Android Performance

The release of MIUI 12 brought a long-standing battle between App developers and ROM developers into the public eye, revealing the intricate details of this technical tug-of-war. As the saying goes, “While the demon rises a foot, the path rises ten feet.” ROM developers, with their higher system-level permissions, generally hold the upper hand. App developers, however, are not easily deterred, employing various “black technologies” for background persistence and cross-app wakeups. Even Google has stepped in to mediate, establishing rules to regulate behavior for both parties. This competition is arguably healthy; a total victory by either side would inevitably lead to stagnation or the loss of useful functionality.

However, the victims of this struggle are undoubtedly the consumers. If App developers succeed, phones become cluttered with persistent background processes that hog CPU and memory. Conversely, if ROM developers are too aggressive, the app experience suffer—a pain well-known to many Android developers.

As discussed later in this article, most smartphone manufacturers have developed their own strategies to handle auto-starts and associated starts. Beyond the technical struggle, there’s the issue of privacy. Baidu’s Robin Li once remarked that “Chinese people are more open about privacy and relatively less sensitive. If they can trade privacy for convenience, safety, or efficiency, they are willing to do so in many cases.” Consider the convenience of copying a phrase in WeChat and having Taobao automatically open to the corresponding item. It’s helpful, isn’t it? But do we really want every app peering into our clipboards?

This is the fifth article in the Systrace series, primarily providing a brief introduction to the workflow of SurfaceFlinger. It covers several important threads within SurfaceFlinger, including Vsync signal interpretation, app buffer display, and jank detection. Since Vsync has already been covered in Systrace Basics - Vsync Explained and Detailed Explanation of Android Rendering Mechanism Based on Choreographer, it won’t be discussed in detail here.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

On Medium, @MindOrks published a 2020 Android Developer Learning Path. Given that some readers may have difficulty accessing the original content, I am sharing it here combined with my own 2020 learning plan for your reference.

The original article is quite simple, mostly listing knowledge points without much explanation. I have added brief introductions for each point and included some additional topics based on my own understanding. This is for your reference only.

This article is primarily for Android developers. If you are a beginner, it will help you find a learning path. If you are an experienced developer, it can help you identify gaps in your knowledge. If you have any other suggestions, feel free to leave a message.

Below is my 2020 reading list. Everything recorded here has been finished - technical books are not included since it’s hard to define when they’re “finished.”

I prefer reading history-related books. Among them, The Siege of Kaifeng was very uncomfortable to read - the weak have no diplomacy, it’s truly realistic; Bad Kids lives up to its name, personally I feel it’s much better than the TV series; Rework 2 and Rework 3 are work-related, covering remote work and work methods, consistent with the 2020 trend of working from home - recommended for white-collar programmers; My Last Diet Book systematically and professionally discusses weight loss knowledge, very useful for someone like me who’s trying to lose weight; finally, Blades of the Guardians is already a classic in Chinese comics - I’ll definitely buy a physical set for collection once it’s complete (same for Attack on Titan).

Didn’t read much in 2020. Need to invest more in this area in 2021. Read + Record + Summarize - reading notes will be added later.

This is the twelfth article in the Systrace series, primarily providing a brief introduction to the CPU information area (Kernel) in Systrace. It covers how to view CPU-related information output by the Kernel module, including CPU frequency, scheduling, frequency locking, and core locking.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This is the eleventh article in the Systrace series, providing a brief introduction to Triple Buffer within Systrace. It covers how to identify jank in Systrace, perform preliminary localization and analysis, and explains the impact of Triple Buffer on performance.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This is the tenth article in the Systrace series, primarily providing a brief introduction to Binder and lock information in Systrace. It covers the basic situation of Binder, the representation of Binder communication in Systrace, how to view Binder information, and analysis of lock contention in SystemServer.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

The content of this blog mainly focuses on Android development and optimization-related topics, including the use of performance tools, Android App optimization knowledge, Android Framework explanations, and performance theory. Here is an organized directory for your reference. You can choose the parts you are interested in. This directory includes not only blog content but also some of my answers on Zhihu or the Knowledge Planet - The Performance. This directory lists my original blog posts. Additionally, I have collected some excellent articles in Must-Knows for Android Performance Optimization, which I update periodically.

This is the seventh article in the Systrace series, primarily introducing the Vsync mechanism in Android. This article examines the display of each frame in the Android system from the perspective of Systrace. Vsync is a critical mechanism in Systrace. Although invisible and intangible when operating a phone, we can see in Systrace how the Android system, guided by Vsync signals, orderly performs rendering and composition for each frame, ensuring stable frame rates.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This article compiles most current Android app startup optimization solutions. If you need optimization guidance, simply reference this article to review others’ approaches and identify gaps. Many solutions require business-specific adjustments, so this article doesn’t detail every method—when you need a particular solution, search online for its specific implementation. This serves as a comprehensive reference.

I’ve also included some system manufacturer optimizations related to startup, though I’ve only listed those I’m aware of. Some manufacturers have proprietary technologies not discussed here. Understanding manufacturer practices may help you—for example, contacting manufacturers for whitelisting or integrating their SDKs.

This article summarizes major Android app startup optimization strategies available today. If you need to optimize your app’s launch performance, use this as a checklist to identify gaps in your current implementation. Since many solutions depend on specific business requirements, I focus on presenting the options rather than deep-diving into every implementation detail. You can easily find specific technical guides for each method online.

I’ve also included some optimizations performed by system manufacturers. Understanding what happens at the OS level can help you make better decisions, such as requesting whitelisting or integrating manufacturer SDKs.

This is the ninth article in the Systrace series, primarily introducing the MainThread and RenderThread in Android Apps—commonly known as the Main Thread and Rendering Thread. This article examines their workflows from the perspective of Systrace and covers related topics: jank, software rendering, and dropped frame calculation.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This is the sixth article in the Systrace series, primarily providing a brief introduction to Input in Systrace. It covers the Input workflow, how Input information is represented in Systrace, and how to combine Input info to analyze related performance issues.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

When an Android app moves to the background, it’s not unusual for it to keep performing work as long as the process isn’t killed—that’s just the nature of Android. However, some apps continue to run “zombie animations”—animations that are completely invisible to the user yet consume precious CPU cycles and battery. When users discover this, the result is often a manual kill, an OS-level background restriction, or an outright uninstallation.

Most developers never notice this issue. However, if you use Systrace regularly, you can easily spot it. If you open several apps, return to the home screen, and capture a trace while swiping between launcher pages, you’ll often see background apps still firing animation callbacks.

“Zombie animations” occur when an app, despite being invisible, continues to push CALLBACK_ANIMATION requests to the Choreographer. Every app is different, but the root cause is usually a missing pause or stop call.

This article introduces Choreographer, a class that app developers rarely encounter but is crucial in the Android Framework rendering pipeline. It covers the background of Choreographer‘s introduction, an overview, source code analysis, its relationship with MessageQueue, its use in APM, and optimization ideas from mobile manufacturers.

Choreographer was introduced to coordinate with Vsync, providing a stable timing for handling Messages in app rendering. When Vsync arrives, the system adjusts the Vsync signal period to control the timing of drawing operations for each frame. Most phones currently have a 60Hz refresh rate (16.6ms). To match this, the system sets the Vsync period to 16.6ms, waking Choreographer every period to perform app drawing—this is its primary role. Understanding Choreographer also helps developers grasp the principles of frame execution and deepens knowledge of Message, Handler, Looper, MessageQueue, Measure, Layout, and Draw.