use 5.010;
use strict;
use warnings;

use IO::Socket::INET;
use IO::Poll;
use Time::HiRes;

my $port = shift // 7777;
my $sock = IO::Socket::INET->new(LocalPort => $port, Listen => 10);
$sock->blocking(0);

for ( 1 .. 3 ) {
    my $pid = fork;
    unless ($pid) {
        my $poll = IO::Poll->new;
        $poll->mask( $sock => POLLIN );
        while ( $poll->poll >= 0 ) {
            say "$$ got out of poll";
            my $cli = $sock->accept;
            if ($cli) {
                say "$$ accepted connection from " . $cli->peerport;
                print while <$cli>;
                exit 0;
            }
            else {
                say "$$ got nothing from accept";
            }
        }
    }
}
__END__
4367 got out of poll
4367 accepted connection from 58442
4365 got out of poll
4366 got out of poll
4366 got nothing from accept
4365 accepted connection from 58446