from multiprocessing import shared_memory
import struct
import sys

def connect_shm(name):
    shm_r = shared_memory.SharedMemory(name)
    print("Attached to shared memory")
    print(struct.unpack("i", bytes(shm_r.buf[0:4])))

    shm_r.close()

def create_shm(name, spin=False):
    shm_c = shared_memory.SharedMemory(name=name, create=True, size=4096*5)

    print("Created shared memory")

    buf = shm_c.buf

    buf[0:4] = struct.pack("i", 4096)

    shm_c.close()

if __name__ == "__main__":
    mode = sys.argv[1]

    name = "test"

    if mode == "-create":
        create_shm(name, True)
    elif mode == "-attach":
        connect_shm(name)

python3.8 shm.py -create
python3.7 shm.py -attach