Threading Simplified - Part 2 (Multithreading Concepts)

In case, you have not had a look at our first article, go through the following link:

Threading Simplified: Part 1

Before multithreading, let's talk about some other related concepts.

Multiprogramming

It is the core concept behind multithreading today. Multiprogramming is the ability to load multiple programs into memory and execute them when required. The term multiprogramming is usually used in single processor environments.

The idea of multiprogramming arises from a notion to keep the CPU busy as much as possible. To understand how it works, you can see an example when a program or Job1 is awaiting I/O and then Job2 takes the CPU time and so on to keep the CPU busy.

Multitasking is a natural extension of multiprogramming where all the non-blocked or active jobs are allocated the time on a sharing basis. Multitasking helps to mimic the parallelism by allocating time to all the active jobs.

There are various kinds of algorithms available for time scheduling, for example, Round robin and FIFO.

These days most computers or even smaller devices such as smart phones and tablets are designed to support multitasking. The simplest example of multitasking is running media players, typing emails in Outlook and at the same time, responding to someone in the Lync.

In the following example, Job 2, Job 3 and though to Job n are allocated a time slice based on the selected time scheduling algorithm.