我在使用tflite时发现,在推理期间我的多核CPU未被充分利用。我通过使用numpy创建随机输入数据(类似于图像的随机矩阵)消除了IO瓶颈,但是tflite仍然未能充分利用CPU的全部潜力。
文档提到了调整使用线程数的可能性。然而,我无法找到如何在Python API中进行此操作的方法。但是,既然我看到有人为不同的模型使用多个解释器实例,我想一个人也可以使用多个相同模型的实例并在不同的线程/进程上运行它们。我编写了以下简短的脚本:
import numpy as np
import os, time
import tflite_runtime.interpreter as tflite
from multiprocessing import Pool
# global, but for each process the module is loaded, so only one global var per process
interpreter = None
input_details = None
output_details = None
def init_interpreter(model_path):
global interpreter
global input_details
global output_details
interpreter = tflite.Interpreter(model_path=model_path)
input_details = interpreter.get_input_details()
output_details = interpreter.get_output_details()
interpreter.allocate_tensors()
print('done init')
def do_inference(img_idx, img):
print('Processing image %d'%img_idx)
print('interpreter: %r' % (hex(id(interpreter)),))
print('input_details: %r' % (hex(id(input_details)),))
print('output_details: %r' % (hex(id(output_details)),))
tstart = time.time()
img = np.stack([img]*3, axis=2) # replicates layer three time for RGB
img = np.array([img]) # create batch dimension
interpreter.set_tensor(input_details[0]['index'], img )
interpreter.invoke()
logit= interpreter.get_tensor(output_details[0]['index'])
pred = np.argmax(logit, axis=1)[0]
logit = list(logit[0])
duration = time.time() - tstart
return logit, pred, duration
def main_par():
optimized_graph_def_file = r'./optimized_graph.lite'
# init model once to find out input dimensions
interpreter_main = tflite.Interpreter(model_path=optimized_graph_def_file)
input_details = interpreter_main.get_input_details()
input_w, intput_h = tuple(input_details[0]['shape'][1:3])
num_test_imgs=1000
# pregenerate random images with values in [0,1]
test_imgs = np.random.rand(num_test_imgs, input_w,intput_h).astype(input_details[0]['dtype'])
scores = []
predictions = []
it_times = []
tstart = time.time()
with Pool(processes=4, initializer=init_interpreter, initargs=(optimized_graph_def_file,)) as pool: # start 4 worker processes
results = pool.starmap(do_inference, enumerate(test_imgs))
scores, predictions, it_times = list(zip(*results))
duration =time.time() - tstart
print('Parent process time for %d images: %.2fs'%(num_test_imgs, duration))
print('Inference time for %d images: %.2fs'%(num_test_imgs, sum(it_times)))
print('mean time per image: %.3fs +- %.3f' % (np.mean(it_times), np.std(it_times)) )
if __name__ == '__main__':
# main_seq()
main_par()
然而,通过
hex(id(interpreter))
打印的解释器实例的内存地址对于每个进程都是相同的。输入/输出细节的内存地址却是不同的。因此,即使我能够体验到加速,我想知道这种做法是否有潜在问题?如果有,那么如何使用TFLite和Python实现并行推理?tflite_runtime版本:1.14.0,来自此处(x86-64 Python 3.5版本)。
Python版本:3.5。