ValueError: Tensor Tensor xxx is not an element of of this graph的解决方案

问题：

在利用keras+flask构建一个简单的深度学习后台服务器，遇到了如下的问题：

ValueError: Tensor Tensor("fc1000/Softmax:0", shape=(?, 1000), dtype=float32) is not an element of this graph。

 

解决方案如下：

在初始化的时候，加载模型文件和生成graph。

 

完整代码如下：

# USAGE
# Start the server:
# 	python run_keras_server.py
# Submit a request via cURL:
# 	curl -X POST -F [email protected] 'http://localhost:5000/predict'
# Submita a request via Python:
#	python simple_request.py

# import the necessary packages
from keras.applications import ResNet50
from keras.preprocessing.image import img_to_array
from keras.applications import imagenet_utils
from PIL import Image
import numpy as np
import flask
import io
import tensorflow as tf

# initialize our Flask application and the Keras model
app = flask.Flask(__name__)

graph = None
model = None


def load_model():
    # load the pre-trained Keras model (here we are using a model
    # pre-trained on ImageNet and provided by Keras, but you can
    # substitute in your own networks just as easily)
    global graph
    graph = tf.get_default_graph()

    global model
    model = ResNet50(weights="imagenet")


def prepare_image(image, target):
    # if the image mode is not RGB, convert it
    if image.mode != "RGB":
        image = image.convert("RGB")

    # resize the input image and preprocess it
    image = image.resize(target)
    image = img_to_array(image)
    image = np.expand_dims(image, axis=0)
    image = imagenet_utils.preprocess_input(image)

    # return the processed image
    return image


@app.route("/predict", methods=["POST"])
def predict():
    # initialize the data dictionary that will be returned from the
    # view
    data = {"success": False}

    # ensure an image was properly uploaded to our endpoint
    if flask.request.method == "POST":
        if flask.request.files.get("image"):
            # read the image in PIL format
            image = flask.request.files["image"].read()
            image = Image.open(io.BytesIO(image))

            # preprocess the image and prepare it for classification
            image = prepare_image(image, target=(224, 224))

            # classify the input image and then initialize the list
            # of predictions to return to the client
            with graph.as_default():
                preds = model.predict(image)
            results = imagenet_utils.decode_predictions(preds)
            data["predictions"] = []

            # loop over the results and add them to the list of
            # returned predictions
            for (imagenetID, label, prob) in results[0]:
                r = {"label": label, "probability": float(prob)}
                data["predictions"].append(r)

            # indicate that the request was a success
            data["success"] = True

    # return the data dictionary as a JSON response
    return flask.jsonify(data)


# if this is the main thread of execution first load the model and
# then start the server
if __name__ == "__main__":
    print(("* Loading Keras model and Flask starting server..."
           "please wait until server has fully started"))
    load_model()
    app.run()

 

参考：

1.https://github.com/jrosebr1/simple-keras-rest-api/blob/master/run_keras_server.py

2.https://blog.keras.io/building-a-simple-keras-deep-learning-rest-api.html

3.https://www.pyimagesearch.com/2018/02/05/deep-learning-production-keras-redis-flask-apache/

4.https://cloud.tencent.com/developer/article/1167171