class ray.tune.logger.JsonLoggerCallback[source]#

Bases: ray.tune.logger.logger.LoggerCallback

Logs trial results in json format.

Also writes to a results file and param.json file when results or configurations are updated. Experiments must be executed with the JsonLoggerCallback to be compatible with the ExperimentAnalysis tool.

PublicAPI: This API is stable across Ray releases.



Get the state of the callback.


Handle logging when a trial restores.


Handle logging when a trial saves a checkpoint.

on_checkpoint(iteration, trials, trial, ...)

Called after a trial saved a checkpoint with Tune.

on_experiment_end(trials, **info)

Called after experiment is over and all trials have concluded.

on_step_begin(iteration, trials, **info)

Called at the start of each tuning loop step.

on_step_end(iteration, trials, **info)

Called at the end of each tuning loop step.

on_trial_recover(iteration, trials, trial, ...)

Called after a trial instance failed (errored) but the trial is scheduled for retry.


Set the state of the callback.

setup([stop, num_samples, total_num_samples])

Called once at the very beginning of training.