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。通过这个页面我们看到的是在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
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') > (1)()->None
原文出处：http://ourmysql.com/archives/932