open my $fh1, '-|', 'bin/testclient1';
open my $fh2, '-|', 'bin/testclient2';
open my $fh3, '-|', 'bin/testclient3';

my $time1 = 0;
my $time2 = 0;
my $time3 = 0;

while (<condition>) {
  my $testdata = make_foo();

  my $time_a = time;
  print {$fh1} $testdata;
  my $time_b = time;
  print {$fh2} $testdata;
  my $time_c = time;
  print {$fh3} $testdata;
  my $time_d = time;

  $time1 += $time_b - $time_a;
  $time2 += $time_c - $time_b;
  $time3 += $time_d - $time_c;
}

print "method 1: $time1 seconds\n";
print "method 2: $time2 seconds\n";
print "method 3: $time3 seconds\n";

exit;