Add cuda_device_count_stateless (#5473)

tests/distributed/test_utils.py

@@ -0,0 +1,31 @@
+import os
+
+import ray
+
+from vllm.utils import cuda_device_count_stateless
+
+
+@ray.remote
+class _CUDADeviceCountStatelessTestActor():
+
+    def get_count(self):
+        return cuda_device_count_stateless()
+
+    def set_cuda_visible_devices(self, cuda_visible_devices: str):
+        os.environ["CUDA_VISIBLE_DEVICES"] = cuda_visible_devices
+
+    def get_cuda_visible_devices(self):
+        return os.environ["CUDA_VISIBLE_DEVICES"]
+
+
+def test_cuda_device_count_stateless():
+    """Test that cuda_device_count_stateless changes return value if
+    CUDA_VISIBLE_DEVICES is changed."""
+
+    actor = _CUDADeviceCountStatelessTestActor.options(num_gpus=2).remote()
+    assert ray.get(actor.get_cuda_visible_devices.remote()) == "0,1"
+    assert ray.get(actor.get_count.remote()) == 2
+    ray.get(actor.set_cuda_visible_devices.remote("0"))
+    assert ray.get(actor.get_count.remote()) == 1
+    ray.get(actor.set_cuda_visible_devices.remote(""))
+    assert ray.get(actor.get_count.remote()) == 0