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Why the iPad and the iPhone don't support multitasking

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Re: Why the iPad and the iPhone don't support multitasking

#51

Post by theBobMcCormick »

stcredzero wrote: post #32
enjo wrote: post #22

Earlier quoted context omitted.

There are a range of applications, including highly useful ones, that simply needs multi-tasking. Anything that is time based (think calendars, alarm clocks, etc...) really need multi-tasking to work correctly. A host of location aware applications really need multi-tasking to work effectively. I get Apples position. The iPhone is the spiritual successor to the PalmOS. It looks, feels, and works very similarly to it.…

There are a range of applications, including highly useful ones, that simply needs multi-tasking. Anything that is time based (think calendars, alarm clocks, etc...) really need multi-tasking to work correctly. A host of location aware applications really need multi-tasking to work effectively. Very few apps need completely open ended multitasking. Most apps need very specific capabilities. An API for registering tim…

I think you've just made enjo's point for him. You said "Most apps need very specific capabilities. An API for registering time limited functions with timing, location, and other services would take care of 90% of the needs out there." That IS almost exactly the very well thought-out system that Android provides and that enjo was talking about.

Re: Why the iPad and the iPhone don't support multitasking

#52

Post by [deleted] »

tumult wrote: post #13
buster wrote: post #9

Earlier quoted context omitted.

Best thing about those excuses are: Every other mobile OS supports multitasking and all the smartphones i know have similar battery life. Symbian, Windows, Android, all have multitasking and yet people try to convince me that it, "not needed", "not possible", "makes the device unstable", "drains battery too much" which is just not true. My Android phone lasts at least as long as an iphone and i use multitasking all t…

If I leave an app running in the background that keeps the net connection open on my Nexus One, the battery goes from 100 to 0 in about 5 hours.

[deleted]

Re: Why the iPad and the iPhone don't support multitasking

#53

Post by theBobMcCormick »

tumult wrote: post #38
orangecat wrote: post #34

Earlier quoted context omitted.

I was signed in using WiFi, and I normally have WiFi enabled all the time and get over 24 hours of battery life. Maybe some wireless chipsets suck too much power, but it doesn't appear to be a problem on the N1.

Maybe we're doing something different, but I cannot get my Nexus One to stay alive for longer than 5 hours with an active net connection. It if it's a low-traffic connection (calm IRC channels, occasional email polling) it will last a day (same with my G1) but streaming radio, etc will leave it dead in a long afternoon.

Ah.. Streaming radio. By active net connection I thought you meant email polling, IM, etc.

Playing streaming video will kill the battery pretty decently, but IMHO that seems fair. Your keeping the radio pretty busy, the audio hardware, the cpu, etc.

I'd actually like to hear from an iPhone user whether they can run Pandora or Last.fm for 5 hours straight without killing their battery either.

Re: Why the iPad and the iPhone don't support multitasking

#54

Post by theBobMcCormick »

kreneskyp wrote: post #20
orangecat wrote: post #17

Earlier quoted context omitted.

I'd bet that app was poorly written and doing something else in the background. An app that is just listening for data from an open connection should be using roughly zero CPU. But we'll try science; I've signed into AIM on my Nexus One and left it running in the background. The battery is at 81% now, I'll report back in an hour.

If you keep a connection open it drains battery life because the chip can't power down.

Sort of. In tumult's case he's got a connection that's actively downloading data and playing music. I would assume that'd keep the radio chipset (either wifi or cell, whichever he's using) and the CPU both from being able to switch to a lower power standby mode.

However, you can have an open but idle connection open in the background with only minimal battery drain. That's how pretty much every kind of push notification or IM system works, even on cell phones.

Re: Why the iPad and the iPhone don't support multitasking

#55

Post by nooneelse »

0x44 wrote: post #48
nooneelse wrote: post #36

Earlier quoted context omitted.

But Safari being multitasking only solves the "browsing -> other -> back to browsing" case, right? "Something else -> Safari -> back to the first something else" needs the something else to be multitasking enabled or good at storing its state. Trying to predict what the users will and won't ever need to switch to and from and back to again is a crap shoot in general. Sure one can get it right much of the time, but wh…

"something else" -> "web browsing" -> back is handled by the application wrapping the Safari web browser using the included browser control in the API.

Good point. I was just doing an inversion in the example to simplify the argument mechanics a bit.

But doesn't that wrapping rely on something else's developers realizing that the user might want to go off to the browser and back? What if it wasn't Safari in the middle but any one (or three) of the numerous other programs the user might want to take a side trip through. It gets back to the crap shoot of trying to guess every multi-application use case that will be wanted. All this to defend not putting together the general solution which is entirely doable to begin with.

Re: Why the iPad and the iPhone don't support multitasking

#56

Post by tumult »

theBobMcCormick wrote: post #53
tumult wrote: post #38

Earlier quoted context omitted.

Maybe we're doing something different, but I cannot get my Nexus One to stay alive for longer than 5 hours with an active net connection. It if it's a low-traffic connection (calm IRC channels, occasional email polling) it will last a day (same with my G1) but streaming radio, etc will leave it dead in a long afternoon.

Ah.. Streaming radio. By active net connection I thought you meant email polling, IM, etc. Playing streaming video will kill the battery pretty decently, but IMHO that seems fair. Your keeping the radio pretty busy, the audio hardware, the cpu, etc. I'd actually like to hear from an iPhone user whether they can run Pandora or Last.fm for 5 hours straight without killing their battery either.

I'm an iPhone user as well, and it also kills the iPhone. the point was that on iPhone, 3rd party apps are not given the opportunity to do this without the user being aware (because it's in the foreground.) i've had a runaway android app kill my phone after it screwed up and started devouring resources in the background while it was in my pocket.

Re: Why the iPad and the iPhone don't support multitasking

#57

Post by theBobMcCormick »

tumult wrote: post #56
theBobMcCormick wrote: post #53

Earlier quoted context omitted.

Ah.. Streaming radio. By active net connection I thought you meant email polling, IM, etc. Playing streaming video will kill the battery pretty decently, but IMHO that seems fair. Your keeping the radio pretty busy, the audio hardware, the cpu, etc. I'd actually like to hear from an iPhone user whether they can run Pandora or Last.fm for 5 hours straight without killing their battery either.

I'm an iPhone user as well, and it also kills the iPhone. the point was that on iPhone, 3rd party apps are not given the opportunity to do this without the user being aware (because it's in the foreground.) i've had a runaway android app kill my phone after it screwed up and started devouring resources in the background while it was in my pocket.

The user would have to be aware of streaming audio. Also, as stated elsewhere in this thread, apps don't normally run in the background on Android either. I'm curious what app you believe killed your battery life in the background? That sounds... unusual.

Re: Why the iPad and the iPhone don't support multitasking

#58

Post by gte910h »

carbocation wrote: post #2

> "Both the iPad and iPhone, as mobile devices, have limited memory (256MB in the current incarnations) and no hard drive. No hard drive means no swap file." He loses me here. My iPhone has a 32GB SSD hard drive. Sounds like a perfect medium for swap space to me...

> My iPhone has a 32GB SSD hard drive

Embedded engineer here: Solid State Drives do lots of things GREAT. However "being a drive which swap is used on" is not one of them. That's because swap memory is written very often compared to any other portion of the drive. This quickly wears out the drive in that location (and all flash has a limited number of writes, and SSD is a flash technology).

There are specific drivers for doing swap on flash devices. But it isn't easy to do well without compromising usable life of the device.

IF you're interested in doing virtual memory in an app: http://www.alexcurylo.com/blog/2009/05/14/tip-iphone-virtual... is a way to do it, there is a hacked iphone app that also enables it too (don't have a URL offhand).

I dis-recommend doing so.

Re: Why the iPad and the iPhone don't support multitasking

#59

Post by gte910h »

buster wrote: post #9
gte910h wrote: post #6

This guy is just wrong: Apple OS has turned off multitasking for 3rd party apps to maintain battery life. It fully supports it. This is a control situation, where Apple has decided "We want our devices to have good battery life more than we want to allow multitasking".

Best thing about those excuses are: Every other mobile OS supports multitasking and all the smartphones i know have similar battery life. Symbian, Windows, Android, all have multitasking and yet people try to convince me that it, "not needed", "not possible", "makes the device unstable", "drains battery too much" which is just not true. My Android phone lasts at least as long as an iphone and i use multitasking all t…

Android is just now getting reasonable battery life with 2.x when heavy multitasking is in use. Many people need to have process cleaning apps to have zippy performance without rebooting the phone every few days. (And the fact not all android phones are upgradeable to 2.x is an issue meaning many still have crappy multitasking battery life).

Re: Why the iPad and the iPhone don't support multitasking

#60

Post by gte910h »

buster wrote: post #19
tumult wrote: post #13

Earlier quoted context omitted.

If I leave an app running in the background that keeps the net connection open on my Nexus One, the battery goes from 100 to 0 in about 5 hours.

Well, i have atleast running: Facebook, twitter, rss aggregation, gmail and k-9mail imap idle, gtalk plus weather and my phone is at around 30% end of a normal day with a few calls and around 2hrs rss reading on my way to/from work. Only one day battery life is quite sad compared to featurephones but i'd say it's normal for the smartphone of today. Oh, and i have gps/wifi turned on that day. Android 2.1 admittedly ha…

My iphone runs ~2.5 days without a charge...
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