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;
}

Results after running bench.sh which does 100,000 iterations. Random strings are used for the values.

Type	Memory Usage	Real execution Time
stdClass	51,232,368	0m0.156s
Arrays	46,191,568	0m0.137s
Classes	20,537,808	0m0.129s

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