foreach ($queue as $row) {
  $res = restservice->query($row['id']);
}

$res = restservice->batch($queue);

$batch = [];
foreach ($queue as $row) {
  $batch[] = $row;
  if ((count($batch) == 50) || (is_last_iteration($queue))) {
    $res = restservice->batch($batch);
    $batch = [];
  }
}

$batch = [];
$n = count($queue);
$i = 0;
foreach ($queue as $row) {
  $i++;
  $batch[] = $row;
  if (0 == ($i % 50) || ($i==$n)) {
    restservice->batch($batch);
    $batch = [];
  }
}