python mmap使用记录

1、写文件

with open(‘??‘, ‘r+b‘) as f：
    with contextlib.closing(mmap.mmap(f.fileno(), size, flags=mmap.MAP_SHARED, access=mmap.ACCESS_WRITE)) as mm:
    mm = ??
    mm.flush()

2、重点提醒

>>> mmap.ACCESS_READ
1
>>> mmap.ACCESS_WRITE
2
>>> mmap.ACCESS_COPY
3
>>> mmap.ACCESS_READ | mmap.ACCESS_WRITE
3

In other words, access=mmap.ACCESS_READ|mmap.ACCESS_WRITE is the same as access=mmap.ACCESS_COPY. What you want is most likely access=mmap.ACCESS_WRITE, and on Windows that‘s what you get anyway if you don‘t explicitly use that argument.