Memory leak in hhvm?

gistfile1.php

<?php

class Foo
{
    private $bar;
    public function __construct(Bar $bar)
    {
        $this->bar = $bar;
    }
}

class Bar
{
    private $foo;
    public function setFoo(Foo $foo)
    {
        $this->foo = $foo;
    }
}

while(true) {
    $bar = new Bar();
    $foo = new Foo($bar);
    $bar->setFoo($foo);
    echo memory_get_usage() . "\n";
}