[test] refactor tests with spawn (#3452)

* [test] added spawn decorator

* polish code

* polish code

* polish code

* polish code

* polish code

* polish code

tests/test_fx/test_meta/test_aten.py

@@ -3,7 +3,9 @@ from typing import Any, Callable, Union
 import pytest
 import torch
 import torch.nn as nn
+
 from colossalai.fx._compatibility import is_compatible_with_meta
+from colossalai.testing import clear_cache_before_run
 
 if is_compatible_with_meta():
     from colossalai.fx.profiler import MetaTensor
@@ -71,6 +73,7 @@ def run_and_compare(f: Union[nn.Module, Callable], x: torch.Tensor, requires_bac
 
 
 @pytest.mark.skipif(not is_compatible_with_meta(), reason='torch version is lower than 1.12.0')
+@clear_cache_before_run()
 def test_meta_aten():
     for (aten_op, requires_backward), v in registered_meta.items():
         for f, x in v: