feat: Apply WEB_SEARCH_CONCURRENT_REQUESTS to all search engines using semaphore (#20070)

* sequential

* zero default

* fix

backend/open_webui/config.py

@@ -2994,7 +2994,7 @@ WEB_SEARCH_DOMAIN_FILTER_LIST = PersistentConfig(
 WEB_SEARCH_CONCURRENT_REQUESTS = PersistentConfig(
     "WEB_SEARCH_CONCURRENT_REQUESTS",
     "rag.web.search.concurrent_requests",
-    int(os.getenv("WEB_SEARCH_CONCURRENT_REQUESTS", "10")),
+    int(os.getenv("WEB_SEARCH_CONCURRENT_REQUESTS", "0")),
 )
 
 

backend/open_webui/routers/retrieval.py

@@ -2103,16 +2103,38 @@ async def process_web_search(
             f"trying to web search with {request.app.state.config.WEB_SEARCH_ENGINE, form_data.queries}"
         )
 
-        search_tasks = [
-            run_in_threadpool(
-                search_web,
-                request,
-                request.app.state.config.WEB_SEARCH_ENGINE,
-                query,
-                user,
-            )
-            for query in form_data.queries
-        ]
+        # Use semaphore to limit concurrent requests based on WEB_SEARCH_CONCURRENT_REQUESTS
+        # 0 or None = unlimited (previous behavior), positive number = limited concurrency
+        # Set to 1 for sequential execution (rate-limited APIs like Brave free tier)
+        concurrent_limit = request.app.state.config.WEB_SEARCH_CONCURRENT_REQUESTS
+
+        if concurrent_limit:
+            # Limited concurrency with semaphore
+            semaphore = asyncio.Semaphore(concurrent_limit)
+
+            async def search_with_limit(query):
+                async with semaphore:
+                    return await run_in_threadpool(
+                        search_web,
+                        request,
+                        request.app.state.config.WEB_SEARCH_ENGINE,
+                        query,
+                        user,
+                    )
+
+            search_tasks = [search_with_limit(query) for query in form_data.queries]
+        else:
+            # Unlimited parallel execution (previous behavior)
+            search_tasks = [
+                run_in_threadpool(
+                    search_web,
+                    request,
+                    request.app.state.config.WEB_SEARCH_ENGINE,
+                    query,
+                    user,
+                )
+                for query in form_data.queries
+            ]
 
         search_results = await asyncio.gather(*search_tasks)