<?php gc_collect_cycles(); ?> triggers PHP's garbage collector to explicitly search for and clean up circular references - objects that reference each other but are no longer accessible by the program.
Although PHP's garbage collector runs automatically, in long-running scripts or memory-intensive operations (such as daemons, CLI tools, or large loops), calling this function manually can help reduce memory usage and prevent memory leaks.
Example:
<?php
class Node {
public $ref;
}
$a = new Node();
$b = new Node();
$a->ref = $b;
$b->ref = $a;
unset($a, $b);
$collected = gc_collect_cycles();
echo "Collected cycles: $collected\n";
?>