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test(profiler): Remove wall-clock race in continuous profiler auto-start tests #7483

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test(profiler): Remove wall-clock race in continuous profiler auto-start tests #7483

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94 changes: 65 additions & 29 deletions tests/profiler/test_continuous_profiler.py
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Original file line number Diff line number Diff line change
@@ -1,12 +1,14 @@
import threading
import time
from collections import defaultdict
from contextlib import contextmanager
from unittest import mock

import pytest

import sentry_sdk
from sentry_sdk.consts import VERSION
from sentry_sdk.profiler import continuous_profiler as continuous_profiler_module
from sentry_sdk.profiler.continuous_profiler import (
get_profiler_id,
is_profile_session_sampled,
Expand All @@ -27,7 +29,7 @@
requires_gevent = pytest.mark.skipif(gevent is None, reason="gevent not enabled")


def wait_for_profiler_to_stop(envelopes, timeout=1.0):
def wait_for_profiler_to_stop(envelopes, timeout=5.0):
deadline = time.monotonic() + timeout
while time.monotonic() < deadline:
profiler_stopped = get_profiler_id() is None
Expand All @@ -48,6 +50,36 @@ def wait_for_profiler_to_stop(envelopes, timeout=1.0):
), "profiler should have flushed a profile chunk"


@contextmanager
def suspend_profiler_sampling():
"""
Pause the continuous profiler's sampler thread until sampling is resumed.

While suspended, the scheduler cannot observe stopped profiles, so it
neither removes them nor enters soft shutdown: the profiler stays up no
matter how long the test is preempted for. This removes the need to race
the profiler's shutdown grace period with a fixed sleep.

Yields a callable that resumes sampling. Sampling is also resumed, and
the original sampler restored, when the block exits.
"""
scheduler = continuous_profiler_module._scheduler
assert scheduler is not None, "profiler should have been set up"
resumed = threading.Event()
real_sampler = scheduler.sampler

def suspended_sampler(*args, **kwargs):
resumed.wait()
return real_sampler(*args, **kwargs)

scheduler.sampler = suspended_sampler
try:
yield resumed.set
finally:
resumed.set()
scheduler.sampler = real_sampler


def get_client_options(use_top_level_profiler_mode):
def client_options(
mode=None, auto_start=None, profile_session_sample_rate=1.0, lifecycle="manual"
Expand Down Expand Up @@ -810,24 +842,26 @@ def test_continuous_profiler_auto_start_and_stop_sampled(
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)

time.sleep(0.03)

# the profiler takes a while to stop in auto mode so if we start
# a transaction immediately, it'll be part of the same chunk
profiler_id = get_profiler_id()
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)

with sentry_sdk.start_transaction(name="profiling 2"):
profiler_id = get_profiler_id()
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)
with sentry_sdk.start_span(op="op"):
time.sleep(0.1)
# While the sampler is suspended it cannot observe that the
# transaction's profile was stopped, so the scheduler cannot
# soft-shutdown: the profiler stays up and the next transaction
# deterministically reuses the same profiler session and chunk.
with suspend_profiler_sampling() as resume_sampling:
profiler_id = get_profiler_id()
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)

with sentry_sdk.start_transaction(name="profiling 2"):
resume_sampling()
profiler_id = get_profiler_id()
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)
with sentry_sdk.start_span(op="op"):
time.sleep(0.1)
profiler_id = get_profiler_id()
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)

wait_for_profiler_to_stop(envelopes)

assert len(profiler_ids) == 1
Expand Down Expand Up @@ -892,24 +926,26 @@ def test_continuous_profiler_auto_start_and_stop_sampled_span_streaming(
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)

time.sleep(0.03)

# the profiler takes a while to stop in auto mode so if we start
# a transaction immediately, it'll be part of the same chunk
profiler_id = get_profiler_id()
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)

with sentry_sdk.traces.start_span(name="profiling 2"):
profiler_id = get_profiler_id()
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)
with sentry_sdk.traces.start_span(name="op"):
time.sleep(0.1)
# While the sampler is suspended it cannot observe that the
# segment's profile was stopped, so the scheduler cannot
# soft-shutdown: the profiler stays up and the next segment
# deterministically reuses the same profiler session and chunk.
with suspend_profiler_sampling() as resume_sampling:
profiler_id = get_profiler_id()
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)

with sentry_sdk.traces.start_span(name="profiling 2"):
resume_sampling()
profiler_id = get_profiler_id()
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)
with sentry_sdk.traces.start_span(name="op"):
time.sleep(0.1)
profiler_id = get_profiler_id()
assert profiler_id is not None, "profiler should be running"
profiler_ids.add(profiler_id)

wait_for_profiler_to_stop(envelopes)

assert len(profiler_ids) == 1
Expand Down