PHP 7.3 non recursive GC performance comparison

gc_test.php

<?php

class Node
{
    /** @var Node */
    public $previous;
    /** @var Node */
    public $next;
}

function test() {
	$firstNode = new Node();
	$firstNode->previous = $firstNode;
	$firstNode->next = $firstNode;

	$circularDoublyLinkedList = $firstNode;

	for ($i = 0; $i < 30000; $i++) {
	    $currentNode = $circularDoublyLinkedList;
	    $nextNode = $circularDoublyLinkedList->next;

	    $newNode = new Node();

	    $newNode->previous = $currentNode;
	    $currentNode->next = $newNode;
	    $newNode->next = $nextNode;
	    $nextNode->previous = $newNode;

	    $circularDoublyLinkedList = $nextNode;
	}

	return $circularDoublyLinkedList;
}

ini_set('memory_limit', '1G');

$start = microtime(true);
echo "Start running\n";

$all = [];
foreach (range(1, 250) as $i) {
    $all[] = test();
}

$step1 = microtime(true);
echo "Running = " . ($step1 - $start) . "\n";
echo "Memory = " . (memory_get_usage()/1024/1024) . "\n";
echo "Peak memory = " . (memory_get_peak_usage()/1024/1024) . "\n";

gc_collect_cycles();

$step2 = microtime(true);
echo "Running GC without collecting = " . ($step2 - $step1) . "\n";
echo "Memory = " . (memory_get_usage()/1024/1024) . "\n";
echo "Peak memory = " . (memory_get_peak_usage()/1024/1024) . "\n";

$all = null;
gc_collect_cycles();

$step3 = microtime(true);
echo "Running GC with collecting = " . ($step3 - $step2) . "\n";
echo "Memory = " . (memory_get_usage()/1024/1024) . "\n";
echo "Peak memory = " . (memory_get_peak_usage()/1024/1024) . "\n";

echo "Total = " . ($step3 - $start) . "\n";

out--before-change

Start running
Running = 2.8742311000824
Memory = 636.60913085938
Peak memory = 636.62090301514
Running GC without collecting = 0.012032032012939
Memory = 636.60913085938
Peak memory = 636.62090301514
Running GC with collecting = 1.4210410118103
Memory = 64.373695373535
Peak memory = 636.62090301514
Total = 4.3073041439056

out-after-change

Start running
Running = 2.4045481681824
Memory = 636.60913085938
Peak memory = 636.62090301514
Running GC without collecting = 0.0075688362121582
Memory = 636.60913085938
Peak memory = 636.62090301514
Running GC with collecting = 0.80605506896973
Memory = 64.373695373535
Peak memory = 636.62090301514
Total = 3.2181720733643