给Python中的MySQLdb模块添加超时功能的教程

使用Python操作MySQL数据库的时候常使用MySQLdb这个模块。

今天在开发的过程发现MySQLdb.connect有些参数没法设置。通过这个页面我们可以看到在connect的时候，可以设置的option和client_flags和MySQL c api相比差不少。

一个很重要的参数 MYSQL_OPT_READ_TIMEOUT没法设置，这个参数如果不设置，极致状况MySQL处于hang住，自动切换IP漂移，客户端无法重连到新MySQL。

给MySQLdb加Option很简单，只要修改_mysql.c这个把Python对象映射到MySQL操作的文件，添加参数，再加一段mysql_option即可。

下面是修改后的git diff 文件

?View Code BASH

diff --git a/_mysql.c b/_mysql.c

index d42cc54..61a9b34 100644

--- a/_mysql.c

+++ b/_mysql.c

@@ -489,9 +489,10 @@ _mysql_ConnectionObject_Initialize(

"named_pipe", "init_command",

"read_default_file", "read_default_group",

"client_flag", "ssl",

- "local_infile",

+ "local_infile", "read_timeout",

NULL } ;

int connect_timeout = 0;

+ int read_timeout = 0;

int compress = -1, named_pipe = -1, local_infile = -1;

char *init_command=NULL,

*read_default_file=NULL,

@@ -500,7 +501,7 @@ _mysql_ConnectionObject_Initialize(

self->converter = NULL;

self->open = 0;

check_server_init(-1);

- if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|ssssisOiiisssiOi:connect",

+ if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|ssssisOiiisssiOii:connect",

kwlist,

&host, &user, &passwd, &db,

&port, &unix_socket, &conv,

@@ -509,7 +510,8 @@ _mysql_ConnectionObject_Initialize(

&init_command, &read_default_file,

&read_default_group,

&client_flag, &ssl,

- &local_infile /* DO NOT PATCH FOR RECONNECT, IDIOTS

+ &local_infile, &read_timeout

+ /* DO NOT PATCH FOR RECONNECT, IDIOTS

IF YOU DO THIS, I WILL NOT SUPPORT YOUR PACKAGES. */

))

return -1;

@@ -540,6 +542,12 @@ _mysql_ConnectionObject_Initialize(

mysql_options(&(self->connection), MYSQL_OPT_CONNECT_TIMEOUT,

(char *)&timeout);

}

+

+ if (read_timeout) {

+ unsigned int timeout = read_timeout;

+ mysql_options(&(self->connection), MYSQL_OPT_READ_TIMEOUT, (char *)&timeout);

+ }

+

if (compress != -1) {

mysql_options(&(self->connection), MYSQL_OPT_COMPRESS, 0);

client_flag |= CLIENT_COMPRESS;

代码修改完毕，python setup.py install 即可，如果出现mysql_config找不到的问题。你还要修改setup_posix.py文件。

hoterran@hoterran-laptop:~/Projects/MySQL-python-1.2.3$ git diff setup_posix.py

diff --git a/setup_posix.py b/setup_posix.py

index 86432f5..f4f08f1 100644

--- a/setup_posix.py

+++ b/setup_posix.py

@@ -23,7 +23,7 @@ def mysql_config(what):

if ret/256 > 1:

raise EnvironmentError("%s not found" % (mysql_config.path,))

return data

-mysql_config.path = "mysql_config"

+mysql_config.path = "/usr/local/mysql/bin/mysql_config"

def get_config():

import os, sys

编译通过，我们来试试添加的read_timeout这个参数。

conn = MySQLdb.connect(host = DB_SERVER,user = DB_USERNAME,passwd = DB_PASSWORD,db = DB_NAME, port=int(DB_PORT), client_flag = 2, read_timeout = 10)

然后执行语句前，你试着把mysql用gdb hang住10s后，python就会异常抛错

OperationalError: (2013, 'Lost connection to MySQL server during query')

>/home/hoterran/Projects/dbaas/trunk/dbtest.py(18)()

>mydb.execute_sql(conn, sql)

(Pdb)

--Return--

> /home/hoterran/Projects/dbaas/trunk/dbtest.py(18)()->None

> mydb.execute_sql(conn, sql)

(Pdb)

OperationalError: (2013, 'Lost connection to MySQL server during query')

> <string>(1)<module>()->None