perf: build info log messages lazily so raising the log level actually saves work (#27837)

Raising GLOBAL_LOG_LEVEL to WARNING buys quieter output but not less work: 241 INFO call sites interpolate their payload into an f-string before the logging call gets to drop it. The heaviest is get_doc, which logs every chunk id and metadata dict in a collection, so on the full-context retrieval path that is the entire knowledge base, once per chat request.

That one line at WARNING, CPython 3.12:

| knowledge base | payload | before   | after   |
| -------------- | ------- | -------- | ------- |
| top-k of 3     | 1.2 kB  | 3.8 us   | 0.07 us |
| 500 chunks     | 201 kB  | 583.6 us | 0.08 us |
| 5000 chunks    | 2.0 MB  | 5.8 ms   | 0.15 us |

The lazy form log.info('query_doc:result %s %s', result.ids, result.metadatas) hands the payload to record.getMessage(), which the InterceptHandler only reaches once a record has passed the level check. Output at INFO is byte-identical. Two sites that already built their message eagerly, one str concat and one % operator, move to the same lazy form.

backend/open_webui/retrieval/utils.py

@@ -318,7 +318,7 @@ def query_doc(collection_name: str, query_embedding: list[float], k: int, user:
         )
 
         if result:
-            log.info(f'query_doc:result {result.ids} {result.metadatas}')
+            log.info('query_doc:result %s %s', result.ids, result.metadatas)
 
         return result
     except Exception as e:
@@ -332,7 +332,7 @@ def get_doc(collection_name: str, user: UserModel = None):
         result = VECTOR_DB_CLIENT.get(collection_name=collection_name)
 
         if result:
-            log.info(f'query_doc:result {result.ids} {result.metadatas}')
+            log.info('query_doc:result %s %s', result.ids, result.metadatas)
 
         return result
     except Exception as e:
@@ -585,7 +585,7 @@ async def query_doc_with_hybrid_search(
             'metadatas': [metadatas],
         }
 
-        log.info('query_doc_with_hybrid_search:result ' + f'{result["metadatas"]} {result["distances"]}')
+        log.info('query_doc_with_hybrid_search:result %s %s', result['metadatas'], result['distances'])
         return result
     except Exception as e:
         log.exception(f'Error querying doc {collection_name} with hybrid search: {e}')
@@ -812,7 +812,7 @@ async def query_collection_with_hybrid_search(
 
     collection_results = dict(await asyncio.gather(*(_fetch_collection(name) for name in collection_names)))
 
-    log.info(f'Starting hybrid search for {len(queries)} queries in {len(collection_names)} collections...')
+    log.info('Starting hybrid search for %s queries in %s collections...', len(queries), len(collection_names))
 
     async def process_query(collection_name, query):
         try: