Inter Process Communication (IPC) in OS

By : Nathaniel Brooks Nathaniel Brooks
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⚡ Smart Summary

Inter-process communication (IPC) is a set of operating system mechanisms that let processes and threads exchange data, coordinate activities, and synchronize actions, whether they run on one computer or across several machines connected by a network.

  • 🔗 Definition: IPC lets concurrent processes exchange data and coordinate work, so one program can handle many user requests at the same time.
  • 🛠️ Methods: Common approaches include pipes, message passing, message queues, direct and indirect communication, shared memory, and FIFOs.
  • 🧠 Two models: Shared memory is the fastest approach but needs synchronization, while message passing is safer and works across networked machines.
  • 🔔 Key terms: Semaphores signal and control resource access, while signals notify a destination process identified by a number.
  • ⚙️ Why it matters: IPC supports modularity, computational speedup, privilege separation, and convenient data sharing between processes.
  • 🤖 AI angle: Distributed AI systems rely on message passing between services, and Copilot helps generate pipe, socket, and shared-memory code.
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Inter Process Communication (IPC) in OS

What is Inter Process Communication?

Inter process communication (IPC) is used for exchanging data between multiple threads in one or more processes or programs. The processes may be running on a single computer or on multiple computers connected by a network. The full form of IPC is inter-process communication.

It is a set of programming interfaces that allow a programmer to coordinate activities among various program processes, which can run concurrently in an operating system. This allows a single program to handle many user requests at the same time.

Since every user request may result in multiple processes running in the operating system, these processes may need to communicate with each other. Each IPC approach has its own advantages and limitations, so it is not unusual for a single program to use several of the IPC methods.

Approaches for Inter-Process Communication

Here are a few important methods for inter-process communication:

Approaches for Inter-Process Communication

Inter-Process Communication Approaches

Pipes

A pipe is widely used for communication between two related processes. This is a half-duplex method, so the first process communicates with the second process. However, to achieve full-duplex communication, another pipe is needed.

Message Passing

It is a mechanism for a process to communicate and synchronize. Using message passing, processes communicate with each other without resorting to shared variables.

The IPC mechanism provides two operations:

  • Send (message) — the message size can be fixed or variable
  • Receive (message)

Message Queues

A message queue is a linked list of messages stored within the kernel. It is identified by a message queue identifier. This method offers communication between single or multiple processes with full-duplex capacity.

Direct Communication

In this type of inter-process communication, processes must name each other explicitly. In this method, a link is established between one pair of communicating processes, and between each pair, only one link exists.

Indirect Communication

Indirect communication is established only when processes share a common mailbox. Each pair of processes can share several communication links, and a single link can communicate with many processes. The link may be bidirectional or unidirectional.

Shared Memory

Shared memory is a region of memory shared between two or more processes. This memory must be protected from concurrent access by synchronizing the processes that use it.

FIFO

FIFO is used for communication between two unrelated processes. It is a full-duplex method, which means that the first process can communicate with the second process, and the opposite can also happen.

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Why IPC?

Here are the reasons for using the inter-process communication protocol for information sharing:

  • It helps to speed up modularity.
  • Computational speedup.
  • Privilege separation.
  • Convenience.
  • It helps processes and the operating system communicate and synchronize their actions.

Terms Used in IPC

The following are a few important terms used in IPC:

Semaphores: A semaphore is a signaling mechanism. This OS method either allows or disallows access to a resource, depending on how it is set up.

Signals: A signal is a method of communicating between multiple processes by way of signaling. The source process sends a signal, which is recognized by a number, and the destination process handles it.

Reading Suggestion: What is Semaphore? Binary, Counting Types with Example

What is Like FIFOS and Unlike FIFOS

The following table compares like FIFOs and unlike FIFOs:

Like FIFOS Unlike FIFOS
It follows the FIFO method. It uses a method to pull specific urgent messages before they reach the front.
FIFO exists independently of both the sending and receiving processes. Always ready, so there is no need to open or close it.
Allows data transfer among unrelated processes. Does not have any synchronization problems between open and close.

FAQs

A socket is a communication endpoint identified by an IP address and a port number. Sockets let processes exchange data on the same machine or across a network, which makes them a common IPC method in distributed and client-server systems.

When processes share resources such as memory, synchronization keeps their access ordered. It prevents race conditions and inconsistent data by using tools like semaphores, mutexes, and locks so that only one process updates shared data at a time.

A pipe connects two related processes, is unnamed, and exists only while those processes run. A named pipe, or FIFO, has a name in the file system, persists after the processes end, and allows unrelated processes to communicate.

The kernel creates and manages IPC objects such as message queues, shared-memory segments, and semaphores. It enforces access permissions and, for message passing, copies data between processes so they can communicate safely without direct access to each other’s memory.

A race condition happens when two or more processes access shared data at the same time and the result depends on their timing. Proper synchronization with semaphores or locks prevents the inconsistent output a race condition can cause.

AI systems split work across many processes, so message passing and shared memory move data between data-loading, training, and model-serving components. Distributed machine learning frameworks rely on IPC to coordinate GPUs and services across networked machines.

Yes. GitHub Copilot can generate pipe, socket, message-queue, and shared-memory examples in C, Python, or Java, along with the synchronization logic. Developers should still test the code for deadlocks, race conditions, and correct cleanup of IPC resources.

IPC is the general set of methods that let processes exchange data on one machine or a network. Remote Procedure Call (RPC) is one such method that lets a program call a procedure in another process or on a remote machine as if it were local.

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