Detailed explanation of PHP coroutines: a powerful tool for mastering parallel programming

Coroutine is a lightweight thread that can significantly improve the efficiency of parallel programming in PHP. It allows functions to pause execution (using yield) and resume from the pause, while sharing memory space for efficient data passing. To use coroutines, you need to define a coroutine function (Generator suffix) and use yield to pause execution. Create and execute coroutines via Generator methods (current and send). Coroutines are widely used in scenarios such as HTTP concurrent requests, Socket communication, and data processing pipelines. It should be noted that the coroutine function must be of type Generator, yield must return a value, and the coroutine does not support parallel file or database write operations.

Detailed explanation of PHP coroutines: a powerful tool for mastering parallel programming

Preface

A coroutine is a lightweight thread that can pause and resume its execution without waiting for I/O operations to complete. In PHP, coroutines can greatly improve the efficiency of parallel programming. This article will provide an in-depth introduction to PHP coroutines, including their principles, usage, and practical cases.

Coroutine Principle

Coroutine is essentially a function or method, which has the following characteristics:

• Its execution can be suspended, Transfer control to other coroutines through the yield keyword.
• Its execution can be resumed, continuing from where it was paused.
• Share the same memory space with other coroutines, so data can be passed efficiently.

Using PHP coroutines

Using coroutines in PHP requires the following steps:

1. Define the coroutine function, use function keyword and add Generator suffix.
2. Use the yield keyword in a coroutine function to pause execution and return a value.
3. To create a coroutine and execute it, you can use the Generator::current() and Generator::send() methods.

Code examples

<?php
function fibonacci($n) {
    $a = 0;
    $b = 1;

    for ($i = 0; $i < $n; $i++) {
        yield $a;
        $temp = $a;
        $a = $b;
        $b = $temp + $b;
    }
}

$generator = fibonacci(10);

foreach ($generator as $value) {
    echo $value . PHP_EOL;
}
?>

Practical cases

In the following scenarios, coroutines can play a significant role Function:

• HTTP concurrent requests: HTTP requests can be sent in parallel through coroutines to improve response speed.
• Socket concurrent communication: Coroutines can monitor multiple Socket connections at the same time to achieve high-throughput network communication.
• Data processing pipeline: Coroutines can create data processing pipelines to efficiently transfer data between different coroutines.

Notes

You should pay attention to the following when using coroutines:

• The coroutine function must be declared as Generator type.
• When using the yield keyword, a value must be returned.
• Local variables of the coroutine will be retained when execution is suspended and resumed.
• Coroutines in PHP do not support operations such as writing files or databases in parallel.

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