Multitasking allows a computer to handle many different jobs at once. This makes your programs feel smooth and allows them to perform multiple actions simultaneously.

Computer Multitasking Basics

A thread is like a single worker following a list of instructions. A single program can have many workers, or threads, helping it finish tasks faster.

Tiny Paths of Work

Concurrency is switching between tasks very quickly to look like they are running at once. Parallelism is when the computer actually does two things at the exact same moment.

Taking Turns vs Simultaneous

Every app has a primary path of work that handles what you see on the screen. If this task gets too busy with a heavy job, the app will appear to freeze.

The Main Control Task

A lock ensures that only one worker can change a specific piece of information at a time. This prevents errors that happen when two tasks try to edit the same data at once.

Using Digital Locks

This occurs when two tasks compete to update the same information at the same time. The result is often messy or incorrect because the tasks interfered with each other.

The Data Race Problem

A deadlock happens when two tasks are stuck waiting for each other to finish, causing the program to stop. It is like two people blocking a narrow hallway, each waiting for the other to move first.

The Deadlock Freeze

The computer swaps between different jobs so fast that they seem to happen all at once. This clever trick allows one brain to handle dozens of different requests effectively.

Rapid Task Switching

A worker pool is a group of tasks already created and waiting for an assignment. This saves the computer's energy because it doesn't have to hire a new worker for every tiny job.

Pre-Hired Worker Teams

An atomic action is a step that happens all at once without any interruptions. It ensures a change is either completely finished or not started at all, with no halfway state.

One Simple Action

Many apps perform heavy work behind the scenes so the screen remains responsive. This allows you to keep typing while the computer saves a file or downloads an update.

Invisible Background Tasks

Tasks often need to communicate to stay coordinated. They do this by leaving notes for each other in the computer's memory or by sending digital messages.

Sharing Important Information

Sometimes a task needs to pause until a timer goes off or another job finishes. This prevents the task from wasting the computer's power while there is nothing to do.

Waiting and Sleeping

The computer decides which jobs are most urgent and should be finished first. This ensures that clicking a button happens instantly, even if the computer is busy with other work.

Setting Task Importance

Once a job is complete, the computer must properly close that path of work. This cleans up the system and makes room for new tasks to start.

The Hiring Problem