Tensor is not an element of this graph; deploying Keras model

Question

Im deploying a keras model and sending the test data to the model via a flask api. I have two files:

First: My Flask App:

# Let\'s startup the Flask          


        

Answer 1

It's so much simpler to wrap your keras model in a class and that class can keep track of it's own graph and session. This prevents the problems that having multiple threads/processes/models can cause which is almost certainly the cause of your issue. While other solutions will work this is by far the most general, scalable and catch all. Use this one:

import os
from keras.models import model_from_json
from keras import backend as K
import tensorflow as tf
import logging

logger = logging.getLogger('root')


class NeuralNetwork:
    def __init__(self):
        self.session = tf.Session()
        self.graph = tf.get_default_graph()
        # the folder in which the model and weights are stored
        self.model_folder = os.path.join(os.path.abspath("src"), "static")
        self.model = None
        # for some reason in a flask app the graph/session needs to be used in the init else it hangs on other threads
        with self.graph.as_default():
            with self.session.as_default():
                logging.info("neural network initialised")

    def load(self, file_name=None):
        """
        :param file_name: [model_file_name, weights_file_name]
        :return:
        """
        with self.graph.as_default():
            with self.session.as_default():
                try:
                    model_name = file_name[0]
                    weights_name = file_name[1]

                    if model_name is not None:
                        # load the model
                        json_file_path = os.path.join(self.model_folder, model_name)
                        json_file = open(json_file_path, 'r')
                        loaded_model_json = json_file.read()
                        json_file.close()
                        self.model = model_from_json(loaded_model_json)
                    if weights_name is not None:
                        # load the weights
                        weights_path = os.path.join(self.model_folder, weights_name)
                        self.model.load_weights(weights_path)
                    logging.info("Neural Network loaded: ")
                    logging.info('\t' + "Neural Network model: " + model_name)
                    logging.info('\t' + "Neural Network weights: " + weights_name)
                    return True
                except Exception as e:
                    logging.exception(e)
                    return False

    def predict(self, x):
        with self.graph.as_default():
            with self.session.as_default():
                y = self.model.predict(x)
        return y