How to Achieve Multithreading in PHP

1. Use the Parallel Parallel Concurrency Extension to Achieve Multithreading in PHP
2. Use the popen() Function to Achieve Multithreading in PHP

Multithreading is a form of program execution, where a single process creates several threads, and they execute simultaneously. This tutorial will discuss multithreading in PHP and demonstrate how to achieve it.

Use the Parallel Parallel Concurrency Extension to Achieve Multithreading in PHP

Using the Parallel parallel concurrency extension, we can achieve multithreading in PHP.

The extension provides a interpreter thread parallel\Runtime. We can create an object from the parallel\Runtime() class and thus create a thread.

The class provides a method run() that schedules the tasks to run parallelly. We can pass Closure as the parameter to the run method.

The parameter is generally called task, and we can also specify an array as the method’s second parameter. The content of the array is passed to the task.

There are some requirements before downloading the Parallel parallel concurrency extension. The PHP version should be 8.0, and Zend Thread Safe (ZTS) should be enabled.

The <pthread.h> header is another requirement. We can download the extension from pecl as follows.

pecl install parallel

We can test the parallel execution of the program using the for loop.

For example, we can run a loop inside the run() method and another loop outside the method. In such conditions, the code execution will be parallel.

For example, create an object $rt of the parallel\Runtime class and then invoke the run() method with the object. Inside the run() method, write an anonymous function.

First, write a for loop to print the + sign fifty times inside the function. Next, outside the run() method, write another for loop to print the - sign fifty times.

As the loop inside the run() method runs in a separate thread, the loop outside the run() method will execute concurrently. As a result, the - and + sign are printed simultaneously, as shown in the output section below.

Therefore, we can use the parallel concurrency extension to achieve multithreading in PHP.

Example Code:

$rt = new \parallel\Runtime();

$rt->run(function(){
 for ($i = 0; $i < 50; $i++)
 echo "+";
});

for ($i = 0; $i < 50; $i++) {
 echo "-";
}

Output:

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Use the popen() Function to Achieve Multithreading in PHP

We can use the popen() function to open parallel processes in PHP.

The function forks the process, and as a result, parallel processing is achieved. There is no sharing of the resources by the processes.

In this way, we can achieve multithreading in PHP. The popen() function creates a pipe to the forked process.

We can loop over the popen() function and create several processes to achieve multithreading. The popen() function takes command as the first parameter and mode as the second parameter.

The mode can be either r or w.

For example, create a for loop that loops five times. Inside the loop, create another for loop that loops over five times.

Inside the child loop, create an array $process that stores the popen() function. Set the PHP file message.php and the r mode as the first and second parameters.

Next, create another child loop and use the pclose() function to close the $process.

Here, the five processes execute parallelly in the first child loop. The processes are terminated in the second child loop with the pclose() function.

This is how we can achieve multithreading using the popen() function in PHP.

Example Code:

for ($i=0; $i<5; $i++) {
 
 for ($j=0; $j<5; $j++) {
 $process[$j] = popen('message.php', 'r');
 }

 for ($j=0; $j<5; ++$j) {
 pclose($process[$j]);
 }
}