sub process_scheme{
          my ($output_file) = @_;
          open (OUTPUT_FILE, ">", $output_file) || die "cannot open log file";
          my $scheme_pid = open (WORKER, "worker_program < $input |") 
               || die "cannot pipe worker";
          my $str;
          while (1) {
              eval{
                  local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required
                  alarm 1;
                  if (eof(WORKER)){    
                      close WORKER;
                      close OUTPUT;
                      return 1;
                  }

                  $str = <WORKER>;
                  alarm 0; # if this line is removed, the signal is caught, but outside of eval, so it halts the script
              };
              if ($@) {
                  close OUTPUT_FILE;
                  close WORKER;
                  return 0;
              }

              # process the line
              #  some code ...
              # print the line to log
              print OUTPUT_FILE $str;
          }
      }