use IO::Select qw( );
use IO::Handle qw( );

pipe(my $rfh, my $wfh) or die;
$wfh->autoflush(1);

if (fork()) {
    my $sel = IO::Select->new($rfh);
    while ($sel->can_read()) {
        my $got = <$rfh>;
        last if !defined($got);
        chomp $got;
        print("It took ", (time()-$got), " seconds to get the msg\n");
    }
} else {
    for (;;) {
        print($wfh time(), "\n") or die;
        print($wfh time(), "\n") or die;
        sleep(3);
    }
}

##</code><code>##

It took 0 seconds to get the msg
It took 3 seconds to get the msg
It took 0 seconds to get the msg
It took 3 seconds to get the msg
It took 0 seconds to get the msg
...

##</code><code>##

    my $sel = IO::Select->new($rfh);
    my $buf = '';
    while ($sel->can_read()) {
        sysread($rfh, $buf, 64*1024, length($buf)) or last;
        while ($buf =~ s/^(.*)\n//) {
            my $got = $1;
            print("It took ", (time()-$got), " seconds to get the msg\n");
        }
    }

##</code><code>##

It took 0 seconds to get the msg
It took 0 seconds to get the msg
It took 0 seconds to get the msg
It took 0 seconds to get the msg
It took 0 seconds to get the msg
It took 0 seconds to get the msg
...