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 = [
+        # Use semaphore to limit concurrent requests based on WEB_SEARCH_CONCURRENT_REQUESTS
-            run_in_threadpool(
+        # 0 or None = unlimited (previous behavior), positive number = limited concurrency
-                search_web,
+        # Set to 1 for sequential execution (rate-limited APIs like Brave free tier)
-                request,
+        concurrent_limit = request.app.state.config.WEB_SEARCH_CONCURRENT_REQUESTS
-                request.app.state.config.WEB_SEARCH_ENGINE,
+
-                query,
+        if concurrent_limit:
-                user,
+            # Limited concurrency with semaphore
-            )
+            semaphore = asyncio.Semaphore(concurrent_limit)
-            for query in form_data.queries
+
-        ]
+            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)
 

src/lib/components/admin/Settings/WebSearch.svelte

@@ -630,19 +630,6 @@
 									/>
 								</div>
 							</div>
-						{:else if webConfig.WEB_SEARCH_ENGINE === 'ddgs' || webConfig.WEB_SEARCH_ENGINE === 'duckduckgo'}
-							<div class="w-full mb-2.5">
-								<div class=" self-center text-xs font-medium mb-1">
-									{$i18n.t('Concurrent Requests')}
-								</div>
-
-								<input
-									class="w-full rounded-lg py-2 px-4 text-sm bg-gray-50 dark:text-gray-300 dark:bg-gray-850 outline-hidden"
-									placeholder={$i18n.t('Concurrent Requests')}
-									bind:value={webConfig.WEB_SEARCH_CONCURRENT_REQUESTS}
-									required
-								/>
-							</div>
 						{:else if webConfig.WEB_SEARCH_ENGINE === 'external'}
 							<div class="mb-2.5 flex w-full flex-col">
 								<div>
@@ -692,6 +679,22 @@
 										required
 									/>
 								</div>
+
+								<div class="w-full">
+									<div class=" self-center text-xs font-medium mb-1">
+										<Tooltip content={$i18n.t('Limit concurrent search queries. 0 = unlimited (default). Set to 1 for sequential execution (recommended for APIs with strict rate limits like Brave free tier).')} placement="top-start">
+											{$i18n.t('Concurrent Requests')}
+										</Tooltip>
+									</div>
+
+									<input
+										class="w-full rounded-lg py-2 px-4 text-sm bg-gray-50 dark:text-gray-300 dark:bg-gray-850 outline-hidden"
+										placeholder={$i18n.t('Concurrent Requests')}
+										bind:value={webConfig.WEB_SEARCH_CONCURRENT_REQUESTS}
+										type="number"
+										min="0"
+									/>
+								</div>
 							</div>
 						</div>