from twisted.internet import reactor

def write_csv(item, **kwargs):
    f = kwargs['csv_file_obj']
    formatted_data = format(item)
    f.writerow(formatted_data)
def format(item):
    pass


#from scrapy
# store the file object
class Yourpipeline(object):
    def process_item(self, item, spider):
        reactor.callInThread(write_csv, item = item, csv_file_obj = spider.csv_file_obj)
        return item