Examples of synchronous and asynchronous code in PHP

1. Using Synchronous 

The program waits for the current task to finish before starting the next task

<?php

$start = microtime(true);

echo 'start' . PHP_EOL;

function run() {

echo 'before' . PHP_EOL;

usleep(3000000); // equivalent of setTimeout in Node.js

echo 'wait 3 seconds' . PHP_EOL;

echo 'after' . PHP_EOL;

}

run();

echo 'end' . PHP_EOL;

$end = microtime(true);

$time_taken = $end - $start;

echo "Time taken: " . number_format($time_taken, 5) . " seconds";

output

start
before
wait 3 seconds
after
end
Time taken: 3.00017 seconds

Or

<?php

$start = microtime(true);

echo 'start' . PHP_EOL;

function run() {

echo 'before' . PHP_EOL;

// usleep(3000000); // equivalent of setTimeout in Node.js

echo 'wait 3 seconds' . PHP_EOL;

echo 'after' . PHP_EOL;

}

run();

echo 'end' . PHP_EOL;

$end = microtime(true);

$time_taken = $end - $start;

echo "Time taken: " . number_format($time_taken, 5) . " seconds";

output

start
before
wait 3 seconds
after
end
Time taken: 0.00004 seconds

2. Using Asynchronous 

The program can continue to execute while waiting for a task to complete

You have to install ReactPHP to use asynchronous in PHP

Thank you