ref(profiling): Do not error if already setup (#1731)

We currently error if profiling is already setup which can be error prone
depending on the end user's setup. This change ensures that we only setup
profiling once and once setup, it's reused.

Author: Zylphrex

sentry_sdk/profiler.py

@@ -31,6 +31,7 @@
 from sentry_sdk.utils import (
     filename_for_module,
     handle_in_app_impl,
+    logger,
     nanosecond_time,
 )
 
@@ -92,7 +93,6 @@
     )
 
 
-_sample_buffer = None  # type: Optional[SampleBuffer]
 _scheduler = None  # type: Optional[Scheduler]
 
 
@@ -103,33 +103,33 @@ def setup_profiler(options):
     `buffer_secs` determines the max time a sample will be buffered for
     `frequency` determines the number of samples to take per second (Hz)
     """
-    buffer_secs = 30
-    frequency = 101
 
-    if not PY33:
-        from sentry_sdk.utils import logger
+    global _scheduler
 
-        logger.warn("profiling is only supported on Python >= 3.3")
+    if _scheduler is not None:
+        logger.debug("profiling is already setup")
         return
 
-    global _sample_buffer
-    global _scheduler
+    if not PY33:
+        logger.warn("profiling is only supported on Python >= 3.3")
+        return
 
-    assert _sample_buffer is None and _scheduler is None
+    buffer_secs = 30
+    frequency = 101
 
     # To buffer samples for `buffer_secs` at `frequency` Hz, we need
     # a capcity of `buffer_secs * frequency`.
-    _sample_buffer = SampleBuffer(capacity=buffer_secs * frequency)
+    buffer = SampleBuffer(capacity=buffer_secs * frequency)
 
     profiler_mode = options["_experiments"].get("profiler_mode", SleepScheduler.mode)
     if profiler_mode == SigprofScheduler.mode:
-        _scheduler = SigprofScheduler(sample_buffer=_sample_buffer, frequency=frequency)
+        _scheduler = SigprofScheduler(sample_buffer=buffer, frequency=frequency)
     elif profiler_mode == SigalrmScheduler.mode:
-        _scheduler = SigalrmScheduler(sample_buffer=_sample_buffer, frequency=frequency)
+        _scheduler = SigalrmScheduler(sample_buffer=buffer, frequency=frequency)
     elif profiler_mode == SleepScheduler.mode:
-        _scheduler = SleepScheduler(sample_buffer=_sample_buffer, frequency=frequency)
+        _scheduler = SleepScheduler(sample_buffer=buffer, frequency=frequency)
     elif profiler_mode == EventScheduler.mode:
-        _scheduler = EventScheduler(sample_buffer=_sample_buffer, frequency=frequency)
+        _scheduler = EventScheduler(sample_buffer=buffer, frequency=frequency)
     else:
         raise ValueError("Unknown profiler mode: {}".format(profiler_mode))
     _scheduler.setup()
@@ -140,13 +140,11 @@ def setup_profiler(options):
 def teardown_profiler():
     # type: () -> None
 
-    global _sample_buffer
     global _scheduler
 
     if _scheduler is not None:
         _scheduler.teardown()
 
-    _sample_buffer = None
     _scheduler = None
 
 
@@ -728,7 +726,7 @@ def _should_profile(transaction, hub):
         return False
 
     # The profiler hasn't been properly initialized.
-    if _sample_buffer is None or _scheduler is None:
+    if _scheduler is None:
         return False
 
     hub = hub or sentry_sdk.Hub.current