fix(socket-mode): settle aiohttp tasks on close

Stop connect attempts once client shutdown begins, discard sessions that complete after close, and await cancellation of SDK-owned tasks before closing the aiohttp session.\n\nAdds lifecycle regressions for closed clients, close races, current-task ownership, backoff, and task/session cleanup.\n\nRefs #1913

Author: xero-aiescape

slack_sdk/socket_mode/aiohttp/__init__.py

@@ -349,7 +349,7 @@ async def connect(self):
         # a new monitor and a new message receiver are also created.
         # If a new session is created but we failed to create the new
         # monitor or the new message, we should try it.
-        while True:
+        while not self.closed:
             try:
                 old_session: Optional[ClientWebSocketResponse] = (
                     None if self.current_session is None else self.current_session
@@ -369,18 +369,28 @@ async def connect(self):
                 except Exception as e:
                     self.logger.exception(f"Failed to close the old session : {e}")
 
+                if self.closed:
+                    break
+
                 if self.wss_uri is None:
                     # If the underlying WSS URL does not exist,
                     # acquiring a new active WSS URL from the server-side first
                     self.wss_uri = await self.issue_new_wss_url()
 
-                self.current_session = await self.aiohttp_client_session.ws_connect(
+                if self.closed:
+                    break
+
+                new_session = await self.aiohttp_client_session.ws_connect(
                     self.wss_uri,
                     autoping=False,
                     heartbeat=self.ping_interval,
                     proxy=self.proxy,
                     ssl=self.web_client.ssl if self.web_client.ssl is not None else True,
                 )
+                if self.closed:
+                    await new_session.close()
+                    break
+                self.current_session = new_session
                 session_id: str = await self.session_id()
                 self.auto_reconnect_enabled = self.default_auto_reconnect_enabled
                 self.stale = False
@@ -405,6 +415,8 @@ async def connect(self):
                     self.logger.debug(f"A new receive_messages() executor has been recreated for {session_id}")
                 break
             except Exception as e:
+                if self.closed:
+                    break
                 self.logger.exception(f"Failed to connect (error: {e}); Retrying...")
                 await asyncio.sleep(self.ping_interval)
 
@@ -447,12 +459,17 @@ async def close(self):
         self.closed = True
         self.auto_reconnect_enabled = False
         await self.disconnect()
-        if self.message_processor is not None:
-            self.message_processor.cancel()
-        if self.current_session_monitor is not None:
-            self.current_session_monitor.cancel()
-        if self.message_receiver is not None:
-            self.message_receiver.cancel()
+
+        current_task = asyncio.current_task()
+        owned_tasks = []
+        for task in (self.message_processor, self.current_session_monitor, self.message_receiver):
+            if task is not None and task is not current_task and task not in owned_tasks:
+                if not task.done():
+                    task.cancel()
+                owned_tasks.append(task)
+        if owned_tasks:
+            await asyncio.gather(*owned_tasks, return_exceptions=True)
+
         if self.aiohttp_client_session is not None:
             await self.aiohttp_client_session.close()
 

tests/slack_sdk_async/socket_mode/test_aiohttp.py

@@ -1,4 +1,5 @@
 import asyncio
+import time
 import unittest
 
 from slack_sdk.socket_mode.aiohttp import SocketModeClient
@@ -8,6 +9,74 @@
 from tests.mock_web_api_server import setup_mock_web_api_server_async, cleanup_mock_web_api_server_async
 
 
+class ControlledClientSession:
+    def __init__(self):
+        self.closed = False
+        self.attempts = 0
+        self.attempt_started = asyncio.Event()
+        self.closed_event = asyncio.Event()
+
+    async def ws_connect(self, *args, **kwargs):
+        self.attempts += 1
+        self.attempt_started.set()
+        await self.closed_event.wait()
+        raise RuntimeError("Session is closed")
+
+    async def close(self):
+        self.closed = True
+        self.closed_event.set()
+
+
+class CompletingClientSession:
+    def __init__(self):
+        self.closed = False
+        self.attempts = 0
+        self.attempt_started = asyncio.Event()
+        self.closed_event = asyncio.Event()
+        self.websocket = ConnectedWebSocket()
+
+    async def ws_connect(self, *args, **kwargs):
+        self.attempts += 1
+        self.attempt_started.set()
+        await self.closed_event.wait()
+        return self.websocket
+
+    async def close(self):
+        self.closed = True
+        self.closed_event.set()
+
+
+class ConnectedWebSocket:
+    def __init__(self):
+        self.closed = False
+        self.receive_forever = asyncio.Event()
+
+    async def close(self):
+        self.closed = True
+
+    async def ping(self, data):
+        pass
+
+    async def receive(self):
+        await self.receive_forever.wait()
+
+
+class RetryingClientSession:
+    def __init__(self):
+        self.closed = False
+        self.attempt_times = []
+        self.websocket = ConnectedWebSocket()
+
+    async def ws_connect(self, *args, **kwargs):
+        self.attempt_times.append(time.monotonic())
+        if len(self.attempt_times) == 1:
+            raise ConnectionError("temporary failure")
+        return self.websocket
+
+    async def close(self):
+        self.closed = True
+
+
 class TestAiohttp(unittest.TestCase):
     def setUp(self):
         setup_mock_web_api_server_async(self, MockHandler)
@@ -44,6 +113,167 @@ async def test_init_with_loop(self):
         finally:
             await client.close()
 
+    @async_test
+    async def test_connect_returns_when_client_is_already_closed(self):
+        client = SocketModeClient(
+            app_token="xapp-A111-222-xyz",
+            web_client=self.web_client,
+            auto_reconnect_enabled=False,
+            ping_interval=0.01,
+        )
+        client.wss_uri = "ws://127.0.0.1:1/link"
+
+        await client.close()
+        await asyncio.wait_for(client.connect(), timeout=0.05)
+
+        self.assertTrue(client.closed)
+        self.assertTrue(client.aiohttp_client_session.closed)
+
+    @async_test
+    async def test_connect_stops_when_close_lands_during_an_attempt(self):
+        client = SocketModeClient(
+            app_token="xapp-A111-222-xyz",
+            web_client=self.web_client,
+            auto_reconnect_enabled=False,
+            ping_interval=0.01,
+        )
+        await client.aiohttp_client_session.close()
+        controlled_session = ControlledClientSession()
+        client.aiohttp_client_session = controlled_session
+        client.wss_uri = "ws://127.0.0.1:1/link"
+
+        connect_task = asyncio.create_task(client.connect())
+        await controlled_session.attempt_started.wait()
+        await client.close()
+
+        await asyncio.wait_for(asyncio.shield(connect_task), timeout=0.05)
+        self.assertTrue(connect_task.done())
+        self.assertEqual(1, controlled_session.attempts)
+        self.assertTrue(controlled_session.closed)
+
+    @async_test
+    async def test_connect_discards_session_completed_after_close(self):
+        client = SocketModeClient(
+            app_token="xapp-A111-222-xyz",
+            web_client=self.web_client,
+            auto_reconnect_enabled=False,
+            ping_interval=0.01,
+        )
+        await client.aiohttp_client_session.close()
+        completing_session = CompletingClientSession()
+        client.aiohttp_client_session = completing_session
+        client.wss_uri = "ws://127.0.0.1:1/link"
+
+        connect_task = asyncio.create_task(client.connect())
+        await completing_session.attempt_started.wait()
+        await client.close()
+        await asyncio.wait_for(connect_task, timeout=0.05)
+
+        self.assertTrue(completing_session.websocket.closed)
+        self.assertIsNone(client.current_session)
+        self.assertIsNone(client.current_session_monitor)
+        self.assertIsNone(client.message_receiver)
+
+    @async_test
+    async def test_connect_preserves_ping_interval_backoff_for_live_client(self):
+        client = SocketModeClient(
+            app_token="xapp-A111-222-xyz",
+            web_client=self.web_client,
+            auto_reconnect_enabled=False,
+            ping_interval=0.03,
+        )
+        await client.aiohttp_client_session.close()
+        retrying_session = RetryingClientSession()
+        client.aiohttp_client_session = retrying_session
+        client.wss_uri = "ws://127.0.0.1:1/link"
+
+        try:
+            await client.connect()
+            self.assertEqual(2, len(retrying_session.attempt_times))
+            self.assertGreaterEqual(
+                retrying_session.attempt_times[1] - retrying_session.attempt_times[0],
+                client.ping_interval,
+            )
+        finally:
+            await client.close()
+
+    @async_test
+    async def test_close_awaits_owned_task_settlement_before_session_close(self):
+        client = SocketModeClient(
+            app_token="xapp-A111-222-xyz",
+            web_client=self.web_client,
+            auto_reconnect_enabled=False,
+        )
+        client.message_processor.cancel()
+        await asyncio.gather(client.message_processor, return_exceptions=True)
+        await client.aiohttp_client_session.close()
+        controlled_session = ControlledClientSession()
+        client.aiohttp_client_session = controlled_session
+
+        started = [asyncio.Event() for _ in range(3)]
+        cancelling = [asyncio.Event() for _ in range(3)]
+        release_cleanup = asyncio.Event()
+
+        async def owned_task(index):
+            started[index].set()
+            try:
+                await asyncio.Event().wait()
+            except asyncio.CancelledError:
+                cancelling[index].set()
+                await release_cleanup.wait()
+                raise
+
+        owned_tasks = [asyncio.create_task(owned_task(index)) for index in range(3)]
+        client.message_processor, client.current_session_monitor, client.message_receiver = owned_tasks
+        for event in started:
+            await event.wait()
+
+        close_task = asyncio.create_task(client.close())
+        for event in cancelling:
+            await event.wait()
+
+        self.assertFalse(close_task.done())
+        self.assertFalse(controlled_session.closed)
+
+        release_cleanup.set()
+        await asyncio.wait_for(close_task, timeout=0.05)
+
+        self.assertTrue(controlled_session.closed)
+        self.assertTrue(all(task.done() for task in owned_tasks))
+        self.assertTrue(all(task.cancelled() for task in owned_tasks))
+
+    @async_test
+    async def test_close_does_not_cancel_or_await_current_reconnect_owner(self):
+        client = SocketModeClient(
+            app_token="xapp-A111-222-xyz",
+            web_client=self.web_client,
+            auto_reconnect_enabled=False,
+        )
+        client.message_processor.cancel()
+        await asyncio.gather(client.message_processor, return_exceptions=True)
+        await client.aiohttp_client_session.close()
+        controlled_session = ControlledClientSession()
+        client.aiohttp_client_session = controlled_session
+
+        async def settled_task():
+            pass
+
+        settled = asyncio.create_task(settled_task())
+        await settled
+        client.message_processor = settled
+        client.message_receiver = settled
+
+        async def reconnect_owner():
+            client.current_session_monitor = asyncio.current_task()
+            await client.close()
+
+        owner_task = asyncio.create_task(reconnect_owner())
+        await asyncio.wait_for(asyncio.shield(owner_task), timeout=0.05)
+
+        self.assertTrue(owner_task.done())
+        self.assertFalse(owner_task.cancelled())
+        self.assertTrue(controlled_session.closed)
+
     @async_test
     async def test_issue_new_wss_url(self):
         client = SocketModeClient(