Multithreading vs Multitasking

Aspect	Multitasking	Multithreading
Definition	Running multiple tasks or processes simultaneously.	Running multiple threads (smaller units of a process) simultaneously within a single process.
Level	Operates at the OS level (processes).	Operates at the program or application level (threads).
Resource Sharing	Each task has its own memory and resources.	Threads share the same memory and resources within the parent process.
Overhead	Higher, as creating and managing processes is resource-intensive.	Lower, as threads share resources and are lightweight compared to processes.
Communication	Inter-process communication (IPC) is required and more complex.	Easier communication since threads share memory and resources.
Efficiency	Less efficient for closely related tasks due to overhead.	More efficient for closely related tasks as threads operate in the same process.
Example	Running a web browser, media player, and text editor at the same time.	A web browser running multiple tabs, where each tab is handled by a separate thread.
Use Case	Ideal for independent tasks (e.g., running separate applications).	Ideal for tasks that need to share data or context (e.g., a game engine handling rendering and logic).
Context Switching	Requires a full process context switch, which is slower.	Thread context switching is faster as threads share process-level resources.

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Practical Examples:

Multitasking Example:

1. Scenario: You’re working on your computer, streaming music, browsing the internet, and editing a document.

2. Behavior: The operating system allocates CPU time to each task, giving the appearance that all tasks are running simultaneously.

Multithreading Example:

1. Scenario: Your web browser has multiple open tabs.

2. Behavior: Each tab runs in a separate thread, allowing you to load content in one tab while scrolling in another.

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Interview Questions:

1. Q: What are the key differences between multitasking and multithreading? A: Multitasking involves running multiple processes simultaneously, while multithreading runs multiple threads within a single process. Multitasking has higher overhead and resource usage due to process isolation, whereas multithreading is more lightweight and allows threads to share resources.

2. Q: Which is more efficient for tasks requiring shared data, and why? A: Multithreading is more efficient for tasks requiring shared data because threads share the same memory space and resources, allowing faster communication and lower overhead.

3. Q: Can multithreading be used in multitasking systems? A: Yes, multithreading can operate within multitasking systems. For example, in a multitasking OS, a single application can use multithreading to perform parallel operations internally.