Operating System Concepts Chapter 3: Processes

Questions and Answers

What happens to a child process if its parent terminates?

All child processes are terminated due to cascading termination. (correct)

Only the child process terminates if it has completed its task.

The child continues execution independently.

The child is allowed to run but cannot communicate with the parent.

Which system call can a parent use to terminate a child process?

abort() (correct)

exit()

wait()

kill()

What is a possible reason for a parent process to abort a child process?

The child has completed its tasks successfully.

The child has exceeded its allocated resources. (correct)

The parent process has received an external request.

The child process is performing optimally.

What is indicated if a child process cannot continue after its parent terminates?

Cascading termination is enforced by the operating system. Signup and view all the answers

How does a parent process wait for the termination of its child processes?

By utilizing the wait() system call. Signup and view all the answers

Which statement about child processes is NOT true?

Child processes can run independently of their parent. Signup and view all the answers

What are the two primary operations provided by the interprocess communication facility?

send(message) and receive(message) Signup and view all the answers

Which of the following is NOT a consideration when implementing communication links between processes?

What programming language should be used? Signup and view all the answers

When two processes want to communicate, what must they first establish?

A communication link Signup and view all the answers

In a message passing system, what determines if processes can effectively communicate?

The existence of a communication link Signup and view all the answers

Which aspect of message passing defines how many processes can share a communication link?

Link association Signup and view all the answers

What is a possible characteristic of links in message passing systems?

Links can be either unidirectional or bidirectional Signup and view all the answers

What describes a process in an operating system?

A program in execution that can include multiple execution threads. Signup and view all the answers

Which of the following is NOT a state of a process?

Paused Signup and view all the answers

What is included in the Process Control Block (PCB)?

Information about process state and scheduling. Signup and view all the answers

What role does the short-term scheduler play in process management?

Selects which process should be executed next on the CPU. Signup and view all the answers

What happens during a context switch?

The current process state is saved and the new process state is loaded. Signup and view all the answers

What is the main function of process creation in an operating system?

To create a hierarchy of processes managed by a main process. Signup and view all the answers

In UNIX systems, which system call is used to create a new process?

fork() Signup and view all the answers

How do I/O-bound processes generally operate compared to CPU-bound processes?

They perform many short CPU bursts and spend more time doing I/O. Signup and view all the answers

What is a characteristic of a long-term scheduler?

Controls the degree of multiprogramming. Signup and view all the answers

What is one of the functions of interprocess communication (IPC)?

To enable processes to share memory directly. Signup and view all the answers

What happens to a process if its parent terminates without invoking wait()?

It becomes an orphan process. Signup and view all the answers

Which of the following is NOT a type of process in the Google Chrome multiprocess architecture?

Server process Signup and view all the answers

Which is a reason for using cooperating processes?

Increasing computation speedup Signup and view all the answers

What is the primary purpose of the renderer process in Chrome?

Render web pages and handle HTML. Signup and view all the answers

What status information does the call wait() return?

Pid of the terminated process and status information. Signup and view all the answers

Which interprocess communication model involves sharing a common memory area?

Shared memory Signup and view all the answers

What is the function of the browser process in Google Chrome?

Manage the user interface and I/O operations. Signup and view all the answers

What occurs if no parent process invokes wait() for a terminated process?

The process becomes a zombie. Signup and view all the answers

What is the purpose of the handle that the server returns to the client?

To facilitate message exchange through a specific port Signup and view all the answers

Which of the following statements about sockets is true?

A socket is a combination of IP address and port number Signup and view all the answers

What type of socket allows data to be sent to multiple recipients in Java?

MulticastSocket Signup and view all the answers

What is the primary function of stubs in Remote Procedure Calls?

To act as proxies for procedures on the server Signup and view all the answers

What does External Data Representation (XDL) account for in remote communication?

Data format between different architectures Signup and view all the answers

What is the primary issue with communication via pipes?

The direction of communication can vary Signup and view all the answers

Which of the following best describes the connection between two sockets?

It consists of a one-to-one communication channel Signup and view all the answers

What is the significance of ports below 1024?

They are well-known ports used for standard services Signup and view all the answers

What enhances the reliability of remote communication in RPC?

Messages can be delivered exactly once Signup and view all the answers

What role does the rendezvous service play in remote communication?

It connects clients and servers Signup and view all the answers

Study Notes

Process Concept

A process is a program in execution, consisting of program code, current activity (including the program counter and processor registers), stack (temporary data), data section (global variables), and heap (dynamically allocated memory).
Execution begins when an executable file is loaded into memory, distinguishing a process from a passive program stored on disk.
Multiple processes can derive from the same program, especially with multiple users executing the same application.

Process States

Processes can be in various states:
- New: Creating process.
- Running: Executing instructions.
- Waiting: Awaiting an event.
- Ready: Prepared to execute when assigned to a processor.
- Terminated: Finished execution.

Process Control Block (PCB)

PCB stores essential information for each process, including:
- Process state (e.g., running or waiting).
- Program counter location.
- Contents of CPU registers.
- CPU scheduling information (e.g., priorities).
- Memory management data (allocated memory).
- Accounting info (CPU usage, elapsed time).
- I/O status information (allocated devices, open files).

Process Scheduling

Objective: Maximize CPU utilization and facilitate quick process switching for time-sharing.
Scheduling queues include:
- Job queue: All processes in the system.
- Ready queue: Processes in memory, ready to execute.
- Device queues: Processes waiting for I/O devices.
Processes can migrate among these queues.

Types of Schedulers

Short-term scheduler (CPU scheduler): Selects the next process for execution; called frequently and must operate quickly.
Long-term scheduler (job scheduler): Determines which processes to bring into the ready queue; invoked infrequently and may operate slowly.
Processes are either I/O-bound (frequent short CPU bursts) or CPU-bound (few long CPU bursts).

Context Switching

A context switch occurs when the CPU switches processes, saving the state of the old process and loading the new one's state.
Context-switch time is an overhead, reducing efficiency, particularly in complex systems.
Hardware support affects speed; some CPUs provide multiple register sets for faster context switches.

Process Operations

Operating systems must manage process creation, termination, and other aspects for effective resource handling.
Processes are identified and managed through a unique process identifier (pid).

Process Creation

Parent processes create child processes, forming a hierarchical structure.
Child processes can share resources with the parent or operate independently, either concurrently or waiting for termination.
System calls like fork() create new processes, while exec() replaces the current process’s memory space.

Process Termination

A process terminates using the exit() system call, which also passes status data to the parent.
The parent can terminate child processes using abort(), especially if resources are exceeded or tasks are no longer necessary.
Cascading termination occurs when a parent process exits, leading to the termination of all its children.

Interprocess Communication (IPC)

IPC allows processes to share data and synchronize activities.
Cooperating processes require IPC to share information, speed up computation, and enhance modularity.
Two IPC models are:
- Shared memory: Processes communicate through shared variables.
- Message passing: Processes communicate without shared variables using send/receive operations.

Message Passing Mechanism

Processes establish communication links and exchange messages to synchronize actions.
The IPC facility provides operations for sending and receiving messages, which can vary in size.
Key implementation issues include link establishment, capacity, unidirectionality vs. bidirectionality, and message size limits.### Client-Server Communication
A client initiates a connection by sending a request to a server.
The server responds by creating two private communication ports and provides the client with the handle to one.
Client and server use the port handle for message exchange and listening for replies.

Communication Mechanisms in Client-Server Systems

Various methods include:
- Sockets
- Remote Procedure Calls (RPC)
- Pipes
- Remote Method Invocation (Java)

Understanding Sockets

A socket serves as an endpoint for communication, represented by a combination of an IP address and port number.
Example: Socket 161.25.19.8:1625 indicates using port 1625 on a host with IP address 161.25.19.8.
Communication occurs between a pair of sockets; ports below 1024 are designated as "well-known" for standard services.
The loopback address 127.0.0.1 is used to refer to the local system.

Socket Types in Java

Java supports three socket types:
- Connection-oriented (TCP): Establishes a reliable connection.
- Connectionless (UDP): Does not establish a connection prior to sending data.
- MulticastSocket: Allows data to be sent to multiple recipients simultaneously.

Remote Procedure Calls (RPC)

RPC simplifies the process of invoking procedures across networked systems.
Uses port numbers to differentiate services.
Stubs function as client-side proxies to the actual server procedure.
The client-side stub finds the server, marshals parameters, while the server-side stub unpacks them for execution.

Data Representation in RPC

External Data Representation (XDL) is utilized to manage data across different architectures (big-endian and little-endian).
RPC entails more complex failure scenarios than local calls, ensuring messages can be delivered exactly once rather than potentially being lost.

Additional Features of RPC

Operating systems often provide a rendezvous (matchmaker) service to facilitate client-server connections.

Pipes

Pipes function as conduits for communication between processes.
Important considerations include whether the communication is unidirectional or bidirectional.

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Description

Explore the fundamental concepts of processes in operating systems through this quiz based on Chapter 3 of 'Operating System Concepts'. Understand process scheduling, interprocess communication, and IPC systems, including client-server communication examples. Test your knowledge and grasp of these critical topics!