Evenement not freeing up memory?

gistfile1.php

<?php
$loader = include __DIR__ . '/../vendor/autoload.php';
$loop = React\EventLoop\Factory::create();

$counter = 0;
$timer = $loop->addPeriodicTimer(10, function() use(&$timer, &$counter) {

    $counter++;
    $type = 'None';

    if ($counter > 1 && $counter <= 6) {
        $type = 'Arr Numbers';
        $queue = [];
        $queue[$counter] = [];

        for ($i = 0; $i < 100000; $i++) {
            $queue[$counter] = rand(1,9999);
        }
        unset($queue);
    }

    else if ($counter > 7 && $counter <= 12) {
        $type = 'Arr Objects';
        $queue = [];
        $queue[$counter] = [];

        for ($i = 0; $i < 100000; $i++) {
             $o = new stdClass();
            $queue[$counter] = $o;
        }

        unset($queue);
    }

    else if ($counter > 13 && $counter <= 18) {
        $emitter = [];
        $emitter[$counter] = new \Evenement\EventEmitter();
        $type = 'Evenement';

        for ($i = 0; $i < 10000; $i++) {
            $rand =  $counter . ':' . $i  . ':' . rand(1, 1000);

            $emitter[$counter]->on('event1' . $rand, function () {});
            $emitter[$counter]->on('event2' . $rand, function () {});
            $emitter[$counter]->once('event3' . $rand, function () {});
        }

        // try unsetting manually?
        //foreach ($emitter[$counter]->listeners as $i => $listener) {
        //    unset($emitter[$counter]->listeners[$i]);
        //}

        $emitter[$counter]->removeAllListeners();
        unset($emitter);
    }


    echo
        'Counter: ' . $counter . "\n" .
        'Type: ' . $type . "\n" .
        'Memory: ' . round(memory_get_usage() / 1024 / 1024, 2) . " MB\n" .
        'Memory True: ' . round(memory_get_usage(true) / 1024 / 1024, 2) . " MB\n" .
        'Peak Memory: ' . round(memory_get_peak_usage() / 1024 / 1024, 2) . "MB \n" .
        'Peak Memory True : ' . round(memory_get_peak_usage(true) / 1024 / 1024, 2) . "MB \n" . "\n\n";

    if ($counter > 20)
        die;
});

$loop->run();


/** outputs *//
Counter: 1
Type: None
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 2
Type: Arr Numbers
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 3
Type: Arr Numbers
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 4
Type: Arr Numbers
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 5
Type: Arr Numbers
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 6
Type: Arr Numbers
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 7
Type: None
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 8
Type: Arr Objects
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 9
Type: Arr Objects
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 10
Type: Arr Objects
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 11
Type: Arr Objects
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 12
Type: Arr Objects
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 13
Type: None
Memory: 0.29 MB
Memory True: 0.5 MB
Peak Memory: 0.38MB
Peak Memory True : 0.5MB


Counter: 14
Type: Evenement
Memory: 4.52 MB
Memory True: 10.75 MB
Peak Memory: 39.05MB
Peak Memory True : 40MB


Counter: 15
Type: Evenement
Memory: 4.54 MB
Memory True: 13.25 MB
Peak Memory: 39.05MB
Peak Memory True : 40MB


Counter: 16
Type: Evenement
Memory: 4.56 MB
Memory True: 15.25 MB
Peak Memory: 39.05MB
Peak Memory True : 40MB


Counter: 17
Type: Evenement
Memory: 4.58 MB
Memory True: 17 MB
Peak Memory: 39.06MB
Peak Memory True : 40MB


Counter: 18
Type: Evenement
Memory: 4.6 MB
Memory True: 20.25 MB
Peak Memory: 39.06MB
Peak Memory True : 40MB


Counter: 19
Type: None
Memory: 4.6 MB
Memory True: 20.25 MB
Peak Memory: 39.06MB
Peak Memory True : 40MB


Counter: 20
Type: None
Memory: 4.6 MB
Memory True: 20.25 MB
Peak Memory: 39.06MB
Peak Memory True : 40MB


Counter: 21
Type: None
Memory: 4.6 MB
Memory True: 20.25 MB
Peak Memory: 39.06MB
Peak Memory True : 40MB