在使用python 對wordpress tag 進行細化代碼處理時，遇到了調用MySQLdb模塊時的出錯，由于錯誤提示和問題原因相差甚遠，查看了N久代碼也未發現代碼有問題。后來問了下師傅，被告知MySQLdb里有一個斷接的坑 ，需要進行數據庫重連解決。
一、報錯代碼及提示
運行出錯的代碼如下：
import MySQLdbdef 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 Nonedef 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
直接可以執行，在第for循環里第二次調用getTerm函數時，報錯如下：
Traceback (most recent call last): File "a.py", line 40, in <module> 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、解決方法
初始時以為是編碼問題了，又細核對了幾遍未發現編碼有問題，在python代碼里也未發現異常。后來問過師傅后，師傅來了句提示：
只看代碼有啥用，mysql 的超時時間調長點或捕獲異常從連，原因是
cursor. connection 沒有關閉
但是socket已經斷了
cursor 這個行為不會再建立一次socket的
重新執行一次MysqlDB.connect()
看的有點懵懂，先從mysql 里查看了所有timeout相關的變量
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)
發現最小的超時時間是10s ，而我的程序執行起來顯然就不了10s 。因為之前查過相關的報錯，這里估計這個很可能是另外一個報錯：2006，MySQL server has gone away 。即然和這個超時時間應該沒關系，那就嘗試通過MySQLdb ping測試，如果捕獲異常，就再進行重連，修改后的代碼為：
#!/usr/bin/python#coding=utf-8import MySQLdbdef 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 Nonedef 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
再執行發現竟然OK了，而細看下結果，發現基本上每1－2次getTerm或addTerm函數調用就會打印一次'mysql connect have been close' 。
三、使用torndb模塊解決mysql斷連問題
1.MySQLdb和torndb的代碼樣例對比
torndb是facebook開源的一個基于MySQLdb二次封裝的一個mysql模塊，新封裝的這個模塊比較小，是一個只有2百多行代碼的py文件。雖然代碼短，功能確相較MySQLdb簡便不少，并且該模塊由于增加了reconnect方法和max_idel_time參數，解決了mysql的斷連問題。比較下使用原生MySQLdb模塊和使用torndb模塊的代碼：
使用MySQLdb模塊的代碼
import MySQLdbdef 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 Nonedef 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)def addCTag(db,data): cursor = db.cursor() query = '''INSERT INTO `wp_term_relationships` ( `object_id` , `term_taxonomy_id` ) VALUES ( %s, %s) ''' cursor.executemany(query,data) db.commit() db.close()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: if termid: try: dbconn.ping() except: dbconn = MySQLdb.connect(host='localhost', user='root', passwd='123456', db='361way', port=3306, charset='utf8', init_command='set names utf8') print tag, 'tag id is ',termid termid = getTerm(dbconn,tag) tagids.extend(termid) else: try: dbconn.ping() except: dbconn = MySQLdb.connect(host='localhost', user='root', passwd='123456', db='361way', port=3306, charset='utf8', init_command='set names utf8') termid = addTerm(dbconn,tag) print 'add tag',tag,'id is ' ,termid tagids.append(termid)print 'tag id is ',tagidspostid = '35'tagids = list(set(tagids))ctagdata = []for tagid in tagids: ctagdata.append((postid,tagid))try: dbconn.ping()except: dbconn = MySQLdb.connect(host='localhost', user='root', passwd='123456', db='361way', port=3306, charset='utf8', init_command='set names utf8') addCTag(dbconn,ctagdata)
使用torndb的代碼
#!/usr/bin/python#coding=utf-8import torndbdef getTerm(db,tag): query = "SELECT term_id FROM wp_terms where name=%s " rows = db.query(query,tag) termid = [] for row in rows: termid.extend(row.values()) return termiddef addTerm(db,tag): query = "INSERT into wp_terms (name,slug,term_group) values (%s,%s,0)" term_id = db.execute_lastrowid(query,tag,tag) sql = "INSERT into wp_term_taxonomy (term_id,taxonomy,description) values (%s,'post_tag',%s) " db.execute(sql,term_id,tag) return term_iddef addCTag(db,data): query = "INSERT INTO wp_term_relationships (object_id,term_taxonomy_id) VALUES (%s, %s) " db.executemany(query,data)dbconn = torndb.Connection('localhost:3306','361way',user='root',password='123456')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 'All tags id is ',tagidspostid = '35'tagids = list(set(tagids))ctagdata = []for tagid in tagids: ctagdata.append((postid,tagid))addCTag(dbconn,ctagdata)從兩者的代碼上來看，使用torndb模塊和原生相比，發現可以省略如下兩部分：
torndb模塊不需要db.cursor進行處理，無不需要db.comment提交，torndb是自動提交的；
torndb不需要在每次調用時，進行db.ping()判斷數據庫socket連接是否斷開，因為torndb增加了reconnect方法，支持自動重連。
2.torndb的方法
torndb提供的參數和方法有：
execute 執行語句不需要返回值的操作。
execute_lastrowid 執行后獲得表id，一般用于插入后獲取返回值。
executemany 可以執行批量插入。返回值為第一次請求的表id。
executemany_rowcount 批量執行。返回值為第一次請求的表id。
get 執行后獲取一行數據，返回dict。
iter 執行查詢后，返回迭代的字段和數據。
query 執行后獲取多行數據，返回是List。
close 關閉
max_idle_time 最大連接時間
reconnect 關閉后再連接
使用示例：
mysql> CREATE TABLE `ceshi` (`id` int(1) NULL AUTO_INCREMENT ,`num` int(1) NULL ,PRIMARY KEY (`id`));
>>> import torndb>>> db = torndb.Connection("127.0.0.1","數據庫名","用戶名", "密碼", 24*3600) # 24*3600為超時時間>>> get_id1 = db.execute_lastrowid("insert ceshi(num) values('1')")>>> print get_id11>>> args1 = [('2'),('3'),('4')]>>> get1 = db.executemany("insert ceshi(num) values(%s)", args1)>>> print get12>>> rows = db.iter("select * from ceshi")>>> for i in rows:… print i在使用過程中可能遇到的錯誤：
File "/home/361way/database.py", line 145, in execute_lastrowid self._execute(cursor, query, parameters) File "/home/361way/database.py", line 207, in _execute return cursor.execute(query, parameters) File "/usr/lib/pymodules/python2.7/MySQLdb/cursors.py", line 159, in execute query = query % db.literal(args)TypeError: not enough arguments for format string
寫上面的代碼時，我剛開始還是試著使用MySQLdb模塊的方式引用數據，結果發現報參數的錯誤 ，經查看代碼發現 ，torndb在使用幾個sql方法時較MySQLdb精簡過了。具體各個方法的傳參方法如下（注意參數個數）：
close()reconnect()iter(query, *parameters, **kwparameters)query(query, *parameters, **kwparameters)get(query, *parameters, **kwparameters)execute(query, *parameters, **kwparameters)execute_lastrowid(query, *parameters, **kwparameters)execute_rowcount(query, *parameters, **kwparameters)executemany(query, parameters)executemany_lastrowid(query, parameters)executemany_rowcount(query, parameters)update(query, *parameters, **kwparameters)updatemany(query, parameters)insert(query, *parameters, **kwparameters)insertmany(query, parameters)
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