Python: Use mmap to create shared memory for IPC

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There are several ways to achieve IPC, shared memory is one of those. In this post, we will try to create shared memory via mmap module in python.

Write to shared memory

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#!/usr/bin/python3
import mmap
import contextlib


def write_to_mem(file, share_data):
    with contextlib.closing(mmap.mmap(file.fileno(), 1024, access=mmap.ACCESS_WRITE)) as mem:
        mem.seek(0)
        mem.write(share_data.encode())
        mem.write('\x00'.encode() * (1024 - len(share_data.encode())))
        mem.flush()


with open('data.dat', 'w') as f:
    f.write('\x00' * 1024)

file = open('data.dat', 'r+')
write_to_mem(file, 'hello')

Here we created a 1026 bytes file, which will be mapped to memory.

Read from shared memory

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#!/usr/bin/python3
import mmap
import contextlib
import time

with open('data.dat', 'r') as f:
    with contextlib.closing(mmap.mmap(f.fileno(), 1024, access=mmap.ACCESS_READ)) as mem:
        s = mem.read(1024)
        print(s)

Here we mapped data.dat file to memory and read from it.