free threading: do not enable GIL (#775)

fix #766

README.md

@@ -21,6 +21,17 @@ Or when you have question about MySQL/MariaDB:
 * [MySQL Support](https://dev.mysql.com/support/)
 * [Getting Help With MariaDB](https://mariadb.com/kb/en/getting-help-with-mariadb/)
 
+## Free threading Python
+
+> [!NOTE]
+> The support for Free threading Python is experimental.
+
+Since v2.2.8, free threading is supported when importing the extension module. Therefore, importing MySQLdb does not acquire GIL.
+
+However, this library does not support simultaneous operations on a single Connection object from multiple threads, regardless of free threading, and the behavior in such cases remains undefined.
+
+> [!WARNING]
+> Do not use a single Connection object from multiple threads simultaneously.
 
 ## Install
 

src/MySQLdb/_mysql.c

@@ -2911,7 +2911,9 @@ PyInit__mysql(void)
 
     module = PyModule_Create(&_mysqlmodule);
     if (!module) return module; /* this really should never happen */
-
+#ifdef Py_GIL_DISABLED
+    PyUnstable_Module_SetGIL(module, Py_MOD_GIL_NOT_USED);
+#endif
     if (!(dict = PyModule_GetDict(module))) goto error;
     if (PyDict_SetItemString(dict, "version_info",
                    PyRun_String(QUOTE(version_info), Py_eval_input,