<?php

class Entity { }
echo "EXAMPLE 1".PHP_EOL;
$entities = array();
echo "START: ". number_format(memory_get_usage()) . "\n";
for($i = 0; $i < 100000; ++$i)
{
    $entities[] = new Entity;
}
echo "BEFORE UNSET: ". number_format(memory_get_usage()) . "\n";
unset($entities);
echo "AFTER UNSET: ". number_format(memory_get_usage()) . "\n";

echo "\n------------------------------\n\n";
echo "EXAMPLE 2".PHP_EOL;
$entities = array();
echo "START: ". number_format(memory_get_usage()) . "\n";
for($i = 0; $i < 100000; ++$i)
{
    $entity = new Entity;
    $entities[] = &$entity;
}
echo "BEFORE UNSET: ". number_format(memory_get_usage()) . "\n";
unset($entities);
echo "AFTER UNSET: ". number_format(memory_get_usage()) . "\n";

echo "\n------------------------------\n\n";
echo "EXAMPLE 3".PHP_EOL;
$entities = array();
echo "START: ". number_format(memory_get_usage()) . "\n";
for($i = 0; $i < 100000; ++$i)
{
    $entities[] = new Entity;
}
echo "BEFORE UNSET: ". number_format(memory_get_usage()) . "\n";
foreach($entities as &$entity) {
    unset($entity);
}
unset($entities);
echo "AFTER UNSET: ". number_format(memory_get_usage()) . "\n";

echo "\n------------------------------\n\n";

EXAMPLE 1
START: 52,248
BEFORE UNSET: 21,298,216
AFTER UNSET: 3,238,304

------------------------------

EXAMPLE 2
START: 3,238,336
BEFORE UNSET: 8,146,588
AFTER UNSET: 3,238,472

------------------------------

EXAMPLE 3
START: 3,238,524
BEFORE UNSET: 21,298,404
AFTER UNSET: 3,238,312

------------------------------