[Python]图片保存性能对比（mmap,open,cv.imwrite）

import mmap
import timeit
import cv2
import numpy as np

images = open(r'F:\data\five_finger.jpg', 'rb').read()
FILENAME = './mmap_tmp.jpg'
size = len(images)
filename = './cv_tmp.jpg'
# file = open(FILENAME, "w+b")
# file.write(b"\0" * size)
# file.flush()
# file.close()
raw_bytes = images
filename = './tmp.jpg'

def mmap_io_write():

    with open(FILENAME, mode="r+b") as file_obj:
        with mmap.mmap(file_obj.fileno(), length=size) as mmap_obj:
            mmap_obj.write(images)


def write_io():

    with open(filename, mode="wb") as file_obj:
        file_obj.write(raw_bytes)


data = np.frombuffer(images, np.uint8)  # 转换np序列
img = cv2.imdecode(data, cv2.IMREAD_COLOR)  # pylint: disable=E1101

def cv_write():
    cv2.imwrite(filename, img)


print(timeit.timeit("mmap_io_write()", setup="from __main__ import mmap_io_write", number=10000))
print(timeit.timeit("write_io()", setup="from __main__ import write_io", number=10000))
print(timeit.timeit("cv_write()", setup="from __main__ import cv_write", number=10000))

性能对比：

2.9025623
4.7150644999999995
154.8415199

备注：

mmap必须在存在相同大小文件的情况下进行write，否则创建一个大小相同的空文件，则毫无意义。

结论：建议创建文件使用python自带的open方法。