Source code for torch.distributed.elastic.timer.local_timer

# Copyright (c) Facebook, Inc. and its affiliates.
# All rights reserved.
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree.
import logging
import multiprocessing as mp
import os
import signal
import time
from queue import Empty
from typing import Any, Dict, List, Set, Tuple

from .api import RequestQueue, TimerClient, TimerRequest, TimerServer

[docs]class LocalTimerClient(TimerClient): """ Client side of ``LocalTimerServer``. This client is meant to be used on the same host that the ``LocalTimerServer`` is running on and uses pid to uniquely identify a worker. This is particularly useful in situations where one spawns a subprocess (trainer) per GPU on a host with multiple GPU devices. """ def __init__(self, mp_queue): super().__init__() self._mp_queue = mp_queue def acquire(self, scope_id, expiration_time): pid = os.getpid() acquire_request = TimerRequest(pid, scope_id, expiration_time) self._mp_queue.put(acquire_request) def release(self, scope_id): pid = os.getpid() release_request = TimerRequest(pid, scope_id, -1) self._mp_queue.put(release_request)
class MultiprocessingRequestQueue(RequestQueue): """ A ``RequestQueue`` backed by python ``multiprocessing.Queue`` """ def __init__(self, mp_queue: mp.Queue): super().__init__() self._mp_queue = mp_queue def size(self) -> int: return self._mp_queue.qsize() def get(self, size, timeout: float) -> List[TimerRequest]: requests = [] wait = timeout for _ in range(0, size): start = time.time() try: r = self._mp_queue.get(block=True, timeout=wait) except Empty: break requests.append(r) wait = wait - (time.time() - start) if wait <= 0: break return requests
[docs]class LocalTimerServer(TimerServer): """ Server that works with ``LocalTimerClient``. Clients are expected to be subprocesses to the parent process that is running this server. Each host in the job is expected to start its own timer server locally and each server instance manages timers for local workers (running on processes on the same host). """ def __init__( self, mp_queue: mp.Queue, max_interval: float = 60, daemon: bool = True ): super().__init__(MultiprocessingRequestQueue(mp_queue), max_interval, daemon) self._timers: Dict[Tuple[Any, str], TimerRequest] = {} def register_timers(self, timer_requests: List[TimerRequest]) -> None: for request in timer_requests: pid = request.worker_id scope_id = request.scope_id expiration_time = request.expiration_time # negative expiration is a proxy for a release call if expiration_time < 0: self._timers.pop((pid, scope_id), None) else: self._timers[(pid, scope_id)] = request def clear_timers(self, worker_ids: Set[int]) -> None: for (pid, scope_id) in list(self._timers.keys()): if pid in worker_ids: self._timers.pop((pid, scope_id)) def get_expired_timers(self, deadline: float) -> Dict[Any, List[TimerRequest]]: # pid -> [timer_requests...] expired_timers: Dict[Any, List[TimerRequest]] = {} for request in self._timers.values(): if request.expiration_time <= deadline: expired_scopes = expired_timers.setdefault(request.worker_id, []) expired_scopes.append(request) return expired_timers def _reap_worker(self, worker_id: int) -> bool: try: os.kill(worker_id, signal.SIGKILL) return True except ProcessLookupError:"Process with pid={worker_id} does not exist. Skipping") return True except Exception as e: logging.error(f"Error terminating pid={worker_id}", exc_info=e) return False


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