[Qt-qml] Any tips or tricks to help with long app startup times?

[Artem Marchenko]

Hi Todd

Have you tried QML Performance Analyzer from the latest Qt Creator? I failed to get meaningful device data from it, but maybe you could spend more time with it and force it to work. Also if desktop performance is comparable even desktop measurements maybe helpful.

As for a couple of tricks you could use:

1) On Harmattan if it's one of your platforms you could use QML booster - that could help for something like 0.5-1 sec.

2) Splash screen certainly helps hiding low performance, maybe will make it look some 0.5 sec faster

3) QML Loader for loading the not super necessary stuff only when you need

4) WorkerScript is the only QML native way for multithreading. The problem is you can exchange only simple types with WorkerScripts, no image stuff possible

5) XmlHttpRequest is another possibility for loading data asynchronously, but if I've got you correctly, your problem is not with getting data, but with actual instantiation of images

If anything above doesn't help, you'll probably need to restructure your UI significantly. I can hardly believe you need that complex UI at start that it takes whole 7 sec to instantiate. These are just 0.2-0.4KPixels on screen after all.

Best regards,
Artem.

On Sep 27, 2011, at 9:37 PM, Todd Rose wrote:

> Thanks for the response Pelle.  I wonder if it would help if I routed
> all QML Images through one of our native image providers and marked
> them all as asynchronous.  Is the QPixmap cache still used even with
> custom native image providers that return QImage?  Just loading the
> QML and related images takes 7 seconds in our app.   I will look into
> loading only the smallest subset of QML necessary at startup, and
> doing the rest of the UI on-demand or on timers...unfortunately we
> pretty much need the whole UI available at startup, a splash screen or
> progress dialog would look prettier but it doesn't solve the problem.
> -Todd
> 
> On Tue, Sep 27, 2011 at 11:12 AM, Pelle Johnsen <pelle.johnsen at gmail.com> wrote:
>> From my experience QML does generally suffer a bit from slow startup time,
>> especially on embedded platforms :S
>> In the project I'm working on the 2 main problems we found are:
>> 1. Actually creating instances of QML Items. In a large app. there can be
>> thousands. This can to some extend be helped by splitting up the app and
>> sort of delay/demand loading individual parts, so you get the main UI up as
>> fast as possibly
>> 2. QML Image uses QPixmap which can only be created in the UI thread, making
>> it impossible to load QML in a background thread (not sure if there is some
>> changes to this in 4.8). If you are doing custom Ui you probably have lots
>> of images, which do take time to load up.
>> Also see this forum
>> thread: http://developer.qt.nokia.com/forums/viewthread/3144
>>  -Pelle
>> 
>> On Tue, Sep 27, 2011 at 4:58 PM, Todd Rose <teeceeare97 at gmail.com> wrote:
>>> 
>>> We have a relatively large qt-qml application.  The back-end is C++
>>> and front-end ui is about 70 or so QML files.  We're currently seeing
>>> very long initial startup times (ten seconds or more) and we'd like to
>>> know if there's any simple things that we can do to mitigate this.
>>> Some of it is in our application domain and we're working on that
>>> part, but the actual loading and rendering of the QML is also a quite
>>> significant portion of overall initial startup time.  Are there any
>>> tricks to make loading and initializing the qt and qtmobility
>>> libraries faster?  What about the initial QML file load/parse phase?
>>> We have all of our resource files stored in application subdirectories
>>> - would packaging them in a qt resource file make any difference here?
>>> 
>>> Thanks in advance,
>>> Todd
>>> _______________________________________________
>>> Qt-qml mailing list
>>> Qt-qml at qt.nokia.com
>>> http://lists.qt.nokia.com/mailman/listinfo/qt-qml
>> 
>> 
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