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I've been testing the behavior of my program by running a memory-eating application that forces my application to be killed. After reading the answers to Where is the bundle of onSaveInstanceState saved?, I'm confused about some of the results I'm seeing.

Both answers given in that link imply that individual activities, not applications, are destroyed when memory needs to be reclaimed. But according to http://developer.android.com/guide/components/processes-and-threads.html, processes - not individual activities - are killed. And since all components usually run in the same process, I would expect the entire application to be killed in low memory situations. My testing is consistent with the Android documentation in that I no longer see the process running when I run my memory eating app.

So if the entire process is killed, am I correct in assuming that the answers given in that question are incorrect? But if so, what's keeping my Bundle around when I resume my application if the process was killed? Is it really guaranteed to never be written to disk?

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thebnich
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  • "I've been testing the behavior of my program by running a memory-eating application that forces my application to be killed." There is now an option in Debugging options on the device to destroy all activities when paused. – clocksmith Mar 14 '14 at 19:01

2 Answers2

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Both answers given in that link imply that individual activities, not applications, are destroyed when memory needs to be reclaimed.

That is incorrect, though I was confused on this point for a long time myself.

IMHO, at most one of the three answers on that question "imply that individual activities, not applications, are destroyed when memory needs to be reclaimed".

But if so, what's keeping my Bundle around when I resume my application if the process was killed?

Sometimes, nothing is "keeping [your] Bundle around". Other times, a process central to the OS is "keeping [your] Bundle around".

Is it really guaranteed to never be written to disk?

Is not "guaranteed", insofar as it is not documented whether or not it is written to disk. If it is written to disk, it will be done so by an OS process (not yours), and the file should be unreadable by other processes.

CommonsWare
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    While the first answer doesn't explicitly say that individual activities are killed, it does say bundles are "destroyed along with the application when the memory is collected." Since the process (and by extension, the application) is destroyed, but the bundle apparently is not, I take it that statement is false? – thebnich Sep 18 '12 at 00:33
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    @MasterNES: Yes, I would agree that the quoted statement is false. – CommonsWare Sep 18 '12 at 00:37
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As today the documentation says that saved instance state is serialized to disk.

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https://developer.android.com/topic/libraries/architecture/saving-states#options_for_preserving_ui_state

crgarridos
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