[3.6] bpo-31234: Fix dangling thread in test_ftp/poplib (#3554)

* bpo-31234: Fix dangling thread in test_ftp/poplib (#3540)

Explicitly clear the server attribute in test_ftplib and test_poplib
to prevent dangling thread.

(cherry picked from commit d403a29c0055de6b03ed5ae7a5c564e1c95a5950)

* bpo-31234: Fix dangling thread in test_ftplib (#3544)

Clear also self.server_thread attribute in TestTimeouts.tearDown().

(cherry picked from commit b157ce1e58b03988ce4340a55d0b856125833cc5)

1 files changed, 11 insertions, 0 deletions

diff --git a/Lib/test/test_ftplib.py b/Lib/test/test_ftplib.py
index a561e9e..b593313 100644
--- a/Lib/test/test_ftplib.py
+++ b/Lib/test/test_ftplib.py
@@ -470,6 +470,9 @@ class TestFTPClass(TestCase):
     def tearDown(self):
         self.client.close()
         self.server.stop()
+        # Explicitly clear the attribute to prevent dangling thread
+        self.server = None
+        asyncore.close_all(ignore_all=True)
 
     def check_data(self, received, expected):
         self.assertEqual(len(received), len(expected))
@@ -799,6 +802,9 @@ class TestIPv6Environment(TestCase):
     def tearDown(self):
         self.client.close()
         self.server.stop()
+        # Explicitly clear the attribute to prevent dangling thread
+        self.server = None
+        asyncore.close_all(ignore_all=True)
 
     def test_af(self):
         self.assertEqual(self.client.af, socket.AF_INET6)
@@ -857,6 +863,9 @@ class TestTLS_FTPClass(TestCase):
     def tearDown(self):
         self.client.close()
         self.server.stop()
+        # Explicitly clear the attribute to prevent dangling thread
+        self.server = None
+        asyncore.close_all(ignore_all=True)
 
     def test_control_connection(self):
         self.assertNotIsInstance(self.client.sock, ssl.SSLSocket)
@@ -979,6 +988,8 @@ class TestTimeouts(TestCase):
     def tearDown(self):
         ftplib.FTP.port = self.old_port
         self.server_thread.join()
+        # Explicitly clear the attribute to prevent dangling thread
+        self.server_thread = None
 
     def server(self):
         # This method sets the evt 3 times: