formatSize example

$usage = $this->getMemoryUsage();
    $pct_memory = $usage / $this->memoryLimit;
    if (!$threshold = $this->memoryThreshold) {
      return FALSE;
    }
    if ($pct_memory > $threshold) {
      $this->message->display(
        $this->t(
          'Memory usage is @usage (@pct% of limit @limit), reclaiming memory.',
          [
            '@pct' => round($pct_memory * 100),
            '@usage' => $this->formatSize($usage),
            '@limit' => $this->formatSize($this->memoryLimit),
          ]
        ),
        'warning'
      );
      $usage = $this->attemptMemoryReclaim();
      $pct_memory = $usage / $this->memoryLimit;
      // Use a lower threshold - we don't want to be in a situation where we keep       // coming back here and trimming a tiny amount       if ($pct_memory > (0.90 * $threshold)) {
        $this->message->display(
          

  public function onException(ExceptionEvent $event) {
    $exception = $event->getThrowable();
    $request = $event->getRequest();

    // Render a nice error message in case we have a file upload which exceeds     // the configured upload limit.     if ($exception instanceof BrokenPostRequestException && $request->query->has(FormBuilderInterface::AJAX_FORM_REQUEST)) {
      $this->messenger->addError($this->t('An unrecoverable error occurred. The uploaded file likely exceeded the maximum file size (@size) that this server supports.', ['@size' => $this->formatSize($exception->getSize())]));
      $response = new AjaxResponse(NULL, 200);
      $status_messages = ['#type' => 'status_messages'];
      $response->addCommand(new PrependCommand(NULL, $status_messages));
      $event->allowCustomResponseCode();
      $event->setResponse($response);
      return;
    }

    // Extract the form AJAX exception (it may have been passed to another     // exception before reaching here).     if ($exception = $this->getFormAjaxException($exception)) {