Interprocess Communication in Operating Systems

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Questions and Answers

What is a primary reason for processes to cooperate within a system?

Simplifying process management

Resource starvation

Information sharing (correct)

Data independence

Which of the following models of interprocess communication allows processes to share data directly?

Remote procedure calls

Client-server communication

Message passing

Shared memory (correct)

Which system call is NOT typically used for creating processes in an operating system?

exec()

wait()

terminate() (correct)

fork()

In a system, what is a characteristic of cooperating processes compared to independent processes?

They may affect each other's execution. Signup and view all the answers

Which of the following cannot be used for interprocess communication?

Files Signup and view all the answers

What are the two primary operations provided by the IPC facility for message passing?

send and receive Signup and view all the answers

What characteristic of a direct communication link typically holds?

A link is associated with exactly two processes Signup and view all the answers

Which type of communication relies on sharing a common mailbox?

Indirect communication Signup and view all the answers

In the context of indirect communication, what happens if multiple processes share a mailbox?

Only one process can receive messages from the mailbox Signup and view all the answers

Which statement accurately describes the capacity of communication links in message passing?

Links can have variable capacity depending on implementation Signup and view all the answers

What does the term 'counter' represent in the provided producer-consumer code?

The number of items in the buffer Signup and view all the answers

What potential issue is highlighted by the interleaving execution example?

Race condition caused by simultaneous access to counter Signup and view all the answers

In the code snippet for the consumer, what does 'next_consumed = buffer[out];' signify?

Removing an item from the buffer Signup and view all the answers

Why does the race condition not occur in the first solution of the producer-consumer problem?

Counter operations are atomic Signup and view all the answers

What is the purpose of incrementing 'in' using 'in = (in + 1) % BUFFER_SIZE;' in the producer code?

To manage circular buffering Signup and view all the answers

What happens during a blocking send operation?

The sender is blocked until the message is sent and received. Signup and view all the answers

Which of the following describes a non-blocking receive operation?

The receiver can either get a valid message or a null message. Signup and view all the answers

How many processes can be associated with a message link at most?

At most two processes can be associated with a single message link. Signup and view all the answers

What type of message buffering allows the sender to wait until the receiver is ready?

Zero capacity buffering. Signup and view all the answers

What is the result of having both send and receive operations configured as blocking?

A rendezvous occurs, blocking both processes until the message is exchanged. Signup and view all the answers

Study Notes

Chapter 3: Processes

Processes in an operating system are represented and scheduled in various ways.
Processes are created and terminated using system calls.
Processes can communicate through Interprocess Communication (IPC).
Two models of IPC are: shared memory and message passing.
The Producer-Consumer problem demonstrates cooperating processes.
Two variations of the producer-consumer problem are unbounded-buffer and bounded-buffer.
In shared memory, processes access a dynamically allocated shared memory block.
In message passing, processes send messages to each other.
A race condition occurs when multiple processes access and modify shared data concurrently.
Solutions for avoiding race conditions in shared memory systems exist.
IPC methods exist as a message passing capability..
Communication links can be established in various ways: direct and indirect communication methods
Direct communication links are associated with only one pair, while indirect communication links use mailboxes or ports.

IPC in Shared Memory

Shared memory is an area of memory that processes use to communicate without operating system intervention
Synchronization mechanisms are necessary for controlling access to the shared memory to avoid race conditions.
These mechanisms ensure consistency and prevent data corruption.
Synchronization is discussed in depth in Chapters 6 and 7.

Bounded-Buffer – Shared-Memory Solution

A fixed-size buffer is used for communication between producer and consumer processes.
A counter tracks full buffers

Producer Process (Shared Memory)

The producer continually produces items.
It checks if the buffer is full. If it's not, it adds the produced item to the buffer and increments the in-counter,

Consumer Process (Shared Memory)

The consumer continually consumes items.
It checks if the buffer is empty. If it's not, it takes the item from the buffer and increments the out-counter.

IPC – Message Passing

Processes use messages to communicate.
Functions send(message) and receive(message) are used to exchange messages
Message size is either fixed or variable.
Communication links can use different implementations: direct and indirect methods.

Message Passing (Cont.)

Processes establish a communication link to exchange messages.
Implementation issues: links, number of links between communicating processes, capacity of a link and its directionality.

Synchronization

Message passing can be blocking or non-blocking. (synchronous or asynchronous).
Blocking operations block the sender until the message is received.
Non-blocking operations let the sender continue without waiting.

Producer-Consumer: Message Passing

The producer sends messages containing produced items.
The consumer receives messages, consumes the items and acknowledges.

Buffering

Message queues are used for buffering, implementing message queue capacities.
There are three types of ways messages can be buffered: zero capacity,bounded capacity and unbounded capacity queues.

Examples of IPC Systems – Windows

Windows uses the LPC (Local Procedure Call) facility.
Communication channels are established using ports.

Sockets

A socket is an endpoint for communication combining IP address with a port number used by various network services.
Windows uses sockets for inter-process communication.

Socket Communication

Sockets allow communication between processes on different machines.

Sockets in Java

Java has socket classes for various kinds of socket communications

Remote Procedure Calls (RPC)

RPC abstracts procedure calls between processes over a network
Uses ports for differentiation between services and stubs (client-side proxy).

Remote Procedure Calls (Cont.)

The client stub locates the server and marshals parameters
Server stub unpacks the marshalled parameters and executes the procedure on the server.

Execution of RPC

A detailed description is shown on how each of the stages in the RPC process proceeds.

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Description

This quiz explores the concepts of interprocess communication (IPC) in operating systems, including the characteristics and types of communication between processes. It covers various models and system calls related to process cooperation and message passing mechanisms. Test your knowledge on key IPC operations and typical issues faced in these systems.