With the continuous development and changes of network applications, handling parallel and asynchronous requests has become an important topic in PHP back-end API development. In traditional PHP applications, requests are performed synchronously, that is, a request will wait until a response is received, which will affect the response speed and performance of the application. However, PHP now has the ability to process parallel and asynchronous requests. These features allow us to better handle a large number of concurrent requests and improve the response speed and performance of the application.

This article will discuss how to handle parallel and asynchronous requests in PHP backend API development. We'll introduce PHP's parallel and asynchronous request handling mechanisms and discuss how to apply them to API development.

What is parallel and asynchronous request processing?

Parallel processing refers to processing multiple requests or tasks at the same time, that is, performing multiple operations at the same time. This is a way to speed up application processing. Parallel processing can be done using multiple threads, multiple processes, or multiple servers, depending on the characteristics of the application and the environment.

Asynchronous processing is an event-driven programming model that does not block during program execution, but continues processing after execution. In PHP, asynchronous processing is usually done using callback functions or coroutines, which makes it easier for applications to implement non-blocking I/O and high concurrent requests.

PHP’s asynchronous request processing

PHP version 5.3 introduces support for asynchronous request processing. PHP uses multiple extensions to implement asynchronous processing, the most commonly used of which are libevent and event. These extensions provide a set of APIs that can be used to create event loops, register callback functions, listen to sockets, and more. PHP's asynchronous request processing mechanism can realize non-blocking I/O, high concurrent requests, long connections, etc.

The following is a sample code using libevent extension:

$base = event_base_new();

$dns_base = evdns_base_new($base, 1);

$event = event_new();

event_set($event, $socket, EV_READ | EV_PERSIST, function($fd, $what, $arg) {

// Processing the socket Word event

});

event_base_set($event, $base);

event_add($event);

event_base_loop($base);

In this example, we use the event_base_new() function to create an event loop, then use the event_new() function to create an event object, and use the event_set() function to register an event handler for the event object. Finally, we start the event loop to listen for socket events through the event_base_loop() function.

Parallel processing of PHP

PHP can use multiple processes or threads when processing parallel requests. PHP's multi-process support is provided by the pcntl extension, while multi-thread support is implemented through the pthreads extension. We will learn about PHP's parallel processing mechanism by introducing these two extensions.

Multi-process processing

Using PHP's pcntl extension, we can run multiple processes at the same time, thereby speeding up application processing. The following is a sample code that uses the pcntl_fork() function to create a child process:

$pid = pcntl_fork();

if ($pid == -1) {

// Failed to create child process

die('Could not fork');

} else if ($pid) {

//The parent process executes the code here

// Wait for the child process to end

pcntl_wait($status);

} else {

// The child process executes the code here

// Processing requests or tasks

exit;

}

In this example, we use the pcntl_fork() function to create a child process, and then in the child process Process the request or task, and finally use the exit() function to end the child process.

Multi-threading

Using PHP's pthreads extension, we can use threads to process requests or tasks. The following is a sample code that uses pthreads extension to create a thread:

class MyThread extends Thread {

public function run() {

// Processing requests or tasks

}

}

$myThread = new MyThread();

$myThread -> start();

$myThread -> ; join();

In this example, we use the pthreads extension to create a thread object, use the start() function to start the thread, and then use the join() function to wait for the thread to end.

Summary

This article introduces parallel and asynchronous request processing technology in PHP back-end API development. Parallel processing in PHP can use multiple processes or threads, while asynchronous processing is usually done using callback functions or coroutines. These technologies can help us better handle a large number of concurrent requests and improve application response speed and performance.

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