[test] added a decorator for address already in use error with backward compatibility (#760)

* [test] added a decorator for address already in use error with backward compatibility

* [test] added a decorator for address already in use error with backward compatibility

colossalai/testing/__init__.py

 from .comparison import assert_equal, assert_not_equal, assert_close, assert_close_loose, assert_equal_in_group
-from .utils import parameterize, rerun_on_exception
+from .utils import parameterize, rerun_on_exception, rerun_if_address_is_in_use
 
 __all__ = [
     'assert_equal', 'assert_not_equal', 'assert_close', 'assert_close_loose', 'assert_equal_in_group', 'parameterize',
-    'rerun_on_exception'
+    'rerun_on_exception', 'rerun_if_address_is_in_use'
 ]

colossalai/testing/utils.py

 import re
+import torch
 from typing import Callable, List, Any
 from functools import partial
 from inspect import signature
+from packaging import version
 
 
 def parameterize(argument: str, values: List[Any]) -> Callable:
@@ -144,3 +146,29 @@ def rerun_on_exception(exception_type: Exception = Exception, pattern: str = Non
         return _run_until_success
 
     return _wrapper
+
+
+def rerun_if_address_is_in_use():
+    """
+    This function reruns a wrapped function if "address already in use" occurs
+    in testing spawned with torch.multiprocessing
+
+    Usage::
+
+        @rerun_if_address_is_in_use()
+        def test_something():
+            ...
+
+    """
+    # check version
+    torch_version = version.parse(torch.__version__)
+    assert torch_version.major == 1
+
+    # only torch >= 1.8 has ProcessRaisedException
+    if torch_version.minor >= 8:
+        exception = torch.multiprocessing.ProcessRaisedException
+    else:
+        exception = Exception
+
+    func_wrapper = rerun_on_exception(exception_type=exception, pattern=".*Address already in use.*")
+    return func_wrapper