feat(profiling): Continuous profiling lifecycle (#4017)

This introduces auto lifecycle setting for continuous profiling to only
profile while there is an active transaction. This replaces the
experimental auto start setting.

Author: Zylphrex

Diff for: sentry_sdk/consts.py

@@ -38,6 +38,7 @@ class CompressionAlgo(Enum):
     from typing import Any
     from typing import Sequence
     from typing import Tuple
+    from typing_extensions import Literal
     from typing_extensions import TypedDict
 
     from sentry_sdk._types import (
@@ -528,6 +529,7 @@ def __init__(
         profiles_sample_rate=None,  # type: Optional[float]
         profiles_sampler=None,  # type: Optional[TracesSampler]
         profiler_mode=None,  # type: Optional[ProfilerMode]
+        profile_lifecycle="manual",  # type: Literal["manual", "trace"]
         profile_session_sample_rate=None,  # type: Optional[float]
         auto_enabling_integrations=True,  # type: bool
         disabled_integrations=None,  # type: Optional[Sequence[sentry_sdk.integrations.Integration]]

Diff for: sentry_sdk/profiler/continuous_profiler.py

@@ -5,6 +5,7 @@
 import threading
 import time
 import uuid
+from collections import deque
 from datetime import datetime, timezone
 
 from sentry_sdk.consts import VERSION
@@ -27,9 +28,11 @@
 if TYPE_CHECKING:
     from typing import Any
     from typing import Callable
+    from typing import Deque
     from typing import Dict
     from typing import List
     from typing import Optional
+    from typing import Set
     from typing import Type
     from typing import Union
     from typing_extensions import TypedDict
@@ -120,6 +123,9 @@ def setup_continuous_profiler(options, sdk_info, capture_func):
 
 def try_autostart_continuous_profiler():
     # type: () -> None
+
+    # TODO: deprecate this as it'll be replaced by the auto lifecycle option
+
     if _scheduler is None:
         return
 
@@ -129,6 +135,14 @@ def try_autostart_continuous_profiler():
     _scheduler.manual_start()
 
 
+def try_profile_lifecycle_trace_start():
+    # type: () -> Union[ContinuousProfile, None]
+    if _scheduler is None:
+        return None
+
+    return _scheduler.auto_start()
+
+
 def start_profiler():
     # type: () -> None
     if _scheduler is None:
@@ -170,6 +184,14 @@ def determine_profile_session_sampling_decision(sample_rate):
     return random.random() < float(sample_rate)
 
 
+class ContinuousProfile:
+    active: bool = True
+
+    def stop(self):
+        # type: () -> None
+        self.active = False
+
+
 class ContinuousScheduler:
     mode = "unknown"  # type: ContinuousProfilerMode
 
@@ -179,16 +201,21 @@ def __init__(self, frequency, options, sdk_info, capture_func):
         self.options = options
         self.sdk_info = sdk_info
         self.capture_func = capture_func
+
+        self.lifecycle = self.options.get("profile_lifecycle")
+        profile_session_sample_rate = self.options.get("profile_session_sample_rate")
+        self.sampled = determine_profile_session_sampling_decision(
+            profile_session_sample_rate
+        )
+
         self.sampler = self.make_sampler()
         self.buffer = None  # type: Optional[ProfileBuffer]
         self.pid = None  # type: Optional[int]
 
         self.running = False
 
-        profile_session_sample_rate = self.options.get("profile_session_sample_rate")
-        self.sampled = determine_profile_session_sampling_decision(
-            profile_session_sample_rate
-        )
+        self.new_profiles = deque(maxlen=128)  # type: Deque[ContinuousProfile]
+        self.active_profiles = set()  # type: Set[ContinuousProfile]
 
     def is_auto_start_enabled(self):
         # type: () -> bool
@@ -207,15 +234,38 @@ def is_auto_start_enabled(self):
 
         return experiments.get("continuous_profiling_auto_start")
 
+    def auto_start(self):
+        # type: () -> Union[ContinuousProfile, None]
+        if not self.sampled:
+            return None
+
+        if self.lifecycle != "trace":
+            return None
+
+        logger.debug("[Profiling] Auto starting profiler")
+
+        profile = ContinuousProfile()
+
+        self.new_profiles.append(profile)
+        self.ensure_running()
+
+        return profile
+
     def manual_start(self):
         # type: () -> None
         if not self.sampled:
             return
 
+        if self.lifecycle != "manual":
+            return
+
         self.ensure_running()
 
     def manual_stop(self):
         # type: () -> None
+        if self.lifecycle != "manual":
+            return
+
         self.teardown()
 
     def ensure_running(self):
@@ -249,28 +299,97 @@ def make_sampler(self):
 
         cache = LRUCache(max_size=256)
 
-        def _sample_stack(*args, **kwargs):
-            # type: (*Any, **Any) -> None
-            """
-            Take a sample of the stack on all the threads in the process.
-            This should be called at a regular interval to collect samples.
-            """
-
-            ts = now()
-
-            try:
-                sample = [
-                    (str(tid), extract_stack(frame, cache, cwd))
-                    for tid, frame in sys._current_frames().items()
-                ]
-            except AttributeError:
-                # For some reason, the frame we get doesn't have certain attributes.
-                # When this happens, we abandon the current sample as it's bad.
-                capture_internal_exception(sys.exc_info())
-                return
-
-            if self.buffer is not None:
-                self.buffer.write(ts, sample)
+        if self.lifecycle == "trace":
+
+            def _sample_stack(*args, **kwargs):
+                # type: (*Any, **Any) -> None
+                """
+                Take a sample of the stack on all the threads in the process.
+                This should be called at a regular interval to collect samples.
+                """
+
+                # no profiles taking place, so we can stop early
+                if not self.new_profiles and not self.active_profiles:
+                    self.running = False
+                    return
+
+                # This is the number of profiles we want to pop off.
+                # It's possible another thread adds a new profile to
+                # the list and we spend longer than we want inside
+                # the loop below.
+                #
+                # Also make sure to set this value before extracting
+                # frames so we do not write to any new profiles that
+                # were started after this point.
+                new_profiles = len(self.new_profiles)
+
+                ts = now()
+
+                try:
+                    sample = [
+                        (str(tid), extract_stack(frame, cache, cwd))
+                        for tid, frame in sys._current_frames().items()
+                    ]
+                except AttributeError:
+                    # For some reason, the frame we get doesn't have certain attributes.
+                    # When this happens, we abandon the current sample as it's bad.
+                    capture_internal_exception(sys.exc_info())
+                    return
+
+                # Move the new profiles into the active_profiles set.
+                #
+                # We cannot directly add the to active_profiles set
+                # in `start_profiling` because it is called from other
+                # threads which can cause a RuntimeError when it the
+                # set sizes changes during iteration without a lock.
+                #
+                # We also want to avoid using a lock here so threads
+                # that are starting profiles are not blocked until it
+                # can acquire the lock.
+                for _ in range(new_profiles):
+                    self.active_profiles.add(self.new_profiles.popleft())
+                inactive_profiles = []
+
+                for profile in self.active_profiles:
+                    if profile.active:
+                        pass
+                    else:
+                        # If a profile is marked inactive, we buffer it
+                        # to `inactive_profiles` so it can be removed.
+                        # We cannot remove it here as it would result
+                        # in a RuntimeError.
+                        inactive_profiles.append(profile)
+
+                for profile in inactive_profiles:
+                    self.active_profiles.remove(profile)
+
+                if self.buffer is not None:
+                    self.buffer.write(ts, sample)
+
+        else:
+
+            def _sample_stack(*args, **kwargs):
+                # type: (*Any, **Any) -> None
+                """
+                Take a sample of the stack on all the threads in the process.
+                This should be called at a regular interval to collect samples.
+                """
+
+                ts = now()
+
+                try:
+                    sample = [
+                        (str(tid), extract_stack(frame, cache, cwd))
+                        for tid, frame in sys._current_frames().items()
+                    ]
+                except AttributeError:
+                    # For some reason, the frame we get doesn't have certain attributes.
+                    # When this happens, we abandon the current sample as it's bad.
+                    capture_internal_exception(sys.exc_info())
+                    return
+
+                if self.buffer is not None:
+                    self.buffer.write(ts, sample)
 
         return _sample_stack
 
@@ -294,6 +413,7 @@ def run(self):
 
         if self.buffer is not None:
             self.buffer.flush()
+            self.buffer = None
 
 
 class ThreadContinuousScheduler(ContinuousScheduler):

Diff for: sentry_sdk/profiler/transaction_profiler.py

@@ -644,7 +644,7 @@ def _sample_stack(*args, **kwargs):
                 if profile.active:
                     profile.write(now, sample)
                 else:
-                    # If a thread is marked inactive, we buffer it
+                    # If a profile is marked inactive, we buffer it
                     # to `inactive_profiles` so it can be removed.
                     # We cannot remove it here as it would result
                     # in a RuntimeError.

Diff for: sentry_sdk/scope.py

@@ -12,7 +12,11 @@
 from sentry_sdk.attachments import Attachment
 from sentry_sdk.consts import DEFAULT_MAX_BREADCRUMBS, FALSE_VALUES, INSTRUMENTER
 from sentry_sdk.feature_flags import FlagBuffer, DEFAULT_FLAG_CAPACITY
-from sentry_sdk.profiler.continuous_profiler import try_autostart_continuous_profiler
+from sentry_sdk.profiler.continuous_profiler import (
+    get_profiler_id,
+    try_autostart_continuous_profiler,
+    try_profile_lifecycle_trace_start,
+)
 from sentry_sdk.profiler.transaction_profiler import Profile
 from sentry_sdk.session import Session
 from sentry_sdk.tracing_utils import (
@@ -1063,6 +1067,14 @@ def start_transaction(
 
             transaction._profile = profile
 
+            transaction._continuous_profile = try_profile_lifecycle_trace_start()
+
+            # Typically, the profiler is set when the transaction is created. But when
+            # using the auto lifecycle, the profiler isn't running when the first
+            # transaction is started. So make sure we update the profiler id on it.
+            if transaction._continuous_profile is not None:
+                transaction.set_profiler_id(get_profiler_id())
+
             # we don't bother to keep spans if we already know we're not going to
             # send the transaction
             max_spans = (client.options["_experiments"].get("max_spans")) or 1000

Diff for: sentry_sdk/tracing.py

@@ -34,7 +34,8 @@
     P = ParamSpec("P")
     R = TypeVar("R")
 
-    import sentry_sdk.profiler
+    from sentry_sdk.profiler.continuous_profiler import ContinuousProfile
+    from sentry_sdk.profiler.transaction_profiler import Profile
     from sentry_sdk._types import (
         Event,
         MeasurementUnit,
@@ -767,6 +768,7 @@ class Transaction(Span):
         "_measurements",
         "_contexts",
         "_profile",
+        "_continuous_profile",
         "_baggage",
     )
 
@@ -788,9 +790,8 @@ def __init__(  # type: ignore[misc]
         self.parent_sampled = parent_sampled
         self._measurements = {}  # type: Dict[str, MeasurementValue]
         self._contexts = {}  # type: Dict[str, Any]
-        self._profile = (
-            None
-        )  # type: Optional[sentry_sdk.profiler.transaction_profiler.Profile]
+        self._profile = None  # type: Optional[Profile]
+        self._continuous_profile = None  # type: Optional[ContinuousProfile]
         self._baggage = baggage
 
     def __repr__(self):
@@ -843,6 +844,9 @@ def __exit__(self, ty, value, tb):
         if self._profile is not None:
             self._profile.__exit__(ty, value, tb)
 
+        if self._continuous_profile is not None:
+            self._continuous_profile.stop()
+
         super().__exit__(ty, value, tb)
 
     @property