Chapter 6 : Process and Threads

Question 1

What is a process?

Answer 1

1. A process is a program in execution, consisting of the program code, data and system resources

Question 2

List out 3 key characteristics of processes

Answer 2

1. Own memory space
2. Isolated from other processes
3. Managed by the OS

Question 3

List out 5 state of processes

Answer 3

1. New
   
   • Process is being created
2. Ready
   
   • Process is waiting to be assigned to a processor
3. Running
   
   • Process instructions are being executed
4. Waiting
   
   • Process is waiting for some event to occur
5. Terminated
   
   • Process has finished execution

Question 4

What is the full name for IPC?

Answer 4

1. Inter-Process Communication

Question 5

How does IPC allows processes to communicate and synchronize their actions effectively?

Answer 5

1. IPC mechanisms includes shared memory and message passing

Question 6

What is a threads inside a processes?

Answer 6

1. A thread is the smallest unit of execution within a process

Question 7

What does threads share?

Answer 7

1. It shares the process’s resources

• But it operates independently

Question 8

List out 3 characteristics of Threads

Answer 8

1. Shares memory space with other threads in the same process
2. Has its own stack and registers
3. Faster to create and manage compared to processes

Question 9

What is the difference between memory space in Threads and Processes?

Answer 9

1. Processes
   
   • Separate memory space
2. Threads
   
   • Shared memory within the same process

Question 10

What is the difference between communication in Threads and Processes?

Answer 10

1. Processes
   
   • IPC Needed
2. Threads
   
   • Direct communication via shared memory

Question 11

What is the difference between creation in Threads and Processes?

Answer 11

1. Processes
   
   • Slower to Create
2. Threads
   
   • Faster to Create

Question 12

What is the difference between overhead in Threads and Processes?

Answer 12

1. Processes
   
   • Higher overhead due to isolation
2. Threads
   
   • Lower overhead

Question 13

What is Multithreading?

Answer 13

1. Is the ability of a CPU or a single core within a CPU to execute multiple threads concurrently

Question 14

What is the advantages of Multithreading?

Answer 14

1. Improves Application Performance
2. Efficient use of CPU resources
3. Facilitates responsive applications

Question 15

List out 2 example applications tha is using Multithreading

Answer 15

1. Web Servers
2. Modern Operating Systems

Question 16

Why do we need synchronization techniques for process and thread?

Answer 16

1. To avoid race conditions and ensure data consistency when multiple threads/processes access shared recourses

Question 17

List out 4 common synchronization techniques forprocess and thread synchronization

Answer 17

1. Mutexes
2. Semaphores
3. Monitors
4. Locks

Question 18

List out 2 benefits of using threads

Answer 18

1. Improved performance and resource allocation
2. Simplifies program structure for concurrent tasks

Question 19

List out 2 challenges for threads

Answer 19

1. Complexity in synchronization and avoid deadlocks
2. Difficulty in debugging multithreaded applications

Question 20

List out 2 types of Threads in the Operating System

Answer 20

1. User Threads
   
   • Managed by user applications
2. Kernel Threads
   
   • Managed by Kernel

Question 21

List out 3 user threads

Answer 21

1. POSIX Pthreads
2. Windows Threads
3. Java Threads

Question 22

List out 5 Kernel Threads

Answer 22

Virtually all General Purpose Operating System
1. Windows
2. Solaris
3. Linux
4. Tru64 UNIX
5. Mac OS X

Question 23

List out three Multithreading Models

Answer 23

1. Many to One
2. One to One
3. Many to Many

Question 24

What does Many to One mean in Multhithreading Model?

Answer 24

1. Many user-level threads mapped to single kernel thread

• Few Systems currently use this model

Question 25

List out 2 examples for Many-To-One Multhreading Model

Answer 25

1. Solaris Green Threads 2. GNU Portable Threads

Question 26

What does One-to-One mean in Multithreading Model?

Answer 26

1. Each user-level thread maps to kernel thread * Creating a user-level thread creates a kernel thread

Question 27

What is the difference between Many to One and One to One in Multhreading Model?

Answer 27

1. One to One provide more concurrency than many to one

Question 28

What are the disadvantages of One to One Mulithreading Model?

Answer 28

1. Number of threads per process sometimes restricted due to overhead

Question 29

List out 3 examples for Multhreading Model

Answer 29

1. Windows 2. Linux 3. Solaris 9 and later

Question 30

What does Many-to-Many mean in Multithreading Model?

Answer 30

1. Allows many user level threads to be mapped to many kernel threads 2. Allows the OS to create a sufficient number of kernel threads * Example 1. Solaris ( UNIX ) Prior to Version 9 2. Windows with the ThreadFiber package

Question 31

What does Thread Library provides to programmer?

Answer 31

1. With API for creating and managing threads

Question 32

List out 2 ways that programmer implement thread library

Answer 32

1. Library entirely in user space 2. Kernel-level Library supported by the OS

Question 33

List out 2 methods of aborting process / threads to eliminate deadlocks

Answer 33

1. Abort all Deadlocked processes 2. Abort one process at a time until the deadlock is resolved * Then reclaim all resources from terminated processes