reduce performance influence by RecordEvent in Python (#41822)

* reduce performance influence

* add unit test

* fix

python/paddle/fluid/tests/unittests/test_newprofiler.py

@@ -20,6 +20,7 @@ import tempfile
 
 import paddle
 import paddle.profiler as profiler
+import paddle.profiler.utils as utils
 import paddle.nn as nn
 import paddle.nn.functional as F
 from paddle.io import Dataset, DataLoader
@@ -40,11 +41,17 @@ class TestProfiler(unittest.TestCase):
         with profiler.Profiler(targets=[profiler.ProfilerTarget.CPU], ) as prof:
             y = x / 2.0
         prof = None
+        self.assertEqual(utils._is_profiler_used, False)
+        with profiler.RecordEvent(name='test'):
+            y = x / 2.0
+
         with profiler.Profiler(
                 targets=[profiler.ProfilerTarget.CPU],
                 scheduler=(1, 2)) as prof:
+            self.assertEqual(utils._is_profiler_used, True)
             with profiler.RecordEvent(name='test'):
                 y = x / 2.0
+
         prof = None
         with profiler.Profiler(
                 targets=[profiler.ProfilerTarget.CPU],

python/paddle/profiler/profiler.py

@@ -27,6 +27,7 @@ from paddle.fluid.core import (_Profiler, _ProfilerResult, ProfilerOptions,
 
 from .utils import RecordEvent, wrap_optimizers
 from .profiler_statistic import StatisticData, _build_table, SortedKeys
+from paddle.profiler import utils
 from .timer import benchmark
 
 
@@ -482,6 +483,7 @@ class Profiler:
         if self.timer_only:
             return
         # CLOSED -> self.current_state
+        utils._is_profiler_used = True
         if self.current_state == ProfilerState.READY:
             self.profiler.prepare()
         elif self.current_state == ProfilerState.RECORD:
@@ -534,6 +536,7 @@ class Profiler:
             self.profiler_result = self.profiler.stop()
             if self.on_trace_ready:
                 self.on_trace_ready(self)
+        utils._is_profiler_used = False
 
     def step(self, num_samples: Optional[int]=None):
         r"""

python/paddle/profiler/utils.py

@@ -20,6 +20,8 @@ from contextlib import ContextDecorator
 from paddle.fluid import core
 from paddle.fluid.core import (_RecordEvent, TracerEventType)
 
+_is_profiler_used = False
+
 _AllowedEventTypeList = [
     TracerEventType.Dataloader, TracerEventType.ProfileStep,
     TracerEventType.UserDefined, TracerEventType.Forward,
@@ -91,6 +93,8 @@ class RecordEvent(ContextDecorator):
                 result = data1 - data2
                 record_event.end()
         """
+        if not _is_profiler_used:
+            return
         if self.event_type not in _AllowedEventTypeList:
             warn("Only TracerEvent Type in [{}, {}, {}, {}, {}, {},{}]\
                   can be recorded.".format(*_AllowedEventTypeList))