Remove ucp.reset() requirement from test_dgx

By moving the `ucp.get_transports()` call to the subprocess we remove
the requirement to reset UCX from the `pytest` process, preventing
potential interferences with tests that run after.

dask_cuda/tests/test_dgx.py

@@ -128,14 +128,22 @@ def test_tcp_only():
 
 
 def _test_ucx_infiniband_nvlink(
-    protocol, enable_infiniband, enable_nvlink, enable_rdmacm
+    skip_queue, protocol, enable_infiniband, enable_nvlink, enable_rdmacm
 ):
     cupy = pytest.importorskip("cupy")
     if protocol == "ucx":
         ucp = pytest.importorskip("ucp")
     elif protocol == "ucxx":
         ucp = pytest.importorskip("ucxx")
 
+    if enable_infiniband and not any(
+        [at.startswith("rc") for at in ucp.get_active_transports()]
+    ):
+        skip_queue.put("No support available for 'rc' transport in UCX")
+        return
+    else:
+        skip_queue.put("ok")
+
     if enable_infiniband is None and enable_nvlink is None and enable_rdmacm is None:
         enable_tcp_over_ucx = None
         cm_tls = ["all"]
@@ -205,17 +213,16 @@ def check_ucx_options():
 )
 def test_ucx_infiniband_nvlink(protocol, params):
     if protocol == "ucx":
-        ucp = pytest.importorskip("ucp")
+        pytest.importorskip("ucp")
     elif protocol == "ucxx":
-        ucp = pytest.importorskip("ucxx")
+        pytest.importorskip("ucxx")
 
-    if params["enable_infiniband"]:
-        if not any([at.startswith("rc") for at in ucp.get_active_transports()]):
-            pytest.skip("No support available for 'rc' transport in UCX")
+    skip_queue = mp.Queue()
 
     p = mp.Process(
         target=_test_ucx_infiniband_nvlink,
         args=(
+            skip_queue,
             protocol,
             params["enable_infiniband"],
             params["enable_nvlink"],
@@ -225,9 +232,8 @@ def test_ucx_infiniband_nvlink(protocol, params):
     p.start()
     p.join()
 
-    # Starting a new cluster on the same pytest process after an rdmacm cluster
-    # has been used may cause UCX-Py to complain about being already initialized.
-    if params["enable_rdmacm"] is True:
-        ucp.reset()
+    skip_msg = skip_queue.get()
+    if skip_msg != "ok":
+        pytest.skip(skip_msg)
 
     assert not p.exitcode