[cli] support lazy import (#9217)

Co-authored-by: frozenleaves <frozen@Mac.local>

src/llamafactory/chat/chat_model.py

@@ -24,9 +24,6 @@ from typing import TYPE_CHECKING, Any, Optional
 from ..extras.constants import EngineName
 from ..extras.misc import torch_gc
 from ..hparams import get_infer_args
-from .hf_engine import HuggingfaceEngine
-from .sglang_engine import SGLangEngine
-from .vllm_engine import VllmEngine
 
 
 if TYPE_CHECKING:
@@ -49,12 +46,28 @@ class ChatModel:
 
     def __init__(self, args: Optional[dict[str, Any]] = None) -> None:
         model_args, data_args, finetuning_args, generating_args = get_infer_args(args)
+
         if model_args.infer_backend == EngineName.HF:
+            from .hf_engine import HuggingfaceEngine
             self.engine: BaseEngine = HuggingfaceEngine(model_args, data_args, finetuning_args, generating_args)
         elif model_args.infer_backend == EngineName.VLLM:
+            try:
+                from .vllm_engine import VllmEngine
                 self.engine: BaseEngine = VllmEngine(model_args, data_args, finetuning_args, generating_args)
+            except ImportError as e:
+                raise ImportError(
+                    "vLLM not install, you may need to run `pip install vllm`\n"
+                    "or try to use HuggingFace backend: --infer_backend huggingface"
+                ) from e
         elif model_args.infer_backend == EngineName.SGLANG:
+            try:
+                from .sglang_engine import SGLangEngine
                 self.engine: BaseEngine = SGLangEngine(model_args, data_args, finetuning_args, generating_args)
+            except ImportError as e:
+                raise ImportError(
+                    "SGLang not install, you may need to run `pip install sglang[all]`\n"
+                    "or try to use HuggingFace backend: --infer_backend huggingface"
+                ) from e
         else:
             raise NotImplementedError(f"Unknown backend: {model_args.infer_backend}")
 

src/llamafactory/cli.py

@@ -35,16 +35,46 @@ USAGE = (
 )
 
 
+def _run_api():
+    from .api.app import run_api
+    return run_api()
+
+
+def _run_chat():
+    from .chat.chat_model import run_chat
+    return run_chat()
+
+
+def _run_eval():
+    from .eval.evaluator import run_eval
+    return run_eval()
+
+
+def _export_model():
+    from .train.tuner import export_model
+    return export_model()
+
+
+def _run_exp():
+    from .train.tuner import run_exp
+    return run_exp()
+
+
+def _run_web_demo():
+    from .webui.interface import run_web_demo
+    return run_web_demo()
+
+
+def _run_web_ui():
+    from .webui.interface import run_web_ui
+    return run_web_ui()
+
+
 def main():
     from . import launcher
-    from .api.app import run_api
-    from .chat.chat_model import run_chat
-    from .eval.evaluator import run_eval
     from .extras import logging
     from .extras.env import VERSION, print_env
     from .extras.misc import find_available_port, get_device_count, is_env_enabled, use_ray
-    from .train.tuner import export_model, run_exp
-    from .webui.interface import run_web_demo, run_web_ui
 
     logger = logging.get_logger(__name__)
 
@@ -61,14 +91,14 @@ def main():
     )
 
     COMMAND_MAP = {
-        "api": run_api,
+        "api": _run_api,
-        "chat": run_chat,
+        "chat": _run_chat,
         "env": print_env,
-        "eval": run_eval,
+        "eval": _run_eval,
-        "export": export_model,
+        "export": _export_model,
-        "train": run_exp,
+        "train": _run_exp,
-        "webchat": run_web_demo,
+        "webchat": _run_web_demo,
-        "webui": run_web_ui,
+        "webui": _run_web_ui,
         "version": partial(print, WELCOME),
         "help": partial(print, USAGE),
     }