How to use PHP7.0 for concurrent programming?

PHP7.0 is one of the most commonly used server-side programming languages. It has a friendly interface, easy to learn, powerful functions and a rich extension library. In terms of concurrent programming, PHP7.0 also has many excellent tools and technologies. This article will introduce how to perform concurrent programming in PHP7.0.

1. What is concurrent programming

Concurrent programming refers to a programming method that enables multiple tasks to be executed at the same time at the same time through multiple threads, processes or coroutines. In programming, effective use of concurrency techniques can improve program performance and throughput.

2. Concurrent programming tools of PHP7.0

In PHP7.0, there are many tools to choose from for writing concurrent programs. Here are some commonly used tools:

1. PCNTL extension

The PCNTL extension provided by PHP provides a set of functions for managing processes and signal processing. Using this extension, you can easily manage multiple tasks running in the same process at the same time.

2. pthread extension

pthread extension is a useful PHP extension that implements the POSIX thread interface in PHP. This extension provides various facilities for creating, destroying, synchronizing and communicating threads.

3. Swoole extension

Swoole is a PHP extension that provides asynchronous, non-blocking and coroutine programming functions. This extension has become one of the popular open source projects in PHP, providing a complete concurrent programming framework including network protocols, thread pools, asynchronous tasks, and more.

4. AMQP protocol

AMQP protocol, the full name is Advanced Message Queuing Protocol, is a standard message queue protocol. Using the AMQP protocol, asynchronous and distributed operations can be implemented, and concurrent programming can be easily implemented.

3. Technologies and examples of using PHP7.0 for concurrent programming

The following are some technologies and examples of using PHP7.0 for concurrent programming:

1. Use PCNTL extension

The classic way to synchronize multiple tasks is to use the fork mechanism. Using this technology, you can start multiple sub-processes in a single process to run multiple tasks concurrently. The following is a sample code:

$NUM_CHILDREN = 5;  

$pid_array = array();  

for ($i = 0; $i < $NUM_CHILDREN; ++$i) {  
    $pid = pcntl_fork();  

    if ($pid == -1) {  
        die('could not fork');  
    } else if ($pid) {  
        $pid_array[] = $pid;  
    } else {  
        sleep(5);  
        exit(0);  
    }  
}  

while(count($pid_array) > 0) {  
    foreach($pid_array as $key => $pid) {  
        $res = pcntl_waitpid($pid, $status, WNOHANG);  

        if($res == -1 || $res > 0) {  
            unset($pid_array[$key]);  
        }  
    }  
}  

The above example first defines a $num_children variable, indicating the number of tasks that need to be run concurrently. Then, it starts $num_children child processes and waits for them to complete. Note that in this example, the main process will end after the child process completes.

2. Use pthread extension

Using pthread extension, you can easily create and manage multiple concurrent threads to perform multiple tasks at the same time. The following is a simple example:

class MyThread extends Thread {   
    public function run() {  
        echo "Task started";  
        sleep($this->rand(1, 5));  
        echo "Task completed";  
    }  
}  

$thread1 = new MyThread();  
$thread1->start();  

$thread2 = new MyThread();  
$thread2->start();  

$thread1->join();  
$thread2->join();  

In the above code, a custom thread class named MyThread is defined. This class overrides the run method in the Thread class and defines concurrent tasks in it. In the main code section, create a thread instance and use the start() method to start the thread. Then, use the join() method to wait for the thread to complete.

3. Use Swoole extension

Swoole extension provides a convenient concurrent programming framework, which can easily handle asynchronous, non-blocking and coroutine development. The following is an example of concurrent programming using Swoole:

$server = new swoole_http_server("127.0.0.1", 9501);  

$server->on('request', function ($request, $response) {  
    $response->header("Content-Type", "text/plain");  
    $response->end("Hello World
");  
});  

$server->start();

The above code creates a Swoole HTTP server listening on port 9501. When requested, the server will simply return "Hello World". Note that the code written in this example is asynchronous and non-blocking. This allows the server to handle many requests simultaneously with high unit performance.

4. Use AMQP protocol

AMQP protocol is a distributed message queue standard. Using the AMQP protocol, message sending and receiving operations, as well as asynchronous programming can be easily implemented. The following is an example of AMQP concurrent programming:

require __DIR__ . '/vendor/autoload.php';  

use PhpAmqpLibConnectionAMQPConnection;  

$connection = new AMQPConnection('localhost', 5672, 'guest', 'guest');  
$channel = $connection->channel();  

$channel->queue_declare('task_queue', false, true, false, false);  

echo ' [*] Waiting for messages. To exit press CTRL+C', "
";  

$callback = function($msg) {  
  echo " [x] Received ", $msg->body, "
";  
  sleep(substr_count($msg->body, '.'));  
  echo " [x] Done", "
";  
};  

$channel->basic_qos(null, 1, null);  

$channel->basic_consume('task_queue', '', false, true, false, false, $callback);  

while(count($channel->callbacks)) {  
    $channel->wait();  
}  

$channel->close();  
$connection->close();  

In the above code, a task queue is created on the rabbitmq queue using the AMQP protocol to obtain asynchronous tasks, and then reports after the task is completed. In this example, we use the PhpAmqpLib library, which is a PHP extension library that encapsulates the AMQP protocol.

4. Summary

Using PHP7.0 concurrent programming, you can more easily implement high-performance and high-throughput applications. In this article, we introduce some commonly used PHP concurrent programming tools, including PCNTL extension, pthread extension, Swoole extension, and AMQP protocol. In addition, we also show some examples of using these tools. If you want to maximize your application's performance, consider trying these techniques.

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