有没有一种pythonic的方式来尝试最多次数? [英] is there a pythonic way to try something up to a maximum number of times?
问题描述
_mysql_exceptions.OperationalError:(2006, MySQL服务器已经消失了)
如果你以后再次尝试查询,它通常会成功。所以,我想知道python中是否有一个合理的方法来尝试执行一个查询,如果它失败了,再试一次,最多可以尝试一次。可能我想要尝试5次,然后放弃。
这是我有的代码:
$ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $
$ b尝试:
cursor.execute(query)
rows = cursor.fetchall()
行中的行:
#执行某些数据
除了MySQLdb.Error,e:
打印MySQL错误%d:%s%(e.args [0],e.args [1])$ b $ b
显然,我可以通过在except子句中再次尝试,但是这是非常难看的,我有一种感觉,必须有一个体面的方式来实现这一点。
如何:
conn = MySQLdb.connect ,用户,密码,数据库)
cursor = conn.cursor()
attempts = 0
while attempts< 3:
try:
cursor.execute(query)
rows = cursor.fetchall()
行中的行:
#用数据$ b执行某些操作$ b break
除了MySQLdb.Error,e:
尝试+ = 1
打印MySQL错误%d:%s%(e.args [0],e.args [1 ])
I have a python script which is querying a MySQL server on a shared linux host. For some reason, queries to MySQL often return a "server has gone away" error:
_mysql_exceptions.OperationalError: (2006, 'MySQL server has gone away')
If you try the query again immediately afterwards, it usually succeeds. So, I'd like to know if there's a sensible way in python to try to execute a query, and if it fails, to try again, up to a fixed number of tries. Probably I'd want it to try 5 times before giving up altogether.
Here's the kind of code I have:
conn = MySQLdb.connect(host, user, password, database)
cursor = conn.cursor()
try:
cursor.execute(query)
rows = cursor.fetchall()
for row in rows:
# do something with the data
except MySQLdb.Error, e:
print "MySQL Error %d: %s" % (e.args[0], e.args[1])
Clearly I could do it by having another attempt in the except clause, but that's incredibly ugly, and I have a feeling there must be a decent way to achieve this.
How about:
conn = MySQLdb.connect(host, user, password, database)
cursor = conn.cursor()
attempts = 0
while attempts < 3:
try:
cursor.execute(query)
rows = cursor.fetchall()
for row in rows:
# do something with the data
break
except MySQLdb.Error, e:
attempts += 1
print "MySQL Error %d: %s" % (e.args[0], e.args[1])
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