This is the third article in the Android App ANR series, focusing on real-world ANR cases. The series includes:

1. Android App ANR Series 1: Understanding Android ANR Design Philosophy
2. Android App ANR Series 2: ANR Analysis Workflow and Key Logs
3. Android App ANR Series 3: ANR Case Studies

This is the second article in the Android App ANR series, focusing on ANR analysis methodology and key logs. The series includes:

1. Android App ANR Series 1: Understanding Android ANR Design Philosophy
2. Android App ANR Series 2: ANR Analysis Methodology and Key Logs
3. Android App ANR Series 3: ANR Case Studies

This is the first article in the Android App ANR series, mainly analyzing the design philosophy of Android ANR from a system perspective. The series directory is as follows:

1. Android App ANR Series 1: Understanding Android ANR Design Philosophy
2. Android App ANR Series 2: ANR Analysis Routines and Key Log Introduction
3. Android App ANR Series 3: ANR Case Sharing

Recently, I read a new book: Building Smooth Android Apps (JD link: https://item.jd.com/10035215362170.html). I bought it because of the title, and after reading it, I felt it was necessary to write an article so that colleagues who haven’t bought it yet can understand what it’s about.

My personal suggestion is: if you are an experienced developer, I don’t recommend buying it. This book doesn’t go into much depth on principles and doesn’t offer a comprehensive overview of Android smoothness. If you are a beginner, it’s decent for broadening your horizons and identifying gaps in your knowledge, but it’s still a bit lacking for a deep understanding of Android smoothness.

I say this because the book doesn’t focus much on performance or smoothness. It lacks deep theoretical parts. Instead, a large portion is dedicated to static code analysis, using Android Studio Profiler, App architecture, app stay-alive techniques, network performance optimization, APK size optimization, app power consumption, etc. These topics are covered briefly and at a shallow level.

Jank, slow response, and ANRs can share causes or occur together, but they are not three severity levels of the same problem. When a user says an app feels slow, first distinguish uneven animation, a long delay after an action, and a system-detected failure to respond.

Animation and scrolling stutter is usually called jank. Long startup, screen wake-up, or navigation delays are slow response / high latency. An ANR depends on a specific system timeout condition. Frame-drop rate, startup duration, and ANR rate measure different things.

This is the third article in the Responsiveness series, focusing on extended knowledge when using Systrace to analyze app responsiveness, including startup speed testing, log interpretation, state analysis, and third-party startup libraries.

Jank, slow response, and ANRs can share causes or occur together, but they are not three severity levels of the same problem. When a user says an app feels slow, first distinguish uneven animation, a long delay after an action, and a system-detected failure to respond.

Animation and scrolling stutter is usually called jank. Long startup, screen wake-up, or navigation delays are slow response / high latency. An ANR depends on a specific system timeout condition. Frame-drop rate, startup duration, and ANR rate measure different things.

This is the second article in the Responsiveness series, using Android App Cold Start as an example to explain how to use Systrace for analysis.

Jank, Responsiveness, and ANR often appear together and can share contributing causes, but they are not severity levels of one mechanism. Uneven visual progress, delayed feedback, and an ANR triggered by a particular timeout need separate evidence. Treat a user’s “the app is slow/stuttering” as an experience report first, then establish which action and outcome are delayed.

Uneven animation or scrolling is usually called Jank. Long startup, screen-wake, or transition delays are slow response / high latency; ANR means Application Not Responding. These categories can overlap. High latency can coexist with jank, while ANRs must be diagnosed by their specific trigger.

Furthermore, within Apps or manufacturers, Jank, Responsiveness, and ANR have individual metrics like Frame Drop Rate, Startup Speed, and ANR Rate. Mastering the analysis and optimization of these issues is crucial for developers.

This is the first article in the Responsiveness series, focusing on theoretical knowledge, including an overview of performance engineering, key responsiveness concepts, and analysis methodologies.

Different people have different understandings of smoothness (jank/dropped frames) and different perceptions of jitter thresholds. Therefore, before starting this series, it is necessary to clarify the content to avoid misunderstandings. Here are some basic explanations:

1. For mobile users, jank encompasses many scenarios: dropped frames when scrolling lists, excessive white screen during app startup, slow screen wake-up when pressing the power button, unresponsive interface followed by a crash, no response when clicking an icon, incoherent window animations, lagging touch response, or stuttering when entering the desktop after a reboot. These scenarios differ slightly from what developers understand as “jank.” Developers categorize these more finely, which is a cognitive gap between developers and users that must be noted when handling feedback from users or testers.
2. Developers can initially classify feedback as Smoothness (uneven visual progress), Responsiveness (long waits after an action), or Stability (crashes and ANRs). These can overlap. An icon that appears unresponsive is not necessarily a stability failure; input, application state, and logs determine the diagnosis.
3. These are not one Message-timeout mechanism with different thresholds. Long main-thread tasks can delay both input and rendering, but GPU work, SurfaceFlinger, the display stack, scheduling, or remote services can also cause delays. ANRs depend on specific input or component timeout rules; crashes have separate causes such as exceptions or signals. A long Message alone establishes neither.
4. This series primarily analyzes smoothness-related issues. Responsiveness and stability will be covered in dedicated articles. Understanding smoothness first will make analyzing responsiveness and stability much easier.
5. This series focuses on using Systrace (Perfetto) for analysis. Systrace is our entry point because many factors affect smoothness—some within the app itself and others within the system. Systrace (Perfetto) provides a holistic view of the system’s operation during the problem, helping us initially pinpoint the root cause.

Different people have different understandings of smoothness (jank/dropped frames) and different perceptions of jitter thresholds. Therefore, before starting this series, it is necessary to clarify the content to avoid misunderstandings. Here are some basic explanations:

1. For mobile users, jank encompasses many scenarios: dropped frames when scrolling lists, excessive white screen during app startup, slow screen wake-up when pressing the power button, unresponsive interface followed by a crash, no response when clicking an icon, incoherent window animations, lagging touch response, or stuttering when entering the desktop after a reboot. These scenarios differ slightly from what developers understand as “jank.” Developers categorize these more finely, which is a cognitive gap between developers and users that must be noted when handling feedback from users or testers.
2. Developers can initially classify feedback as Smoothness (uneven visual progress), Responsiveness (long waits after an action), or Stability (crashes and ANRs). These can overlap. An icon that appears unresponsive is not necessarily a stability failure; input, application state, and logs determine the diagnosis.
3. These are not one Message-timeout mechanism with different thresholds. Long main-thread tasks can delay both input and rendering, but GPU work, SurfaceFlinger, the display stack, scheduling, or remote services can also cause delays. ANRs depend on specific input or component timeout rules; crashes have separate causes such as exceptions or signals. A long Message alone establishes neither.
4. This series primarily analyzes smoothness-related issues. Responsiveness and stability will be covered in dedicated articles. Understanding smoothness first will make analyzing responsiveness and stability much easier.
5. This series focuses on using Systrace (Perfetto) for analysis. Systrace is our entry point because many factors affect smoothness—some within the app itself and others within the system. Systrace (Perfetto) provides a holistic view of the system’s operation during the problem, helping us initially pinpoint the root cause.

Different people have different understandings of smoothness (jank/dropped frames) and different perceptions of jitter thresholds. Therefore, before starting this series, it is necessary to clarify the content to avoid misunderstandings and help everyone approach these articles with the right questions. Here are some basic explanations:

1. For mobile users, jank encompasses many scenarios: dropped frames when scrolling lists, excessive white screen during app startup, slow screen wake-up when pressing the power button, unresponsive interface followed by a crash, no response when clicking an icon, incoherent window animations, lagging touch response, or stuttering when entering the desktop after a reboot. These scenarios differ slightly from what developers understand as “jank.” Developers categorize these more finely, which is a cognitive gap between developers and users that must be noted when handling feedback from users or testers.
2. Developers can initially classify feedback as Smoothness (uneven visual progress), Responsiveness (long waits after an action), or Stability (crashes and ANRs). These can overlap. An icon that appears unresponsive is not necessarily a stability failure; input, application state, and logs determine the diagnosis.
3. These are not one Message-timeout mechanism with different thresholds. Long main-thread tasks can delay both input and rendering, but GPU work, SurfaceFlinger, the display stack, scheduling, or remote services can also cause delays. ANRs depend on specific input or component timeout rules; crashes have separate causes such as exceptions or signals. A long Message alone establishes neither.
4. This series primarily analyzes smoothness-related issues. Responsiveness and stability will be covered in dedicated articles. Understanding smoothness first will make analyzing responsiveness and stability much easier.
5. This series focuses on using Systrace (Perfetto) for analysis. Systrace is our entry point because many factors affect smoothness—some within the app itself and others within the system. Systrace (Perfetto) provides a holistic view of the system’s operation during the problem, helping us initially pinpoint the root cause.