Detailed explanation of how to use PHP's Opcache acceleration

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Introduction

For PHP version 5.5 or above, you can use PHP's own opcache to enable performance acceleration (the default is off). For versions below PHP 5.5, you need to use APC acceleration

Opcache is a method that avoids the overhead of loading and parsing PHP scripts each time by storing the precompiled bytecode of the parsed PHP script in shared memory. The parser can read the cached bytecode directly from the shared memory, thus greatly improving the execution efficiency of PHP.

Configuration

In PHP 5.5.0 and subsequent versions, PHP has embedded the Opcache function in the release version in the form of an extension library. Opcache is not turned on by default. To accelerate, developers need to add or annotate Opcache related configurations in php.ini. For older versions, Opcache can be installed and configured as a PECL extension library

php.ini:

[opcache]

# 启动操作码缓存
opcache.enable=1

#针对支持CLI版本PHP启动操作码缓存 一般被用来测试和调试
opcache.enable_cli=1

# 共享内存大小，单位为MB
opcache.memory_consumption=128

#存储临时字符串缓存大小，单位为MB，PHP5.3.0以前会忽略此项配置
opcache.interned_strings_buffer=8

#缓存文件数最大限制，命中率不到100%，可以试着提高这个值
opcache.max_accelerated_files=4000

#一定时间内检查文件的修改时间, 这里设置检查的时间周期, 默认为 2, 单位为秒
opcache.revalidate_freq=60

#开启快速停止续发事件，依赖于Zend引擎的内存管理模块，一次释放全部请求变量的内存，而不是依次释放内存块
opcache.fast_shutdown=1

#启用检查 PHP 脚本存在性和可读性的功能，无论文件是否已经被缓存，都会检查操作码缓存,可以提升性能。 但是如果禁用了 opcache.validate_timestamps选项， 可能存在返回过时数据的风险。
opcache.enable_file_override=1

Opcache Notes

1. There is no need to use apc and Xcache acceleration when using Opcache;

Because PHP 5.5.0 and subsequent versions have built-in support for Opcache Support, so PHP realizes its importance. Compared with third-party PHP optimizers such as Xcache, using Opcache will be a better choice. In addition, if both exist at the same time, the number of cache hits of Opcache will be greatly reduced and unnecessary overhead will be added.

2. It is not recommended to turn on Opcache during the development process

After turning on Opcache, the content modified by the developer will not be displayed and take effect immediately because it is affected by opcache.revalidate_freq=60, so It is recommended to turn on Opcache when testing performance after development and testing. Of course, Opcache must always be turned on in the production environment.

3. It is not recommended to set the Opcache indicators too large

The configuration size of each Opcache indicator or whether to enable it needs to be combined with the actual needs of the project and the configuration recommended by Opcache official, and the actual situation of the project needs to be analyzed , which can be combined with the visual cache information analysis and adjustment in Part 4 above.

4. It is not recommended to use the old version of Opcache for a long time

It is recommended to pay attention to the news of Opcache official website in time to learn about its bug fixes, function optimization and new functions in real time, so as to better apply it in your own projects.

5. It is not recommended to put the open source project introduced above into the Web service root directory in a production environment. The reason is very simple, because this open source project does not have access restrictions and security processing. , that is to say, any user who can access the external network can directly access it as long as he knows the access address, so it is not safe. Generally, this open source tool only helps to visually analyze the performance of PHP, and is usually used during the development and debugging phase. If you just want to enable it in a production environment, you must do security restrictions.

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