Source code for dramatiq.middleware.time_limit

# This file is a part of Dramatiq.
#
# Copyright (C) 2017,2018 CLEARTYPE SRL <[email protected]>
#
# Dramatiq is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or (at
# your option) any later version.
#
# Dramatiq is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
# License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import threading
import warnings
from threading import Thread
from time import monotonic, sleep

from ..logging import get_logger
from .middleware import Middleware
from .threading import Interrupt, current_platform, is_gevent_active, raise_thread_exception, supported_platforms


[docs]class TimeLimitExceeded(Interrupt): """Exception used to interrupt worker threads when actors exceed their time limits. """
[docs]class TimeLimit(Middleware): """Middleware that cancels actors that run for too long. Currently, this is only available on CPython. Note: This works by setting an async exception in the worker thread that runs the actor. This means that the exception will only get called the next time that thread acquires the GIL. Concretely, this means that this middleware can't cancel system calls. Parameters: time_limit(float): The maximum number of milliseconds actors may run for. Use `float("inf")` to avoid setting a timeout for the actor. interval(int): The interval (in milliseconds) with which to check for actors that have exceeded the limit. This does not take effect when using gevent because the timers are managed by gevent. """ def __init__(self, *, time_limit=600000, interval=1000): self.logger = get_logger(__name__, type(self)) self.time_limit = time_limit if is_gevent_active(): self.manager = _GeventTimeoutManager(logger=self.logger) else: self.manager = _CtypesTimeoutManager(interval, logger=self.logger) @property def actor_options(self): return {"time_limit"} def after_process_boot(self, broker): if is_gevent_active() or current_platform in supported_platforms: self.manager.start() else: # pragma: no cover msg = "TimeLimit cannot kill threads on your current platform (%r)." warnings.warn(msg % current_platform, category=RuntimeWarning, stacklevel=2) def before_process_message(self, broker, message): actor = broker.get_actor(message.actor_name) limit = message.options.get("time_limit") or actor.options.get("time_limit", self.time_limit) self.manager.add_timeout(threading.get_ident(), limit) def after_process_message(self, broker, message, *, result=None, exception=None): self.manager.remove_timeout(threading.get_ident()) after_skip_message = after_process_message
class _CtypesTimeoutManager(Thread): def __init__(self, interval, logger=None): super().__init__(daemon=True) self.deadlines = {} self.interval = interval / 1000 self.logger = logger or get_logger(__name__, type(self)) self.mu = threading.RLock() def _handle(self): current_time = monotonic() threads_to_kill = [] with self.mu: for thread_id, deadline in self.deadlines.items(): if deadline and current_time >= deadline: self.logger.warning("Time limit exceeded. Raising exception in worker thread %r.", thread_id) self.deadlines[thread_id] = None threads_to_kill.append(thread_id) for thread_id in threads_to_kill: raise_thread_exception(thread_id, TimeLimitExceeded) def run(self): while True: try: self._handle() except Exception: # pragma: no cover self.logger.exception("Unhandled error while running the time limit handler.") sleep(self.interval) def add_timeout(self, thread_id, ttl): with self.mu: self.deadlines[thread_id] = monotonic() + ttl / 1000 def remove_timeout(self, thread_id): with self.mu: self.deadlines[thread_id] = None class _GeventTimeoutManager: def __init__(self, logger=None): self.timers = {} self.logger = logger or get_logger(__name__, type(self)) def start(self): pass def add_timeout(self, thread_id, ttl): self.timers[thread_id] = _GeventTimeout( logger=self.logger, thread_id=thread_id, after_expiration=lambda: self.timers.pop(thread_id, None), seconds=None if ttl == float("inf") else ttl / 1000, exception=TimeLimitExceeded, ) self.timers[thread_id].start() def remove_timeout(self, thread_id): timer = self.timers.pop(thread_id, None) if timer is not None: timer.close() _GeventTimeout = None if is_gevent_active(): from gevent import Timeout class _GeventTimeout(Timeout): """Cooperative timeout class for gevent with logging on timeouts.""" def __init__(self, *args, logger=None, thread_id=None, after_expiration=None, **kwargs): super().__init__(*args, **kwargs) self.logger = logger or get_logger(__name__, type(self)) self.thread_id = thread_id self.after_expiration = after_expiration def _on_expiration(self, prev_greenlet, ex): self.logger.warning( "Time limit exceeded. Raising exception in worker thread %r.", self.thread_id) res = super()._on_expiration(prev_greenlet, ex) if self.after_expiration is not None: self.after_expiration() return res