Modern smartphone users often take the speed of the interface and the smoothness of animations for granted. However, behind every instant touch response there is a complex architecture that links the app code with the physical hardware of the device. The central link in this chain is the runtime environment, known as Android Runtime or ART. Understanding exactly how this technology works allows you to not only dive deeper into the design of the mobile operating system, but also intelligently solve problems with performance or autonomy.
Before the transition to ART in 2014, the Android ecosystem relied on a virtual machine Dalvikwhich used a fundamentally different approach to code processing. The paradigm shift was one of the most significant events in the history of the platform, making it possible to significantly speed up the launch of applications and reduce the load on the processor during their operation. In this article, we will look in detail at what is hidden under the ART acronym, how it compiles applications and why this technology is the foundation of the stability of your gadget.
The evolution of the runtime environment: from Dalvik to ART
The history of Android development is inextricably linked with the search for a balance between speed and energy consumption. Initially, the system used a virtual machine Dalvik, which worked on the principle of JIT compilation (Just-In-Time). This meant that the application code was translated into machine instructions right when it was launched. This approach was convenient for quickly installing apps, but created a constant load on the processor, since compilation occurred “on the fly” with each call to the code. With the release of Android 5.0 Lollipop, Google introduced Lollipop, which replaced the outdated one. The key difference of the new system was the transition to AOT compilation (Ahead-Of-Time). Now the translation of bytecode into machine language occurs not while the application is running, but at the time it is installed on the device. This radically changes the logic of operation: the smartphone spends resources once during installation, but during use the application starts instantly, since the processor does not need to interpret anything.
With the release of Android 5.0 Lollipop, Google introduced Android Runtime, which replaced the outdated Dalvik. The key difference of the new system was the transition to AOT compilation (Ahead-Of-Time). Now the translation of bytecode into machine language occurs not while the application is running, but at the time it is installed on the device. This radically changes the logic of operation: the smartphone spends resources once during installation, but during use the application starts instantly, since the processor does not need to interpret anything.
The transition to ART required more memory space to store the compiled code, but the gain in performance turned out to be a decisive factor. Users have noticed that animations have become smoother and multitasking has become more efficient. Despite the fact that modern versions of Android use hybrid compilation methods, the basic architecture Android Runtime remains unchanged, ensuring a high responsiveness of the interface even on devices in the mid-price segment.
Principles of AOT and JIT compilation
To understand the advantages ART, you need to consider the mechanics compilation. In the classic AOT (Ahead-Of-Time) model that the new framework has introduced, all application code is converted to native machine code before the first launch. This eliminates the delays associated with the processor interpreting instructions in real time. As a result, the application works as if it was written specifically for the architecture of a specific processor.
However, pure AOT compilation has its drawbacks, the main of which is the long installation time of applications and the increased amount of memory occupied. To mitigate these disadvantages, modern versions Android Runtime implemented a code profiler. The system analyzes which parts of the application are used most often and optimizes them, leaving rarely used fragments in the bytecode for on-demand compilation. This hybrid approach combines the best features of old and new technologies.
It is important to note that the optimization process often occurs in the background while the device is connected to charging and idle. You may notice that your phone becomes warmer after a major system update or installation of many new apps. This is normal behavior: ART carries out deep code optimizations to ensure maximum performance in the future.
If your smartphone is slow or hot after a system update, give it a few hours connected to the network. The system will complete background optimization of applications through ART.
Comparative analysis: ART vs Dalvik
The differences between the two runtimes are fundamental and affect almost every aspect of the user interaction with the device. If Dalvik was focused on saving space and quick installation, then Android Runtime puts execution speed and interface responsiveness at the forefront. This is especially critical for modern heavy applications and games, where every millisecond matters.
Below is a table that clearly demonstrates the key differences between the two technologies in the main operating parameters:
| Parameter | Dalvik (JIT) | Android Runtime (AOT/Hybrid) |
|---|---|---|
| Compilation type | Runtime (Just-In-Time) | When installed and in the background (Ahead-Of-Time) |
| Application launch speed | Slower (interpretation required) | High (ready machine code) |
| Load per processor | Constant during operation | Peak during installation, low during operation |
| Memory consumption | Less (code is not duplicated) | More (native code is stored) |
| Installation time | Fast | Long (optimization process) |
As can be seen from the data, ART requires more storage resources, but this is more than compensated by the reduction in processor power consumption during active use of the smartphone. Less CPU load directly impacts battery life, making the new runtime more preferable for mobile devices with limited battery power.
ART's main advantage is that it shifts the processing load from the moment you use the application to the time you install it, which ensures a smooth experience of the interface.
The impact of ART on performance and battery
Users often wonder why, after switching to new versions of Android, phones begin to work faster, despite the complication of the software. The secret lies in the efficiency of resource management that Android Runtimeprovides. Since the code is already compiled, the processor does not need to waste energy constantly translating it, which reduces the overall heat dissipation of the device. However, there are scenarios where operation may raise questions. For example, when you first launch a heavy application after a system update, you may experience a short-term drop in FPS or stuttering. This is because the profiler has not yet collected enough data to fully optimize this particular use case. Typically, this situation corrects itself after several cycles of the app.
However, there are scenarios where work ART may raise questions. For example, when you first launch a heavy application after a system update, you may experience a short-term drop in FPS or stuttering. This is because the profiler has not yet collected enough data to fully optimize this particular use case. Usually this situation corrects itself after several cycles of the app.
For developers, the transition to ART meant the need for more thorough testing of the code. Errors that could previously be hidden by the dynamic nature Dalvikin the environment Android Runtime appear immediately at the compilation or installation stage. This has improved the overall quality of applications in the store Google Playas unstable code simply does not go through the pre-optimization process correctly.
⚠️ Warning: Forcibly disabling application optimization through the developer menu can lead to a significant decrease in system speed and rapid battery drain. Do this for debugging purposes only.
Developer settings and ART operating mode
In modern versions of the operating system, Google has hidden direct switches between compilation modes from the average user, leaving them available only in the developer menu. However, understanding these settings is useful for diagnosing problems. To access advanced settings, you need to activate developer mode by quickly tapping seven times on the build number in the section Settings → About phone.
Inside the developer menu, you can find an item related to selecting the runtime operating mode. Although the optimal balance is selected by default, sometimes it becomes necessary to change the behavior of the system. For example, when testing new applications, developers can switch to full JIT compilation mode to speed up the process of making code changes without waiting for a time-consuming recompilation of the entire project.
Changing parameters often requires the use of debugging tools ADB (Android Debug Bridge). Through the command line, you can manually set the desired compilation mode for a specific application or the entire system. This is a powerful tool, but it requires caution, as incorrect settings can lead to unstable operation of the operating system.
☑️ Preparing to change ART settings
adb shell pm compile -m speed-profile com.example.appExecuting such commands allows you to force the optimization process for the selected application. The speed-profile parameter tells the system to use profiler data for maximum speed, while the interpret-only parameter will force the system to run in interpretation mode, which is useful for saving space, but is slow.
Diagnosing problems and optimizing the system
Sometimes users encounter a situation where the smartphone starts to work unstable after the update. In such cases, the problem may lie in a conflict between the compiled code and the new version of the runtime ART. The standard solution is to clear the compilation cache, which forces the system to re-optimize all installed applications from scratch.
To perform this procedure, you must boot into Recovery mode. The exact combination of buttons depends on the device manufacturer, but most often it is a combination of the power key and the volume up button. In the recovery menu, select Wipe Cache Partition. It is important not to confuse this with a full data reset, which will delete all your personal information.
After clearing the cache and rebooting, you will notice that the system will take longer than usual to boot for the first time. A message about optimizing applications may appear on the screen. Do not interrupt this process, since it is at this moment that Android Runtime rebuilds the machine code to the current state of the system. An interruption can lead to cyclic reboots or errors in app operation.
What to do if optimization is frozen?
If the optimization process lasts more than an hour, try a forced reboot. In rare cases, it is necessary to flash the device via a computer, as the compilation files may have been damaged.
⚠️ Attention: Clearing the Dalvik/ART Cache partition deletes temporary compilation files. This is safe for personal data, but will temporarily slow down the phone until re-optimization is completed.
Frequently asked questions (FAQ)
Is it possible to completely disable ART and return to Dalvik?
On modern versions of Android (starting from 7.0 Nougat) environment Dalvik completely removed from the operating system code. It is impossible to return to it without installing custom firmware, which may be unstable and unsafe. Modern implementations Android Runtime include a JIT compiler for flexibility, so the legacy environment is no longer necessary.
Why does it take so long to install applications?
Long installation times are associated with the AOT compilation process. The system ART translates the application code into machine language, optimizing it for your processor. This takes time and space, but ensures that the application will run as quickly and energy-efficiently as possible right after launch.
Does ART affect compatibility with older applications?
Android Runtime has high backward compatibility. Most applications written for older versions of Android work correctly. However, applications that use outdated native libraries or specific memory hacks may not work correctly, since ART controls resource allocation more strictly than Dalvik.
Do you need to regularly clear the ART cache?
In normal use, regularly clearing the compilation cache is not necessary and is even harmful, as it forces the phone to rebuild spend resources on optimization. You should resort to this procedure only when system errors, interface glitches or after major firmware updates occur.
Why does the phone heat up after a system update?
The heating is caused by background work ARTwhich optimizes all installed applications for the new OS version. This is a normal process that usually completes within a few hours or days with active use of the device. It is recommended not to load the phone with heavy tasks at this time.