their role and difference, the simple point is: Eaccelerator,xcache is a php cache extension, memcached, APC cache is the database cache expansion, the general two only to install one can, do not try. In addition, the actual test found that when the cache number exceeds a certain threshold, the performance of APC is inferior to memcache. So in the expansion of the choice, I will generally choose xcache+memcached this combination.

The above is a small set of PHP to introduce the acceleration, cache expansion of the difference and the role of the detailed explanation (Eaccelerator, memcached, XCache, APC) all the narration, I hope to help you, if you want to learn more content please pay attention to cloud Habitat community website!