From 4423757c0c50afbe2470434778c8d5e5b4a70925 Mon Sep 17 00:00:00 2001
From: Michael Newman <newmaniese@gmail.com>
Date: Sun, 27 May 2012 18:24:35 +0300
Subject: [PATCH] Fixed #18135 -- Close connection used for db version checking

On MySQL when checking the server version, a new connection could be
created but never closed. This could result in open connections on
server startup.
---
 django/db/backends/mysql/base.py        | 13 +++++++++++--
 tests/regressiontests/backends/tests.py |  6 ++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/django/db/backends/mysql/base.py b/django/db/backends/mysql/base.py
index ecbb02f31d..1df487bd92 100644
--- a/django/db/backends/mysql/base.py
+++ b/django/db/backends/mysql/base.py
@@ -418,11 +418,20 @@ class DatabaseWrapper(BaseDatabaseWrapper):
     @cached_property
     def mysql_version(self):
         if not self.server_version:
+            new_connection = False
             if not self._valid_connection():
+                # Ensure we have a connection with the DB by using a temporary
+                # cursor
+                new_connection = True
                 self.cursor().close()
-            m = server_version_re.match(self.connection.get_server_info())
+            server_info = self.connection.get_server_info()
+            if new_connection:
+                # Make sure we close the connection
+                self.connection.close()
+                self.connection = None
+            m = server_version_re.match(server_info)
             if not m:
-                raise Exception('Unable to determine MySQL version from version string %r' % self.connection.get_server_info())
+                raise Exception('Unable to determine MySQL version from version string %r' % server_info)
             self.server_version = tuple([int(x) for x in m.groups()])
         return self.server_version
 
diff --git a/tests/regressiontests/backends/tests.py b/tests/regressiontests/backends/tests.py
index 10e69b65c1..109e1a5bcc 100644
--- a/tests/regressiontests/backends/tests.py
+++ b/tests/regressiontests/backends/tests.py
@@ -89,6 +89,12 @@ class MySQLTests(TestCase):
         else:
             self.assertFalse(found_reset)
 
+    @unittest.skipUnless(connection.vendor == 'mysql',
+                        "Test valid only for MySQL")
+    def test_server_version_connections(self):
+        connection.close()
+        connection.mysql_version
+        self.assertTrue(connection.connection is None)
 
 class DateQuotingTest(TestCase):