What is Multitasking in Smartphones?

Understanding How Multitasking Works on the iPhone and Android

Multitasking on Apple iPhone
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A multitasking operating system is one that allows more than one program or app to run on it simultaneously. We live the multitasking experience every day when we use computers. Here is a typical scenario: you are typing a word processing document while having a file downloading and some cool music playing in the background, all simultaneously. These are apps that you have launched yourself, but there are others that run in the background without you knowing.

Fire up the task manager and you will see.

Multitasking requires the operating system to diligently, even surgically, manage how instructions and processes are handled in the microprocessor, and how their data are stored in main memory.

Now consider your old mobile phone. You could do only one thing at a time on it. This is because the operating system running on it does not support multitasking. Multitasking has come to smartphones, especially in the iPhone (in iOS rather) and Android, but it does not work exactly the same way as in computers.

Multitasking in Smartphones

Here, things are somewhat different. Apps in smartphones (reference made mostly to iOS and Android) that are said to be running in the background do not always necessarily display multitasking. They can, in fact, be in three states: running, suspended (sleeping) and closed. Yes, some apps are squarely closed, due to some problems somewhere.

You probably won’t get a hint on that and discover the fact only when you want to resume the app again, because it is the operating system that manages to multitask, not giving you much control.

When an app is in the running state, it is in the foreground and you are dealing with it. When an app is running, it works more or less like apps do on computers, i.e. its instructions are being executed by the processor and it does take space in memory.

If it is a network app, it can receive and send data.

Most of the time, apps on smartphones are in the suspended (sleeping) state. This means that they are frozen where you left –the app is no longer being executed in the processor and the place it occupies in memory is reclaimed should there be a shortage of memory space due to the running of other apps. In that case, the data it holds in memory is temporarily stored on secondary storage (SD card or phone’s extended memory – that would be analogous to the hard disk on a computer). Then, when you resume the app, it brings you exactly where you left off, rescheduling its instructions to be executed by the processor and bringing back the hibernating data from secondary storage to main memory.

Multitasking and Battery Life

A sleeping app consumes no processor power, no memory and accepts no connection – it is idle. Thus, it consumes no additional battery power. This is why most apps for smartphones adopt the sleeping mode while asked to run in the background; they save battery power. However, apps that require a constant connection, like VoIP apps, should be kept in the running state, making the battery sacrifice. This is because if they are sent to sleep, connections will be refused, calls will be declined, and callers will be notified that the callee is unreachable, as a matter of example.

So, some apps have to run in the background, performing real multitasking, like music apps, location-related apps, network-related apps, push notification apps and especially VoIP apps.

Multitasking in the iPhone and iPad

It started in iOS with version 4. You can leave the running app and switch to a background app by going back to the home screen. Notice here that it is different from closing an app. If you want to resume with an app in the background, you can use the App Switcher, by double-clicking the home button. This will bring the focus to the array of icons at the bottom of the screen, blurring or graying out the rest of the screen content.

The icons that appear are those ‘left open’. You can then swipe to run through the whole list and select any one of them.

iOS also uses push notification, which is essentially a mechanism that accepts entering signals from servers to spring up apps running in the background. The apps listening to push notification cannot go to sleep completely but need to remain in the running state listening to incoming messages. You can choose to ‘kill’ apps in the background by using the long press.

Multitasking in Android

In versions of Android prior to Ice Cream Sandwich 4.0, pressing the home button brings a running app to the background, and long-pressing the home button brings up a list of recently used apps. Ice Cream Sandwich 4.0 changes things a bit. There is a prominent recent app list which gives you the impression of managing the apps, which is in fact not the case, but which is nice. Not all the apps in the recent list are running – some are sleeping and some are already dead. Tapping and selecting one app in the list might spring up from an already running state (which is somewhat rare for reasons discussed above), or wake one up from sleeping state, or load the app afresh.

Apps Designed for Multitasking

Now that smartphones support multitasking, to some extent at least, some apps are also designed to work especially in a multitasking environment. An example is Skype for iOS, which has new capabilities for handling notifications and remaining active in the background while using battery power efficiently.

Skype is a VoIP app that allows voice and video calls and therefore needs to remain active always for better user experience, just like your mobile phone would permanently be listening to signals from incoming calls and text messages.

Some geeky users want to disable multitasking on their devices, probably because they find that apps running in the background slow down their machines and consume battery life. It is possible, but the operating systems do not actually give easy options to do that. You need to use ways gathered in the backstreets. For iOS, there are some steps to follow which are not for everyone, and which I would personally not recommend. It may even require jailbreaking the phone.

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