Overview

Inter-Process Communication (IPC) is a set of mechanisms provided by the operating system to allow processes to communicate and synchronize their actions. Since processes have isolated memory spaces, they cannot simply read/write to each other’s variables.

Core Concepts

• Shared Memory:
  • Two or more processes map the same region of physical memory into their own address spaces.
  • Pros: Fastest IPC method.
  • Cons: Requires synchronization (e.g., mutexes, semaphores) to avoid race conditions.
• Message Passing:
  • Processes communicate by sending and receiving messages.
  • Pipes: Unidirectional communication channels (e.g., ls | grep).
  • Message Queues: Asynchronous communication using a queue.
  • Sockets: Bidirectional communication over a network or locally (Unix Domain Sockets).
• Synchronization Primitives:
  • Mutex (Mutual Exclusion): A lock that only one process can hold at a time.
  • Semaphore: A counter that allows a limited number of processes to access a resource.
  • Condition Variable: Allows a process to sleep until a specific condition is met.
• Deadlock: A state where two or more processes are blocked forever, each waiting for the other to release a resource.

Code Examples

# Example of Pipe IPC in Bash
ls -la | grep ".md"

L

Example of a local socket (conceptual)

server.sock = socket.create(“unix”)

server.bind(“/tmp/server.sock”)

server.listen()

client.connect(“/tmp/server.sock”)