def restore(self, trial: Trial) -> None:
"""Restores training state from a given model checkpoint.
Args:
trial: The trial to be restored.
Raises:
RuntimeError: This error is raised if no runner is found.
AbortTrialExecution: This error is raised if the trial is
ineligible for restoration, given the Tune input arguments.
"""
checkpoint = trial.checkpoint
if checkpoint.dir_or_data is None:
return
if trial.runner is None:
raise RuntimeError(
"Trial {}: Unable to restore - no runner found.".format(trial))
checkpoint_dir = checkpoint.dir_or_data
node_ip = checkpoint.node_ip
if checkpoint.storage_mode == CheckpointStorage.MEMORY:
logger.debug("Trial %s: Attempting restore from object", trial)
# Note that we don't store the remote since in-memory checkpoints
# don't guarantee fault tolerance and don't need to be waited on.
with self._change_working_directory(trial):
trial.runner.restore_from_object.remote(checkpoint_dir)
else:
logger.debug("Trial %s: Attempting restore from %s", trial,
checkpoint_dir)
if (trial.uses_cloud_checkpointing or not trial.sync_on_checkpoint
or not os.path.exists(checkpoint_dir)):
# If using cloud checkpointing, trial will get cp from cloud.
# If not syncing to driver, assume it has access to the cp
# on the local fs.
with self._change_working_directory(trial):
remote = trial.runner.restore.remote(
checkpoint_dir, node_ip)
elif trial.sync_on_checkpoint:
# This provides FT backwards compatibility in the
# case where no cloud checkpoints are provided.
logger.debug("Trial %s: Reading checkpoint into memory", trial)
obj = TrainableUtil.checkpoint_to_object(checkpoint_dir)
with self._change_working_directory(trial):
remote = trial.runner.restore_from_object.remote(obj)
else:
raise _AbortTrialExecution(
"Pass in `sync_on_checkpoint=True` for driver-based trial"
"restoration. Pass in an `upload_dir` for remote "
"storage-based restoration")
self._futures[remote] = (_ExecutorEventType.RESTORING_RESULT,
trial)
trial.restoring_from = checkpoint
def save_to_object(self):
"""Saves the current model state to a Python object.
It also saves to disk but does not return the checkpoint path.
Returns:
Object holding checkpoint data.
"""
tmpdir = tempfile.mkdtemp("save_to_object", dir=self.logdir)
checkpoint_path = self.save(tmpdir)
# Save all files in subtree and delete the tmpdir.
obj = TrainableUtil.checkpoint_to_object(checkpoint_path)
shutil.rmtree(tmpdir)
return obj
