Export all the stats.

        Each export module is ran in a dedicated thread.

def export(self, input_stats=None):
        """Export all the stats.

        Each export module is ran in a dedicated thread.
        """
        # threads = []
        input_stats = input_stats or {}

        for e in self._exports:
            logger.debug("Export stats using the %s module" % e)
            thread = threading.Thread(target=self._exports[e].update,
                                      args=(input_stats,))
            # threads.append(thread)
            thread.start()