fix: stream GET /chats/all to prevent OOM on large chat histories (#24461)

Convert the /chats/all endpoint from loading all user chats into memory
at once to a streaming NDJSON response that fetches chats in batches of
100. This prevents Out-of-Memory crashes for users with large chat
histories.

Backend: Added async generator that paginates through chats with
short-lived DB sessions per batch (critical for SQLite lock release).

Frontend: Updated getAllChats to consume the NDJSON stream via
ReadableStream reader, accumulating results for the export file.

Ref: open-webui#22206

backend/open_webui/routers/chats.py

@@ -676,11 +676,46 @@ async def get_user_pinned_chats(user=Depends(get_verified_user), db: AsyncSessio
 # GetChats
 ############################
 
+CHAT_EXPORT_BATCH_SIZE = 100
 
-@router.get('/all', response_model=list[ChatResponse])
-async def get_user_chats(user=Depends(get_verified_user), db: AsyncSession = Depends(get_async_session)):
-    result = await Chats.get_chats_by_user_id(user.id, db=db)
-    return [ChatResponse(**chat.model_dump()) for chat in result.items]
+
+async def generate_chat_export_ndjson(user_id: str):
+    """
+    Async generator that streams all user chats as NDJSON (one JSON object per line).
+
+    Uses short-lived DB sessions per batch to avoid holding locks for the
+    entire duration, which is critical for SQLite environments.
+    """
+    skip = 0
+
+    while True:
+        result = await Chats.get_chats_by_user_id(
+            user_id,
+            skip=skip,
+            limit=CHAT_EXPORT_BATCH_SIZE,
+            db=None,
+        )
+        if not result.items:
+            break
+
+        for chat in result.items:
+            try:
+                yield ChatResponse(**chat.model_dump()).model_dump_json() + '\n'
+            except Exception as e:
+                log.exception(f'Error serializing chat {chat.id}: {e}')
+
+        if len(result.items) < CHAT_EXPORT_BATCH_SIZE:
+            break
+
+        skip += CHAT_EXPORT_BATCH_SIZE
+
+
+@router.get('/all')
+async def get_user_chats(user=Depends(get_verified_user)):
+    return StreamingResponse(
+        generate_chat_export_ndjson(user.id),
+        media_type='application/x-ndjson',
+    )
 
 
 ############################

src/lib/apis/chats/index.ts

@@ -301,34 +301,53 @@ export const getSharedChatList = async (token: string = '', page: number = 1, fi
 };
 
 export const getAllChats = async (token: string) => {
-	let error = null;
-
 	const res = await fetch(`${WEBUI_API_BASE_URL}/chats/all`, {
 		method: 'GET',
 		headers: {
-			Accept: 'application/json',
-			'Content-Type': 'application/json',
+			Accept: 'application/x-ndjson',
 			...(token && { authorization: `Bearer ${token}` })
 		}
-	})
-		.then(async (res) => {
-			if (!res.ok) throw await res.json();
-			return res.json();
-		})
-		.then((json) => {
-			return json;
-		})
-		.catch((err) => {
-			error = err;
-			console.error(err);
-			return null;
-		});
+	});
 
-	if (error) {
-		throw error;
+	if (!res.ok) {
+		const err = await res.json();
+		console.error(err);
+		throw err;
 	}
 
-	return res;
+	const reader = res.body?.getReader();
+	if (!reader) {
+		throw new Error('Response body is not readable');
+	}
+
+	const decoder = new TextDecoder();
+	const chats: object[] = [];
+	let buffer = '';
+
+	while (true) {
+		const { done, value } = await reader.read();
+		if (done) break;
+
+		buffer += decoder.decode(value, { stream: true });
+		const lines = buffer.split('\n');
+		// Keep the last potentially incomplete line in the buffer
+		buffer = lines.pop() ?? '';
+
+		for (const line of lines) {
+			const trimmed = line.trim();
+			if (trimmed) {
+				chats.push(JSON.parse(trimmed));
+			}
+		}
+	}
+
+	// Process any remaining data in the buffer
+	const remaining = buffer.trim();
+	if (remaining) {
+		chats.push(JSON.parse(remaining));
+	}
+
+	return chats;
 };
 
 export const getChatListBySearchText = async (token: string, text: string, page: number = 1) => {