code: function processServeQueue() {
        while (serveQueue.length) {
          const item = serveQueue.shift();
          _serveFile(item.file, item.done);
          // It is possible start compiling while in release.
          if (state.compilationCompleted !== _currentState) {
            break;
          }
        }
      }
docs: Responsible for flushing the cache and notifying karma.