<?php

echo memory_get_usage(), PHP_EOL;

$payload = array_fill(0, 1024, 'X');

echo memory_get_usage(), PHP_EOL;

define('TOTAL', 1000);

$list = array();

for($i = 0; $i < TOTAL; $i++) {
    $list[$i]['data'] = $payload;
}

for($i = 0; $i < TOTAL; $i++) {
    $list[$i]['prev'] = &$list[($i-1) % TOTAL];
    $list[$i]['next'] = &$list[($i+1) % TOTAL];
}

echo memory_get_usage(), PHP_EOL;

unset($list);

echo memory_get_usage(), PHP_EOL;

unset($payload);

echo memory_get_usage(), PHP_EOL;