refac

backend/open_webui/main.py

@@ -1923,8 +1923,6 @@ async def chat_completion(
             # uses anyio task groups whose cancel scopes enforce
             # same-task exit.  Do NOT wrap in asyncio.shield() or
             # asyncio.wait_for() — both create a new task.
-            # MCPClient.disconnect() self-shields via
-            # anyio.CancelScope(shield=True).
             try:
                 if mcp_clients := metadata.get('mcp_clients'):
                     for client in reversed(list(mcp_clients.values())):
@@ -1932,14 +1930,29 @@ async def chat_completion(
                             await client.disconnect()
                         except Exception as e:
                             log.debug(f'Error disconnecting MCP client: {e}')
+                        except asyncio.CancelledError:
+                            # Let the client close asynchronously by GC
+                            pass
             except Exception as e:
                 log.debug(f'Error cleaning up MCP clients: {e}')
+            except asyncio.CancelledError:
+                pass
 
             try:
                 if metadata.get('chat_id'):
-                    event_emitter = await get_event_emitter(metadata, update_db=False)
-                    if event_emitter:
-                        await event_emitter({'type': 'chat:active', 'data': {'active': False}})
+                    async def emit_inactive_event():
+                        try:
+                            event_emitter = await get_event_emitter(metadata, update_db=False)
+                            if event_emitter:
+                                await event_emitter({'type': 'chat:active', 'data': {'active': False}})
+                        except Exception:
+                            pass
+                    
+                    try:
+                        # Shield the event emission so it finishes even if the main task is cancelled
+                        await asyncio.shield(emit_inactive_event())
+                    except asyncio.CancelledError:
+                        pass
             except Exception:
                 pass
 

backend/open_webui/utils/mcp/client.py

@@ -156,14 +156,14 @@ class MCPClient:
 
         try:
             # IMPORTANT: Do NOT use asyncio.shield() or asyncio.wait_for()
-            # here — both create a new asyncio task.  The MCP SDK's
-            # streamablehttp_client uses anyio task groups / cancel scopes
-            # that MUST be exited in the same task they were entered in.
-            # Using anyio.CancelScope(shield=True) protects from
-            # CancelledError while staying in the current task.
-            with anyio.CancelScope(shield=True):
-                with anyio.fail_after(5.0):
-                    await exit_stack.aclose()
+            # because they create a new asyncio task, which violates the MCP SDK's
+            # requirement that its TaskGroup be exited in the exact same task.
+            # ALSO do NOT use anyio.CancelScope(shield=True) or anyio.fail_after(),
+            # because they push a new cancel scope onto the task, violating LIFO
+            # order when aclose() attempts to exit the inner TaskGroup.
+            # We simply call aclose() directly. If the task is cancelled, the
+            # sockets will eventually be cleaned up by garbage collection.
+            await exit_stack.aclose()
         except TimeoutError:
             log.warning('MCPClient.disconnect() timed out after 5 s')
         except RuntimeError as exc:

backend/requirements-min.txt

@@ -22,6 +22,7 @@ aiocache
 aiofiles
 starlette-compress==1.7.0
 Brotli==1.2.0
+brotlicffi==1.2.0.1
 httpx[socks,http2,zstd,cli,brotli]==0.28.1
 starsessions[redis]==2.2.1