PyMySQL被困在fetch_one()上,没有错误

你好,下面是我的代码:

db = pymysql.connect(
    host = ....., 
    user = ....., 
    passwd = ....., 
    db = ....., 
    port = ....., 
    connect_timeout = 5 , 
    use_unicode = True, 
    charset = "utf8",
    autocommit = True,
)

c = db.cursor(pymysql.cursors.SSDictCursor)
data  = c.execute(my_query) # for example SELECT * FROM PEOPLE
run = True
while run:
    ### processing in batches of 50
    batch = []
    for i in range(50):
        row = data.fetchone()
        if not row:
             run = False 
             break 
        row = do_something(row)
        batch += [row]

    do_stuff_that takes_3_minutes(batch)

我的问题是,大约一个小时后,这个代码就被卡住了 data.fetchone() ,但它不会退出或显示任何错误,只是被卡住了。我知道这是因为,我在每条指令前后都添加了print语句,最后输出到控制台的是之前的print语句 fetchone()