Python MySQLdb 增加連線讀取逾時 (read_timeout) 支援：修改 C 擴充原始碼重編譯

MySQLdb 預設不支援 read_timeout 參數，導致查詢卡住時無法自動中斷。解決方法：修改 _mysql.c 加入選項解析與 mysql_options(MYSQL_OPT_READ_TIMEOUT) 呼叫，重新編譯安裝。

修改 _mysql.c (Git diff 格式)

diff --git a/_mysql.c b/_mysql.c
--- 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;
@@ -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
+        &local_infile, &read_timeout
         /* DO NOT PATCH FOR RECONNECT, IDIOTS */
         )) 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;

編譯安裝

python setup.py build
python setup.py install

若 mysql_config 找不到，修改 setup_posix.py 指定路徑：

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

使用方式

import MySQLdb
conn = MySQLdb.connect(host=DB_SERVER, user=DB_USER, passwd=DB_PASS,
                       db=DB_NAME, port=DB_PORT,
                       client_flag=2, read_timeout=10)  # 秒

驗證

使用 gdb 掛住 MySQL 10 秒，Python 應拋出 OperationalError: (2013, 'Lost connection to MySQL server during query')。

注意事項

• 修改 C 擴充需對應 MySQLdb 版本，升級套件會覆蓋修改。
• 建議向上游提交 PR 或改用支援 read_timeout 的分支 (如 mysqlclient)。
• 現代專案推薦使用 PyMySQL (純 Python) 或 mysqlclient (MySQLdb 分支)，原生支援完整參數。

此修改展示 Python C 擴充客製化流程，解決關鍵生產環境可靠性問題。