在使用python 对wordpress tag 进行细化代码处理时，遇到了调用MySQLdb模块时的出错，由于错误提示和问题原因相差甚远，查看了N久代码也未发现代码有问题。后来问了下师傅，被告知MySQLdb里有一个断接的坑 ，需要进行数据库重连解决。

一、报错代码及提示

运行出错的代码如下：

import MySQLdb

def getTerm(db,tag):

cursor = db.cursor()

query = "SELECT term_id FROM wp_terms where name=%s "

count = cursor.execute(query,tag)

rows = cursor.fetchall()

db.commit()

#db.close()

if count:

term_id = [int(rows[id][0]) for id in range(count)]

return term_id

else:return None

def addTerm(db,tag):

cursor = db.cursor()

query = "INSERT into wp_terms (name,slug,term_group) values (%s,%s,0)"

data = (tag,tag)

cursor.execute(query,data)

db.commit()

term_id = cursor.lastrowid

sql = "INSERT into wp_term_taxonomy (term_id,taxonomy,description) values (%s,'post_tag',%s) "

value = (term_id,tag)

cursor.execute(sql,value)

db.commit()

db.close()

return int(term_id)

dbconn = MySQLdb.connect(host='localhost', user='root', passwd='123456', db='361way', port=3306, charset='utf8', init_command='set names utf8')

tags = ['mysql','1111','aaaa','bbbb','ccccc','php','abc','python','java']

tagids = []

for tag in tags:

termid = getTerm(dbconn,tag)

if termid:

print tag, 'tag id is ',termid

tagids.extend(termid)

else:

termid = addTerm(dbconn,tag)

print 'add tag',tag,'id is ' ,termid

tagids.append(termid)

print 'tag id is ',tagids

直接可以执行，在第for循环里第二次调用getTerm函数时，报错如下：

Traceback (most recent call last):

File "a.py", line 40, in

termid = getTerm(dbconn,tag)

File "a.py", line 11, in getTerm

count = cursor.execute(query,tag)

File "/usr/lib64/python2.6/site-packages/MySQLdb/cursors.py", line 154, in execute

charset = db.character_set_name()

_mysql_exceptions.InterfaceError: (0, '')

二、解决方法

初始时以为是编码问题了，又细核对了几遍未发现编码有问题，在python代码里也未发现异常。后来问过师傅后，师傅来了句提示：

只看代码有啥用，mysql 的超时时间调长点或捕获异常从连，原因是

cursor. connection 没有关闭

但是socket已经断了

cursor 这个行为不会再建立一次socket的

重新执行一次MysqlDB.connect()

看的有点懵懂，先从mysql 里查看了所有timeout相关的变量

mysql> show GLOBAL VARIABLES like "%timeout%";

+----------------------------+-------+

| Variable_name | Value |

+----------------------------+-------+

| connect_timeout | 10 |

| delayed_insert_timeout | 300 |

| innodb_lock_wait_timeout | 50 |

| innodb_rollback_on_timeout | OFF |

| interactive_timeout | 28800 |

| net_read_timeout | 30 |

| net_write_timeout | 60 |

| slave_net_timeout | 3600 |

| table_lock_wait_timeout | 50 |

| wait_timeout | 28800 |

+----------------------------+-------+

10 rows in set (0.00 sec)

发现最小的超时时间是10s ，而我的程序执行起来显然就不了10s 。因为之前查过相关的报错，这里估计这个很可能是另外一个报错：2006，MySQL server has gone away  。即然和这个超时时间应该没关系，那就尝试通过MySQLdb ping测试，如果捕获异常，就再进行重连，修改后的代码为：

#!/usr/bin/python

#coding=utf-8

import MySQLdb

def getTerm(db,tag):

cursor = db.cursor()

query = "SELECT term_id FROM wp_terms where name=%s "

count = cursor.execute(query,tag)

rows = cursor.fetchall()

db.commit()

#db.close()

if count:

term_id = [int(rows[id][0]) for id in range(count)]

print term_id

return term_id

else:return None

def addTerm(db,tag):

cursor = db.cursor()

query = "INSERT into wp_terms (name,slug,term_group) values (%s,%s,0)"

data = (tag,tag)

cursor.execute(query,data)

db.commit()

term_id = cursor.lastrowid

sql = "INSERT into wp_term_taxonomy (term_id,taxonomy,description) values (%s,'post_tag',%s) "

value = (term_id,tag)

cursor.execute(sql,value)

db.commit()

db.close()

return int(term_id)

dbconn = MySQLdb.connect(host='localhost', user='root', passwd='123456', db='361way', port=3306, charset='utf8', init_command='set names utf8')

tags = ['mysql','1111','aaaa','bbbb','ccccc','php','abc','python','java']

if __name__ == "__main__":

tagids = []

for tag in tags:

try:

dbconn.ping()

except:

print 'mysql connect have been close'

dbconn = MySQLdb.connect(host='localhost', user='root', passwd='123456', db='361way', port=3306, charset='utf8', init_command='set names utf8')

termid = getTerm(dbconn,tag)

if termid:

print tag, 'tag id is ',termid

tagids.extend(termid)

else:

termid = addTerm(dbconn,tag)

print 'add tag',tag,'id is ' ,termid

tagids.append(termid)

print 'All tags id is ',tagids

再执行发现竟然OK了，而细看下结果，发现基本上每1－2次getTerm或addTerm函数调用就会打印一次'mysql connect have been close' 。这里问题虽然已经解决，不过并未细挖到真正的根因。

三、建议

从网上要看的结果来看MySQLdb还有不支持长连接的坑，这个可以通过上面提到的修改my.cnf参数解决，也可以考虑使用其他支持设置timeout时间mysql模块。另外，也建议使用MySQLdb时，可以考虑使用一个对其二次封装的模块torndb ---- A lightweight wrapper around MySQLdb 。