tests: use a temporary file:// as rendezvous

Before the change, the test case used a hardcoded port number to run the
tests. This made the test fail in some environments where the port
number was occupied (either by a different service or - more likely - by
a second run of the project test suite).

Signed-off-by: Ihar Hrachyshka <[email protected]>

Author: booxter

tests/attr/test_data_parallel.py

@@ -4,6 +4,7 @@
 import copy
 import os
 from enum import Enum
+import tempfile
 from typing import Any, Callable, cast, Dict, List, Optional, Tuple, Type
 
 import torch
@@ -300,9 +301,8 @@ def _get_dp_attr_methods(
 if torch.cuda.is_available() and torch.cuda.device_count() != 0:
 
     # Distributed Data Parallel env setup
-    os.environ["MASTER_ADDR"] = "localhost"
-    os.environ["MASTER_PORT"] = "29500"
-    dist.init_process_group(backend="gloo", rank=0, world_size=1)
+    f = tempfile.NamedTemporaryFile(delete=False)
+    dist.init_process_group(backend="gloo", init_method=f"file://{f.name}", rank=0, world_size=1)
 
     class DataParallelTest(BaseTest, metaclass=DataParallelMeta):
         @classmethod