On 07.11.2010, at 22:08, Tabitha Roder wrote:
> Re memory usage - we already go through the "please don't open too many
> activities" routine all the time
>
> How come my Android phone is okay with running everything at once?
It doesn't. It just makes it look like it is.
> What does it do that means I don't run out of memory? Can we do that to
> Sugar? Apparently the phone is killing apps when it needs to but when you
> restart the application it picks up where it left off (I might be repeating
> something already discussed on this list?).
Of course you are ;)
Sugar was intended to kill background activities if resources got low, too. But
there never were enough engineering resources to make it work. There have been
experiments with the OOM killer, but I think the only result was to acknowledge
that It Is A Hard Problem.
Sugar is much closer to "regular" Linux than Android. This is intentional, we
wanted to make "sugarizing" normal Linux applications easy, and even allow to
run them directly (both to invite open-source developers and leverage existing
code as possible). We were successful at that, there is indeed very little
difference between an activity and any other X11 app (and we intend to make the
difference even smaller).
So the upside is that a Sugar activity is almost like a regular Linux app. The
downside is that a Sugar activity is almost like a regular Linux app.
Activities are supposed to save their complete state to the Journal. That would
include which view is displayed, where the cursor is, etc. If they did that,
then stopping and resuming an activity would be seamless. The user wouldn't
even notice it happened.
But few Sugar activities do that. There are no general facilities to help the
developer make it work. Also, there is little incentive to do it, since there
is no automatic killing of activity. And one reason there is no killing is that
starting an activity is just too slow. And when sugarizing an existing app it
would be really hard because desktop applications are rarely designed for this.
Android had the luxury of starting with a pretty clean slate. Everything above
the Linux kernel (and even inside it) was designed to make this work. There
isn't even the concept of the whole app staying in RAM, it is only a small part
that stays resident when switching away. Saving the state of that part is
comparatively simple.
I don't see how Sugar could do something similar without a complete redesign.
> Back in the old days, Sugar showed you how many activities were running in
> the home view, that might have been more obvious to kids that they were
> overloading their laptops.
> Would it be possible to have a message pop up that says "you are running out
> of memory, which activity would you like to close" or similar so they are
> alerted to running too much stuff.
Well, asking the user is always the cheap way out, but we might not have the
resources to do better.
- Bert -
PS: Overall it's amazing how much Sugar "got right" on its own though.
Fullscreen apps, automatic saving/resume, sandbox security, app bundles, these
are all features Sugar shares with Android and iOS. But when Sugar development
started in 2006 (*) these were not around yet. There was no obvious software to
use as a base with these features. The Android "preview" SDK was released in
Nov. 2007 but there was no hardware yet, the iPhone SDK was released in March
2008. Still, when OLPC started mass-producing the XO-1 in 2007 there were
third-party Sugar activities already.
(*)
http://dev.laptop.org/git/sugar/commit/?id=2cc103db83ed1550e2a9e92bf3306e4476c1297a
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