def __init__(self, urls=None):
        """
        :param urls: Connection URLs to use. If not provided it uses a default value from
                     the config.
        :type urls: ``list``
        """
        urls = urls or transport_utils.get_messaging_urls()
        connection = transport_utils.get_connection(
            urls=urls, connection_kwargs={"failover_strategy": "round-robin"}
        )
        self.pool = connection.Pool(limit=10)
        self.cluster_size = len(urls)

        :param urls: Connection URLs to use. If not provided it uses a default value from
                     the config.
        :type urls: ``list``
        
st2common/st2common/transport/publishers.py