X-Git-Url: https://wannabe.guru.org/gitweb/?a=blobdiff_plain;f=executors.py;h=6485afa054689c3b668adb1e0708b7f2d29ed8b9;hb=e46158e49121b8a955bb07b73f5bcf9928b79c90;hp=b4cb06b4c9ad80816f0bb13e05e23863846fa8c1;hpb=7ff2af6fe7bffea90dc4a31c93140c189917c659;p=python_utils.git diff --git a/executors.py b/executors.py index b4cb06b..6485afa 100644 --- a/executors.py +++ b/executors.py @@ -1,7 +1,17 @@ #!/usr/bin/env python3 +# -*- coding: utf-8 -*- -from __future__ import annotations +# © Copyright 2021-2022, Scott Gasch + +"""Defines three executors: a thread executor for doing work using a +threadpool, a process executor for doing work in other processes on +the same machine and a remote executor for farming out work to other +machines. +Also defines DefaultExecutors which is a container for references to +global executors / worker pools with automatic shutdown semantics.""" + +from __future__ import annotations import concurrent.futures as fut import logging import os @@ -23,9 +33,10 @@ from overrides import overrides import argparse_utils import config import histogram as hist +import string_utils from ansi import bg, fg, reset, underline from decorator_utils import singleton -from exec_utils import cmd_in_background, cmd_with_timeout, run_silently +from exec_utils import cmd_exitcode, cmd_in_background, run_silently from thread_utils import background_thread logger = logging.getLogger(__name__) @@ -65,12 +76,18 @@ SSH = '/usr/bin/ssh -oForwardX11=no' SCP = '/usr/bin/scp -C' -def make_cloud_pickle(fun, *args, **kwargs): - logger.debug(f"Making cloudpickled bundle at {fun.__name__}") +def _make_cloud_pickle(fun, *args, **kwargs): + """Internal helper to create cloud pickles.""" + logger.debug("Making cloudpickled bundle at %s", fun.__name__) return cloudpickle.dumps((fun, args, kwargs)) class BaseExecutor(ABC): + """The base executor interface definition. The interface for + :class:`ProcessExecutor`, :class:`RemoteExecutor`, and + :class:`ThreadExecutor`. + """ + def __init__(self, *, title=''): self.title = title self.histogram = hist.SimpleHistogram( @@ -105,7 +122,7 @@ class BaseExecutor(ABC): """ self.task_count += delta - logger.debug(f'Adjusted task count by {delta} to {self.task_count}') + logger.debug('Adjusted task count by %d to %d.', delta, self.task_count) def get_task_count(self) -> int: """Change the task count. Note: do not call this method from a @@ -117,6 +134,15 @@ class BaseExecutor(ABC): class ThreadExecutor(BaseExecutor): + """A threadpool executor. This executor uses python threads to + schedule tasks. Note that, at least as of python3.10, because of + the global lock in the interpreter itself, these do not + parallelize very well so this class is useful mostly for non-CPU + intensive tasks. + + See also :class:`ProcessExecutor` and :class:`RemoteExecutor`. + """ + def __init__(self, max_workers: Optional[int] = None): super().__init__() workers = None @@ -124,15 +150,19 @@ class ThreadExecutor(BaseExecutor): workers = max_workers elif 'executors_threadpool_size' in config.config: workers = config.config['executors_threadpool_size'] - logger.debug(f'Creating threadpool executor with {workers} workers') + if workers is not None: + logger.debug('Creating threadpool executor with %d workers', workers) + else: + logger.debug('Creating a default sized threadpool executor') self._thread_pool_executor = fut.ThreadPoolExecutor( max_workers=workers, thread_name_prefix="thread_executor_helper" ) self.already_shutdown = False # This is run on a different thread; do not adjust task count here. - def run_local_bundle(self, fun, *args, **kwargs): - logger.debug(f"Running local bundle at {fun.__name__}") + @staticmethod + def run_local_bundle(fun, *args, **kwargs): + logger.debug("Running local bundle at %s", fun.__name__) result = fun(*args, **kwargs) return result @@ -147,7 +177,7 @@ class ThreadExecutor(BaseExecutor): newargs.append(arg) start = time.time() result = self._thread_pool_executor.submit( - self.run_local_bundle, *newargs, **kwargs + ThreadExecutor.run_local_bundle, *newargs, **kwargs ) result.add_done_callback(lambda _: self.histogram.add_item(time.time() - start)) result.add_done_callback(lambda _: self.adjust_task_count(-1)) @@ -156,7 +186,7 @@ class ThreadExecutor(BaseExecutor): @overrides def shutdown(self, *, wait: bool = True, quiet: bool = False) -> None: if not self.already_shutdown: - logger.debug(f'Shutting down threadpool executor {self.title}') + logger.debug('Shutting down threadpool executor %s', self.title) self._thread_pool_executor.shutdown(wait) if not quiet: print(self.histogram.__repr__(label_formatter='%ds')) @@ -164,6 +194,11 @@ class ThreadExecutor(BaseExecutor): class ProcessExecutor(BaseExecutor): + """An executor which runs tasks in child processes. + + See also :class:`ThreadExecutor` and :class:`RemoteExecutor`. + """ + def __init__(self, max_workers=None): super().__init__() workers = None @@ -171,16 +206,20 @@ class ProcessExecutor(BaseExecutor): workers = max_workers elif 'executors_processpool_size' in config.config: workers = config.config['executors_processpool_size'] - logger.debug(f'Creating processpool executor with {workers} workers.') + if workers is not None: + logger.debug('Creating processpool executor with %d workers.', workers) + else: + logger.debug('Creating a default sized processpool executor') self._process_executor = fut.ProcessPoolExecutor( max_workers=workers, ) self.already_shutdown = False # This is run in another process; do not adjust task count here. - def run_cloud_pickle(self, pickle): + @staticmethod + def run_cloud_pickle(pickle): fun, args, kwargs = cloudpickle.loads(pickle) - logger.debug(f"Running pickled bundle at {fun.__name__}") + logger.debug("Running pickled bundle at %s", fun.__name__) result = fun(*args, **kwargs) return result @@ -190,8 +229,8 @@ class ProcessExecutor(BaseExecutor): raise Exception('Submitted work after shutdown.') start = time.time() self.adjust_task_count(+1) - pickle = make_cloud_pickle(function, *args, **kwargs) - result = self._process_executor.submit(self.run_cloud_pickle, pickle) + pickle = _make_cloud_pickle(function, *args, **kwargs) + result = self._process_executor.submit(ProcessExecutor.run_cloud_pickle, pickle) result.add_done_callback(lambda _: self.histogram.add_item(time.time() - start)) result.add_done_callback(lambda _: self.adjust_task_count(-1)) return result @@ -199,7 +238,7 @@ class ProcessExecutor(BaseExecutor): @overrides def shutdown(self, *, wait: bool = True, quiet: bool = False) -> None: if not self.already_shutdown: - logger.debug(f'Shutting down processpool executor {self.title}') + logger.debug('Shutting down processpool executor %s', self.title) self._process_executor.shutdown(wait) if not quiet: print(self.histogram.__repr__(label_formatter='%ds')) @@ -219,10 +258,21 @@ class RemoteExecutorException(Exception): @dataclass class RemoteWorkerRecord: + """A record of info about a remote worker.""" + username: str + """Username we can ssh into on this machine to run work.""" + machine: str + """Machine address / name.""" + weight: int + """Relative probability for the weighted policy to select this + machine for scheduling work.""" + count: int + """If this machine is selected, what is the maximum number of task + that it can handle?""" def __hash__(self): return hash((self.username, self.machine)) @@ -233,25 +283,71 @@ class RemoteWorkerRecord: @dataclass class BundleDetails: + """All info necessary to define some unit of work that needs to be + done, where it is being run, its state, whether it is an original + bundle of a backup bundle, how many times it has failed, etc... + """ + pickled_code: bytes + """The code to run, cloud pickled""" + uuid: str - fname: str + """A unique identifier""" + + function_name: str + """The name of the function we pickled""" + worker: Optional[RemoteWorkerRecord] + """The remote worker running this bundle or None if none (yet)""" + username: Optional[str] + """The remote username running this bundle or None if none (yet)""" + machine: Optional[str] + """The remote machine running this bundle or None if none (yet)""" + hostname: str + """The controller machine""" + code_file: str + """A unique filename to hold the work to be done""" + result_file: str + """Where the results should be placed / read from""" + pid: int + """The process id of the local subprocess watching the ssh connection + to the remote machine""" + start_ts: float + """Starting time""" + end_ts: float + """Ending time""" + slower_than_local_p95: bool + """Currently slower then 95% of other bundles on remote host""" + slower_than_global_p95: bool + """Currently slower than 95% of other bundles globally""" + src_bundle: Optional[BundleDetails] + """If this is a backup bundle, this points to the original bundle + that it's backing up. None otherwise.""" + is_cancelled: threading.Event + """An event that can be signaled to indicate this bundle is cancelled. + This is set when another copy (backup or original) of this work has + completed successfully elsewhere.""" + was_cancelled: bool + """True if this bundle was cancelled, False if it finished normally""" + backup_bundles: Optional[List[BundleDetails]] + """If we've created backups of this bundle, this is the list of them""" + failure_count: int + """How many times has this bundle failed already?""" def __repr__(self): uuid = self.uuid @@ -261,6 +357,9 @@ class BundleDetails: else: suffix = uuid[-6:] + # We colorize the uuid based on some bits from it to make them + # stand out in the logging and help a reader correlate log messages + # related to the same bundle. colorz = [ fg('violet red'), fg('red'), @@ -277,21 +376,29 @@ class BundleDetails: fg('medium purple'), ] c = colorz[int(uuid[-2:], 16) % len(colorz)] - fname = self.fname if self.fname is not None else 'nofname' + function_name = self.function_name if self.function_name is not None else 'nofname' machine = self.machine if self.machine is not None else 'nomachine' - return f'{c}{suffix}/{fname}/{machine}{reset()}' + return f'{c}{suffix}/{function_name}/{machine}{reset()}' class RemoteExecutorStatus: + """A status 'scoreboard' for a remote executor tracking various + metrics and able to render a periodic dump of global state. + """ + def __init__(self, total_worker_count: int) -> None: + """C'tor. + + Args: + total_worker_count: number of workers in the pool + + """ self.worker_count: int = total_worker_count self.known_workers: Set[RemoteWorkerRecord] = set() self.start_time: float = time.time() self.start_per_bundle: Dict[str, Optional[float]] = defaultdict(float) self.end_per_bundle: Dict[str, float] = defaultdict(float) - self.finished_bundle_timings_per_worker: Dict[ - RemoteWorkerRecord, List[float] - ] = {} + self.finished_bundle_timings_per_worker: Dict[RemoteWorkerRecord, List[float]] = {} self.in_flight_bundles_by_worker: Dict[RemoteWorkerRecord, Set[str]] = {} self.bundle_details_by_uuid: Dict[str, BundleDetails] = {} self.finished_bundle_timings: List[float] = [] @@ -303,12 +410,18 @@ class RemoteExecutorStatus: self.lock: threading.Lock = threading.Lock() def record_acquire_worker(self, worker: RemoteWorkerRecord, uuid: str) -> None: + """Record that bundle with uuid is assigned to a particular worker. + + Args: + worker: the record of the worker to which uuid is assigned + uuid: the uuid of a bundle that has been assigned to a worker + """ with self.lock: self.record_acquire_worker_already_locked(worker, uuid) - def record_acquire_worker_already_locked( - self, worker: RemoteWorkerRecord, uuid: str - ) -> None: + def record_acquire_worker_already_locked(self, worker: RemoteWorkerRecord, uuid: str) -> None: + """Same as above but an entry point that doesn't acquire the lock + for codepaths where it's already held.""" assert self.lock.locked() self.known_workers.add(worker) self.start_per_bundle[uuid] = None @@ -317,10 +430,12 @@ class RemoteExecutorStatus: self.in_flight_bundles_by_worker[worker] = x def record_bundle_details(self, details: BundleDetails) -> None: + """Register the details about a bundle of work.""" with self.lock: self.record_bundle_details_already_locked(details) def record_bundle_details_already_locked(self, details: BundleDetails) -> None: + """Same as above but for codepaths that already hold the lock.""" assert self.lock.locked() self.bundle_details_by_uuid[details.uuid] = details @@ -330,6 +445,7 @@ class RemoteExecutorStatus: uuid: str, was_cancelled: bool, ) -> None: + """Record that a bundle has released a worker.""" with self.lock: self.record_release_worker_already_locked(worker, uuid, was_cancelled) @@ -339,6 +455,7 @@ class RemoteExecutorStatus: uuid: str, was_cancelled: bool, ) -> None: + """Same as above but for codepaths that already hold the lock.""" assert self.lock.locked() ts = time.time() self.end_per_bundle[uuid] = ts @@ -347,16 +464,18 @@ class RemoteExecutorStatus: start = self.start_per_bundle[uuid] assert start is not None bundle_latency = ts - start - x = self.finished_bundle_timings_per_worker.get(worker, list()) + x = self.finished_bundle_timings_per_worker.get(worker, []) x.append(bundle_latency) self.finished_bundle_timings_per_worker[worker] = x self.finished_bundle_timings.append(bundle_latency) def record_processing_began(self, uuid: str): + """Record when work on a bundle begins.""" with self.lock: self.start_per_bundle[uuid] = time.time() def total_in_flight(self) -> int: + """How many bundles are in flight currently?""" assert self.lock.locked() total_in_flight = 0 for worker in self.known_workers: @@ -364,6 +483,7 @@ class RemoteExecutorStatus: return total_in_flight def total_idle(self) -> int: + """How many idle workers are there currently?""" assert self.lock.locked() return self.worker_count - self.total_in_flight() @@ -442,7 +562,12 @@ class RemoteExecutorStatus: class RemoteWorkerSelectionPolicy(ABC): - def register_worker_pool(self, workers): + """A policy for selecting a remote worker base class.""" + + def __init__(self): + self.workers: Optional[List[RemoteWorkerRecord]] = None + + def register_worker_pool(self, workers: List[RemoteWorkerRecord]): self.workers = workers @abstractmethod @@ -455,30 +580,33 @@ class RemoteWorkerSelectionPolicy(ABC): class WeightedRandomRemoteWorkerSelectionPolicy(RemoteWorkerSelectionPolicy): + """A remote worker selector that uses weighted RNG.""" + @overrides def is_worker_available(self) -> bool: - for worker in self.workers: - if worker.count > 0: - return True + if self.workers: + for worker in self.workers: + if worker.count > 0: + return True return False @overrides def acquire_worker(self, machine_to_avoid=None) -> Optional[RemoteWorkerRecord]: grabbag = [] - for worker in self.workers: - if worker.machine != machine_to_avoid: - if worker.count > 0: - for _ in range(worker.count * worker.weight): - grabbag.append(worker) + if self.workers: + for worker in self.workers: + if worker.machine != machine_to_avoid: + if worker.count > 0: + for _ in range(worker.count * worker.weight): + grabbag.append(worker) if len(grabbag) == 0: - logger.debug( - f'There are no available workers that avoid {machine_to_avoid}...' - ) - for worker in self.workers: - if worker.count > 0: - for _ in range(worker.count * worker.weight): - grabbag.append(worker) + logger.debug('There are no available workers that avoid %s', machine_to_avoid) + if self.workers: + for worker in self.workers: + if worker.count > 0: + for _ in range(worker.count * worker.weight): + grabbag.append(worker) if len(grabbag) == 0: logger.warning('There are no available workers?!') @@ -487,51 +615,90 @@ class WeightedRandomRemoteWorkerSelectionPolicy(RemoteWorkerSelectionPolicy): worker = random.sample(grabbag, 1)[0] assert worker.count > 0 worker.count -= 1 - logger.debug(f'Chose worker {worker}') + logger.debug('Selected worker %s', worker) return worker class RoundRobinRemoteWorkerSelectionPolicy(RemoteWorkerSelectionPolicy): + """A remote worker selector that just round robins.""" + def __init__(self) -> None: + super().__init__() self.index = 0 @overrides def is_worker_available(self) -> bool: - for worker in self.workers: - if worker.count > 0: - return True + if self.workers: + for worker in self.workers: + if worker.count > 0: + return True return False @overrides - def acquire_worker( - self, machine_to_avoid: str = None - ) -> Optional[RemoteWorkerRecord]: - x = self.index - while True: - worker = self.workers[x] - if worker.count > 0: - worker.count -= 1 + def acquire_worker(self, machine_to_avoid: str = None) -> Optional[RemoteWorkerRecord]: + if self.workers: + x = self.index + while True: + worker = self.workers[x] + if worker.count > 0: + worker.count -= 1 + x += 1 + if x >= len(self.workers): + x = 0 + self.index = x + logger.debug('Selected worker %s', worker) + return worker x += 1 if x >= len(self.workers): x = 0 - self.index = x - logger.debug(f'Selected worker {worker}') - return worker - x += 1 - if x >= len(self.workers): - x = 0 - if x == self.index: - msg = 'Unexpectedly could not find a worker, retrying...' - logger.warning(msg) - return None + if x == self.index: + logger.warning('Unexpectedly could not find a worker, retrying...') + return None + return None class RemoteExecutor(BaseExecutor): + """An executor that uses processes on remote machines to do work. This + works by creating "bundles" of work with pickled code in each to be + executed. Each bundle is assigned a remote worker based on some policy + heuristics. Once assigned to a remote worker, a local subprocess is + created. It copies the pickled code to the remote machine via ssh/scp + and then starts up work on the remote machine again using ssh. When + the work is complete it copies the results back to the local machine. + + So there is essentially one "controller" machine (which may also be + in the remote executor pool and therefore do task work in addition to + controlling) and N worker machines. This code runs on the controller + whereas on the worker machines we invoke pickled user code via a + shim in :file:`remote_worker.py`. + + Some redundancy and safety provisions are made; e.g. slower than + expected tasks have redundant backups created and if a task fails + repeatedly we consider it poisoned and give up on it. + + .. warning:: + + The network overhead / latency of copying work from the + controller machine to the remote workers is relatively high. + This executor probably only makes sense to use with + computationally expensive tasks such as jobs that will execute + for ~30 seconds or longer. + + See also :class:`ProcessExecutor` and :class:`ThreadExecutor`. + """ + def __init__( self, workers: List[RemoteWorkerRecord], policy: RemoteWorkerSelectionPolicy, ) -> None: + """C'tor. + + Args: + workers: A list of remote workers we can call on to do tasks. + policy: A policy for selecting remote workers for tasks. + """ + super().__init__() self.workers = workers self.policy = policy @@ -544,9 +711,7 @@ class RemoteExecutor(BaseExecutor): raise RemoteExecutorException(msg) self.policy.register_worker_pool(self.workers) self.cv = threading.Condition() - logger.debug( - f'Creating {self.worker_count} local threads, one per remote worker.' - ) + logger.debug('Creating %d local threads, one per remote worker.', self.worker_count) self._helper_executor = fut.ThreadPoolExecutor( thread_name_prefix="remote_executor_helper", max_workers=self.worker_count, @@ -558,18 +723,24 @@ class RemoteExecutor(BaseExecutor): ( self.heartbeat_thread, self.heartbeat_stop_event, - ) = self.run_periodic_heartbeat() + ) = self._run_periodic_heartbeat() self.already_shutdown = False @background_thread - def run_periodic_heartbeat(self, stop_event: threading.Event) -> None: + def _run_periodic_heartbeat(self, stop_event: threading.Event) -> None: + """ + We create a background thread to invoke :meth:`_heartbeat` regularly + while we are scheduling work. It does some accounting such as + looking for slow bundles to tag for backup creation, checking for + unexpected failures, and printing a fancy message on stdout. + """ while not stop_event.is_set(): time.sleep(5.0) logger.debug('Running periodic heartbeat code...') - self.heartbeat() + self._heartbeat() logger.debug('Periodic heartbeat thread shutting down.') - def heartbeat(self) -> None: + def _heartbeat(self) -> None: # Note: this is invoked on a background thread, not an # executor thread. Be careful what you do with it b/c it # needs to get back and dump status again periodically. @@ -578,16 +749,18 @@ class RemoteExecutor(BaseExecutor): # Look for bundles to reschedule via executor.submit if config.config['executors_schedule_remote_backups']: - self.maybe_schedule_backup_bundles() + self._maybe_schedule_backup_bundles() + + def _maybe_schedule_backup_bundles(self): + """Maybe schedule backup bundles if we see a very slow bundle.""" - def maybe_schedule_backup_bundles(self): assert self.status.lock.locked() num_done = len(self.status.finished_bundle_timings) num_idle_workers = self.worker_count - self.task_count now = time.time() if ( - num_done > 2 - and num_idle_workers > 1 + num_done >= 2 + and num_idle_workers > 0 and (self.last_backup is None or (now - self.last_backup > 9.0)) and self.backup_lock.acquire(blocking=False) ): @@ -628,21 +801,15 @@ class RemoteExecutor(BaseExecutor): if start_ts is not None: runtime = now - start_ts score += runtime - logger.debug( - f'score[{bundle}] => {score} # latency boost' - ) + logger.debug('score[%s] => %.1f # latency boost', bundle, score) if bundle.slower_than_local_p95: score += runtime / 2 - logger.debug( - f'score[{bundle}] => {score} # >worker p95' - ) + logger.debug('score[%s] => %.1f # >worker p95', bundle, score) if bundle.slower_than_global_p95: score += runtime / 4 - logger.debug( - f'score[{bundle}] => {score} # >global p95' - ) + logger.debug('score[%s] => %.1f # >global p95', bundle, score) # Prefer backups of bundles that don't # have backups already. @@ -656,12 +823,12 @@ class RemoteExecutor(BaseExecutor): else: score = 0 logger.debug( - f'score[{bundle}] => {score} # {backup_count} dup backup factor' + 'score[%s] => %.1f # {backup_count} dup backup factor', + bundle, + score, ) - if score != 0 and ( - best_score is None or score > best_score - ): + if score != 0 and (best_score is None or score > best_score): bundle_to_backup = bundle assert bundle is not None assert bundle.backup_bundles is not None @@ -670,44 +837,46 @@ class RemoteExecutor(BaseExecutor): # Note: this is all still happening on the heartbeat # runner thread. That's ok because - # schedule_backup_for_bundle uses the executor to + # _schedule_backup_for_bundle uses the executor to # submit the bundle again which will cause it to be # picked up by a worker thread and allow this thread # to return to run future heartbeats. if bundle_to_backup is not None: self.last_backup = now logger.info( - f'=====> SCHEDULING BACKUP {bundle_to_backup} (score={best_score:.1f}) <=====' + '=====> SCHEDULING BACKUP %s (score=%.1f) <=====', + bundle_to_backup, + best_score, ) - self.schedule_backup_for_bundle(bundle_to_backup) + self._schedule_backup_for_bundle(bundle_to_backup) finally: self.backup_lock.release() - def is_worker_available(self) -> bool: + def _is_worker_available(self) -> bool: + """Is there a worker available currently?""" return self.policy.is_worker_available() - def acquire_worker( - self, machine_to_avoid: str = None - ) -> Optional[RemoteWorkerRecord]: + def _acquire_worker(self, machine_to_avoid: str = None) -> Optional[RemoteWorkerRecord]: + """Try to acquire a worker.""" return self.policy.acquire_worker(machine_to_avoid) - def find_available_worker_or_block( - self, machine_to_avoid: str = None - ) -> RemoteWorkerRecord: + def _find_available_worker_or_block(self, machine_to_avoid: str = None) -> RemoteWorkerRecord: + """Find a worker or block until one becomes available.""" with self.cv: - while not self.is_worker_available(): + while not self._is_worker_available(): self.cv.wait() - worker = self.acquire_worker(machine_to_avoid) + worker = self._acquire_worker(machine_to_avoid) if worker is not None: return worker msg = "We should never reach this point in the code" logger.critical(msg) raise Exception(msg) - def release_worker(self, bundle: BundleDetails, *, was_cancelled=True) -> None: + def _release_worker(self, bundle: BundleDetails, *, was_cancelled=True) -> None: + """Release a previously acquired worker.""" worker = bundle.worker assert worker is not None - logger.debug(f'Released worker {worker}') + logger.debug('Released worker %s', worker) self.status.record_release_worker( worker, bundle.uuid, @@ -718,16 +887,18 @@ class RemoteExecutor(BaseExecutor): self.cv.notify() self.adjust_task_count(-1) - def check_if_cancelled(self, bundle: BundleDetails) -> bool: + def _check_if_cancelled(self, bundle: BundleDetails) -> bool: + """See if a particular bundle is cancelled. Do not block.""" with self.status.lock: if bundle.is_cancelled.wait(timeout=0.0): - logger.debug(f'Bundle {bundle.uuid} is cancelled, bail out.') + logger.debug('Bundle %s is cancelled, bail out.', bundle.uuid) bundle.was_cancelled = True return True return False - def launch(self, bundle: BundleDetails, override_avoid_machine=None) -> Any: + def _launch(self, bundle: BundleDetails, override_avoid_machine=None) -> Any: """Find a worker for bundle or block until one is available.""" + self.adjust_task_count(+1) uuid = bundle.uuid hostname = bundle.hostname @@ -739,7 +910,7 @@ class RemoteExecutor(BaseExecutor): avoid_machine = bundle.src_bundle.machine worker = None while worker is None: - worker = self.find_available_worker_or_block(avoid_machine) + worker = self._find_available_worker_or_block(avoid_machine) assert worker is not None # Ok, found a worker. @@ -747,20 +918,18 @@ class RemoteExecutor(BaseExecutor): machine = bundle.machine = worker.machine username = bundle.username = worker.username self.status.record_acquire_worker(worker, uuid) - logger.debug(f'{bundle}: Running bundle on {worker}...') + logger.debug('%s: Running bundle on %s...', bundle, worker) # Before we do any work, make sure the bundle is still viable. # It may have been some time between when it was submitted and # now due to lack of worker availability and someone else may # have already finished it. - if self.check_if_cancelled(bundle): + if self._check_if_cancelled(bundle): try: - return self.process_work_result(bundle) + return self._process_work_result(bundle) except Exception as e: - logger.warning( - f'{bundle}: bundle says it\'s cancelled upfront but no results?!' - ) - self.release_worker(bundle) + logger.warning('%s: bundle says it\'s cancelled upfront but no results?!', bundle) + self._release_worker(bundle) if is_original: # Weird. We are the original owner of this # bundle. For it to have been cancelled, a backup @@ -771,84 +940,101 @@ class RemoteExecutor(BaseExecutor): # thing. logger.exception(e) logger.error( - f'{bundle}: We are the original owner thread and yet there are ' - + 'no results for this bundle. This is unexpected and bad.' + '%s: We are the original owner thread and yet there are ' + 'no results for this bundle. This is unexpected and bad.', + bundle, ) - return self.emergency_retry_nasty_bundle(bundle) + return self._emergency_retry_nasty_bundle(bundle) else: - # Expected(?). We're a backup and our bundle is - # cancelled before we even got started. Something - # went bad in process_work_result (I acutually don't - # see what?) but probably not worth worrying - # about. Let the original thread worry about - # either finding the results or complaining about - # it. + # We're a backup and our bundle is cancelled + # before we even got started. Do nothing and let + # the original bundle's thread worry about either + # finding the results or complaining about it. return None # Send input code / data to worker machine if it's not local. if hostname not in machine: try: - cmd = ( - f'{SCP} {bundle.code_file} {username}@{machine}:{bundle.code_file}' - ) + cmd = f'{SCP} {bundle.code_file} {username}@{machine}:{bundle.code_file}' start_ts = time.time() - logger.info(f"{bundle}: Copying work to {worker} via {cmd}.") + logger.info("%s: Copying work to %s via %s.", bundle, worker, cmd) run_silently(cmd) xfer_latency = time.time() - start_ts - logger.debug(f"{bundle}: Copying to {worker} took {xfer_latency:.1f}s.") + logger.debug("%s: Copying to %s took %.1fs.", bundle, worker, xfer_latency) except Exception as e: - self.release_worker(bundle) + self._release_worker(bundle) if is_original: - # Weird. We tried to copy the code to the worker and it failed... - # And we're the original bundle. We have to retry. + # Weird. We tried to copy the code to the worker + # and it failed... And we're the original bundle. + # We have to retry. logger.exception(e) logger.error( - f"{bundle}: Failed to send instructions to the worker machine?! " - + "This is not expected; we\'re the original bundle so this shouldn\'t " - + "be a race condition. Attempting an emergency retry..." + "%s: Failed to send instructions to the worker machine?! " + "This is not expected; we\'re the original bundle so this shouldn\'t " + "be a race condition. Attempting an emergency retry...", + bundle, ) - return self.emergency_retry_nasty_bundle(bundle) + return self._emergency_retry_nasty_bundle(bundle) else: # This is actually expected; we're a backup. # There's a race condition where someone else # already finished the work and removed the source - # code file before we could copy it. No biggie. - msg = f'{bundle}: Failed to send instructions to the worker machine... ' - msg += 'We\'re a backup and this may be caused by the original (or some ' - msg += 'other backup) already finishing this work. Ignoring this.' - logger.warning(msg) + # code_file before we could copy it. Ignore. + logger.warning( + '%s: Failed to send instructions to the worker machine... ' + 'We\'re a backup and this may be caused by the original (or ' + 'some other backup) already finishing this work. Ignoring.', + bundle, + ) return None # Kick off the work. Note that if this fails we let - # wait_for_process deal with it. + # _wait_for_process deal with it. self.status.record_processing_began(uuid) cmd = ( f'{SSH} {bundle.username}@{bundle.machine} ' - f'"source py38-venv/bin/activate &&' + f'"source py39-venv/bin/activate &&' f' /home/scott/lib/python_modules/remote_worker.py' f' --code_file {bundle.code_file} --result_file {bundle.result_file}"' ) - logger.debug(f'{bundle}: Executing {cmd} in the background to kick off work...') + logger.debug('%s: Executing %s in the background to kick off work...', bundle, cmd) p = cmd_in_background(cmd, silent=True) bundle.pid = p.pid - logger.debug( - f'{bundle}: Local ssh process pid={p.pid}; remote worker is {machine}.' - ) - return self.wait_for_process(p, bundle, 0) + logger.debug('%s: Local ssh process pid=%d; remote worker is %s.', bundle, p.pid, machine) + return self._wait_for_process(p, bundle, 0) - def wait_for_process( + def _wait_for_process( self, p: Optional[subprocess.Popen], bundle: BundleDetails, depth: int ) -> Any: + """At this point we've copied the bundle's pickled code to the remote + worker and started an ssh process that should be invoking the + remote worker to have it execute the user's code. See how + that's going and wait for it to complete or fail. Note that + this code is recursive: there are codepaths where we decide to + stop waiting for an ssh process (because another backup seems + to have finished) but then fail to fetch or parse the results + from that backup and thus call ourselves to continue waiting + on an active ssh process. This is the purpose of the depth + argument: to curtail potential infinite recursion by giving up + eventually. + + Args: + p: the Popen record of the ssh job + bundle: the bundle of work being executed remotely + depth: how many retries we've made so far. Starts at zero. + + """ + machine = bundle.machine assert p is not None - pid = p.pid + pid = p.pid # pid of the ssh process if depth > 3: logger.error( - f"I've gotten repeated errors waiting on this bundle; giving up on pid={pid}." + "I've gotten repeated errors waiting on this bundle; giving up on pid=%d", pid ) p.terminate() - self.release_worker(bundle) - return self.emergency_retry_nasty_bundle(bundle) + self._release_worker(bundle) + return self._emergency_retry_nasty_bundle(bundle) # Spin until either the ssh job we scheduled finishes the # bundle or some backup worker signals that they finished it @@ -857,22 +1043,20 @@ class RemoteExecutor(BaseExecutor): try: p.wait(timeout=0.25) except subprocess.TimeoutExpired: - if self.check_if_cancelled(bundle): - logger.info( - f'{bundle}: looks like another worker finished bundle...' - ) + if self._check_if_cancelled(bundle): + logger.info('%s: looks like another worker finished bundle...', bundle) break else: - logger.info(f"{bundle}: pid {pid} ({machine}) is finished!") + logger.info("%s: pid %d (%s) is finished!", bundle, pid, machine) p = None break # If we get here we believe the bundle is done; either the ssh # subprocess finished (hopefully successfully) or we noticed # that some other worker seems to have completed the bundle - # and we're bailing out. + # before us and we're bailing out. try: - ret = self.process_work_result(bundle) + ret = self._process_work_result(bundle) if ret is not None and p is not None: p.terminate() return ret @@ -884,16 +1068,19 @@ class RemoteExecutor(BaseExecutor): # Otherwise, time for an emergency reschedule. except Exception as e: logger.exception(e) - logger.error(f'{bundle}: Something unexpected just happened...') + logger.error('%s: Something unexpected just happened...', bundle) if p is not None: - msg = f"{bundle}: Failed to wrap up \"done\" bundle, re-waiting on active ssh." - logger.warning(msg) - return self.wait_for_process(p, bundle, depth + 1) + logger.warning( + "%s: Failed to wrap up \"done\" bundle, re-waiting on active ssh.", bundle + ) + return self._wait_for_process(p, bundle, depth + 1) else: - self.release_worker(bundle) - return self.emergency_retry_nasty_bundle(bundle) + self._release_worker(bundle) + return self._emergency_retry_nasty_bundle(bundle) + + def _process_work_result(self, bundle: BundleDetails) -> Any: + """A bundle seems to be completed. Check on the results.""" - def process_work_result(self, bundle: BundleDetails) -> Any: with self.status.lock: is_original = bundle.src_bundle is None was_cancelled = bundle.was_cancelled @@ -911,11 +1098,15 @@ class RemoteExecutor(BaseExecutor): if bundle.hostname not in bundle.machine: cmd = f'{SCP} {username}@{machine}:{result_file} {result_file} 2>/dev/null' logger.info( - f"{bundle}: Fetching results back from {username}@{machine} via {cmd}" + "%s: Fetching results back from %s@%s via %s", + bundle, + username, + machine, + cmd, ) # If either of these throw they are handled in - # wait_for_process. + # _wait_for_process. attempts = 0 while True: try: @@ -923,17 +1114,15 @@ class RemoteExecutor(BaseExecutor): except Exception as e: attempts += 1 if attempts >= 3: - raise (e) + raise e else: break + # Cleanup remote /tmp files. run_silently( - f'{SSH} {username}@{machine}' - f' "/bin/rm -f {code_file} {result_file}"' - ) - logger.debug( - f'Fetching results back took {time.time() - bundle.end_ts:.1f}s.' + f'{SSH} {username}@{machine}' f' "/bin/rm -f {code_file} {result_file}"' ) + logger.debug('Fetching results back took %.2fs', time.time() - bundle.end_ts) dur = bundle.end_ts - bundle.start_ts self.histogram.add_item(dur) @@ -942,25 +1131,25 @@ class RemoteExecutor(BaseExecutor): # original is also the only job that may delete result_file # from disk. Note that the original may have been cancelled # if one of the backups finished first; it still must read the - # result from disk. + # result from disk. It still does that here with is_cancelled + # set. if is_original: - logger.debug(f"{bundle}: Unpickling {result_file}.") + logger.debug("%s: Unpickling %s.", bundle, result_file) try: with open(result_file, 'rb') as rb: serialized = rb.read() result = cloudpickle.loads(serialized) except Exception as e: logger.exception(e) - msg = f'Failed to load {result_file}... this is bad news.' - logger.critical(msg) - self.release_worker(bundle) + logger.error('Failed to load %s... this is bad news.', result_file) + self._release_worker(bundle) - # Re-raise the exception; the code in wait_for_process may - # decide to emergency_retry_nasty_bundle here. - raise Exception(e) - logger.debug(f'Removing local (master) {code_file} and {result_file}.') - os.remove(f'{result_file}') - os.remove(f'{code_file}') + # Re-raise the exception; the code in _wait_for_process may + # decide to _emergency_retry_nasty_bundle here. + raise e + logger.debug('Removing local (master) %s and %s.', code_file, result_file) + os.remove(result_file) + os.remove(code_file) # Notify any backups that the original is done so they # should stop ASAP. Do this whether or not we @@ -969,7 +1158,7 @@ class RemoteExecutor(BaseExecutor): if bundle.backup_bundles is not None: for backup in bundle.backup_bundles: logger.debug( - f'{bundle}: Notifying backup {backup.uuid} that it\'s cancelled' + '%s: Notifying backup %s that it\'s cancelled', bundle, backup.uuid ) backup.is_cancelled.set() @@ -986,27 +1175,29 @@ class RemoteExecutor(BaseExecutor): orig_bundle = bundle.src_bundle assert orig_bundle is not None logger.debug( - f'{bundle}: Notifying original {orig_bundle.uuid} we beat them to it.' + '%s: Notifying original %s we beat them to it.', bundle, orig_bundle.uuid ) orig_bundle.is_cancelled.set() - self.release_worker(bundle, was_cancelled=was_cancelled) + self._release_worker(bundle, was_cancelled=was_cancelled) return result - def create_original_bundle(self, pickle, fname: str): - from string_utils import generate_uuid + def _create_original_bundle(self, pickle, function_name: str): + """Creates a bundle that is not a backup of any other bundle but + rather represents a user task. + """ - uuid = generate_uuid(omit_dashes=True) + uuid = string_utils.generate_uuid(omit_dashes=True) code_file = f'/tmp/{uuid}.code.bin' result_file = f'/tmp/{uuid}.result.bin' - logger.debug(f'Writing pickled code to {code_file}') - with open(f'{code_file}', 'wb') as wb: + logger.debug('Writing pickled code to %s', code_file) + with open(code_file, 'wb') as wb: wb.write(pickle) bundle = BundleDetails( pickled_code=pickle, uuid=uuid, - fname=fname, + function_name=function_name, worker=None, username=None, machine=None, @@ -1025,10 +1216,14 @@ class RemoteExecutor(BaseExecutor): failure_count=0, ) self.status.record_bundle_details(bundle) - logger.debug(f'{bundle}: Created an original bundle') + logger.debug('%s: Created an original bundle', bundle) return bundle - def create_backup_bundle(self, src_bundle: BundleDetails): + def _create_backup_bundle(self, src_bundle: BundleDetails): + """Creates a bundle that is a backup of another bundle that is + running too slowly.""" + + assert self.status.lock.locked() assert src_bundle.backup_bundles is not None n = len(src_bundle.backup_bundles) uuid = src_bundle.uuid + f'_backup#{n}' @@ -1036,7 +1231,7 @@ class RemoteExecutor(BaseExecutor): backup_bundle = BundleDetails( pickled_code=src_bundle.pickled_code, uuid=uuid, - fname=src_bundle.fname, + function_name=src_bundle.function_name, worker=None, username=None, machine=None, @@ -1056,25 +1251,31 @@ class RemoteExecutor(BaseExecutor): ) src_bundle.backup_bundles.append(backup_bundle) self.status.record_bundle_details_already_locked(backup_bundle) - logger.debug(f'{backup_bundle}: Created a backup bundle') + logger.debug('%s: Created a backup bundle', backup_bundle) return backup_bundle - def schedule_backup_for_bundle(self, src_bundle: BundleDetails): + def _schedule_backup_for_bundle(self, src_bundle: BundleDetails): + """Schedule a backup of src_bundle.""" + assert self.status.lock.locked() assert src_bundle is not None - backup_bundle = self.create_backup_bundle(src_bundle) + backup_bundle = self._create_backup_bundle(src_bundle) logger.debug( - f'{backup_bundle.uuid}/{backup_bundle.fname}: Scheduling backup for execution...' + '%s/%s: Scheduling backup for execution...', + backup_bundle.uuid, + backup_bundle.function_name, ) - self._helper_executor.submit(self.launch, backup_bundle) + self._helper_executor.submit(self._launch, backup_bundle) # Results from backups don't matter; if they finish first # they will move the result_file to this machine and let - # the original pick them up and unpickle them. + # the original pick them up and unpickle them (and return + # a result). + + def _emergency_retry_nasty_bundle(self, bundle: BundleDetails) -> Optional[fut.Future]: + """Something unexpectedly failed with bundle. Either retry it + from the beginning or throw in the towel and give up on it.""" - def emergency_retry_nasty_bundle( - self, bundle: BundleDetails - ) -> Optional[fut.Future]: is_original = bundle.src_bundle is None bundle.worker = None avoid_last_machine = bundle.machine @@ -1088,36 +1289,41 @@ class RemoteExecutor(BaseExecutor): if bundle.failure_count > retry_limit: logger.error( - f'{bundle}: Tried this bundle too many times already ({retry_limit}x); giving up.' + '%s: Tried this bundle too many times already (%dx); giving up.', + bundle, + retry_limit, ) if is_original: raise RemoteExecutorException( - f'{bundle}: This bundle can\'t be completed despite several backups and retries' + f'{bundle}: This bundle can\'t be completed despite several backups and retries', ) else: logger.error( - f'{bundle}: At least it\'s only a backup; better luck with the others.' + '%s: At least it\'s only a backup; better luck with the others.', bundle ) return None else: msg = f'>>> Emergency rescheduling {bundle} because of unexected errors (wtf?!) <<<' logger.warning(msg) warnings.warn(msg) - return self.launch(bundle, avoid_last_machine) + return self._launch(bundle, avoid_last_machine) @overrides def submit(self, function: Callable, *args, **kwargs) -> fut.Future: + """Submit work to be done. This is the user entry point of this + class.""" if self.already_shutdown: raise Exception('Submitted work after shutdown.') - pickle = make_cloud_pickle(function, *args, **kwargs) - bundle = self.create_original_bundle(pickle, function.__name__) + pickle = _make_cloud_pickle(function, *args, **kwargs) + bundle = self._create_original_bundle(pickle, function.__name__) self.total_bundles_submitted += 1 - return self._helper_executor.submit(self.launch, bundle) + return self._helper_executor.submit(self._launch, bundle) @overrides def shutdown(self, *, wait: bool = True, quiet: bool = False) -> None: + """Shutdown the executor.""" if not self.already_shutdown: - logging.debug(f'Shutting down RemoteExecutor {self.title}') + logging.debug('Shutting down RemoteExecutor %s', self.title) self.heartbeat_stop_event.set() self.heartbeat_thread.join() self._helper_executor.shutdown(wait) @@ -1128,17 +1334,53 @@ class RemoteExecutor(BaseExecutor): @singleton class DefaultExecutors(object): + """A container for a default thread, process and remote executor. + These are not created until needed and we take care to clean up + before process exit automatically for the caller's convenience. + Instead of creating your own executor, consider using the one + from this pool. e.g.:: + + @par.parallelize(method=par.Method.PROCESS) + def do_work( + solutions: List[Work], + shard_num: int, + ... + ): + + + + def start_do_work(all_work: List[Work]): + shards = [] + logger.debug('Sharding work into groups of 10.') + for subset in list_utils.shard(all_work, 10): + shards.append([x for x in subset]) + + logger.debug('Kicking off helper pool.') + try: + for n, shard in enumerate(shards): + results.append( + do_work( + shard, n, shared_cache.get_name(), max_letter_pop_per_word + ) + ) + smart_future.wait_all(results) + finally: + # Note: if you forget to do this it will clean itself up + # during program termination including tearing down any + # active ssh connections. + executors.DefaultExecutors().process_pool().shutdown() + """ + def __init__(self): self.thread_executor: Optional[ThreadExecutor] = None self.process_executor: Optional[ProcessExecutor] = None self.remote_executor: Optional[RemoteExecutor] = None - def ping(self, host) -> bool: - logger.debug(f'RUN> ping -c 1 {host}') + @staticmethod + def _ping(host) -> bool: + logger.debug('RUN> ping -c 1 %s', host) try: - x = cmd_with_timeout( - f'ping -c 1 {host} >/dev/null 2>/dev/null', timeout_seconds=1.0 - ) + x = cmd_exitcode(f'ping -c 1 {host} >/dev/null 2>/dev/null', timeout_seconds=1.0) return x == 0 except Exception: return False @@ -1157,17 +1399,17 @@ class DefaultExecutors(object): if self.remote_executor is None: logger.info('Looking for some helper machines...') pool: List[RemoteWorkerRecord] = [] - if self.ping('cheetah.house'): + if self._ping('cheetah.house'): logger.info('Found cheetah.house') pool.append( RemoteWorkerRecord( username='scott', machine='cheetah.house', - weight=30, - count=6, + weight=24, + count=5, ), ) - if self.ping('meerkat.cabin'): + if self._ping('meerkat.cabin'): logger.info('Found meerkat.cabin') pool.append( RemoteWorkerRecord( @@ -1177,33 +1419,33 @@ class DefaultExecutors(object): count=2, ), ) - if self.ping('wannabe.house'): + if self._ping('wannabe.house'): logger.info('Found wannabe.house') pool.append( RemoteWorkerRecord( username='scott', machine='wannabe.house', - weight=25, - count=10, + weight=14, + count=2, ), ) - if self.ping('puma.cabin'): + if self._ping('puma.cabin'): logger.info('Found puma.cabin') pool.append( RemoteWorkerRecord( username='scott', machine='puma.cabin', - weight=30, - count=6, + weight=24, + count=5, ), ) - if self.ping('backup.house'): + if self._ping('backup.house'): logger.info('Found backup.house') pool.append( RemoteWorkerRecord( username='scott', machine='backup.house', - weight=8, + weight=9, count=2, ), ) @@ -1211,8 +1453,8 @@ class DefaultExecutors(object): # The controller machine has a lot to do; go easy on it. for record in pool: if record.machine == platform.node() and record.count > 1: - logger.info(f'Reducing workload for {record.machine}.') - record.count = 1 + logger.info('Reducing workload for %s.', record.machine) + record.count = max(int(record.count / 2), 1) policy = WeightedRandomRemoteWorkerSelectionPolicy() policy.register_worker_pool(pool)