.. _tensorflow-servingx-neuronrt-visible-cores:

Using NEURON_RT_VISIBLE_CORES with TensorFlow Serving
=====================================================

TensorFlow serving allows customers to scale-up inference workloads
across a network. TensorFlow Neuron Serving uses the same API as normal
TensorFlow Serving with two differences: (a) the saved model must be
compiled for neuron and (b) the entry point is a different binary
named ``tensorflow_model_server_neuron``. The binary is found at
``/usr/local/bin/tensorflow_model_server_neuron`` and is pre-installed
in the DLAMI or installed with APT/YUM tensorflow-model-server-neuronx package.

Install TensorFlow Model Server and Serving API
-----------------------------------------------

Follow the steps in the :ref:`install-neuronx-tensorflow`.

Then ensure you install using either apt-get or yum.

.. code:: bash

  sudo apt-get install tensorflow-model-server-neuronx

or

.. code:: bash

  sudo yum install tensorflow-model-server-neuronx

Also, you would need TensorFlow Serving API (use --no-deps to prevent
installation of regular tensorflow).

.. code:: bash

   pip install --no-deps tensorflow_serving_api

For the example image preprocessing using Keras preprocessing, the
Python Imaging Library Pillow is required:

.. code:: bash

   pip install pillow

To workaround h5py issue https://github.com/aws/aws-neuron-sdk/issues/220:

.. code:: bash

   pip install "h5py<3.0.0"


Export and Compile Saved Model
------------------------------

The following example shows graph construction followed by the addition
of Neuron compilation step before exporting to saved model.

.. code:: python

    import tensorflow as tf
    import tensorflow_neuronx as tfnx
    import numpy as np

    tf.keras.backend.set_learning_phase(0)
    tf.keras.backend.set_image_data_format('channels_last')
    image_sizes = [224, 224]
    model = tf.keras.applications.ResNet50(weights='imagenet')
    example_inputs = tf.random.uniform([1, *image_sizes, 3], dtype=tf.float32)

    model_neuron = tfnx.trace(model, example_inputs)
    # run the model once to define the forward pass and allow for saving
    model_neuron(example_inputs)
    tf.keras.models.save_model(model_neuron, './resnet50_neuron/1')



Serving Saved Model
-------------------

User can now serve the saved model with the
tensorflow_model_server_neuron binary. To utilize multiple NeuronCores,
it is recommended to launch multiple tensorflow model servers that
listen to the same gRPC port:

.. code:: bash

   export NEURON_RT_VISIBLE_CORES=0  # important to set this environment variable before launching model servers
   tensorflow_model_server_neuron --model_name=resnet50_neuron \
        --model_base_path=$(pwd)/resnet50_neuron/ --port=8500

   # then to run another server on a different neuron core open another
   # window and run this, except this time set NEURON_RT_VISIBLE_CORES=1
   # you can keep doing this up to the number of Neuron Cores on your machine

   export NEURON_RT_VISIBLE_CORES=1
   tensorflow_model_server_neuron --model_name=resnet50_neuron \
        --model_base_path=$(pwd)/resnet50_neuron/ --port=8500

The compiled model is staged in neuron DRAM by the server to prepare
for inference.

Generate inference requests to the model server
-----------------------------------------------

Now run inferences via GRPC as shown in the following sample client
code:

.. code:: python

    import numpy as np
    import grpc
    import tensorflow as tf
    from tensorflow.keras.preprocessing import image
    from tensorflow.keras.applications.resnet50 import preprocess_input
    from tensorflow_serving.apis import predict_pb2
    from tensorflow_serving.apis import prediction_service_pb2_grpc
    from tensorflow.keras.applications.resnet50 import decode_predictions

    tf.keras.backend.set_image_data_format('channels_last')

    if __name__ == '__main__':
        channel = grpc.insecure_channel('localhost:8500')
        stub = prediction_service_pb2_grpc.PredictionServiceStub(channel)
        img_file = tf.keras.utils.get_file(
            "./kitten_small.jpg",
            "https://raw.githubusercontent.com/awslabs/mxnet-model-server/master/docs/images/kitten_small.jpg")
        img = image.load_img(img_file, target_size=(224, 224))
        img_array = preprocess_input(image.img_to_array(img)[None, ...])
        request = predict_pb2.PredictRequest()
        request.model_spec.name = 'resnet50_neuron'
        request.inputs['input_1'].CopyFrom(
            tf.make_tensor_proto(img_array, shape=img_array.shape))
        result = stub.Predict(request)
        prediction = tf.make_ndarray(result.outputs['output_1'])
        print(decode_predictions(prediction))