Multitasking on Phones from Gizmodo

eliassami5

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Snippet for android os:

Android
The Android model is perhaps the most interesting, a hybrid system that's fairly open about allowing stuff running in the background, but at the same time aims to be completely invisible to you, the end user, so that you don't have to actively manage whether an app is open or closed. It's a little complicated so we talked to an Android engineer about what's going on inside.

What happens when I switch to another app?
The app you switched from doesn't stop—the process stays open. At least, as long as it can. When Android detects it's running low on memory, then it kills processes to free up resources. It asks apps to save their state when you switch, so that any can be killed at any point, then reopen like it was never killed when you return to it.

What can apps do in the background?
Android has two basic facilities for third-party multitasking—broadcast receivers and services. With a broadcast receiver, an app that goes into the background is basically asking to be told about an event, like if you move 500 meters, or your battery level hits a certain percentage. (That's how Google's apps that use push, like Gmail work—instead of pinging the server for mail constantly, it waits to receive a notification that mail has arrived.) That way the app can go away, and not use resources, but restart when something happens that it needs to act on.

Services are what you'd consider more traditional background processes, with apps running to play music, or do turn-by-turn navigation—they're essentially a request from the app to say it needs to run for X amount of time.

What can't apps do in the background?
Remember Android's garbage battery life when it first came out? That's because there really were no restrictions on what kind of resources an app could consume in the background. Since Android 1.5, apps running in the background are capped at using 5-10 percent of the CPU altogether—which is the only major restriction placed on apps in the background. The other is that it's not easy for app to push itself to the foreground—they're supposed to the window shade notifications system.
 

Droids

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Decent article, not sure why it includes iPhone OS 4 as it is still vaporware at this time (neither the software or hardware exist except on prototypes). Windows Phone 7 continues the Microsoft phone software downward trend to oblivion. And the usual apple fanbois making idiotic comments about Android's home button only showing 6 running apps (wow, some of them are so clueless).

Thanks for posting this jimnutt, hope you know I'm only flaming the article, not you. :) It's worthwhile to read, but it biased and the comments...
 
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jimnutt

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I actually agree with most of your criticisms of the article. It is, however, a good overview of how multitasking is (or will be) handled on phones. I came away from the article thinking that Apple is actually moving more toward a restricted version of the Android model. And that WebOS has a nice interface to multitasking, but requiring the user to manage all the tasks is kind of ugly.
 

Darkseider

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Hopefully... just hopefully. EVERYONE on this forum, ALL 50k+ users read this article and realize there is NO NEED FOR TASK KILLERS. Seriously mods. This should be made a Sticky and re-titled to "Be all and End all about Task Killers for Android"
 

digi-head

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Hopefully... just hopefully. EVERYONE on this forum, ALL 50k+ users read this article and realize there is NO NEED FOR TASK KILLERS. Seriously mods. This should be made a Sticky and re-titled to "Be all and End all about Task Killers for Android"

I just had to chime in on this and say that your "Be all and End all" argument does not hold water, IMHO. The article states: "apps running in the background are capped at using 5-10 percent of the CPU altogether—which is the only major restriction placed on apps in the background". To me, this means that 10 apps running in the background can use 100% of the CPU. It also means that those background apps could be using the data connection every 30 seconds to look for new data. I'm certainly not gonna stop using my task killer.
 

Darkseider

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" "apps running in the background are capped at using 5-10 percent of the CPU altogether"

Meaning no matter how many apps are running in the background it is capped at 10% max. not EACH. Hence the word ALTOGETHER. Also note that the apps in the background will not be using 10% all the time but only if and when they require to perform a function, ie: update, retrieve data, send data, etc... Once the app. is done with the process it goes into a dormant state.
 

digi-head

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Well, I guess I missed the "altogether" keyword there. :redface: Seems to me, though, that those background apps still could use up battery life with data connections. It also seems that too many in the background could cause issues if there are multiple background apps fighting for that 10% of CPU if your media player is in the background as well. Nevertheless, I can agree that the need for a task killer might be drastically over-hyped given this multi-tasking implementation, but I'm not quite convinced that they are pointless.
 

Grettski

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Hey all...Ive been reading the threads about the taskiller. I'd like to put my two cents in. I was and engineer in the Air Force for 23 years and I learned REAL early on that there is a bold line between what something is designed to do, and what it does in the field. So here is my story. Had my droid eris for two months, took it off the charger at 730 AM and went to work. Check facebook a couple times, few texts and maybe a five minute call. At noon I had 30 percent. Charge it on lunch and at 5 I would be lucky if it was still on at all. Now, I kill apps when I walk into work, at lunch I have around 85 percent, look at USA today for a while, no charging, kill apps after lunch, and I have around 55 percent on the way home. The ONLY thing I do different is use the free version of taskiller.
But thats just me.

BTW, any new news of the update? Ready to get rid of 1.5!
 

wuliwong

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I'm not sure how someone could conclude that there is no need for a "task killer" app or some form of user controlled background management after reading this article? Even assuming that the total background usage is capped at 10%, why is that acceptable if the background tasks are unnecessary? I want the background processes to use 0% of the CPU if at all possible. Making a statement saying that the applications only use the CPU for getting data or something where they are only active for a moment is naive. You are assuming that these applications are designed well and you are ignoring the other option where they can stay active for "X" amount of time. I have definitely seen improved battery performance with my Incredible since I started using a task killer application.
 
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