clean up tests/test_profiler.py (#867)

* cleanup docstrings, _get_total_cprofile_duration in module

* relax profiler overhead tolerance

tests/test_profiler.py

@@ -4,26 +4,26 @@
 
 from pytorch_lightning.profiler import Profiler, AdvancedProfiler
 
-PROFILER_OVERHEAD_MAX_TOLERANCE = 0.0001
+PROFILER_OVERHEAD_MAX_TOLERANCE = 0.001
 
 
 @pytest.fixture
 def simple_profiler():
+    """Creates a new profiler for every test with `simple_profiler` as an arg."""
     profiler = Profiler()
     return profiler
 
 
 @pytest.fixture
 def advanced_profiler():
+    """Creates a new profiler for every test with `advanced_profiler` as an arg."""
     profiler = AdvancedProfiler()
     return profiler
 
 
 @pytest.mark.parametrize("action,expected", [("a", [3, 1]), ("b", [2]), ("c", [1])])
 def test_simple_profiler_durations(simple_profiler, action, expected):
-    """
-    ensure the reported durations are reasonably accurate
-    """
+    """Ensure the reported durations are reasonably accurate."""
 
     for duration in expected:
         with simple_profiler.profile(action):
@@ -37,9 +37,7 @@ def test_simple_profiler_durations(simple_profiler, action, expected):
 
 
 def test_simple_profiler_overhead(simple_profiler, n_iter=5):
-    """
-    ensure that the profiler doesn't introduce too much overhead during training
-    """
+    """Ensure that the profiler doesn't introduce too much overhead during training."""
     for _ in range(n_iter):
         with simple_profiler.profile("no-op"):
             pass
@@ -49,24 +47,25 @@ def test_simple_profiler_overhead(simple_profiler, n_iter=5):
 
 
 def test_simple_profiler_describe(simple_profiler):
-    """
-    ensure the profiler won't fail when reporting the summary
-    """
+    """Ensure the profiler won't fail when reporting the summary."""
     simple_profiler.describe()
 
 
+def _get_total_cprofile_duration(profile):
+    return sum([x.totaltime for x in profile.getstats()])
+
+
 @pytest.mark.parametrize("action,expected", [("a", [3, 1]), ("b", [2]), ("c", [1])])
 def test_advanced_profiler_durations(advanced_profiler, action, expected):
-    def _get_total_duration(profile):
-        return sum([x.totaltime for x in profile.getstats()])
+    """Ensure the reported durations are reasonably accurate."""
 
     for duration in expected:
         with advanced_profiler.profile(action):
             time.sleep(duration)
 
     # different environments have different precision when it comes to time.sleep()
     # see: https://github.com/PyTorchLightning/pytorch-lightning/issues/796
-    recored_total_duration = _get_total_duration(
+    recored_total_duration = _get_total_cprofile_duration(
         advanced_profiler.profiled_actions[action]
     )
     expected_total_duration = np.sum(expected)
@@ -76,21 +75,17 @@ def _get_total_duration(profile):
 
 
 def test_advanced_profiler_overhead(advanced_profiler, n_iter=5):
-    """
-    ensure that the profiler doesn't introduce too much overhead during training
-    """
+    """Ensure that the profiler doesn't introduce too much overhead during training."""
     for _ in range(n_iter):
         with advanced_profiler.profile("no-op"):
             pass
 
     action_profile = advanced_profiler.profiled_actions["no-op"]
-    total_duration = sum([x.totaltime for x in action_profile.getstats()])
+    total_duration = _get_total_cprofile_duration(action_profile)
     average_duration = total_duration / n_iter
     assert average_duration < PROFILER_OVERHEAD_MAX_TOLERANCE
 
 
 def test_advanced_profiler_describe(advanced_profiler):
-    """
-    ensure the profiler won't fail when reporting the summary
-    """
+    """Ensure the profiler won't fail when reporting the summary."""
     advanced_profiler.describe()