ubuntu-phone team mailing list archive

[Michael Zanetti <michael.zanetti@xxxxxxxxxxxxx>]

On 09.10.2015 11:49, Pete Woods wrote:
> 
> 
> On Thu, Oct 8, 2015 at 12:41 PM, Thomas Voß <thomas.voss@xxxxxxxxxxxxx
> <mailto:thomas.voss@xxxxxxxxxxxxx>> wrote:
> 
>     On Thu, Oct 8, 2015 at 1:36 PM, Michi Henning
>     <michi.henning@xxxxxxxxxxxxx <mailto:michi.henning@xxxxxxxxxxxxx>>
>     wrote:
>     >> you can indeed build apps in C++ if you want, but C++ is more complex to
>     >> understand and write (if you ever did a dynamic web page in your life
>     >> you likely know the basics of js). C++ needs a (cross) compile
>     >> environment set up while js means you can just dump a txt (well, .qml)
>     >> file in place and it just works. Doing C++ is just a lot more work and
>     >> while you can use C++ I think people find it easier to simply use js (I
>     >> surely do, i can write a ready made QML app including rolling the click
>     >> and uploading it to the store with a plain text editor within 20min, I
>     >> (personally) cant do that in C++)) ...
>     >
>     > Writing a dynamic web page in C++ is a bit like writing a neural network in COBOL. Don't.
>     >
>     > Would I write a device driver in JS? Probably not.
>     >
>     > Would I try to tighten a Phillips head screw with a nail file? Probably not either.
>     >
>     > I think you get the drift… :-)
>     >
> 
>     +1 :)
> 
>     Please note that qml and c++ components are happily mixed together
>     with QML/Qt. If there is a serious performance issue with using pure
>     QML,
>     falling back to C++ is always possible.
> 
> 
> Remember everyone, that Android apps launch pretty quickly, and they are
> Java based
> (and were only natively compiled with the release of Lollipop's ART).
> 
> This is achieved through the use of a "Zygote" process and some clever
> copy-on-write
> page management (I *think* using special kernel patches). There is always a
> pre-warmed instance of the JVM ready, and it is forked each time a new
> app / service
> wants to launch. The page copy-on-write behaviour allows a new JVM
> instance to be
> spawned with almost no effort to the phone (you only copy the memory if
> you alter the
> Java runtime libs in some way, which is uncommon) and comes with large
> memory savings.
> 
> The summary of what I'm saying is the old adage "there are no slow
> programming languages,
> only slow programs". I think a lot of our app launch speed troubles
> could be alleviated by
> employing the same techniques that Google does. The answer to
> performance issues
> is rarely to "switch programming language", assuming you're using a
> language that at
> least has a JIT compiler.
> 

FWIW, Benjamin is experimenting with MeeGo's applauncherd/booster, which
in principle does pretty much what you're describing. First tests do
suggest that it does improve the situation quite a bit. Details still to
be ironed out tho.

Br,
Michael

Attachment: signature.asc
Description: OpenPGP digital signature