在分布式训练中，为USER_CUDA_VISIBLE_DEVICES为None的情况添加提醒

fastNLP/core/drivers/paddle_driver/fleet.py

@@ -191,8 +191,8 @@ class PaddleFleetDriver(PaddleDriver):
             不管是什么情况，`PaddleFleetDriver` 在 `setup` 函数的最后，都会将所有进程的 pid 主动记录下来，这样当一个进程出现 exception 后，
              driver 的 on_exception 函数就会被 trainer 调用，其会调用 os.kill 指令将其它进程 kill 掉；
         """
-        # if USER_CUDA_VISIBLE_DEVICES not in os.environ:
-        #     raise RuntimeError("To run paddle distributed training, please set `FASTNLP_BACKEND` to 'paddle' before using FastNLP.")
+        if USER_CUDA_VISIBLE_DEVICES not in os.environ:
+            raise RuntimeError("To run paddle distributed training, please set `FASTNLP_BACKEND` to 'paddle' before using FastNLP.")
         super(PaddleFleetDriver, self).__init__(model, fp16=fp16, **kwargs)
 
         # 如果不是通过 launch 启动，要求用户必须传入 parallel_device

fastNLP/core/drivers/paddle_driver/initialize_paddle_driver.py

@@ -7,6 +7,7 @@ from .single_device import PaddleSingleDriver
 from .fleet import PaddleFleetDriver
 
 from fastNLP.envs.imports import _NEED_IMPORT_PADDLE
+from fastNLP.envs.env import USER_CUDA_VISIBLE_DEVICES
 from fastNLP.core.utils import is_in_paddle_launch_dist, get_paddle_gpu_str
 from fastNLP.core.log import logger
 
@@ -30,8 +31,10 @@ def initialize_paddle_driver(driver: str, device: Optional[Union[str, int, List[
     """
     if driver != "paddle":
         raise ValueError("When initialize PaddleDriver, parameter `driver` must be 'paddle'.")
-    user_visible_devices = os.getenv("USER_CUDA_VISIBLE_DEVICES")
+    user_visible_devices = os.getenv(USER_CUDA_VISIBLE_DEVICES)
     if is_in_paddle_launch_dist():
+        if user_visible_devices is None:
+            raise RuntimeError("To run paddle distributed training, please set `FASTNLP_BACKEND` to 'paddle' before using FastNLP.")
         if device is not None:
             logger.warning_once("Parameter `device` would be ignored when you are using `paddle.distributed.launch` to pull "
                            "up your script. And we will directly get the local device via environment variables.")
@@ -65,6 +68,7 @@ def initialize_paddle_driver(driver: str, device: Optional[Union[str, int, List[
         device = [get_paddle_gpu_str(g) for g in device]
     elif device is not None and not isinstance(device, str):
         raise ValueError("Parameter `device` is wrong type, please check our documentation for the right use.")
+    
     if isinstance(device, List):
         return PaddleFleetDriver(model, device, **kwargs)
     else: