High quality notes are here! About PHP7 performance optimization

Opcache

1. Opcache principle
The normal execution process of PHP is as follows

request (nginx, apache, cli, etc.) –> The Zend engine reads the .php file –> Scans its dictionary and expressions –> Parses the file –> Creates computer code to be executed (called Opcode) –> ;Finally execute Opcode–> response return

Each time the PHP script is requested, the above steps will be executed. If the PHP source code does not change, then the Opcode will not change. Obviously, there is no need to regenerate the Opcode every time. Combined with the ubiquitous caching mechanism in the Web, we can cache Opcode. Wouldn't it be faster to directly access the cached Opcode in the future? The flow chart after enabling Opcode caching is as follows:

The purpose of Opcode cache is to avoid repeated compilation and reduce CPU and memory overhead.
2. Opcache configuration
Add under php.ini:

// 加载opcache(需确认已安装opcache拓展)
zend_extension=opcache.so
// 开启opcache
opcache.enable = 1
// OPcache共享内存存储大小,单位MB
opcache.memory_consumption=1024 // 1G
// PHP使用了一种叫做字符串驻留，默认是4MB
opcache.interned_strings_buffer=32
// 这个选项用于控制内存中最多可以缓存多少个PHP文件,这个选项必须得设置得足够大，大于你的项目中的所有PHP文件的总和
opcache.max_accelerated_files=80000
// 设置缓存的过期时间（单位是秒）,为0的话每次都要检查
opcache.revalidate_freq=3
// 从字面上理解就是“允许更快速关闭”
opcache.fast_shutdown=1
// CLI环境下，PHP启用OPcache
opcache.enable_cli=1

HugePage

1. HugePage principle
By enabling this feature, PHP7 will "move" its own TEXT segment (execution body) to Huagepage. In previous tests, we can steadily see a 2% to 3% QPS increase on WordPress.
Regarding what Hugepage is, to put it simply, the default memory is paged in 4KB, and the virtual address and the memory address need to be converted, and this conversion requires a table lookup. In order to speed up the table lookup process, the CPU will Built-in TLB (Translation Lookaside Buffer), it is obvious that if the virtual page is smaller, the number of entries in the table will be more, and the TLB size is limited, the more entries, the higher the Cache Miss of the TLB will be, so if we Enabling large memory pages can indirectly reduce this TLB Cache Miss. As for the detailed introduction, I will not go into details after searching a lot on Google. Here I mainly explain how to enable this new feature, which will bring significant performance improvements.
2. HugePage configuration

$ sudo sysctl vm.nr_hugepages=512 // 切勿越大越好，会长占内存

Allocate 512 reserved huge page memory:

cat /proc/meminfo  | grep Huge
AnonHugePages:    106496 kB
HugePages_Total:     512
HugePages_Free:      504
HugePages_Rsvd:       27
HugePages_Surp:        0
Hugepagesize:       2048 kB

Then add in php.ini:

opcache.huge_code_pages=1

Opcache file cache

1. Introduction to Opcache file cache
Use opcache to store compiled php files as files to achieve php source code protection and scripts Acceleration, there will be obvious performance improvement
2. Opcache file cache configuration
Add in php.ini:

opcache.file_cache=/tmp

So that PHP will be in the /tmp directory Cache some Opcode binary export files, which can exist across the PHP life cycle.

You need to restart php-fpm after configuration

Personal test

System: centOs 7
php version: 7.4
nginx
laravel: 8.5

Before optimization

cpu:95%- 96%
Memory: 2G/16G
10 minutes 4W concurrency
Failure rate: 24%

Aggregation report

Processing transactions per second
![PHP7 Performance Optimization]
![PHP7 Performance Optimization Notes]

##After optimization

cpu:20%-40 %

Memory: 5.8G/16G (here my HugePage is set to 2048)
4W concurrency in 10 minutes
Failure rate: 0%

First stress test

Aggregation report

Transactions processed per second

Second stress test

Aggregation report

Processing transactions per second

Recommended study: "

PHP7 Tutorial》

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