Checkpoints#
Determined provides APIs for downloading checkpoints and loading them into memory in a Python process.
This guide discusses:
Querying model checkpoints from trials and experiments.
Loading model checkpoints in Python.
Storing additional user-defined metadata in a checkpoint.
Using the Determined CLI to download checkpoints to disk.
The Checkpoint Export API is a subset of the features found in the
client module.
Querying Checkpoints#
Use the Experiment class to reference an experiment. The
list_checkpoints() method, when called without
arguments, returns checkpoints sorted based on the metric and smaller_is_better values from
the experiment configuration’s searcher field.
For example, in the following experiment configuration file snippet, Determined will sort checkpoints by the loss metric and in ascending order.
searcher:
metric: "loss"
smaller_is_better: true
After generating a checkpoint for the specified experiment, you can run the Python code below. This
code retrieves a list of sorted Checkpoint instances
associated with the experiment and selects the checkpoint with the best validation metric.
from determined.experimental import client
checkpoint = client.get_experiment(id).list_checkpoints()[0]
To sort checkpoints by any metric, use the sort_by argument to specify the metric and
order_by to define the sorting order (ascending or descending).
from determined.experimental import checkpoint, client
checkpoints = (
client.get_experiment(id).list_checkpoints(
sort_by="accuracy",
order_by=client.OrderBy.DESC
)
)
To sort checkpoints using preset checkpoint parameters, use the
CheckpointSortBy class. The example below fetches all
checkpoints for an experiment, sorting them by trial ID in descending order.
from determined.experimental import checkpoint, client
checkpoints = client.get_experiment(id).list_checkpoints(
sort_by=checkpoint.CheckpointSortBy.TRIAL_ID,
order_by=client.OrderBy.DESC
)
Trial is used for fine-grained control over checkpoint
selection within a trial. It contains a
list_checkpoints() method, which mirrors
list_checkpoints() for an experiment.
The following code illustrates methods to select specific checkpoints from a trial:
from determined.experimental import checkpoint, client
trial = client.get_trial(id)
most_recent_checkpoint = trial.list_checkpoints(
sort_by=checkpoint.CheckpointSortBy.END_TIME,
order_by=client.OrderBy.DESC,
max_results=1
)[0]
# Sort checkpoints by "accuracy" metric, if your training code reports it.
most_accurate_checkpoint = trial.list_checkpoints(
sort_by="accuracy",
order_by=client.OrderBy.DESC,
max_results=1
)[0]
specific_checkpoint = client.get_checkpoint(uuid="uuid-for-checkpoint")
Using the Checkpoint Class#
The Checkpoint class can both download the checkpoint from
persistent storage and load it into memory in a Python process.
The download() method downloads a checkpoint from
persistent storage to a directory on the local file system. By default, checkpoints are downloaded
to checkpoints/<checkpoint-uuid>/ (relative to the current working directory). The
download() method accepts path as an optional
parameter, which changes the checkpoint download location.
from determined.experimental import client
checkpoint = client.get_experiment(id).list_checkpoints()[0]
checkpoint_path = checkpoint.download()
specific_path = checkpoint.download(path="specific-checkpoint-path")
The load() method downloads the checkpoint, if it
does not already exist locally, and loads it into memory. The return type and behavior is different
depending on whether you are using TensorFlow or PyTorch.
PyTorch Checkpoints#
When using PyTorch models, the load() method
returns a parameterized instance of your trial class as defined in the experiment config under the
entrypoint field. The trained model can then be accessed from
the model attribute of the Trial object, as shown in the following snippet.
from determined.experimental import client
from determined import pytorch
checkpoint = client.get_experiment(id).list_checkpoints()[0]
path = checkpoint.download()
trial = pytorch.load_trial_from_checkpoint_path(path)
model = trial.model
predictions = model(samples)
PyTorch checkpoints are saved using pickle and loaded as PyTorch API objects (see the PyTorch documentation for details).
TensorFlow Checkpoints#
When using TensorFlow models, the load() method
returns a compiled model with weights loaded. This will be the same TensorFlow model returned by
your build_model() method defined in your trial class specified by the experiment config
entrypoint field. The trained model can then be used to make
predictions as shown in the following snippet.
from determined.experimental import client
from determined import keras
checkpoint = client.get_experiment(id).list_checkpoints()[0]
path = checkpoint.download()
model = keras.load_model_from_checkpoint_path(path)
predictions = model(samples)
TensorFlow checkpoints are saved in either the saved_model or h5 formats and are loaded as
trackable objects (see documentation for tf.compat.v1.saved_model.load_v2 for details).
Adding User-Defined Checkpoint Metadata#
You can add arbitrary user-defined metadata to a checkpoint via the Python SDK. This feature is useful for storing post-training metrics, labels, information related to deployment, etc.
from determined.experimental import client
checkpoint = client.get_experiment(id).list_checkpoints()[0]
checkpoint.add_metadata({"environment": "production"})
# Metadata will be stored in Determined and accessible on the checkpoint object.
print(checkpoint.metadata)
You may store an arbitrarily nested dictionary using the
add_metadata() method. If the top level key already
exists the entire tree beneath it will be overwritten.
from determined.experimental import client
checkpoint = client.get_experiment(id).list_checkpoints()[0]
checkpoint.add_metadata({"metrics": {"loss": 0.12}})
checkpoint.add_metadata({"metrics": {"acc": 0.92}})
print(checkpoint.metadata) # Output: {"metrics": {"acc": 0.92}}
You may remove metadata via the remove_metadata()
method. The method accepts a list of top level keys. The entire tree beneath the keys passed will be
deleted.
from determined.experimental import client
checkpoint = client.get_experiment(id).list_checkpoints()[0]
checkpoint.remove_metadata(["metrics"])
Downloading Checkpoints using the CLI#
The Determined CLI can be used to view all the checkpoints associated with an experiment:
$ det experiment list-checkpoints <experiment-id>
Checkpoints are saved to external storage, according to the checkpoint_storage section in the experiment configuration. Each checkpoint has a UUID, which is used as the name of the checkpoint directory on the external storage system. For example, if the experiment is configured to save checkpoints to a shared file system:
checkpoint_storage:
type: shared_fs
host_path: /mnt/nfs-volume-1
A checkpoint with UUID b3ed462c-a6c9-41e9-9202-5cb8ff00e109 can be found in the directory
/mnt/nfs-volume-1/b3ed462c-a6c9-41e9-9202-5cb8ff00e109.
Determined offers the following CLI commands for downloading checkpoints locally:
det checkpoint downloaddet trial downloaddet experiment download
Warning
When downloading checkpoints in a shared file system, we assume the same shared file system is mounted locally.
The det checkpoint download command downloads a checkpoint for the given UUID as shown below:
# Download a specific checkpoint.
det checkpoint download 46985143-af68-4d48-ab91-a6447052ca49
The command should display output resembling the following upon successfully downloading the checkpoint.
Local checkpoint path:
checkpoints/46985143-af68-4d48-ab91-a6447052ca49
Batch | Checkpoint UUID | Validation Metrics
-----------+--------------------------------------+---------------------------------------------
1000 | 46985143-af68-4d48-ab91-a6447052ca49 | {
| | "num_inputs": 0,
| | "validation_metrics": {
| | "loss": 7.906739711761475,
| | "accuracy": 0.9646000266075134,
| | "global_step": 1000,
| | "average_loss": 0.12492649257183075
| | }
| | }
The det trial download command downloads checkpoints for a specified trial. Similar to the
Trial API, the det trial download command accepts
--best, --latest, and --uuid options.
# Download best checkpoint.
det trial download <trial_id> --best
# Download best checkpoint to a particular directory.
det trial download <trial_id> --best --output-dir local_checkpoint
The command should display output resembling the following upon successfully downloading the checkpoint.
Local checkpoint path:
checkpoints/46985143-af68-4d48-ab91-a6447052ca49
Batch | Checkpoint UUID | Validation Metrics
-----------+--------------------------------------+---------------------------------------------
1000 | 46985143-af68-4d48-ab91-a6447052ca49 | {
| | "num_inputs": 0,
| | "validation_metrics": {
| | "loss": 7.906739711761475,
| | "accuracy": 0.9646000266075134,
| | "global_step": 1000,
| | "average_loss": 0.12492649257183075
| | }
| | }
The --latest and --uuid options are used as follows:
# Download the most recent checkpoint.
det trial download <trial_id> --latest
# Download a specific checkpoint.
det trial download <trial_id> --uuid <uuid-for-checkpoint>
Finally, the det experiment download command provides a similar experience to using the
Python SDK.
# Download the best checkpoint for a given experiment.
det experiment download <experiment_id>
# Download the best 3 checkpoints for a given experiment.
det experiment download <experiment_id> --top-n 3
The command should display output resembling the following upon successfully downloading the checkpoints.
Local checkpoint path:
checkpoints/8d45f621-8652-4268-8445-6ae9a735e453
Batch | Checkpoint UUID | Validation Metrics
-----------+--------------------------------------+------------------------------------------
400 | 8d45f621-8652-4268-8445-6ae9a735e453 | {
| | "num_inputs": 56,
| | "validation_metrics": {
| | "val_loss": 0.26509127765893936,
| | "val_categorical_accuracy": 1
| | }
| | }
Local checkpoint path:
checkpoints/62131ba1-983c-49a8-98ef-36207611d71f
Batch | Checkpoint UUID | Validation Metrics
-----------+--------------------------------------+------------------------------------------
1600 | 62131ba1-983c-49a8-98ef-36207611d71f | {
| | "num_inputs": 50,
| | "validation_metrics": {
| | "val_loss": 0.04411194706335664,
| | "val_categorical_accuracy": 1
| | }
| | }
Local checkpoint path:
checkpoints/a36d2a61-a384-44f7-a84b-8b30b09cb618
Batch | Checkpoint UUID | Validation Metrics
-----------+--------------------------------------+------------------------------------------
400 | a36d2a61-a384-44f7-a84b-8b30b09cb618 | {
| | "num_inputs": 46,
| | "validation_metrics": {
| | "val_loss": 0.07265569269657135,
| | "val_categorical_accuracy": 1
| | }
| | }
Next Steps#
Python SDK Overview: The reference documentation for this API.