ray.tune.schedulers.HyperBandForBOHB#

class ray.tune.schedulers.HyperBandForBOHB(time_attr: str = 'training_iteration', metric: Optional[str] = None, mode: Optional[str] = None, max_t: int = 81, reduction_factor: float = 3, stop_last_trials: bool = True)[source]#

Bases: ray.tune.schedulers.hyperband.HyperBandScheduler

Extends HyperBand early stopping algorithm for BOHB.

This implementation removes the HyperBandScheduler pipelining. This class introduces key changes:

1. Trials are now placed so that the bracket with the largest size is filled first.

2. Trials will be paused even if the bracket is not filled. This allows BOHB to insert new trials into the training.

See ray.tune.schedulers.HyperBandScheduler for parameter docstring.

PublicAPI: This API is stable across Ray releases.

on_trial_add(trial_runner: ray.tune.execution.trial_runner.TrialRunner, trial: ray.tune.experiment.trial.Trial)[source]#

Adds new trial.

On a new trial add, if current bracket is not filled, add to current bracket. Else, if current band is not filled, create new bracket, add to current bracket. Else, create new iteration, create new bracket, add to bracket.

on_trial_result(trial_runner: ray.tune.execution.trial_runner.TrialRunner, trial: ray.tune.experiment.trial.Trial, result: Dict) → str[source]#

If bracket is finished, all trials will be stopped.

If a given trial finishes and bracket iteration is not done, the trial will be paused and resources will be given up.

This scheduler will not start trials but will stop trials. The current running trial will not be handled, as the trialrunner will be given control to handle it.

choose_trial_to_run(trial_runner: ray.tune.execution.trial_runner.TrialRunner, allow_recurse: bool = True) → Optional[ray.tune.experiment.trial.Trial][source]#

Fair scheduling within iteration by completion percentage.

List of trials not used since all trials are tracked as state of scheduler. If iteration is occupied (ie, no trials to run), then look into next iteration.