Fixed failure to try next host after single-host connection timeout

CHANGES/7342.breaking.rst

@@ -0,0 +1,3 @@
+Fixed failure to try next host after single-host connection timeout -- by :user:`brettdh`.
+
+The default client :class:`aiohttp.ClientTimeout` params has changed to include a ``sock_connect`` timeout of 30 seconds so that this correct behavior happens by default.

CONTRIBUTORS.txt

@@ -63,6 +63,7 @@ Boris Feld
 Borys Vorona
 Boyi Chen
 Brett Cannon
+Brett Higgins
 Brian Bouterse
 Brian C. Lane
 Brian Muller

aiohttp/client.py

@@ -214,7 +214,7 @@ class ClientTimeout:
 
 
 # 5 Minute default read timeout
-DEFAULT_TIMEOUT: Final[ClientTimeout] = ClientTimeout(total=5 * 60)
+DEFAULT_TIMEOUT: Final[ClientTimeout] = ClientTimeout(total=5 * 60, sock_connect=30)
 
 # https://www.rfc-editor.org/rfc/rfc9110#section-9.2.2
 IDEMPOTENT_METHODS = frozenset({"GET", "HEAD", "OPTIONS", "TRACE", "PUT", "DELETE"})

aiohttp/connector.py

@@ -1243,7 +1243,7 @@ async def _create_direct_connection(
                     req=req,
                     client_error=client_error,
                 )
-            except ClientConnectorError as exc:
+            except (ClientConnectorError, asyncio.TimeoutError) as exc:
                 last_exc = exc
                 aiohappyeyeballs.pop_addr_infos_interleave(addr_infos, self._interleave)
                 continue

docs/client_quickstart.rst

@@ -408,7 +408,8 @@ Timeouts
 Timeout settings are stored in :class:`ClientTimeout` data structure.
 
 By default *aiohttp* uses a *total* 300 seconds (5min) timeout, it means that the
-whole operation should finish in 5 minutes.
+whole operation should finish in 5 minutes. In order to allow time for DNS fallback,
+the default ``sock_connect`` timeout is 30 seconds.
 
 The value could be overridden by *timeout* parameter for the session (specified in seconds)::
 

docs/client_reference.rst

@@ -150,10 +150,14 @@ The client session supports the context manager protocol for self closing.
       higher.
 
    :param timeout: a :class:`ClientTimeout` settings structure, 300 seconds (5min)
-        total timeout by default.
+        total timeout, 30 seconds socket connect timeout by default.
 
       .. versionadded:: 3.3
 
+      .. versionchanged:: 3.10.9
+
+         The default value for the ``sock_connect`` timeout has been changed to 30 seconds.
+
    :param bool auto_decompress: Automatically decompress response body (``True`` by default).
 
       .. versionadded:: 2.3
@@ -882,7 +886,7 @@ certification chaining.
       .. versionadded:: 3.7
 
    :param timeout: a :class:`ClientTimeout` settings structure, 300 seconds (5min)
-        total timeout by default.
+        total timeout, 30 seconds socket connect timeout by default.
 
    :param loop: :ref:`event loop<asyncio-event-loop>`
                 used for processing HTTP requests.

tests/test_connector.py

@@ -1063,6 +1063,115 @@ async def create_connection(
                 established_connection.close()
 
 
+@pytest.mark.parametrize(
+    ("request_url"),
+    [
+        ("http://mocked.host"),
+        ("https://mocked.host"),
+    ],
+)
+async def test_tcp_connector_multiple_hosts_one_timeout(
+    loop: asyncio.AbstractEventLoop,
+    request_url: str,
+) -> None:
+    conn = aiohttp.TCPConnector()
+
+    ip1 = "192.168.1.1"
+    ip2 = "192.168.1.2"
+    ips = [ip1, ip2]
+    ips_tried = []
+    ips_success = []
+    timeout_error = False
+    connected = False
+
+    req = ClientRequest(
+        "GET",
+        URL(request_url),
+        loop=loop,
+    )
+
+    async def _resolve_host(
+        host: str, port: int, traces: object = None
+    ) -> List[ResolveResult]:
+        return [
+            {
+                "hostname": host,
+                "host": ip,
+                "port": port,
+                "family": socket.AF_INET6 if ":" in ip else socket.AF_INET,
+                "proto": 0,
+                "flags": socket.AI_NUMERICHOST,
+            }
+            for ip in ips
+        ]
+
+    async def start_connection(
+        addr_infos: Sequence[AddrInfoType],
+        *,
+        interleave: Optional[int] = None,
+        **kwargs: object,
+    ) -> socket.socket:
+        nonlocal timeout_error
+
+        addr_info = addr_infos[0]
+        addr_info_addr = addr_info[-1]
+
+        ip = addr_info_addr[0]
+        ips_tried.append(ip)
+
+        if ip == ip1:
+            timeout_error = True
+            raise asyncio.TimeoutError
+
+        if ip == ip2:
+            mock_socket = mock.create_autospec(
+                socket.socket, spec_set=True, instance=True
+            )
+            mock_socket.getpeername.return_value = addr_info_addr
+            return mock_socket  # type: ignore[no-any-return]
+
+        assert False
+
+    async def create_connection(
+        *args: object, sock: Optional[socket.socket] = None, **kwargs: object
+    ) -> Tuple[ResponseHandler, ResponseHandler]:
+        nonlocal connected
+
+        assert isinstance(sock, socket.socket)
+        addr_info = sock.getpeername()
+        ip = addr_info[0]
+        ips_success.append(ip)
+        connected = True
+
+        # Close the socket since we are not actually connecting
+        # and we don't want to leak it.
+        sock.close()
+        tr = create_mocked_conn(loop)
+        pr = create_mocked_conn(loop)
+        return tr, pr
+
+    with mock.patch.object(
+        conn, "_resolve_host", autospec=True, spec_set=True, side_effect=_resolve_host
+    ), mock.patch.object(
+        conn._loop,
+        "create_connection",
+        autospec=True,
+        spec_set=True,
+        side_effect=create_connection,
+    ), mock.patch(
+        "aiohttp.connector.aiohappyeyeballs.start_connection", start_connection
+    ):
+        established_connection = await conn.connect(req, [], ClientTimeout())
+
+    assert ips_tried == ips
+    assert ips_success == [ip2]
+
+    assert timeout_error
+    assert connected
+
+    established_connection.close()
+
+
 async def test_tcp_connector_resolve_host(loop: asyncio.AbstractEventLoop) -> None:
     conn = aiohttp.TCPConnector(use_dns_cache=True)