change _agenerate in to use gather

langchain/llms/base.py

@@ -494,13 +494,17 @@ class LLM(BaseLLM):
         run_manager: Optional[AsyncCallbackManagerForLLMRun] = None,
     ) -> LLMResult:
         """Run the LLM on the given prompt and input."""
-        generations = []
         new_arg_supported = inspect.signature(self._acall).parameters.get("run_manager")
-        for prompt in prompts:
-            text = (
+
+        async def get_completion(prompt):
+            return (
                 await self._acall(prompt, stop=stop, run_manager=run_manager)
                 if new_arg_supported
                 else await self._acall(prompt, stop=stop)
             )
-            generations.append([Generation(text=text)])
-        return LLMResult(generations=generations)
+
+        generations = await asyncio.gather(
+            *(get_completion(prompt) for prompt in prompts)
+        )
+
+        return LLMResult(generations=[[Generation(text=text)] for text in generations])