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,"|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