AttributeError: ‘NoneType’ object has no attribute ‘create_execution_context’

在使用tensorrt推理时

import pycuda.autoinit
import numpy as np
import pycuda.driver as cuda
import tensorrt as trt
import torch
import os
import time
from PIL import Image
import cv2
import torchvision

filename = 'test.jpg'
max_batch_size = 1
onnx_model_path = 'resnet50.onnx'

TRT_LOGGER = trt.Logger()  # This logger is required to build an engine


def get_img_np_nchw(filename):
    image = cv2.imread(filename)
    image_cv = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
    image_cv = cv2.resize(image_cv, (224, 224))
    miu = np.array([0.485, 0.456, 0.406])
    std = np.array([0.229, 0.224, 0.225])
    img_np = np.array(image_cv, dtype=float) / 255.
    r = (img_np[:, :, 0] - miu[0]) / std[0]
    g = (img_np[:, :, 1] - miu[1]) / std[1]
    b = (img_np[:, :, 2] - miu[2]) / std[2]
    img_np_t = np.array([r, g, b])
    img_np_nchw = np.expand_dims(img_np_t, axis=0)
    return img_np_nchw


class HostDeviceMem(object):
    def __init__(self, host_mem, device_mem):
        """Within this context, host_mom means the cpu memory and device means the GPU memory
        """
        self.host = host_mem
        self.device = device_mem

    def __str__(self):
        return "Host:\n" + str(self.host) + "\nDevice:\n" + str(self.device)

    def __repr__(self):
        return self.__str__()


def allocate_buffers(engine):
    inputs = []
    outputs = []
    bindings = []
    stream = cuda.Stream()
    for binding in engine:
        size = trt.volume(engine.get_binding_shape(binding)) * engine.max_batch_size
        dtype = trt.nptype(engine.get_binding_dtype(binding))
        # Allocate host and device buffers
        host_mem = cuda.pagelocked_empty(size, dtype)
        device_mem = cuda.mem_alloc(host_mem.nbytes)
        # Append the device buffer to device bindings.
        bindings.append(int(device_mem))
        # Append to the appropriate list.
        if engine.binding_is_input(binding):
            inputs.append(HostDeviceMem(host_mem, device_mem))
        else:
            outputs.append(HostDeviceMem(host_mem, device_mem))
    return inputs, outputs, bindings, stream


def get_engine(max_batch_size=1, onnx_file_path="", engine_file_path="", \
               fp16_mode=False, int8_mode=False, save_engine=False,
               ):
    """Attempts to load a serialized engine if available, otherwise builds a new TensorRT engine and saves it."""

    def build_engine(max_batch_size, save_engine):
        """Takes an ONNX file and creates a TensorRT engine to run inference with"""
        with trt.Builder(TRT_LOGGER) as builder, \
                builder.create_network() as network, \
                trt.OnnxParser(network, TRT_LOGGER) as parser:

            builder.max_workspace_size = 1 << 30  # Your workspace size
            builder.max_batch_size = max_batch_size
            # pdb.set_trace()
            builder.fp16_mode = fp16_mode  # Default: False
            builder.int8_mode = int8_mode  # Default: False
            if int8_mode:
                # To be updated
                raise NotImplementedError

            # Parse model file
            if not os.path.exists(onnx_file_path):
                quit('ONNX file {} not found'.format(onnx_file_path))

            print('Loading ONNX file from path {}...'.format(onnx_file_path))
            with open(onnx_file_path, 'rb') as model:
                print('Beginning ONNX file parsing')
                parser.parse(model.read())

            print('Completed parsing of ONNX file')
            print('Building an engine from file {}; this may take a while...'.format(onnx_file_path))

            engine = builder.build_cuda_engine(network)
            print("Completed creating Engine")

            if save_engine:
                with open(engine_file_path, "wb") as f:
                    f.write(engine.serialize())
            return engine

    if os.path.exists(engine_file_path):
        # If a serialized engine exists, load it instead of building a new one.
        print("Reading engine from file {}".format(engine_file_path))
        with open(engine_file_path, "rb") as f, trt.Runtime(TRT_LOGGER) as runtime:
            return runtime.deserialize_cuda_engine(f.read())
    else:
        return build_engine(max_batch_size, save_engine)


def do_inference(context, bindings, inputs, outputs, stream, batch_size=1):
    # Transfer data from CPU to the GPU.
    [cuda.memcpy_htod_async(inp.device, inp.host, stream) for inp in inputs]
    # Run inference.
    context.execute_async(batch_size=batch_size, bindings=bindings, stream_handle=stream.handle)
    # Transfer predictions back from the GPU.
    [cuda.memcpy_dtoh_async(out.host, out.device, stream) for out in outputs]
    # Synchronize the stream
    stream.synchronize()
    # Return only the host outputs.
    return [out.host for out in outputs]


def postprocess_the_outputs(h_outputs, shape_of_output):
    h_outputs = h_outputs.reshape(*shape_of_output)
    return h_outputs


img_np_nchw = get_img_np_nchw(filename)
img_np_nchw = img_np_nchw.astype(dtype=np.float32)

# These two modes are dependent on hardwares
fp16_mode = False
int8_mode = False
trt_engine_path = './model_fp16_{}_int8_{}.trt'.format(fp16_mode, int8_mode)
# Build an engine
engine = get_engine(max_batch_size, onnx_model_path, trt_engine_path, fp16_mode, int8_mode)
# Create the context for this engine
context = engine.create_execution_context()
# Allocate buffers for input and output
inputs, outputs, bindings, stream = allocate_buffers(engine)  # input, output: host # bindings

# Do inference
shape_of_output = (max_batch_size, 1000)
# Load data to the buffer
inputs[0].host = img_np_nchw.reshape(-1)

# inputs[1].host = ... for multiple input
t1 = time.time()
trt_outputs = do_inference(context, bindings=bindings, inputs=inputs, outputs=outputs, stream=stream)  # numpy data
t2 = time.time()
feat = postprocess_the_outputs(trt_outputs[0], shape_of_output)

print('TensorRT ok')

model = torchvision.models.resnet50(pretrained=True).cuda()
resnet_model = model.eval()

input_for_torch = torch.from_numpy(img_np_nchw).cuda()
t3 = time.time()
feat_2 = resnet_model(input_for_torch)
t4 = time.time()
feat_2 = feat_2.cpu().data.numpy()
print('Pytorch ok!')

mse = np.mean((feat - feat_2) ** 2)
print("Inference time with the TensorRT engine: {}".format(t2 - t1))
print("Inference time with the PyTorch model: {}".format(t4 - t3))
print('MSE Error = {}'.format(mse))

print('All completed!')

会出现AttributeError: ‘NoneType’ object has no attribute ‘create_execution_context’问题，需要在engine前添加以下两行

            last_layer = network.get_layer(network.num_layers - 1)
            network.mark_output(last_layer.get_output(0))

            engine = builder.build_cuda_engine(network)
            print("Completed creating Engine")         

这可能会继续引发以下错误

python: ../builder/Network.cpp:1205: virtual nvinfer1::ILayer* nvinfer1::Network::getLayer(int) const: Assertion `layerIndex >= 0' failed.

此处应该为trt7.0以上，只能使用explicitBatch flag set的原因，此处将建立build的代码进行修改，需要添加trt.NetworkDefinitionCreationFlag.EXPLICIT_BATCH，同时将explicit_batch填入 ==builder.create_network(explicit_batch)==即可

    def build_engine(max_batch_size, save_engine):
        """Takes an ONNX file and creates a TensorRT engine to run inference with"""
        explicit_batch = 1 << (int)(trt.NetworkDefinitionCreationFlag.EXPLICIT_BATCH)
        with trt.Builder(TRT_LOGGER) as builder, \
                builder.create_network(explicit_batch) as network, \
                trt.OnnxParser(network, TRT_LOGGER) as parser:

更改后的完整代码如下
推荐使用tensorrt7版本，如果使用tensorrt6版本则不要使用trt.NetworkDefinitionCreationFlag.EXPLICIT_BATCH，==builder.create_network()==参数为空即可

# Do inference
shape_of_output = (max_batch_size, 1000)

同时需要将上面的1000修改成模型最后输出的量
目标识别：识别的种类（1000为imagenet的classes）
目标检测：以yolo为例（classes * （（13 * 13）+（26 * 26）+（52 * 52）））
此代码会自动下载resent50的pth文件，并与resent50进行比较，如果不需要可以屏蔽
或者删除model = torchvision.models.resnet50(pretrained=True).cuda()，并将model替换成自己的网络和pth权重

import sys
sys.path.append(r'/home/kamiyuuki/Downloads/yolox-pytorch-main')

import pycuda.autoinit
import numpy as np
import pycuda.driver as cuda
import tensorrt as trt
import torch
import os
import time
from PIL import Image
import cv2
import torchvision
from logs.two_asff.model import YoloBody

filename = '../img/1.jpg'
max_batch_size = 1
onnx_model_path = '../two_asff.onnx'
model_path      = '../logs/two_asff/yolox/99.09.pth'
phi = 'shufflenet'
TRT_LOGGER = trt.Logger()  # This logger is required to build an engine


def get_img_np_nchw(filename):
    image = cv2.imread(filename)
    image_cv = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
    image_cv = cv2.resize(image_cv, (224, 224))
    miu = np.array([0.485, 0.456, 0.406])
    std = np.array([0.229, 0.224, 0.225])
    img_np = np.array(image_cv, dtype=float) / 255.
    r = (img_np[:, :, 0] - miu[0]) / std[0]
    g = (img_np[:, :, 1] - miu[1]) / std[1]
    b = (img_np[:, :, 2] - miu[2]) / std[2]
    img_np_t = np.array([r, g, b])
    img_np_nchw = np.expand_dims(img_np_t, axis=0)
    return img_np_nchw


class HostDeviceMem(object):
    def __init__(self, host_mem, device_mem):
        """Within this context, host_mom means the cpu memory and device means the GPU memory
        """
        self.host = host_mem
        self.device = device_mem

    def __str__(self):
        return "Host:\n" + str(self.host) + "\nDevice:\n" + str(self.device)

    def __repr__(self):
        return self.__str__()


def allocate_buffers(engine):
    inputs = []
    outputs = []
    bindings = []
    stream = cuda.Stream()
    for binding in engine:
        size = trt.volume(engine.get_binding_shape(binding)) * engine.max_batch_size
        dtype = trt.nptype(engine.get_binding_dtype(binding))
        # Allocate host and device buffers
        host_mem = cuda.pagelocked_empty(size, dtype)
        device_mem = cuda.mem_alloc(host_mem.nbytes)
        # Append the device buffer to device bindings.
        bindings.append(int(device_mem))
        # Append to the appropriate list.
        if engine.binding_is_input(binding):
            inputs.append(HostDeviceMem(host_mem, device_mem))
        else:
            outputs.append(HostDeviceMem(host_mem, device_mem))
    return inputs, outputs, bindings, stream


def get_engine(max_batch_size=1, onnx_file_path="", engine_file_path="", \
               fp16_mode=False, int8_mode=False, save_engine=False,
               ):
    """Attempts to load a serialized engine if available, otherwise builds a new TensorRT engine and saves it."""

    def build_engine(max_batch_size, save_engine):
        """Takes an ONNX file and creates a TensorRT engine to run inference with"""
        explicit_batch = 1 << (int)(trt.NetworkDefinitionCreationFlag.EXPLICIT_BATCH)
        with trt.Builder(TRT_LOGGER) as builder, \
                builder.create_network(explicit_batch) as network, \
                trt.OnnxParser(network, TRT_LOGGER) as parser:

            builder.max_workspace_size = 1 << 30  # Your workspace size
            builder.max_batch_size = max_batch_size
            # pdb.set_trace()
            builder.fp16_mode = fp16_mode  # Default: False
            builder.int8_mode = int8_mode  # Default: False
            if int8_mode:
                # To be updated
                raise NotImplementedError

            # Parse model file
            if not os.path.exists(onnx_file_path):
                quit('ONNX file {} not found'.format(onnx_file_path))

            print('Loading ONNX file from path {}...'.format(onnx_file_path))
            with open(onnx_file_path, 'rb') as model:
                print('Beginning ONNX file parsing')
                parser.parse(model.read())

            print('Completed parsing of ONNX file')
            print('Building an engine from file {}; this may take a while...'.format(onnx_file_path))
            last_layer = network.get_layer(network.num_layers - 1)
            network.mark_output(last_layer.get_output(0))

            engine = builder.build_cuda_engine(network)
            print("Completed creating Engine")

            if save_engine:
                with open(engine_file_path, "wb") as f:
                    f.write(engine.serialize())
            return engine

    if os.path.exists(engine_file_path):
        # If a serialized engine exists, load it instead of building a new one.
        print("Reading engine from file {}".format(engine_file_path))
        with open(engine_file_path, "rb") as f, trt.Runtime(TRT_LOGGER) as runtime:
            return runtime.deserialize_cuda_engine(f.read())
    else:
        return build_engine(max_batch_size, save_engine)


def do_inference(context, bindings, inputs, outputs, stream, batch_size=1):
    # Transfer data from CPU to the GPU.
    [cuda.memcpy_htod_async(inp.device, inp.host, stream) for inp in inputs]
    # Run inference.
    context.execute_async(batch_size=batch_size, bindings=bindings, stream_handle=stream.handle)
    # Transfer predictions back from the GPU.
    [cuda.memcpy_dtoh_async(out.host, out.device, stream) for out in outputs]
    # Synchronize the stream
    stream.synchronize()
    # Return only the host outputs.
    return [out.host for out in outputs]


def postprocess_the_outputs(h_outputs, shape_of_output):
    h_outputs = h_outputs.reshape(*shape_of_output)
    return h_outputs


img_np_nchw = get_img_np_nchw(filename)
img_np_nchw = img_np_nchw.astype(dtype=np.float32)

# These two modes are dependent on hardwares
fp16_mode = False
int8_mode = False
trt_engine_path = './model_fp16_{}_int8_{}.trt'.format(fp16_mode, int8_mode)
# Build an engine
engine = get_engine(max_batch_size, onnx_model_path, trt_engine_path, fp16_mode, int8_mode)
# Create the context for this engine
context = engine.create_execution_context()
# Allocate buffers for input and output
inputs, outputs, bindings, stream = allocate_buffers(engine)  # input, output: host # bindings

# Do inference
shape_of_output = (max_batch_size, 4056)
# Load data to the buffer
inputs[0].host = img_np_nchw.reshape(-1)

# inputs[1].host = ... for multiple input
t1 = time.time()
trt_outputs = do_inference(context, bindings=bindings, inputs=inputs, outputs=outputs, stream=stream)  # numpy data
t2 = time.time()
print("Inference time with the TensorRT engine: {}".format(t2 - t1))
feat = postprocess_the_outputs(trt_outputs[0], shape_of_output)

print('TensorRT ok')


model    =    YoloBody(1, phi)
device      = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
model.load_state_dict(torch.load(model_path, map_location=device))

# model = torchvision.models.resnet50(pretrained=True).cuda()
resnet_model = model.eval()
model = model.cuda()

input_for_torch = torch.from_numpy(img_np_nchw).cuda()
t3 = time.time()
feat_2 = resnet_model(input_for_torch)
t4 = time.time()
print("Inference time with the PyTorch model: {}".format(t4 - t3))
feat_2 = feat_2.data.numpy()
print('Pytorch ok!')

mse = np.mean((feat - feat_2) ** 2)
print("Inference time with the TensorRT engine: {}".format(t2 - t1))
print("Inference time with the PyTorch model: {}".format(t4 - t3))
print('MSE Error = {}'.format(mse))

print('All completed!')

来源：kamiyuuki