Deep Performance Tuning (深度效能優化)

Instructions

•僅在有量測數據或明確瓶頸時使用
•依照下方章節順序套用
•一次只施作一種優化並驗證效果
•完成後對照 Quick Checklist

When to Use

•Scenario D：效能問題排查
•Scenario E：發布前效能驗證

Example Prompts

•"請參考 App Startup Optimization，建立 Macrobenchmark 測量"
•"用 Memory Analysis 章節，規劃記憶體分析流程"
•"請依照 R8/Proguard Optimization，檢查規則是否完整"

Workflow

•先建立量測基準（Startup/Memory/UI）
•再逐一套用對應優化手段
•最後用 Quick Checklist 驗收

Practical Notes (2026)

•Baseline Profile + Macrobenchmark 作為預設流程
•每次只做一項優化並量測差異
•效能門檻要進 CI Gate

Minimal Template

code

目標: 
量測基準: 
優化範圍: 
回歸指標: 
驗收: Quick Checklist

App Startup Optimization

Macrobenchmark 測量

kotlin

@LargeTest
@RunWith(AndroidJUnit4::class)
class StartupBenchmark {
    
    @get:Rule
    val benchmarkRule = MacrobenchmarkRule()
    
    @Test
    fun startupCompilationNone() = startup(CompilationMode.None())
    
    @Test
    fun startupCompilationPartial() = startup(CompilationMode.Partial())
    
    private fun startup(compilationMode: CompilationMode) {
        benchmarkRule.measureRepeated(
            packageName = "com.example.app",
            metrics = listOf(StartupTimingMetric()),
            compilationMode = compilationMode,
            iterations = 5,
            startupMode = StartupMode.COLD
        ) {
            pressHome()
            startActivityAndWait()
        }
    }
}

Baseline Profiles

kotlin

// 生成 Baseline Profile
@RunWith(AndroidJUnit4::class)
class BaselineProfileGenerator {
    
    @get:Rule
    val rule = BaselineProfileRule()
    
    @Test
    fun generate() {
        rule.collect("com.example.app") {
            pressHome()
            startActivityAndWait()
            
            // 關鍵路徑
            device.findObject(By.text("Login")).click()
            device.wait(Until.hasObject(By.text("Home")), 5000)
        }
    }
}

Application onCreate 優化

kotlin

class MyApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        
        // ❌ 同步初始化 (Block UI)
        // Firebase.initialize(this)
        // Timber.plant(DebugTree())
        
        // ✅ 延遲初始化
        AppInitializer.getInstance(this)
            .initializeComponent(FirebaseInitializer::class.java)
        
        // ✅ 背景初始化
        ProcessLifecycleOwner.get().lifecycle.addObserver(
            object : DefaultLifecycleObserver {
                override fun onCreate(owner: LifecycleOwner) {
                    lifecycleScope.launch(Dispatchers.Default) {
                        // 非關鍵初始化
                    }
                }
            }
        )
    }
}

Memory Analysis

Heap Dump 分析

bash

# 取得 Heap Dump
adb shell am dumpheap com.example.app /data/local/tmp/heap.hprof
adb pull /data/local/tmp/heap.hprof

# 使用 Android Studio Profiler 分析
# 或使用 MAT (Memory Analyzer Tool)

LeakCanary 設定

kotlin

// build.gradle.kts
debugImplementation("com.squareup.leakcanary:leakcanary-android:2.12")

// 自定義報告
class MyApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        LeakCanary.config = LeakCanary.config.copy(
            retainedVisibleThreshold = 3,
            objectInspectors = AndroidObjectInspectors.appDefaults
        )
    }
}

Bitmap 記憶體管理

kotlin

// 使用 Coil 自動管理
AsyncImage(
    model = ImageRequest.Builder(LocalContext.current)
        .data(imageUrl)
        .size(Size.ORIGINAL)  // 根據需求調整
        .memoryCachePolicy(CachePolicy.ENABLED)
        .build(),
    contentDescription = null
)

R8/Proguard Optimization

自定義規則

proguard

# 保留 Serializable
-keepclassmembers class * implements java.io.Serializable {
    static final long serialVersionUID;
    private static final java.io.ObjectStreamField[] serialPersistentFields;
    !static !transient <fields>;
    private void writeObject(java.io.ObjectOutputStream);
    private void readObject(java.io.ObjectInputStream);
}

# 保留 Retrofit Interface
-keep,allowobfuscation interface * {
    @retrofit2.http.* <methods>;
}

# 保留 Compose stability
-keep class * {
    @androidx.compose.runtime.Stable *;
    @androidx.compose.runtime.Immutable *;
}

APK Size 分析

bash

# 使用 bundletool
bundletool build-apks --bundle=app.aab --output=app.apks
bundletool get-size total --apks=app.apks

# Android Studio: Build > Analyze APK

UI Performance

JankStats

kotlin

class MainActivity : ComponentActivity() {
    private lateinit var jankStats: JankStats
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        jankStats = JankStats.createAndTrack(window) { frameData ->
            if (frameData.isJank) {
                Log.w("Jank", "Frame took ${frameData.frameDurationUiNanos / 1_000_000}ms")
            }
        }
    }
}

Compose Recomposition Tracking

kotlin

// 開啟 Composition Tracking
@Composable
fun DebugComposable() {
    SideEffect {
        Log.d("Recomposition", "DebugComposable recomposed")
    }
}

// 使用 Layout Inspector 檢查 recomposition count

Quick Checklist

• Startup: Baseline Profiles 生成
• Startup: Application onCreate 延遲初始化
• Memory: LeakCanary 無洩漏
• APK: R8 規則完善
• UI: JankStats 無嚴重掉幀