two version of R2R are hereHEADmaster

1 files changed, 837 insertions, 0 deletions

diff --git a/.venv/lib/python3.12/site-packages/sentry_sdk/profiler/transaction_profiler.py b/.venv/lib/python3.12/site-packages/sentry_sdk/profiler/transaction_profiler.py
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+++ b/.venv/lib/python3.12/site-packages/sentry_sdk/profiler/transaction_profiler.py
@@ -0,0 +1,837 @@
+"""
+This file is originally based on code from https://github.com/nylas/nylas-perftools,
+which is published under the following license:
+
+The MIT License (MIT)
+
+Copyright (c) 2014 Nylas
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+"""
+
+import atexit
+import os
+import platform
+import random
+import sys
+import threading
+import time
+import uuid
+import warnings
+from abc import ABC, abstractmethod
+from collections import deque
+
+import sentry_sdk
+from sentry_sdk._lru_cache import LRUCache
+from sentry_sdk.profiler.utils import (
+    DEFAULT_SAMPLING_FREQUENCY,
+    extract_stack,
+)
+from sentry_sdk.utils import (
+    capture_internal_exception,
+    get_current_thread_meta,
+    is_gevent,
+    is_valid_sample_rate,
+    logger,
+    nanosecond_time,
+    set_in_app_in_frames,
+)
+
+from typing import TYPE_CHECKING
+
+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_extensions import TypedDict
+
+    from sentry_sdk.profiler.utils import (
+        ProcessedStack,
+        ProcessedFrame,
+        ProcessedThreadMetadata,
+        FrameId,
+        StackId,
+        ThreadId,
+        ExtractedSample,
+    )
+    from sentry_sdk._types import Event, SamplingContext, ProfilerMode
+
+    ProcessedSample = TypedDict(
+        "ProcessedSample",
+        {
+            "elapsed_since_start_ns": str,
+            "thread_id": ThreadId,
+            "stack_id": int,
+        },
+    )
+
+    ProcessedProfile = TypedDict(
+        "ProcessedProfile",
+        {
+            "frames": List[ProcessedFrame],
+            "stacks": List[ProcessedStack],
+            "samples": List[ProcessedSample],
+            "thread_metadata": Dict[ThreadId, ProcessedThreadMetadata],
+        },
+    )
+
+
+try:
+    from gevent.monkey import get_original
+    from gevent.threadpool import ThreadPool as _ThreadPool
+
+    ThreadPool = _ThreadPool  # type: Optional[Type[_ThreadPool]]
+    thread_sleep = get_original("time", "sleep")
+except ImportError:
+    thread_sleep = time.sleep
+
+    ThreadPool = None
+
+
+_scheduler = None  # type: Optional[Scheduler]
+
+
+# The minimum number of unique samples that must exist in a profile to be
+# considered valid.
+PROFILE_MINIMUM_SAMPLES = 2
+
+
+def has_profiling_enabled(options):
+    # type: (Dict[str, Any]) -> bool
+    profiles_sampler = options["profiles_sampler"]
+    if profiles_sampler is not None:
+        return True
+
+    profiles_sample_rate = options["profiles_sample_rate"]
+    if profiles_sample_rate is not None and profiles_sample_rate > 0:
+        return True
+
+    profiles_sample_rate = options["_experiments"].get("profiles_sample_rate")
+    if profiles_sample_rate is not None:
+        logger.warning(
+            "_experiments['profiles_sample_rate'] is deprecated. "
+            "Please use the non-experimental profiles_sample_rate option "
+            "directly."
+        )
+        if profiles_sample_rate > 0:
+            return True
+
+    return False
+
+
+def setup_profiler(options):
+    # type: (Dict[str, Any]) -> bool
+    global _scheduler
+
+    if _scheduler is not None:
+        logger.debug("[Profiling] Profiler is already setup")
+        return False
+
+    frequency = DEFAULT_SAMPLING_FREQUENCY
+
+    if is_gevent():
+        # If gevent has patched the threading modules then we cannot rely on
+        # them to spawn a native thread for sampling.
+        # Instead we default to the GeventScheduler which is capable of
+        # spawning native threads within gevent.
+        default_profiler_mode = GeventScheduler.mode
+    else:
+        default_profiler_mode = ThreadScheduler.mode
+
+    if options.get("profiler_mode") is not None:
+        profiler_mode = options["profiler_mode"]
+    else:
+        profiler_mode = options.get("_experiments", {}).get("profiler_mode")
+        if profiler_mode is not None:
+            logger.warning(
+                "_experiments['profiler_mode'] is deprecated. Please use the "
+                "non-experimental profiler_mode option directly."
+            )
+        profiler_mode = profiler_mode or default_profiler_mode
+
+    if (
+        profiler_mode == ThreadScheduler.mode
+        # for legacy reasons, we'll keep supporting sleep mode for this scheduler
+        or profiler_mode == "sleep"
+    ):
+        _scheduler = ThreadScheduler(frequency=frequency)
+    elif profiler_mode == GeventScheduler.mode:
+        _scheduler = GeventScheduler(frequency=frequency)
+    else:
+        raise ValueError("Unknown profiler mode: {}".format(profiler_mode))
+
+    logger.debug(
+        "[Profiling] Setting up profiler in {mode} mode".format(mode=_scheduler.mode)
+    )
+    _scheduler.setup()
+
+    atexit.register(teardown_profiler)
+
+    return True
+
+
+def teardown_profiler():
+    # type: () -> None
+
+    global _scheduler
+
+    if _scheduler is not None:
+        _scheduler.teardown()
+
+    _scheduler = None
+
+
+MAX_PROFILE_DURATION_NS = int(3e10)  # 30 seconds
+
+
+class Profile:
+    def __init__(
+        self,
+        sampled,  # type: Optional[bool]
+        start_ns,  # type: int
+        hub=None,  # type: Optional[sentry_sdk.Hub]
+        scheduler=None,  # type: Optional[Scheduler]
+    ):
+        # type: (...) -> None
+        self.scheduler = _scheduler if scheduler is None else scheduler
+
+        self.event_id = uuid.uuid4().hex  # type: str
+
+        self.sampled = sampled  # type: Optional[bool]
+
+        # Various framework integrations are capable of overwriting the active thread id.
+        # If it is set to `None` at the end of the profile, we fall back to the default.
+        self._default_active_thread_id = get_current_thread_meta()[0] or 0  # type: int
+        self.active_thread_id = None  # type: Optional[int]
+
+        try:
+            self.start_ns = start_ns  # type: int
+        except AttributeError:
+            self.start_ns = 0
+
+        self.stop_ns = 0  # type: int
+        self.active = False  # type: bool
+
+        self.indexed_frames = {}  # type: Dict[FrameId, int]
+        self.indexed_stacks = {}  # type: Dict[StackId, int]
+        self.frames = []  # type: List[ProcessedFrame]
+        self.stacks = []  # type: List[ProcessedStack]
+        self.samples = []  # type: List[ProcessedSample]
+
+        self.unique_samples = 0
+
+        # Backwards compatibility with the old hub property
+        self._hub = None  # type: Optional[sentry_sdk.Hub]
+        if hub is not None:
+            self._hub = hub
+            warnings.warn(
+                "The `hub` parameter is deprecated. Please do not use it.",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+
+    def update_active_thread_id(self):
+        # type: () -> None
+        self.active_thread_id = get_current_thread_meta()[0]
+        logger.debug(
+            "[Profiling] updating active thread id to {tid}".format(
+                tid=self.active_thread_id
+            )
+        )
+
+    def _set_initial_sampling_decision(self, sampling_context):
+        # type: (SamplingContext) -> None
+        """
+        Sets the profile's sampling decision according to the following
+        precedence rules:
+
+        1. If the transaction to be profiled is not sampled, that decision
+        will be used, regardless of anything else.
+
+        2. Use `profiles_sample_rate` to decide.
+        """
+
+        # The corresponding transaction was not sampled,
+        # so don't generate a profile for it.
+        if not self.sampled:
+            logger.debug(
+                "[Profiling] Discarding profile because transaction is discarded."
+            )
+            self.sampled = False
+            return
+
+        # The profiler hasn't been properly initialized.
+        if self.scheduler is None:
+            logger.debug(
+                "[Profiling] Discarding profile because profiler was not started."
+            )
+            self.sampled = False
+            return
+
+        client = sentry_sdk.get_client()
+        if not client.is_active():
+            self.sampled = False
+            return
+
+        options = client.options
+
+        if callable(options.get("profiles_sampler")):
+            sample_rate = options["profiles_sampler"](sampling_context)
+        elif options["profiles_sample_rate"] is not None:
+            sample_rate = options["profiles_sample_rate"]
+        else:
+            sample_rate = options["_experiments"].get("profiles_sample_rate")
+
+        # The profiles_sample_rate option was not set, so profiling
+        # was never enabled.
+        if sample_rate is None:
+            logger.debug(
+                "[Profiling] Discarding profile because profiling was not enabled."
+            )
+            self.sampled = False
+            return
+
+        if not is_valid_sample_rate(sample_rate, source="Profiling"):
+            logger.warning(
+                "[Profiling] Discarding profile because of invalid sample rate."
+            )
+            self.sampled = False
+            return
+
+        # Now we roll the dice. random.random is inclusive of 0, but not of 1,
+        # so strict < is safe here. In case sample_rate is a boolean, cast it
+        # to a float (True becomes 1.0 and False becomes 0.0)
+        self.sampled = random.random() < float(sample_rate)
+
+        if self.sampled:
+            logger.debug("[Profiling] Initializing profile")
+        else:
+            logger.debug(
+                "[Profiling] Discarding profile because it's not included in the random sample (sample rate = {sample_rate})".format(
+                    sample_rate=float(sample_rate)
+                )
+            )
+
+    def start(self):
+        # type: () -> None
+        if not self.sampled or self.active:
+            return
+
+        assert self.scheduler, "No scheduler specified"
+        logger.debug("[Profiling] Starting profile")
+        self.active = True
+        if not self.start_ns:
+            self.start_ns = nanosecond_time()
+        self.scheduler.start_profiling(self)
+
+    def stop(self):
+        # type: () -> None
+        if not self.sampled or not self.active:
+            return
+
+        assert self.scheduler, "No scheduler specified"
+        logger.debug("[Profiling] Stopping profile")
+        self.active = False
+        self.stop_ns = nanosecond_time()
+
+    def __enter__(self):
+        # type: () -> Profile
+        scope = sentry_sdk.get_isolation_scope()
+        old_profile = scope.profile
+        scope.profile = self
+
+        self._context_manager_state = (scope, old_profile)
+
+        self.start()
+
+        return self
+
+    def __exit__(self, ty, value, tb):
+        # type: (Optional[Any], Optional[Any], Optional[Any]) -> None
+        self.stop()
+
+        scope, old_profile = self._context_manager_state
+        del self._context_manager_state
+
+        scope.profile = old_profile
+
+    def write(self, ts, sample):
+        # type: (int, ExtractedSample) -> None
+        if not self.active:
+            return
+
+        if ts < self.start_ns:
+            return
+
+        offset = ts - self.start_ns
+        if offset > MAX_PROFILE_DURATION_NS:
+            self.stop()
+            return
+
+        self.unique_samples += 1
+
+        elapsed_since_start_ns = str(offset)
+
+        for tid, (stack_id, frame_ids, frames) in sample:
+            try:
+                # Check if the stack is indexed first, this lets us skip
+                # indexing frames if it's not necessary
+                if stack_id not in self.indexed_stacks:
+                    for i, frame_id in enumerate(frame_ids):
+                        if frame_id not in self.indexed_frames:
+                            self.indexed_frames[frame_id] = len(self.indexed_frames)
+                            self.frames.append(frames[i])
+
+                    self.indexed_stacks[stack_id] = len(self.indexed_stacks)
+                    self.stacks.append(
+                        [self.indexed_frames[frame_id] for frame_id in frame_ids]
+                    )
+
+                self.samples.append(
+                    {
+                        "elapsed_since_start_ns": elapsed_since_start_ns,
+                        "thread_id": tid,
+                        "stack_id": self.indexed_stacks[stack_id],
+                    }
+                )
+            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())
+
+    def process(self):
+        # type: () -> ProcessedProfile
+
+        # This collects the thread metadata at the end of a profile. Doing it
+        # this way means that any threads that terminate before the profile ends
+        # will not have any metadata associated with it.
+        thread_metadata = {
+            str(thread.ident): {
+                "name": str(thread.name),
+            }
+            for thread in threading.enumerate()
+        }  # type: Dict[str, ProcessedThreadMetadata]
+
+        return {
+            "frames": self.frames,
+            "stacks": self.stacks,
+            "samples": self.samples,
+            "thread_metadata": thread_metadata,
+        }
+
+    def to_json(self, event_opt, options):
+        # type: (Event, Dict[str, Any]) -> Dict[str, Any]
+        profile = self.process()
+
+        set_in_app_in_frames(
+            profile["frames"],
+            options["in_app_exclude"],
+            options["in_app_include"],
+            options["project_root"],
+        )
+
+        return {
+            "environment": event_opt.get("environment"),
+            "event_id": self.event_id,
+            "platform": "python",
+            "profile": profile,
+            "release": event_opt.get("release", ""),
+            "timestamp": event_opt["start_timestamp"],
+            "version": "1",
+            "device": {
+                "architecture": platform.machine(),
+            },
+            "os": {
+                "name": platform.system(),
+                "version": platform.release(),
+            },
+            "runtime": {
+                "name": platform.python_implementation(),
+                "version": platform.python_version(),
+            },
+            "transactions": [
+                {
+                    "id": event_opt["event_id"],
+                    "name": event_opt["transaction"],
+                    # we start the transaction before the profile and this is
+                    # the transaction start time relative to the profile, so we
+                    # hardcode it to 0 until we can start the profile before
+                    "relative_start_ns": "0",
+                    # use the duration of the profile instead of the transaction
+                    # because we end the transaction after the profile
+                    "relative_end_ns": str(self.stop_ns - self.start_ns),
+                    "trace_id": event_opt["contexts"]["trace"]["trace_id"],
+                    "active_thread_id": str(
+                        self._default_active_thread_id
+                        if self.active_thread_id is None
+                        else self.active_thread_id
+                    ),
+                }
+            ],
+        }
+
+    def valid(self):
+        # type: () -> bool
+        client = sentry_sdk.get_client()
+        if not client.is_active():
+            return False
+
+        if not has_profiling_enabled(client.options):
+            return False
+
+        if self.sampled is None or not self.sampled:
+            if client.transport:
+                client.transport.record_lost_event(
+                    "sample_rate", data_category="profile"
+                )
+            return False
+
+        if self.unique_samples < PROFILE_MINIMUM_SAMPLES:
+            if client.transport:
+                client.transport.record_lost_event(
+                    "insufficient_data", data_category="profile"
+                )
+            logger.debug("[Profiling] Discarding profile because insufficient samples.")
+            return False
+
+        return True
+
+    @property
+    def hub(self):
+        # type: () -> Optional[sentry_sdk.Hub]
+        warnings.warn(
+            "The `hub` attribute is deprecated. Please do not access it.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return self._hub
+
+    @hub.setter
+    def hub(self, value):
+        # type: (Optional[sentry_sdk.Hub]) -> None
+        warnings.warn(
+            "The `hub` attribute is deprecated. Please do not set it.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        self._hub = value
+
+
+class Scheduler(ABC):
+    mode = "unknown"  # type: ProfilerMode
+
+    def __init__(self, frequency):
+        # type: (int) -> None
+        self.interval = 1.0 / frequency
+
+        self.sampler = self.make_sampler()
+
+        # cap the number of new profiles at any time so it does not grow infinitely
+        self.new_profiles = deque(maxlen=128)  # type: Deque[Profile]
+        self.active_profiles = set()  # type: Set[Profile]
+
+    def __enter__(self):
+        # type: () -> Scheduler
+        self.setup()
+        return self
+
+    def __exit__(self, ty, value, tb):
+        # type: (Optional[Any], Optional[Any], Optional[Any]) -> None
+        self.teardown()
+
+    @abstractmethod
+    def setup(self):
+        # type: () -> None
+        pass
+
+    @abstractmethod
+    def teardown(self):
+        # type: () -> None
+        pass
+
+    def ensure_running(self):
+        # type: () -> None
+        """
+        Ensure the scheduler is running. By default, this method is a no-op.
+        The method should be overridden by any implementation for which it is
+        relevant.
+        """
+        return None
+
+    def start_profiling(self, profile):
+        # type: (Profile) -> None
+        self.ensure_running()
+        self.new_profiles.append(profile)
+
+    def make_sampler(self):
+        # type: () -> Callable[..., None]
+        cwd = os.getcwd()
+
+        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.
+            """
+            # no profiles taking place, so we can stop early
+            if not self.new_profiles and not self.active_profiles:
+                # make sure to clear the cache if we're not profiling so we dont
+                # keep a reference to the last stack of frames around
+                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)
+
+            now = nanosecond_time()
+
+            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:
+                    profile.write(now, sample)
+                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)
+
+        return _sample_stack
+
+
+class ThreadScheduler(Scheduler):
+    """
+    This scheduler is based on running a daemon thread that will call
+    the sampler at a regular interval.
+    """
+
+    mode = "thread"  # type: ProfilerMode
+    name = "sentry.profiler.ThreadScheduler"
+
+    def __init__(self, frequency):
+        # type: (int) -> None
+        super().__init__(frequency=frequency)
+
+        # used to signal to the thread that it should stop
+        self.running = False
+        self.thread = None  # type: Optional[threading.Thread]
+        self.pid = None  # type: Optional[int]
+        self.lock = threading.Lock()
+
+    def setup(self):
+        # type: () -> None
+        pass
+
+    def teardown(self):
+        # type: () -> None
+        if self.running:
+            self.running = False
+            if self.thread is not None:
+                self.thread.join()
+
+    def ensure_running(self):
+        # type: () -> None
+        """
+        Check that the profiler has an active thread to run in, and start one if
+        that's not the case.
+
+        Note that this might fail (e.g. in Python 3.12 it's not possible to
+        spawn new threads at interpreter shutdown). In that case self.running
+        will be False after running this function.
+        """
+        pid = os.getpid()
+
+        # is running on the right process
+        if self.running and self.pid == pid:
+            return
+
+        with self.lock:
+            # another thread may have tried to acquire the lock
+            # at the same time so it may start another thread
+            # make sure to check again before proceeding
+            if self.running and self.pid == pid:
+                return
+
+            self.pid = pid
+            self.running = True
+
+            # make sure the thread is a daemon here otherwise this
+            # can keep the application running after other threads
+            # have exited
+            self.thread = threading.Thread(name=self.name, target=self.run, daemon=True)
+            try:
+                self.thread.start()
+            except RuntimeError:
+                # Unfortunately at this point the interpreter is in a state that no
+                # longer allows us to spawn a thread and we have to bail.
+                self.running = False
+                self.thread = None
+                return
+
+    def run(self):
+        # type: () -> None
+        last = time.perf_counter()
+
+        while self.running:
+            self.sampler()
+
+            # some time may have elapsed since the last time
+            # we sampled, so we need to account for that and
+            # not sleep for too long
+            elapsed = time.perf_counter() - last
+            if elapsed < self.interval:
+                thread_sleep(self.interval - elapsed)
+
+            # after sleeping, make sure to take the current
+            # timestamp so we can use it next iteration
+            last = time.perf_counter()
+
+
+class GeventScheduler(Scheduler):
+    """
+    This scheduler is based on the thread scheduler but adapted to work with
+    gevent. When using gevent, it may monkey patch the threading modules
+    (`threading` and `_thread`). This results in the use of greenlets instead
+    of native threads.
+
+    This is an issue because the sampler CANNOT run in a greenlet because
+    1. Other greenlets doing sync work will prevent the sampler from running
+    2. The greenlet runs in the same thread as other greenlets so when taking
+       a sample, other greenlets will have been evicted from the thread. This
+       results in a sample containing only the sampler's code.
+    """
+
+    mode = "gevent"  # type: ProfilerMode
+    name = "sentry.profiler.GeventScheduler"
+
+    def __init__(self, frequency):
+        # type: (int) -> None
+
+        if ThreadPool is None:
+            raise ValueError("Profiler mode: {} is not available".format(self.mode))
+
+        super().__init__(frequency=frequency)
+
+        # used to signal to the thread that it should stop
+        self.running = False
+        self.thread = None  # type: Optional[_ThreadPool]
+        self.pid = None  # type: Optional[int]
+
+        # This intentionally uses the gevent patched threading.Lock.
+        # The lock will be required when first trying to start profiles
+        # as we need to spawn the profiler thread from the greenlets.
+        self.lock = threading.Lock()
+
+    def setup(self):
+        # type: () -> None
+        pass
+
+    def teardown(self):
+        # type: () -> None
+        if self.running:
+            self.running = False
+            if self.thread is not None:
+                self.thread.join()
+
+    def ensure_running(self):
+        # type: () -> None
+        pid = os.getpid()
+
+        # is running on the right process
+        if self.running and self.pid == pid:
+            return
+
+        with self.lock:
+            # another thread may have tried to acquire the lock
+            # at the same time so it may start another thread
+            # make sure to check again before proceeding
+            if self.running and self.pid == pid:
+                return
+
+            self.pid = pid
+            self.running = True
+
+            self.thread = ThreadPool(1)  # type: ignore[misc]
+            try:
+                self.thread.spawn(self.run)
+            except RuntimeError:
+                # Unfortunately at this point the interpreter is in a state that no
+                # longer allows us to spawn a thread and we have to bail.
+                self.running = False
+                self.thread = None
+                return
+
+    def run(self):
+        # type: () -> None
+        last = time.perf_counter()
+
+        while self.running:
+            self.sampler()
+
+            # some time may have elapsed since the last time
+            # we sampled, so we need to account for that and
+            # not sleep for too long
+            elapsed = time.perf_counter() - last
+            if elapsed < self.interval:
+                thread_sleep(self.interval - elapsed)
+
+            # after sleeping, make sure to take the current
+            # timestamp so we can use it next iteration
+            last = time.perf_counter()