As we all know, php is an interpreted language, and its execution can be divided into the following processes:

1. Scanning (Lexing), Convert PHP code into language fragments (Tokens)

2. Parsing, convert Tokens into simple and meaningful expressions

3. Compilation, compiles expressions into Opocdes

4. Execution, executes Opcodes sequentially, one at a time, thereby realizing the functions of PHP scripts.

In this case, repeated requests for the same file will require continuous parsing, compilation and execution of PHP scripts, consuming too many resources.

php traditional operating mode:

In order to solve this problem, opcodecaching technology came into being.

So what is opcode cache?

After the interpreter completes the analysis of the script code, it generates intermediate codes that can be run directly, also called operation codes (Operate Code, opcode). Opcode caching is to cache the compiled Opcode code in the memory. The next time you execute this script, you will directly find the opcode code in the cache and directly execute the last step without the need for intermediate steps. Its purpose is to avoid Repeat compilation to reduce CPU and memory overhead.

After the interpreter completes the analysis of the script code, it generates intermediate codes that can be run directly, also called operation codes (Operate Code, opcode). Opcode caching is to cache the compiled Opcode code in the memory. The next time you execute this script, you will directly find the opcode code in the cache and directly execute the last step without the need for intermediate steps. Its purpose is to avoid Repeat compilation to reduce CPU and memory overhead.

Cache operation mode:

opcache is an opcode cache tool.

The biggest difference between Opcache and other caching tools, which can also be said to be its advantage, is that it has entered the php source code tree and become an official product. It will always be updated with php, while the others have been around for a long time. It is no longer updated. Currently, it does not support the new version of PHP or has poor compatibility. Secondly, after testing, opcache is also more efficient than other tools.

So how to enable the use of opcache?

Now that opcahce has entered the PHP source tree, as a built-in tool, the opening method must be very simple. The following is the recommended configuration:

zend_extension=.././...php_opcache.dll（路径）
opcache.memory_consumption=128   #共享内存opcache.interned_strings_buffer=8   #存储临时字符串opcache.max_accelerated_files=4000   #缓存文件数opcache.revalidate_freq=60  #缓存时间opcache.fast_shutdown=1opcache.enable_cli=1 opcache.enable=1   #是否开启opcode缓存

You only need to remove the previous; .

Of course opcache has many configurations, so I won’t list them all here. The above ones are standard configurations and can meet general needs.

Theoretically, the larger the PHP file and the more complex the logic, the more obvious the effect of opcache will be, and it will play a great role in speed and anti-concurrency.

The test results in the local environment are as follows (computer performance is limited):

Service Server test:

There is a significant improvement in efficiency.

It should be noted that since opcache will cache the opcode executed for the first time in the file, it should not be opened in the test environment. The reason is that you know that the code is changed during development, but the result is different. Unchanged…………..

To manually clear the opcache cache, you need to run opcache_reset() to clear it, so if opcache is configured online, it needs to be cleared You can use this function.

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