Runtime environment

Question 1

ART is

Answer 1

Android Runtime (ART) is an application runtime environment used by the Android operating system

Question 2

ART was introduced in

Answer 2

Android 4.4 KitKat brought a technology preview of ART, including it as an alternative runtime environment and keeping Dalvik as the default virtual machine. In the subsequent major Android release, Android 5.0 Lollipop, Dalvik was entirely replaced by ART.

Question 3

ART JIT

Answer 3

Android 7.0 Nougat introduced JIT compiler with code profiling to ART, which lets it constantly improve the performance of Android apps as they run. The JIT compiler complements ART’s current Ahead of Time compiler and helps improve runtime performance.

Question 4

ART vs Dalvik

Answer 4

Dalvik is process virtual machine, while ART performs the translation of the application’s bytecode into native instructions that are later executed by the device’s runtime environment.

Question 5

ART Advantages

Answer 5

• Ahead-of-time (AOT) compilation
• Improved garbage collection
• Support for sampling profiler (more accurate profiling)
• Support for more debugging features ()

Question 6

ART Sampling Profiler

Answer 6

ART adds support for a dedicated sampling profiler that is not skewed by the per-method-call overhead of Dalvik profiler, and its use does not affects run time performance as noticeably.

Question 7

ART Debugging Features

Answer 7

• See what locks are held in stack traces, then jump to the thread that holds a lock.
• Ask how many live instances there are of a given class, ask to see the instances, and see what references are keeping an object live.
• Filter events (like breakpoint) for a specific instance.
• See the value returned by a method when it exits (using “method-exit” events).
• Set field watchpoint to suspend the execution of a program when a specific field is accessed and/or modified.

Question 8

ART Crash Reports

Answer 8

ART gives you as much context and detail as possible when runtime exceptions occur. ART provides expanded exception detail for java.lang.ClassCastException, java.lang.ClassNotFoundException, and java.lang.NullPointerException

Question 9

Dalvik

Answer 9

Dalvik is a discontinued process virtual machine (VM) in Google’s Android operating system (while its bytecode format is still used as a distribution format, but no longer at runtime in newer Android) that executes applications written for Android