how to simulate low memory condition on the device or emulator.

[cht]

for the developer, we must to deal with the "low memory" exception.
when other applications run forground, sometimes our application will
be killed for "low memory" reason .

so we have to test our application's performance under this condition.
but it is not easy to case a low memory condition. is there a good way
to set up condition?

thank you!

[lbcoder]

You can do this simply by using up memory.
Write a console program that has a malloc() call in a loop. Run that
console application from a different foreground application. Then just
watch the logcat for when your application gets bumped from memory.

[Dianne Hackborn]

You can just use the shell to kill your app's process.  All the system does when low on memory is select processes to kill to reclaim more, so your code will be going through pretty much the same experience if you manually kill it yourself.

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Note: please don't send private questions to me, as I don't have time to provide private support, and so won't reply to such e-mails.  All such questions should be posted on public forums, where I and others can see and answer them.

[lbcoder]

Really?
I was under the impression that there were several stages to
application shutdown, even in the event of memory shortages... onPause
(), onStop(), onDestroy()...

I.e., user selects to load a new activity, system calls onPause() on
current activity, system launches new activity (onCreate(), etc.),
system calls onStop() on old activity, system runs low on memory -->
runs onDestroy() on old activity. Yes, I realize that onStop() and
onDestroy() aren't guaranteed to be run, but it isn't exactly clear
what condition affects whether these do or do not run.... Is it
related to the activity being within the same process as the
foreground activity? I.e., if it *is* within the same process, then it
runs the sane shutdown on the old activity, if it isn't, it brutally
kills the old processes?

From http://developer.android.com/guide/topics/fundamentals.html :
"onDestroy(): ....or because the system is temporarily destroying this
instance of the activity to save space."

Note that both cases *do* need to be tested independently, and killing
the process wouldn't be suitable for both cases (old activity in same
process as foreground activity, old activity in different process than
foreground activity).

On Jan 5, 4:30 pm, Dianne Hackborn <hack...@android.com> wrote:
> You can just use the shell to kill your app's process.  All the system does
> when low on memory is select processes to kill to reclaim more, so your code
> will be going through pretty much the same experience if you manually kill
> it yourself.
>
>
>
>
>
> On Tue, Jan 5, 2010 at 1:18 AM, cht <caoht...@gmail.com> wrote:
> > for the developer, we must to deal with the "low memory" exception.
> > when other applications run forground, sometimes our application will
> > be killed for "low memory" reason .
>
> > so we have to test our application's performance under this condition.
> > but it is not easy to case a low memory condition. is there a good way
> > to  set up condition?
>
> > thank you!
>
> > --
>
> > You received this message because you are subscribed to the Google Groups
> > "android-platform" group.
> > To post to this group, send email to android-...@googlegroups.com.
> > To unsubscribe from this group, send email to

> > android-platfo...@googlegroups.com<android-platform%2Bunsubscrib e...@googlegroups.com>

> > .
> > For more options, visit this group at
> >http://groups.google.com/group/android-platform?hl=en.
>
> --
> Dianne Hackborn
> Android framework engineer

> hack...@android.com

[Dianne Hackborn]

On Wed, Jan 6, 2010 at 5:33 AM, lbcoder <lbc...@gmail.com> wrote:

Really?
I was under the impression that there were several stages to
application shutdown, even in the event of memory shortages... onPause
(), onStop(), onDestroy()...

Nope.  Processes stay running until their memory is needed elsewhere, at which point the kernel kills the process in its tracks.

 

I.e., user selects to load a new activity, system calls onPause() on
current activity, system launches new activity (onCreate(), etc.),
system calls onStop() on old activity, system runs low on memory -->
runs onDestroy() on old activity. Yes, I realize that onStop() and
onDestroy() aren't guaranteed to be run, but it isn't exactly clear
what condition affects whether these do or do not run.... Is it
related to the activity being within the same process as the
foreground activity? I.e., if it *is* within the same process, then it
runs the sane shutdown on the old activity, if it isn't, it brutally
kills the old processes?

They don't run if the process is killed to free memory for others.  The decision about what order to kill processes in is driven by the lifecycle of the components in the process, as described in the docs.

 

From http://developer.android.com/guide/topics/fundamentals.html :
"onDestroy(): ....or because the system is temporarily destroying this
instance of the activity to save space."

It may also ask individual activities to be destroyed if the process has a larger number actively running in it.  In practice this is a very rare case.

 

Note that both cases *do* need to be tested independently, and killing
the process wouldn't be suitable for both cases (old activity in same
process as foreground activity, old activity in different process than
foreground activity).

The onDestroy() being called case is effectively the same as switching orientation.  If you are not skipping normal orientation switching (via the activity being destroyed and restarted), then this is all you need to test.

And as I said, the situation when onDestroy() is called because of too many activities is very rare, and something you would need to do some work to make happen in your app.

--
Dianne Hackborn
Android framework engineer

hac...@android.com

[Kevin Kowalewski]

Hi Dianne,

Which signal is sent to processes on low memory?

Seems like the onDestroy method of my service is not being called. Hopefully its not SIG 9.

Thanks,
Kevin

[Dianne Hackborn]

On Tue, Jul 31, 2012 at 11:42 AM, Kevin Kowalewski <kowalews...@gmail.com> wrote:

Which signal is sent to processes on low memory?

The process is killed, period.  It is SIG KILL.

[Dianne Hackborn]

On Fri, Sep 7, 2012 at 11:41 AM, Octo <lani...@gmail.com> wrote:

When this happens Android seems to remember which activity to start.

For instance:
- start your app opens activity1
- do something opens activity2 and finishes activity1
- go play with other applications or leave device idle until your process is killed by Android
- re-open your app by clicking on the icon
- the app is opened on activity2

When I kill the process manually, it always re-open on activity1.

Are you killing them while in the foreground?  If the app is in the foreground, it hasn't had a chance to save its state, so it can't be restored.  This is the reason behind much of the activity lifecycle, for activities to go into the background in a controlled way with their state being saved along the way, so once there their process can be killed as needed.

[Shai Barack]

I'm not sure I understand your question, but if you're just looking to trigger your application's onTrimMemory callbacks, then you can use this:

adb shell am send-trim-memory <process-name> <level>

e.g. adb shell am send-trim-memory com.example.app MODERATE

[rigortek robin]

I use easily fill RAM app to simulate system low memory in my OS, it's a easy and useful APP, you can refer to :

https://play.google.com/store/apps/details?id=me.empirical.android.application.fillmemory&hl=en_US&rdid=me.empirical.android.application.fillmemory&pli=1