# in child
Mojo::IOLoop->singleton-reset;

my $ioloop = Mojo::IOLoop->new;
my $delay = $ioloop->delay;

$delay->on(finish => sub {
    my $delay = shift;
    process_async_responses(@_);
}

my $ua = Mojo::UA->new;
map { $ua->get($_ => $delay->begin); } @urls