[Android-development] Warm application start time

ekke ekke at ekkes-corner.org
Wed Jun 15 09:16:48 CEST 2016

Am 15.06.16 um 08:00 schrieb Лагнер, Сергей:
> Indeed. I have checked it carefully. I call QApplication quit if my
> StackView has the last Page. 
> But what should I do to hide the app once user presses the back button?
just noticed:
if app becomes inactive because user uses Home or Overview Button,
re-opening is very fast
if user uses BACK button app is closed and re-opening took a long time

you can overwrite BACK behavior:





But I don't know how to set the correct state now to avoid closing the
app from BACK and doing the same as from HOME

> 2016-06-15 1:57 GMT+06:00 Xavier Bigand <flamaros.xavier at gmail.com
> <mailto:flamaros.xavier at gmail.com>>:
>     I don't really understand, because if the process isn't killed
>     Android don't release anything that you have loaded. So normally
>     when the OS put the application back to the active state it should
>     be really fast.
>     With our app we don't have a such issue.
>     Maybe you catch the back button in QML or C++ and you call the
>     QApplication quit method or something else that finally make your
>     application exiting.
>     Try to launch your app with a debugger, you'll see in the console
>     if the process is killed when pressing the back button.
>     2016-06-14 21:31 GMT+02:00 Лагнер, Сергей <developer at lagner.ru
>     <mailto:developer at lagner.ru>>:
>         Thank you for advice
>         We are already doing our best to optimize QML loading time. We
>         use Loaders from QML side 
>         and lazy loading for models from C++ side. But the application
>         still too heavy. 
>         It takes 6 sec approximately to launch on Nexus 5. 
>         Therefore we are looking for other ways to improve our app. 
>         Now I'm care about warm start. 
>         Lets consider the following scenario:
>         - I launch the app. It takes 6 sec.
>         - Press back and see a home screen
>         - Launch the app again in a second. And again it takes 6 sec.  
>         That is mean that all resources were freed and second start
>         was completely from scratch. 
>         I wonder if I could speed up the second(warm) start from java
>         side. 
>         For example, is it possible so save preloaded native libraries
>         until the OS has the real lack of memory?
>         2016-06-14 21:56 GMT+06:00 Xavier Bigand
>         <flamaros.xavier at gmail.com <mailto:flamaros.xavier at gmail.com>>:
>             Hi,
>             If you are using QML you may have to use Loaders to avoid
>             loading of GUI parts that are not displayed directly.
>             You can also take a look to the QtQuick compiler to
>             improve qml loading.
>             There is a profiler on QtCreator for QML which can help
>             you to find your binding that are slow, be sure to not
>             having binding loops.
>             2016-06-14 16:33 GMT+02:00 Лагнер, Сергей
>             <developer at lagner.ru <mailto:developer at lagner.ru>>:
>                 Hi all.
>                 I'm trying to optimize start time of my android
>                 application. For now I'm interested in warm start time 
>                 when the user presses back and quickly returns to the
>                 app. If we consider java application the 
>                 warm start is faster, it seems like android caches
>                 something or so.
>                 But it does not work for Qt applications. My
>                 application spends constant time for each start, even
>                 if I closed it a second ago. 
>                 Is there any way to optimize warm start of Qt
>                 application? 
>                 Any hints are highly appreciated.
>                 Thanks,
>                 Sergey
>                 _______________________________________________
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>             -- 
>             Xavier
>     -- 
>     Xavier
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