[PR #11150/996ad00 backport][3.12] fix: leak of aiodns.DNSResolver when ClientSession is closed (#11152)

Co-authored-by: J. Nick Koston <nick@koston.org>

Author: Tasssadar

CHANGES/11150.bugfix.rst

@@ -0,0 +1,3 @@
+Fixed leak of ``aiodns.DNSResolver`` when :py:class:`~aiohttp.TCPConnector` is closed and no resolver was passed when creating the connector -- by :user:`Tasssadar`.
+
+This was a regression introduced in version 3.12.0 (:pr:`10897`).

CONTRIBUTORS.txt

@@ -368,6 +368,7 @@ Vladimir Shulyak
 Vladimir Zakharov
 Vladyslav Bohaichuk
 Vladyslav Bondar
+Vojtěch Boček
 W. Trevor King
 Wei Lin
 Weiwei Wang

aiohttp/connector.py

@@ -926,9 +926,14 @@ def __init__(
         )
 
         self._ssl = _merge_ssl_params(ssl, verify_ssl, ssl_context, fingerprint)
+
+        self._resolver: AbstractResolver
         if resolver is None:
-            resolver = DefaultResolver(loop=self._loop)
-        self._resolver = resolver
+            self._resolver = DefaultResolver(loop=self._loop)
+            self._resolver_owner = True
+        else:
+            self._resolver = resolver
+            self._resolver_owner = False
 
         self._use_dns_cache = use_dns_cache
         self._cached_hosts = _DNSCacheTable(ttl=ttl_dns_cache)
@@ -956,6 +961,12 @@ def _close(self) -> List[Awaitable[object]]:
 
         return waiters
 
+    async def close(self) -> None:
+        """Close all opened transports."""
+        if self._resolver_owner:
+            await self._resolver.close()
+        await super().close()
+
     @property
     def family(self) -> int:
         """Socket family like AF_INET."""
@@ -1709,7 +1720,8 @@ def __init__(
             loop=loop,
         )
         if not isinstance(
-            self._loop, asyncio.ProactorEventLoop  # type: ignore[attr-defined]
+            self._loop,
+            asyncio.ProactorEventLoop,  # type: ignore[attr-defined]
         ):
             raise RuntimeError(
                 "Named Pipes only available in proactor loop under windows"

aiohttp/resolver.py

@@ -258,9 +258,10 @@ def release_resolver(
             loop: The event loop the resolver was using.
         """
         # Remove client from its loop's tracking
-        if loop not in self._loop_data:
+        current_loop_data = self._loop_data.get(loop)
+        if current_loop_data is None:
             return
-        resolver, client_set = self._loop_data[loop]
+        resolver, client_set = current_loop_data
         client_set.discard(client)
         # If no more clients for this loop, cancel and remove its resolver
         if not client_set:

tests/test_connector.py

@@ -1270,6 +1270,7 @@ async def test_tcp_connector_dns_cache_not_expired(loop, dns_response) -> None:
     with mock.patch("aiohttp.connector.DefaultResolver") as m_resolver:
         conn = aiohttp.TCPConnector(loop=loop, use_dns_cache=True, ttl_dns_cache=10)
         m_resolver().resolve.return_value = dns_response()
+        m_resolver().close = mock.AsyncMock()
         await conn._resolve_host("localhost", 8080)
         await conn._resolve_host("localhost", 8080)
         m_resolver().resolve.assert_called_once_with("localhost", 8080, family=0)
@@ -1281,6 +1282,7 @@ async def test_tcp_connector_dns_cache_forever(loop, dns_response) -> None:
     with mock.patch("aiohttp.connector.DefaultResolver") as m_resolver:
         conn = aiohttp.TCPConnector(loop=loop, use_dns_cache=True, ttl_dns_cache=10)
         m_resolver().resolve.return_value = dns_response()
+        m_resolver().close = mock.AsyncMock()
         await conn._resolve_host("localhost", 8080)
         await conn._resolve_host("localhost", 8080)
         m_resolver().resolve.assert_called_once_with("localhost", 8080, family=0)
@@ -1292,6 +1294,7 @@ async def test_tcp_connector_use_dns_cache_disabled(loop, dns_response) -> None:
     with mock.patch("aiohttp.connector.DefaultResolver") as m_resolver:
         conn = aiohttp.TCPConnector(loop=loop, use_dns_cache=False)
         m_resolver().resolve.side_effect = [dns_response(), dns_response()]
+        m_resolver().close = mock.AsyncMock()
         await conn._resolve_host("localhost", 8080)
         await conn._resolve_host("localhost", 8080)
         m_resolver().resolve.assert_has_calls(
@@ -1308,6 +1311,7 @@ async def test_tcp_connector_dns_throttle_requests(loop, dns_response) -> None:
     with mock.patch("aiohttp.connector.DefaultResolver") as m_resolver:
         conn = aiohttp.TCPConnector(loop=loop, use_dns_cache=True, ttl_dns_cache=10)
         m_resolver().resolve.return_value = dns_response()
+        m_resolver().close = mock.AsyncMock()
         loop.create_task(conn._resolve_host("localhost", 8080))
         loop.create_task(conn._resolve_host("localhost", 8080))
         await asyncio.sleep(0)
@@ -1322,6 +1326,7 @@ async def test_tcp_connector_dns_throttle_requests_exception_spread(loop) -> Non
         conn = aiohttp.TCPConnector(loop=loop, use_dns_cache=True, ttl_dns_cache=10)
         e = Exception()
         m_resolver().resolve.side_effect = e
+        m_resolver().close = mock.AsyncMock()
         r1 = loop.create_task(conn._resolve_host("localhost", 8080))
         r2 = loop.create_task(conn._resolve_host("localhost", 8080))
         await asyncio.sleep(0)
@@ -1341,6 +1346,7 @@ async def test_tcp_connector_dns_throttle_requests_cancelled_when_close(
     with mock.patch("aiohttp.connector.DefaultResolver") as m_resolver:
         conn = aiohttp.TCPConnector(loop=loop, use_dns_cache=True, ttl_dns_cache=10)
         m_resolver().resolve.return_value = dns_response()
+        m_resolver().close = mock.AsyncMock()
         loop.create_task(conn._resolve_host("localhost", 8080))
         f = loop.create_task(conn._resolve_host("localhost", 8080))
 
@@ -1384,6 +1390,7 @@ def exception_handler(loop, context):
             use_dns_cache=False,
         )
         m_resolver().resolve.return_value = dns_response_error()
+        m_resolver().close = mock.AsyncMock()
         f = loop.create_task(conn._create_direct_connection(req, [], ClientTimeout(0)))
 
         await asyncio.sleep(0)
@@ -1419,6 +1426,7 @@ async def test_tcp_connector_dns_tracing(loop, dns_response) -> None:
         conn = aiohttp.TCPConnector(loop=loop, use_dns_cache=True, ttl_dns_cache=10)
 
         m_resolver().resolve.return_value = dns_response()
+        m_resolver().close = mock.AsyncMock()
 
         await conn._resolve_host("localhost", 8080, traces=traces)
         on_dns_resolvehost_start.assert_called_once_with(
@@ -1460,6 +1468,7 @@ async def test_tcp_connector_dns_tracing_cache_disabled(loop, dns_response) -> N
         conn = aiohttp.TCPConnector(loop=loop, use_dns_cache=False)
 
         m_resolver().resolve.side_effect = [dns_response(), dns_response()]
+        m_resolver().close = mock.AsyncMock()
 
         await conn._resolve_host("localhost", 8080, traces=traces)
 
@@ -1514,6 +1523,7 @@ async def test_tcp_connector_dns_tracing_throttle_requests(loop, dns_response) -
     with mock.patch("aiohttp.connector.DefaultResolver") as m_resolver:
         conn = aiohttp.TCPConnector(loop=loop, use_dns_cache=True, ttl_dns_cache=10)
         m_resolver().resolve.return_value = dns_response()
+        m_resolver().close = mock.AsyncMock()
         loop.create_task(conn._resolve_host("localhost", 8080, traces=traces))
         loop.create_task(conn._resolve_host("localhost", 8080, traces=traces))
         await asyncio.sleep(0)
@@ -1528,6 +1538,14 @@ async def test_tcp_connector_dns_tracing_throttle_requests(loop, dns_response) -
         await conn.close()
 
 
+async def test_tcp_connector_close_resolver() -> None:
+    m_resolver = mock.AsyncMock()
+    with mock.patch("aiohttp.connector.DefaultResolver", return_value=m_resolver):
+        conn = aiohttp.TCPConnector(use_dns_cache=True, ttl_dns_cache=10)
+        await conn.close()
+        m_resolver.close.assert_awaited_once()
+
+
 async def test_dns_error(loop) -> None:
     connector = aiohttp.TCPConnector(loop=loop)
     connector._resolve_host = mock.AsyncMock(
@@ -3691,6 +3709,7 @@ async def resolve_response() -> List[ResolveResult]:
 
     with mock.patch("aiohttp.connector.DefaultResolver") as m_resolver:
         m_resolver().resolve.return_value = resolve_response()
+        m_resolver().close = mock.AsyncMock()
 
         connector = TCPConnector()
         traces = [DummyTracer()]