PHP Object vs Array memory usage with random values

loose-obj.php

<?php
include_once "./randomString.php";

$s = [];

for ($x = 0; $x < 100000; $x++) {
    $obj = new stdClass();
    $obj->name = randomString();
    $obj->age = rand(1, 100);
    $s[] = $obj;
}
echo "stdClass objects only peak memory usage: " . memory_get_peak_usage() . "b\n";

php-obj-arr-bench_arr.php

<?php

include_once "./randomString.php";

$s = [];
for ($x = 0; $x < 100000; $x++) {
    $s[] = [
        "name" => randomString(),
        "age" => rand(1, 100),
    ];
}
echo "Arrays only peak memory usage: " . memory_get_peak_usage() . "b\n";

php-obj-arr-bench_bench.sh

#!/usr/bin/env bash

time php ./arr.php
time php ./loose-obj.php
time php ./obj.php

php-obj-arr-bench_obj.php

<?php
include_once "./randomString.php";

$s = [];

class MyArrayObject {
    public $name, $age;

    public function __construct(string $name, string $age) {
        $this->name = $name;
        $this->age = $age;
    }
}

for ($x = 0; $x < 100000; $x++) {
    $s[] = new MyArrayObject(randomString(), rand(1, 100));
}
echo "Objects only peak memory usage: " . memory_get_peak_usage() . "b\n";

php-obj-arr-bench_randomString.php

<?php

function randomString($length = 10) {
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $charactersLength = strlen($characters);
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, $charactersLength - 1)];
    }
    return $randomString;
}

I've tested with another structure of class and it turn out it use even less memory.

Normally I will recast an array into an object because of readability like this:

$obj = (object) [
  'key' => 'value'
];

but according to this test, this will consumes memory the most. anyway I don't like to repeat properties assignment inside every class so I made an abstract class with a constructor accepting an array as only parameter. then constructor will loop through parameter and assign the value

abstract class Main {
  public function __construct( $properties = [] ) {
    foreach( $properties as $property => $value ) {
      if( property_exists( $this, $property ) ) {
        $this->$property = $value;
      }
    }
  }
}

class MyArrayObject extends Main {
  public $name, $age;
}

for( $x = 0 ; $x < 100000 ; $x++ ) {
    $s[] = new MyArrayObject([
      'name' => randomString(),
      'age' => rand(1, 100)
    ]);
}

from what I've tested, this use even less memory. (16.82MB vs 19.60MB) https://docs.google.com/spreadsheets/d/1jviu-peSDFMP4F5CmFm3TgN1Wlnh4QvaeTXEeAy9HiA/edit?usp=sharing