MySQL数据库报错pymysql.err.InterfaceError: (0, '')

今天入库的时候出现了报错pymysql.err.InterfaceError: (0, '')，经过排查，发现是由于把连接数据库的代码放到了插入函数的外部，导致多线程运行出错

 def write_into_db(data):
     db = pymysql.connect(host=db_host, user=db_user, password=db_password, port=db_port, db=db_name, charset='utf8')
     cursor = db.cursor()
     print('start inserting into db')
     print(data)
     t = datetime.now()
     t = str(t).split('.')[0]
     sql = "INSERT INTO fixed_asset_new (resource_id,resource_type,name,address,location,land_use,sell_type,land_type,is_bid,deal_status,source_url,province,city,district,plot_rate,declaration_time,start_time,expiration_time,start_price,transaction_price,min_raise_price,cash_deposit,trading_place,assignee,fixture_time,consult_tel,subject_type,housing_area,land_area,evaluate_price,auction_stage,memo,is_deleted,gmt_created,gmt_modified) VALUES (%d,%d,'%s','%s','%s',%d,%d,%d,%d,%d,'%s','%s','%s','%s','%s','%s','%s','%s',%d,%d,%d,%d,'%s','%s','%s','%s',%d ,'%s','%s',%d,%d,'%s',%d,'%s','%s')" % (data['resource_id'],data['resource_type'],data['name'],data['address'],data['location'],data['land_use'],data['sell_type'],data['land_type'],0,data['deal_status'],data['source_url'],data['province'],data['city'],data['district'],data['plot_rate'],data['declaration_time'],data['start_time'],data['expiration_time'],data['start_price'],data['transaction_price'],data['min_raise_price'],data['cash_deposit'],data['trading_place'],data['assignee'],data['fixture_time'],data['consult_tel'],data['subject_type'],data['housing_area'],data['land_area'],data['evaluate_price'],data['auction_stage'],data['memo'],data['is_deleted'],t,t)
     try:
         cursor.execute(sql)
         db.commit()
         print('successful')
     except Exception as e:
         print(e)
         db.rollback()

也就是把2,3行代码放在了函数外面，而write_into_db函数是放在线程主函数中的，如果放在函数外面，就会导致无法连接数据库