mirror of
https://github.com/wassname/ray.git
synced 2026-06-28 07:50:30 +08:00
Eric Liang
233 lines
8.9 KiB
Python
233 lines
8.9 KiB
Python
from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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import os
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import ray
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import time
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import traceback
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from ray.tune import TuneError
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from ray.tune.trial import Trial, Resources
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from ray.tune.trial_scheduler import FIFOScheduler, TrialScheduler
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class TrialRunner(object):
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"""A TrialRunner implements the event loop for scheduling trials on Ray.
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Example:
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runner = TrialRunner()
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runner.add_trial(Trial(...))
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runner.add_trial(Trial(...))
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while not runner.is_finished():
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runner.step()
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print(runner.debug_string())
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The main job of TrialRunner is scheduling trials to efficiently use cluster
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resources, without overloading the cluster.
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While Ray itself provides resource management for tasks and actors, this is
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not sufficient when scheduling trials that may instantiate multiple actors.
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This is because if insufficient resources are available, concurrent trials
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could deadlock waiting for new resources to become available. Furthermore,
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oversubscribing the cluster could degrade training performance, leading to
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misleading benchmark results.
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"""
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def __init__(self, scheduler=None):
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"""Initializes a new TrialRunner."""
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self._scheduler_alg = scheduler or FIFOScheduler()
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self._trials = []
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self._running = {}
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self._avail_resources = Resources(cpu=0, gpu=0)
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self._committed_resources = Resources(cpu=0, gpu=0)
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self._resources_initialized = False
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# For debugging, it may be useful to halt trials after some time has
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# elapsed. TODO(ekl) consider exposing this in the API.
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self._global_time_limit = float(
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os.environ.get("TRIALRUNNER_WALLTIME_LIMIT", float('inf')))
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self._total_time = 0
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def is_finished(self):
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"""Returns whether all trials have finished running."""
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if self._total_time > self._global_time_limit:
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print(
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"Exceeded global time limit {} / {}".format(
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self._total_time, self._global_time_limit))
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return True
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for t in self._trials:
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if t.status in [Trial.PENDING, Trial.RUNNING, Trial.PAUSED]:
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return False
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return True
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def step(self):
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"""Runs one step of the trial event loop.
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Callers should typically run this method repeatedly in a loop. They
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may inspect or modify the runner's state in between calls to step().
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"""
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if self._can_launch_more():
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self._launch_trial()
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elif self._running:
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self._process_events()
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else:
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for trial in self._trials:
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if trial.status == Trial.PENDING:
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if not self.has_resources(trial.resources):
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raise TuneError(
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"Insufficient cluster resources to launch trial",
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(trial.resources, self._avail_resources))
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elif trial.status == Trial.PAUSED:
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raise TuneError(
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"There are paused trials, but no more pending "
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"trials with sufficient resources.")
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raise TuneError("Called step when all trials finished?")
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def get_trials(self):
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"""Returns the list of trials managed by this TrialRunner.
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Note that the caller usually should not mutate trial state directly.
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"""
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return self._trials
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def add_trial(self, trial):
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"""Adds a new trial to this TrialRunner.
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Trials may be added at any time.
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"""
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self._scheduler_alg.on_trial_add(self, trial)
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self._trials.append(trial)
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def debug_string(self):
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"""Returns a human readable message for printing to the console."""
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messages = ["== Status =="]
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messages.append(self._scheduler_alg.debug_string())
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if self._resources_initialized:
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messages.append(
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"Resources used: {}/{} CPUs, {}/{} GPUs".format(
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self._committed_resources.cpu,
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self._avail_resources.cpu,
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self._committed_resources.gpu,
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self._avail_resources.gpu))
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for local_dir in sorted(set([t.local_dir for t in self._trials])):
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messages.append("Tensorboard logdir: {}".format(local_dir))
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for t in self._trials:
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if t.local_dir == local_dir:
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messages.append(
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" - {}:\t{}".format(t, t.progress_string()))
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return "\n".join(messages) + "\n"
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def has_resources(self, resources):
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"""Returns whether this runner has at least the specified resources."""
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cpu_avail = self._avail_resources.cpu - self._committed_resources.cpu
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gpu_avail = self._avail_resources.gpu - self._committed_resources.gpu
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return resources.cpu <= cpu_avail and resources.gpu <= gpu_avail
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def _can_launch_more(self):
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self._update_avail_resources()
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trial = self._get_runnable()
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return trial is not None
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def _launch_trial(self):
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trial = self._get_runnable()
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self._commit_resources(trial.resources)
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try:
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trial.start()
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self._running[trial.train_remote()] = trial
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except Exception:
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print("Error starting runner, retrying:", traceback.format_exc())
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time.sleep(2)
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trial.stop(error=True)
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try:
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trial.start()
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self._running[trial.train_remote()] = trial
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except Exception:
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print("Error starting runner, abort:", traceback.format_exc())
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trial.stop(error=True)
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# note that we don't return the resources, since they may
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# have been lost
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def _process_events(self):
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[result_id], _ = ray.wait(self._running.keys())
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trial = self._running[result_id]
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del self._running[result_id]
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try:
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result = ray.get(result_id)
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trial.result_logger.on_result(result)
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print("result", result)
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trial.last_result = result
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self._total_time += result.time_this_iter_s
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if trial.should_stop(result):
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self._scheduler_alg.on_trial_complete(self, trial, result)
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self._stop_trial(trial)
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else:
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decision = self._scheduler_alg.on_trial_result(
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self, trial, result)
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if decision == TrialScheduler.CONTINUE:
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if trial.should_checkpoint():
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# TODO(rliaw): This is a blocking call
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trial.checkpoint()
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self._running[trial.train_remote()] = trial
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elif decision == TrialScheduler.PAUSE:
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self._pause_trial(trial)
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elif decision == TrialScheduler.STOP:
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self._stop_trial(trial)
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else:
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assert False, "Invalid scheduling decision: {}".format(
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decision)
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except Exception:
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print("Error processing event:", traceback.format_exc())
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if trial.status == Trial.RUNNING:
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self._scheduler_alg.on_trial_error(self, trial)
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self._stop_trial(trial, error=True)
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def _get_runnable(self):
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return self._scheduler_alg.choose_trial_to_run(self)
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def _commit_resources(self, resources):
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self._committed_resources = Resources(
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self._committed_resources.cpu + resources.cpu,
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self._committed_resources.gpu + resources.gpu)
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def _return_resources(self, resources):
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self._committed_resources = Resources(
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self._committed_resources.cpu - resources.cpu,
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self._committed_resources.gpu - resources.gpu)
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assert self._committed_resources.cpu >= 0
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assert self._committed_resources.gpu >= 0
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def _stop_trial(self, trial, error=False):
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"""Only returns resources if resources allocated."""
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prior_status = trial.status
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trial.stop(error=error)
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if prior_status == Trial.RUNNING:
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self._return_resources(trial.resources)
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def _pause_trial(self, trial):
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"""Only returns resources if resources allocated."""
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prior_status = trial.status
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trial.pause()
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if prior_status == Trial.RUNNING:
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self._return_resources(trial.resources)
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def _update_avail_resources(self):
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clients = ray.global_state.client_table()
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local_schedulers = [
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entry for client in clients.values() for entry in client
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if (entry['ClientType'] == 'local_scheduler' and not
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entry['Deleted'])
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]
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num_cpus = sum(ls['NumCPUs'] for ls in local_schedulers)
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num_gpus = sum(ls['NumGPUs'] for ls in local_schedulers)
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self._avail_resources = Resources(int(num_cpus), int(num_gpus))
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self._resources_initialized = True
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