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In Linux, when a project is large, it may be divided into multiple project groups. Different groups need to communicate and collaborate to complete the project successfully. This requires an effective communication mechanism between project groups. There are various ways for project groups to communicate, and we will plan them one by one.
Imagine a large-scale web application project where:
- Project Group A is responsible for the web server.
- Project Group B is responsible for the database service.
These two groups need a mechanism to communicate efficiently. One common way to achieve this in Linux is using sockets for IPC.
Linux Message Queues
A Message Queue is a form of Inter-Process Communication (IPC) that allows processes (or different project groups) to exchange messages asynchronously. Unlike sockets or shared memory, message queues do not require direct process synchronization, making them a buffered and persistent way to communicate between processes.
In Linux, message queues are managed within the kernel, which means they persist even if the sending or receiving process terminates.
Key Advantages of Message Queues
✅ Asynchronous Communication — The sender doesn’t need to wait for the receiver to be available.
✅ Kernel-Managed — Messages persist even if the sender or receiver process crashes.
✅ Efficient for Short Messages — Ideal for small text-based communications.
Limitations of Message Queues
❌ Limited Size — The size of messages is constrained by system settings (msgmax).
❌ More Overhead – Since messages are stored in the kernel, they are slightly slower than shared memory.
❌ Not Suitable for Large Data – Better alternatives like shared memory exist for large file or data exchange.
Examples
This is a simple example where one process (sender) sends a message, and another process (receiver) retrieves it using System V message queues.
