Issue #21566: Make use of socket.listen() default backlog.

Lib/multiprocessing/forkserver.py

@@ -107,7 +107,7 @@ class ForkServer(object):
                 address = connection.arbitrary_address('AF_UNIX')
                 listener.bind(address)
                 os.chmod(address, 0o600)
-                listener.listen(100)
+                listener.listen()
 
                 # all client processes own the write end of the "alive" pipe;
                 # when they all terminate the read end becomes ready.

Lib/test/_test_multiprocessing.py

@@ -2543,7 +2543,7 @@ class _TestPicklingConnections(BaseTestCase):
 
         l = socket.socket()
         l.bind((test.support.HOST, 0))
-        l.listen(1)
+        l.listen()
         conn.send(l.getsockname())
         new_conn, addr = l.accept()
         conn.send(new_conn)
@@ -3190,7 +3190,7 @@ class TestWait(unittest.TestCase):
         from multiprocessing.connection import wait
         l = socket.socket()
         l.bind((test.support.HOST, 0))
-        l.listen(4)
+        l.listen()
         addr = l.getsockname()
         readers = []
         procs = []

Lib/test/test_asynchat.py

@@ -37,7 +37,7 @@ if threading:
             self.start_resend_event = None
 
         def run(self):
-            self.sock.listen(1)
+            self.sock.listen()
             self.event.set()
             conn, client = self.sock.accept()
             self.buffer = b""

Lib/test/test_asyncio/test_events.py

@@ -428,7 +428,7 @@ class EventLoopTestsMixin:
         listener = socket.socket()
         listener.setblocking(False)
         listener.bind(('127.0.0.1', 0))
-        listener.listen(1)
+        listener.listen()
         client = socket.socket()
         client.connect(listener.getsockname())
 

Lib/test/test_asyncore.py

@@ -64,7 +64,7 @@ class crashingdummy:
 # used when testing senders; just collects what it gets until newline is sent
 def capture_server(evt, buf, serv):
     try:
-        serv.listen(5)
+        serv.listen()
         conn, addr = serv.accept()
     except socket.timeout:
         pass

Lib/test/test_epoll.py

@@ -44,7 +44,7 @@ class TestEPoll(unittest.TestCase):
     def setUp(self):
         self.serverSocket = socket.socket()
         self.serverSocket.bind(('127.0.0.1', 0))
-        self.serverSocket.listen(1)
+        self.serverSocket.listen()
         self.connections = [self.serverSocket]
 
     def tearDown(self):

Lib/test/test_ftplib.py

@@ -137,7 +137,7 @@ class DummyFTPHandler(asynchat.async_chat):
     def cmd_pasv(self, arg):
         with socket.socket() as sock:
             sock.bind((self.socket.getsockname()[0], 0))
-            sock.listen(5)
+            sock.listen()
             sock.settimeout(TIMEOUT)
             ip, port = sock.getsockname()[:2]
             ip = ip.replace('.', ','); p1 = port / 256; p2 = port % 256
@@ -155,7 +155,7 @@ class DummyFTPHandler(asynchat.async_chat):
     def cmd_epsv(self, arg):
         with socket.socket(socket.AF_INET6) as sock:
             sock.bind((self.socket.getsockname()[0], 0))
-            sock.listen(5)
+            sock.listen()
             sock.settimeout(TIMEOUT)
             port = sock.getsockname()[1]
             self.push('229 entering extended passive mode (|||%d|)' %port)
@@ -983,7 +983,7 @@ class TestTimeouts(TestCase):
         #  1) when the connection is ready to be accepted.
         #  2) when it is safe for the caller to close the connection
         #  3) when we have closed the socket
-        self.sock.listen(5)
+        self.sock.listen()
         # (1) Signal the caller that we are ready to accept the connection.
         self.evt.set()
         try:

Lib/test/test_httplib.py

@@ -919,7 +919,7 @@ class SourceAddressTest(TestCase):
         self.serv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         self.port = support.bind_port(self.serv)
         self.source_port = support.find_unused_port()
-        self.serv.listen(5)
+        self.serv.listen()
         self.conn = None
 
     def tearDown(self):
@@ -951,7 +951,7 @@ class TimeoutTest(TestCase):
     def setUp(self):
         self.serv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         TimeoutTest.PORT = support.bind_port(self.serv)
-        self.serv.listen(5)
+        self.serv.listen()
 
     def tearDown(self):
         self.serv.close()

Lib/test/test_kqueue.py

@@ -89,7 +89,7 @@ class TestKQueue(unittest.TestCase):
     def test_queue_event(self):
         serverSocket = socket.socket()
         serverSocket.bind(('127.0.0.1', 0))
-        serverSocket.listen(1)
+        serverSocket.listen()
         client = socket.socket()
         client.setblocking(False)
         try:

Lib/test/test_poplib.py

@@ -451,7 +451,7 @@ class TestTimeouts(TestCase):
         del self.thread  # Clear out any dangling Thread objects.
 
     def server(self, evt, serv):
-        serv.listen(5)
+        serv.listen()
         evt.set()
         try:
             conn, addr = serv.accept()

Lib/test/test_selectors.py

@@ -24,7 +24,7 @@ else:
     def socketpair(family=socket.AF_INET, type=socket.SOCK_STREAM, proto=0):
         with socket.socket(family, type, proto) as l:
             l.bind((support.HOST, 0))
-            l.listen(3)
+            l.listen()
             c = socket.socket(family, type, proto)
             try:
                 c.connect(l.getsockname())

Lib/test/test_smtplib.py

@@ -31,7 +31,7 @@ if sys.platform == 'darwin':
 
 
 def server(evt, buf, serv):
-    serv.listen(5)
+    serv.listen()
     evt.set()
     try:
         conn, addr = serv.accept()

Lib/test/test_socket.py

@@ -72,7 +72,7 @@ class SocketTCPTest(unittest.TestCase):
     def setUp(self):
         self.serv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         self.port = support.bind_port(self.serv)
-        self.serv.listen(1)
+        self.serv.listen()
 
     def tearDown(self):
         self.serv.close()
@@ -441,7 +441,7 @@ class SocketListeningTestMixin(SocketTestBase):
 
     def setUp(self):
         super().setUp()
-        self.serv.listen(1)
+        self.serv.listen()
 
 
 class ThreadedSocketTestMixin(ThreadSafeCleanupTestCase, SocketTestBase,
@@ -3784,7 +3784,7 @@ class NonBlockingTCPTests(ThreadedTCPSocketTest):
         self.serv = socket.socket(socket.AF_INET, socket.SOCK_STREAM |
                                                   socket.SOCK_NONBLOCK)
         self.port = support.bind_port(self.serv)
-        self.serv.listen(1)
+        self.serv.listen()
         # actual testing
         start = time.time()
         try:
@@ -4559,7 +4559,7 @@ class TestLinuxAbstractNamespace(unittest.TestCase):
         address = b"\x00python-test-hello\x00\xff"
         with socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) as s1:
             s1.bind(address)
-            s1.listen(1)
+            s1.listen()
             with socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) as s2:
                 s2.connect(s1.getsockname())
                 with s1.accept()[0] as s3:
@@ -4791,7 +4791,7 @@ class TIPCThreadableTest(unittest.TestCase, ThreadableTest):
         srvaddr = (socket.TIPC_ADDR_NAMESEQ, TIPC_STYPE,
                 TIPC_LOWER, TIPC_UPPER)
         self.srv.bind(srvaddr)
-        self.srv.listen(5)
+        self.srv.listen()
         self.serverExplicitReady()
         self.conn, self.connaddr = self.srv.accept()
         self.addCleanup(self.conn.close)

Lib/test/test_ssl.py

@@ -1211,7 +1211,7 @@ class SSLErrorTests(unittest.TestCase):
         ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
         with socket.socket() as s:
             s.bind(("127.0.0.1", 0))
-            s.listen(5)
+            s.listen()
             c = socket.socket()
             c.connect(s.getsockname())
             c.setblocking(False)
@@ -1736,7 +1736,7 @@ else:
 
         def run(self):
             self.sock.settimeout(0.05)
-            self.sock.listen(5)
+            self.sock.listen()
             self.active = True
             if self.flag:
                 # signal an event
@@ -2162,7 +2162,7 @@ else:
             # and sets Event `listener_gone` to let the main thread know
             # the socket is gone.
             def listener():
-                s.listen(5)
+                s.listen()
                 listener_ready.set()
                 newsock, addr = s.accept()
                 newsock.close()
@@ -2590,7 +2590,7 @@ else:
             finish = False
 
             def serve():
-                server.listen(5)
+                server.listen()
                 started.set()
                 conns = []
                 while not finish:
@@ -2647,7 +2647,7 @@ else:
             peer = None
             def serve():
                 nonlocal remote, peer
-                server.listen(5)
+                server.listen()
                 # Block on the accept and wait on the connection to close.
                 evt.set()
                 remote, peer = server.accept()

Lib/test/test_support.py

@@ -84,7 +84,7 @@ class TestSupport(unittest.TestCase):
     def test_bind_port(self):
         s = socket.socket()
         support.bind_port(s)
-        s.listen(1)
+        s.listen()
         s.close()
 
     # Tests for temp_dir()

Lib/test/test_telnetlib.py

@@ -11,7 +11,7 @@ threading = support.import_module('threading')
 HOST = support.HOST
 
 def server(evt, serv):
-    serv.listen(5)
+    serv.listen()
     evt.set()
     try:
         conn, addr = serv.accept()

Lib/test/test_timeout.py

@@ -243,14 +243,14 @@ class TCPTimeoutTestCase(TimeoutTestCase):
     def testAcceptTimeout(self):
         # Test accept() timeout
         support.bind_port(self.sock, self.localhost)
-        self.sock.listen(5)
+        self.sock.listen()
         self._sock_operation(1, 1.5, 'accept')
 
     def testSend(self):
         # Test send() timeout
         with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as serv:
             support.bind_port(serv, self.localhost)
-            serv.listen(5)
+            serv.listen()
             self.sock.connect(serv.getsockname())
             # Send a lot of data in order to bypass buffering in the TCP stack.
             self._sock_operation(100, 1.5, 'send', b"X" * 200000)
@@ -259,7 +259,7 @@ class TCPTimeoutTestCase(TimeoutTestCase):
         # Test sendto() timeout
         with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as serv:
             support.bind_port(serv, self.localhost)
-            serv.listen(5)
+            serv.listen()
             self.sock.connect(serv.getsockname())
             # The address argument is ignored since we already connected.
             self._sock_operation(100, 1.5, 'sendto', b"X" * 200000,
@@ -269,7 +269,7 @@ class TCPTimeoutTestCase(TimeoutTestCase):
         # Test sendall() timeout
         with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as serv:
             support.bind_port(serv, self.localhost)
-            serv.listen(5)
+            serv.listen()
             self.sock.connect(serv.getsockname())
             # Send a lot of data in order to bypass buffering in the TCP stack.
             self._sock_operation(100, 1.5, 'sendall', b"X" * 200000)

Lib/test/test_urllib.py

@@ -1333,7 +1333,7 @@ class URLopener_Tests(unittest.TestCase):
 #     serv.settimeout(3)
 #     serv.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
 #     serv.bind(("", 9093))
-#     serv.listen(5)
+#     serv.listen()
 #     try:
 #         conn, addr = serv.accept()
 #         conn.send("1 Hola mundo\n")