With the release of Android 4.4 KitKat, Google introduced a
new Runtime environment. Named as ART, an acronym for Android RunTime, it is
deployed to help Android perform better. With the consistent 5 year use of
default runtime Dalvik, KitKat ships with both runtimes available to be used.
But hey, what’s
Dalvik?
The word “Runtime Environment” is the software environment
created by the Operating System when a software is it in its running state. Dalvik
is no exception. It is a process Virtual Machine RTE (Run Time Environment)
that Google uses to run apps in Android OS. It is the base layer of the Android
Apps. On the top of it, the Android apps execute. Android apps are coded in
Java, and that code is converted to a code which is handled by Dalvik.
By the way, how does
it work?
Dalvik has a Just-In-Time (JIT) Compiler. The Just In Time
code means that code which is not compiled already, but when required, it gets converted to the executable code. The best example is Javascript code. A
Javascript code always stays as non-precompiled in the website directory, but
when user clicks on some spot where it is called, the code gets converted to an
executable state.
Similarly Dalvik works. Android apps are not the compiled
code, they are in a simply packed form. After installation, it gets stored on
the hard disk of the phone (or a tablet). When it is executed, Android combines
all the uncompiled code together, complies it and converts the code in Dalvik
Executable .dex format. Then this
.dex file is executed by Dalvik.
It is always a good option for application environments, but
what the problem is that the dalvik executable takes much execution time and
also battery hogs and CPU loads. Although it is not that much as it sounds, but
still in the world where a single cycle of CPU and response time matters,
Dalvik is not matching the requirements.
So, here we’ve got
ART
As an alternative solution to Dalvik, Google came with a new
runtime environment called as “ART” or Android RunTime. ART incorporates AOT (Ahead-Of-Time)
compiler, rather than JIT compiler. Instead of compiling the code at the time
of calling, this environment has a different policy. Once an app is downloaded,
it unpacks and gets compiled. If the user opens the app, the app opens up
faster than Dalvik. This is because in ART there’s no compilation process
occurs, hence it saves the processing time. Although it takes more space on the
disk, but it results in lesser CPU usage and battery drain.
Google has kept ART turned off by default. Users can always
switch from Dalvik to ART from Settings > Developer Options > Select
Runtime.
Is it really faster?
Developers, those who have tested apps on ART, have said
apps to be working 50% faster than in Dalvik. The small apps don’t have a
notable difference, but large apps such as Photoshop Touch accounted fast
opening in ART mode. Currently ART is in the testing phase. Not all of the apps
work in the new environment.
The reason that developers should switch to start using ART
Dalvik over ART is that they need to write the same code, and it results in
faster apps. There is less UI latency, faster response, lesser battery drain
and CPU usage gets reduced. ART is the future of Android. Google has worked two
years to develop it, and finally it has made its inside the OS.
Oh yes, by the way, following video shows Dalvik v/s ART which we found on YouTube.
