Use DJL with the SageMaker Python SDK¶
With the SageMaker Python SDK, you can use Deep Java Library to host models on Amazon SageMaker.
Deep Java Library (DJL) Serving is a high performance universal stand-alone model serving solution powered by DJL. DJL Serving supports loading models trained with a variety of different frameworks. With the SageMaker Python SDK you can use DJL Serving to host large models using backends like DeepSpeed and HuggingFace Accelerate.
For information about supported versions of DJL Serving, see the AWS documentation. We recommend that you use the latest supported version because that’s where we focus our development efforts.
For general information about using the SageMaker Python SDK, see Using the SageMaker Python SDK.
Deploy DJL models¶
With the SageMaker Python SDK, you can use DJL Serving to host models that have been saved in the HuggingFace pretrained format. These can either be models you have trained/fine-tuned yourself, or models available publicly from the HuggingFace Hub. DJL Serving in the SageMaker Python SDK supports hosting models for the popular HuggingFace NLP tasks, as well as Stable Diffusion.
You can either deploy your model using DeepSpeed, FasterTransformer, or HuggingFace Accelerate, or let DJL Serving determine the best backend based on your model architecture and configuration.
# Create a DJL Model, backend is chosen automatically djl_model = DJLModel( "s3://my_bucket/my_saved_model_artifacts/", # This can also be a HuggingFace Hub model id "my_sagemaker_role", dtype="fp16", task="text-generation", number_of_partitions=2 # number of gpus to partition the model across ) # Deploy the model to an Amazon SageMaker Endpoint and get a Predictor predictor = djl_model.deploy("ml.g5.12xlarge", initial_instance_count=1)
If you want to use a specific backend, then you can create an instance of the corresponding model directly.
# Create a model using the DeepSpeed backend deepspeed_model = DeepSpeedModel( "s3://my_bucket/my_saved_model_artifacts/", # This can also be a HuggingFace Hub model id "my_sagemaker_role", dtype="bf16", task="text-generation", tensor_parallel_degree=2, # number of gpus to partition the model across using tensor parallelism ) # Create a model using the HuggingFace Accelerate backend hf_accelerate_model = HuggingFaceAccelerateModel( "s3://my_bucket/my_saved_model_artifacts/", # This can also be a HuggingFace Hub model id "my_sagemaker_role", dtype="fp16", task="text-generation", number_of_partitions=2, # number of gpus to partition the model across ) # Create a model using the FasterTransformer backend fastertransformer_model = FasterTransformerModel( "s3://my_bucket/my_saved_model_artifacts/", # This can also be a HuggingFace Hub model id "my_sagemaker_role", data_type="fp16", task="text-generation", tensor_parallel_degree=2, # number of gpus to partition the model across ) # Deploy the model to an Amazon SageMaker Endpoint and get a Predictor deepspeed_predictor = deepspeed_model.deploy("ml.g5.12xlarge", initial_instance_count=1) hf_accelerate_predictor = hf_accelerate_model.deploy("ml.g5.12xlarge", initial_instance_count=1) fastertransformer_predictor = fastertransformer_model.deploy("ml.g5.12xlarge", initial_instance_count=1)
Regardless of which way you choose to create your model, a
Predictor object is returned. You can use this
to do inference on the endpoint hosting your DJLModel.
Predictor provides a
predict method, which can do inference with json data, numpy arrays, or Python lists.
Inference data are serialized and sent to the DJL Serving model server by an
InvokeEndpoint SageMaker operation. The
predict method returns the result of inference against your model.
By default, the inference data is serialized to a json string, and the inference result is a Python dictionary.
Model Directory Structure¶
There are two components that are needed to deploy DJL Serving Models on Sagemaker. 1. Model Artifacts (required) 2. Inference code and Model Server Properties (optional)
These are stored and handled separately. Model artifacts should not be stored with the custom inference code and model server configuration.
DJL Serving supports two ways to load models for inference. 1. A HuggingFace Hub model id. 2. Uncompressed model artifacts stored in a S3 bucket.
HuggingFace Hub model id¶
Using a HuggingFace Hub model id is the easiest way to get started with deploying Large Models via DJL Serving on SageMaker.
DJL Serving will use this model id to download the model at runtime via the HuggingFace Transformers
This method makes it easy to deploy models quickly, but for very large models the download time can become unreasonable.
For example, you can deploy the EleutherAI gpt-j-6B model like this:
model = DJLModel( "EleutherAI/gpt-j-6B", "my_sagemaker_role", dtype="fp16", number_of_partitions=2 ) predictor = model.deploy("ml.g5.12xlarge")
Uncompressed Model Artifacts stored in a S3 bucket¶
For models that are larger than 20GB (total checkpoint size), we recommend that you store the model in S3. Download times will be much faster compared to downloading from the HuggingFace Hub at runtime. DJL Serving Models expect a different model structure than most of the other frameworks in the SageMaker Python SDK. Specifically, DJLModels do not support loading models stored in tar.gz format. This is because DJL Serving is optimized for large models, and it implements a fast downloading mechanism for large models that require the artifacts be uncompressed.
For example, lets say you want to deploy the EleutherAI/gpt-j-6B model available on the HuggingFace Hub. You can download the model and upload to S3 like this:
# Requires Git LFS git clone https://huggingface.co/EleutherAI/gpt-j-6B # Upload to S3 aws s3 sync gpt-j-6B s3://my_bucket/gpt-j-6B
You would then pass “s3://my_bucket/gpt-j-6B” as
model_id to the
DJLModel like this:
model = DJLModel( "s3://my_bucket/gpt-j-6B", "my_sagemaker_role", dtype="fp16", number_of_partitions=2 ) predictor = model.deploy("ml.g5.12xlarge")
For language models we expect that the model weights, model config, and tokenizer config are provided in S3. The model should be loadable from the HuggingFace Transformers AutoModelFor<Task>.from_pretrained API, where task is the NLP task you want to host the model for. The weights must be stored as PyTorch compatible checkpoints.
my_bucket/my_model/ |- config.json |- added_tokens.json |- config.json |- pytorch_model-*-of-*.bin # model weights can be partitioned into multiple checkpoints |- tokenizer.json |- tokenizer_config.json |- vocab.json
For Stable Diffusion models, the model should be loadable from the HuggingFace Diffusers DiffusionPipeline.from_pretrained API.
Inference code and Model Server Properties¶
You can provide custom inference code and model server configuration by specifying the
entry_point arguments of the
DJLModel. These are not required. The model server configuration can be generated
based on the arguments passed to the constructor, and we provide default inference handler code for DeepSpeed,
HuggingFaceAccelerate, and Stable Diffusion. You can find these handler implementations in the DJL Serving Github repository.
You can find documentation for the model server configurations on the DJL Serving Docs website.
The code and configuration you want to deploy can either be stored locally or in S3. These files will be bundled into a tar.gz file that will be uploaded to SageMaker.
sourcedir/ |- script.py # Inference handler code |- serving.properties # Model Server configuration file |- requirements.txt # Additional Python requirements that will be installed at runtime via PyPi
In the above example, sourcedir will be bundled and compressed into a tar.gz file and uploaded as part of creating the Inference Endpoint.
The DJL Serving Model Server¶
The endpoint you create with
deploy runs the DJL Serving model server.
The model server loads the model from S3 and performs inference on the model in response to SageMaker
InvokeEndpoint API calls.
DJL Serving is highly customizable. You can control aspects of both model loading and model serving. Most of the model server
configuration are exposed through the
DJLModel API. The SageMaker Python SDK will use the values it is passed to
create the proper configuration file used when creating the inference endpoint. You can optionally provide your own
serving.properties file via the
source_dir argument. You can find documentation about serving.properties in the
DJL Serving Documentation for model specific settings.
Within the SageMaker Python SDK, DJL Serving is used in Python mode. This allows users to provide their inference script, and data processing scripts in python. For details on how to write custom inference and data processing code, please see the DJL Serving Documentation on Python Mode.
For more information about DJL Serving, see the DJL Serving documentation.
Ahead of time partitioning¶
To optimize the deployment of large models that do not fit in a single GPU, the model’s tensor weights are partitioned at runtime and each partition is loaded in individual GPU. But runtime partitioning takes significant amount of time and memory on model loading. So, DJLModel offers an ahead of time partitioning capability for DeepSpeed and FasterTransformer engines, which lets you partition your model weights and save them before deployment. HuggingFace does not support tensor parallelism, so ahead of time partitioning cannot be done for it. In our experiment with GPT-J model, loading this model with partitioned checkpoints increased the model loading time by 40%.
partition method invokes an Amazon SageMaker Training job to partition the model and upload those partitioned checkpoints to S3 bucket. You can either provide your desired S3 bucket to upload the partitioned checkpoints or it will be uploaded to the default SageMaker S3 bucket. Please note that this S3 bucket will be remembered for deployment. When you call deploy method after partition, DJLServing downloads the partitioned model checkpoints directly from the uploaded s3 url, if available.
# partitions the model using Amazon Sagemaker Training Job. djl_model.partition("ml.g5.12xlarge") predictor = deepspeed_model.deploy("ml.g5.12xlarge", initial_instance_count=1)
SageMaker DJL Classes¶
For information about the different DJL Serving related classes in the SageMaker Python SDK, see https://sagemaker.readthedocs.io/en/stable/frameworks/djl/sagemaker.djl_inference.html.
SageMaker DJL Serving Containers¶
For information about the SageMaker DJL Serving containers, see: