Process management (running programs) in Intro to Computing - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ trace

intermediate

Trace the process states during program execution

Consider a program that is loaded into memory and executed by the CPU. Which sequence correctly shows the typical states a process goes through from start to finish?

A 1,3,2,4,5

B 1,2,3,4,5

C 2,1,3,4,5

D 1,2,4,3,5

💡 Hint

Think about the order: a process is created, waits to run, runs, may wait for input/output, then finishes.

The typical process lifecycle starts with creation (New), then moves to Ready state waiting for CPU time, then Running when executing. If it needs to wait for input/output, it goes to Waiting, and finally ends in Terminated.

🧠 Conceptual

intermediate

Identify the role of the process scheduler

What is the main job of the process scheduler in an operating system?

A To manage file storage on the hard drive

B To load programs from disk into memory

C To decide which process runs next on the CPU

D To handle user input from keyboard and mouse

💡 Hint

Think about how the CPU chooses which program to run when multiple are ready.

The process scheduler manages CPU time by selecting which process to run next, ensuring fair and efficient use of the CPU.

❓ Comparison

advanced

Compare process and thread differences

Which of the following statements correctly distinguishes a process from a thread?

A A process has its own memory space; threads share memory within the same process

B Threads have separate memory spaces; processes share memory

C Processes run only one at a time; threads run simultaneously

D Threads are independent programs; processes are parts of a program

💡 Hint

Consider how memory is allocated and shared between processes and threads.

Processes have separate memory spaces, so they do not share data directly. Threads run inside a process and share the same memory, allowing faster communication but requiring careful synchronization.

❓ identification

advanced

Identify the cause of a zombie process

What causes a process to become a zombie in an operating system?

A The process is waiting for input/output to complete

B The process is blocked due to a deadlock

C The process is currently running on the CPU

D The process has finished execution but its parent has not yet read its exit status

💡 Hint

Think about what happens after a process ends but before the system cleans it up.

A zombie process is one that has completed execution but still has an entry in the process table because its parent process has not yet collected its exit status.

🚀 Application

expert

Determine the output of process ID code snippet

Given the following Python code snippet that uses the os module to create a child process, what will be printed?

import os
pid = os.fork()
if pid == 0:
    print(f"Child process: {os.getpid()}")
else:
    print(f"Parent process: {os.getpid()}, child PID: {pid}")

Intro to Computing

import os
pid = os.fork()
if pid == 0:
    print(f"Child process: {os.getpid()}")
else:
    print(f"Parent process: {os.getpid()}, child PID: {pid}")

A Two lines printed: one from child showing its PID, one from parent showing its PID and child's PID

B Only one line printed from the parent process showing its PID

C Only one line printed from the child process showing its PID

D SyntaxError because os.fork() is not valid in Python

💡 Hint

Remember that os.fork() creates a new process that runs the same code after the fork.

The os.fork() call creates a child process. The child process gets 0 as the return value, so it prints its own PID. The parent gets the child's PID and prints both its own PID and the child's PID. Thus, two lines are printed.