use strict;
use warnings;

use IO::Select qw( );
use Time::HiRes qw( time );

{
   open(my $fh, '>', 'log') or die;
}

{
   open(my $fh, '<', 'log') or die;

   my $sel = IO::Select->new($fh);

   my @times;

   push(@times, time);
   for (1..5) {
      push(@times, time);
      my @r = $sel->can_read();
      push(@times, time);
      read($fh, my $buf='', 1000);
   }

   local $, = "\n";
   local $\ = "\n";
   print @times;
}

unlink 'log';