How does PHP8 improve file loading speed through Just-In-Time Compilation?

How does PHP8 improve file loading speed through Just-In-Time Compilation?

With the development of the Internet, the performance requirements of web applications are becoming higher and higher. PHP, as a programming language widely used in web development, has always been criticized in terms of performance. However, with the release of PHP8, the Just-In-Time Compilation function was introduced, which greatly improved the performance of PHP. This article will introduce the principle of Just-In-Time Compilation in PHP8 in detail, and demonstrate through specific code examples how to improve file loading speed through Just-In-Time Compilation.

1. What is Just-In-Time Compilation?
   Just-In-Time Compilation is a dynamic compilation technology that compiles code into machine code on the fly during runtime to improve the running efficiency of the program. The traditional PHP execution process is to parse the PHP code into an abstract syntax tree, then translate it into bytecode, and finally execute the bytecode through the Zend virtual machine. Just-In-Time Compilation introduces the ability of just-in-time compilation into the Zend virtual machine, which directly compiles bytecode into machine code, avoiding the overhead of bytecode interpretation and execution, thus improving the execution speed of the program.
2. How to enable Just-In-Time Compilation?
   In PHP8, enabling Just-In-Time Compilation is very simple. You only need to enable it in the opcache option in php.ini. By setting the opcache.jit_buffer_size and opcache.jit=tracing (or opcache.jit=static) parameters, you can specify the size of the JIT buffer and the method of JIT compilation.
3. How does Just-In-Time Compilation improve file loading speed?
   When the PHP code is compiled and stored in the opcache cache, the next time the file is executed, PHP does not need to parse and compile the file again, and reads and executes it directly from the cache. In the traditional PHP execution process, every time a PHP file is executed, it needs to go through the process of parsing and compiling, which will lead to a longer loading time when there are many files or the file size is large. Through Just-In-Time Compilation, PHP8 can directly compile bytecode into machine code and store it in the opcache cache, thus avoiding the process of parsing and compiling every time a file is loaded, greatly improving file loading speed.

The following uses specific code examples to demonstrate how to improve file loading speed through Just-In-Time Compilation:

<?php
// 普通的PHP文件，没有启用Just-In-Time Compilation

// 耗时的计算函数
function expensiveCalculation($num)
{
    $result = 0;
    for ($i = 1; $i <= $num; $i++) {
        $result += $i;
    }
    return $result;
}

$start = microtime(true);

for ($i = 0; $i < 1000; $i++) {
    expensiveCalculation(10000);
}

$end = microtime(true);

echo "耗时：" . ($end - $start) . "秒";

?>

<?php
// 启用Just-In-Time Compilation的PHP文件

// 耗时的计算函数
function expensiveCalculation($num)
{
    $result = 0;
    for ($i = 1; $i <= $num; $i++) {
        $result += $i;
    }
    return $result;
}

$start = microtime(true);

for ($i = 0; $i < 1000; $i++) {
    expensiveCalculation(10000);
}

$end = microtime(true);

echo "耗时：" . ($end - $start) . "秒";

?>

As can be seen from the above code examples, by enabling Just-In-Time Compilation After Time Compilation, PHP code does not need to be parsed and compiled every time it is executed, thus greatly improving file loading speed. In actual applications, especially in scenarios where the file size is large or needs to be loaded frequently, the performance advantages of Just-In-Time Compilation will be more obvious.

Summary:
The Just-In-Time Compilation function introduced in PHP8 has greatly improved the performance of PHP. By directly compiling bytecode into machine code, it avoids the overhead of bytecode interpretation and execution. , thereby improving the execution speed of the program. By enabling Just-In-Time Compilation, file loading speed can be greatly improved, especially in scenarios where the files are large or need to be loaded frequently. Developers can enable Just-In-Time Compilation by setting relevant parameters in php.ini and verify its performance benefits through specific code examples.

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