use strict;
use warnings;

keep_alive(1);
sub main_program {
  my $x = 10;
  while($x--) {
    print STDERR "sleep $x";
    sleep(5);        
  }
}

sub keep_alive {
    my $first = shift;
    my $timeout = eval {
      local $SIG{ALRM} = sub {print "SERVER-PING!\n"; keep_alive(0)};
      alarm(15);
      main_program() if $first == 1;
      alarm(0);
    };
}