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📧 Interprocess Communication: Shared Memory

🎯 Learning Objective

Understand interprocess communication (IPC) mechanisms using shared memory.
Identify the role of the operating system in managing network connections.

📜 Statement

In this exercise, you will create two Python modules for

🔧 Step 1 – Writer Module

Create a file called writer.py and copy the following code:

# writer.py
from multiprocessing import shared_memory
import time

# Create a new shared memory block
shm = shared_memory.SharedMemory(name="demo_shm", create=True, size=1024)

# Write some bytes
shm.buf[:10] = b"Hello IPC!"

print("Writer: wrote to shared memory.")
time.sleep(60)  # Give reader time to read it

# Clean up
shm.close()
shm.unlink()  # Only the creating process should unlink

💬 Step 2 – Reader Module

Create a file reader.py:

# reader.py
from multiprocessing import shared_memory

# Connect to existing shared memory
existing_shm = shared_memory.SharedMemory(name="demo_shm")

# Read from it
data = bytes(existing_shm.buf[:11])
print("Reader: read from shared memory:", data.decode())

existing_shm.close()

🔁 Step 3 – Test

To test, open two terminals. In the first terminal, run the writer.py module:

python writer.py

In the second terminal, run the reader.py module:

python reader.py

📝 Step 4 – The Operating System

What is the role of the operating system in managing shared memory?
Which processes can access the shared memory named demo_shm?
What happens if the writer.py process finishes before reader.py can read the data?
Does the operating system manage synchronization between processes accessing shared memory?

🎯 Learning Objective
📜 Statement