[fix] Support local mode without setting CUDA_VISIBLE_DEVICES (#38)

If `CUDA_VISIBLE_DEVICES` is not set, it means that all the
devices will be available for use. If it's an empty string,
it means no device is available for the process to use.

As a result, if `CUDA_VISIBLE_DEVICES` does not exist, the
default value should be equivalent to all the devices instead
of an empty one.

Signed-off-by: Hollow Man <hollowman@opensuse.org>

realhf/scheduler/local/client.py

@@ -13,6 +13,7 @@ from typing import Dict, List, Optional, Tuple, Union
 import psutil
 
 import realhf.base.logging as logging
+from realhf.base import gpu_utils
 from realhf.base.constants import LOG_ROOT
 from realhf.scheduler.client import (
     JobException,
@@ -87,7 +88,7 @@ class LocalSchedulerClient(SchedulerClient):
 
         self._gpu_counter = 0
         self._cuda_devices: List[str] = os.environ.get(
-            "CUDA_VISIBLE_DEVICES", ""
+            "CUDA_VISIBLE_DEVICES", ",".join(map(str, range(gpu_utils.gpu_count())))
         ).split(",")
 
         self._job_counter: Dict[str, int] = defaultdict(int)