Apple's iPad

[Asher]

So then what is the root password? Or does it use a wheel group to prevent use of setuid?

It has some proprietary way to lock it out, I haven't looked into it at all.

Also it would need to use some of the flash rom as swap space if it persists one of the apps...slow, and uses up storage space. And you can't really use this kind flash as virtual memory because of write limits so they can't just implement swap in the standard way.

Yeah, it would be far from ideal. I have a feeling it'll only be truly useful on the iPad, which has more RAM...

[Asher]

See, Wiggy?

I was exactly right.

I'm awesome.

[Hauldren Collider]

Link?

[Wiglaf]

You only saw fast app switching coming, not the other APIs

[Asher]

You only saw fast app switching coming, not the other APIs

No, I specifically and repeatedly mentioned low-resource background threads.

To be fair, I've been developing iPhone OS 4 apps for a month now and have full access to the developer documentation.

[Asher]

I can tell you right now it's not going to be true multitasking support -- at least not for the iPhone 2G, iPhone 3G, and iPhone 3GS. Best case is they'll open up an API that gives you a scant amount of resources to do something in the background and better natively support app persistence.

[Asher]

Link?

I'm sure it's all over the place.

Summary: Double-tapping the home button will bring up a grid of 4 icons (scrollable to either side) at the bottom with a list of running applications. You can switch between them. It's not actually running these apps at the same time (true multitasking), but it instead just saved the state (took a memory snapshot) of the app and saved it so it can be resumed later.

In addition to this, it supports a variety of different kinds of background threads that apps CAN run in the background at the same time. These are resource constrained (they cap the memory and CPU usage) and are intended for specific tasks: playing audio, polling a network for data (twitter, MSN, etc), keeping track of your location, etc.

It's not true multitasking, but it's better than what they had before. Even then, this stuff is only available on iPhone 3GS and iPod Touch 3rd gen or higher.

[BlackCat]

[giblets]

What advantages would true multitasking have over saving the state and background threads?

edit:

excellent post, comat ingrid!

[Asher]

What advantages would true multitasking have over saving the state and background threads?

You know from using a PC. You can have full versions of Firefox/Chrome/Safari open while you quickly and instantly switch between other apps running like Twitter and IM or iTunes or a playing movie.

The apps keep processing as you switch focus to a different app in true multitasking. One or more applications are simultaneously using your processor in true multitasking. I can have iTunes running while it downloads and processes new music purchase while I switch to tweet about the new music I bought while I watch a video on YouTube as it finishes.

The problem with saving the state then switching apps is the lag. It takes a decent amount of time to write out the current state to flash memory, then restore the app you're switching to. It won't be instantaneous (Caveat: there's an API for "fast app switching" so apps can be specifically designed to be quick, but they have a LOT of restrictions).

[BlackCat]

Well, couldn't be bothered for browsing through nine pages to see if others had posted it

[Wiglaf]

Asher, give one example where Apple's multitasking is not as good as everyone else's mulitasking :m,ad ;

[Asher]

Android has true multitasking...if you leave one app open and switch to another, it's instantaneous and keeps any processing in the other app going (unless the app decides to pause on the event of a task switch, which many do).

Either way, it's virtually instantaneous since both are kept in RAM.

[Wiglaf]

I cannot think of a single practical reason why that difference matters.

So, plants vs. zombies will freeze when I check my mail. So what? What's the big deal? It'd pause anyway.

[Asher]

One switches instantly, the other will take 5-6 seconds. One permits the app you're switching from to keep running, the other does not.

If you don't think it matters, you're a '****.