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Hong Mong 5 Development Treasure Case Sharing Performance Optimization Case Analysis

HarmonyOS Performance Optimization Treasure Guide: Practical Tools and Code Case Analysis

Hello everyone! While browsing the HarmonyOS developer documentation today, I accidentally discovered a treasure trove of performance optimization—it turns out the official team has already provided tons of practical tools and cases, but many developers might not have noticed! This article will walk you through these amazing tools step by step, with code-level solutions to make your app run smoother than ever~

🛠️ 1. HarmonyOS Performance Tools Suite

1. Development Stage: Static Code Scanning (Code Linter)

Purpose: Real-time detection of performance risks during coding, such as redundant layouts and excessive rendering.

Practical Example:

// Problematic code: Nested loops cause repeated layout measurement  
Component build() {  
    Column() {  
        ForEach(this.dataList, (item) => {  
            Row() {  // Each row contains complex subcomponents  
                Image($r(item.img)).width(100).height(100)  
                Text(item.name).fontSize(18)  
            }  
        })  
    }  
}
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Code Linter Warning:

⚠️ AvoidDeepNestLayout: Detected 3-level nested layout, which may cause rendering lag!

Optimization Solution: Use List instead of ForEach+Row to reuse components:

List({ space: 5 }) {  
    ForEach(this.dataList, (item) => {  
        ListItem() {  
            MyListItemComponent(item) // Encapsulated subcomponent  
        }  
    })  
}
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2. Testing Stage: Application Health Check Tool (Benchmark)

Purpose: Automatically detect issues like lag and memory leaks, generate reports, and pinpoint code locations.

Typical Issue: List scrolling lag

  • Health Check Report Tip:

❌ FrameDropRate > 10%: Severe frame drops during list scrolling!

📍 Related file: src/main/ets/pages/ProductList.ets

Cause Analysis:

// Synchronously loading large images in list items  
Image(item.url)  
    .onAppear(() => {  
        loadHighResImage(); // Main thread blocked!  
    })
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Optimization Solution:

// Switch to asynchronous loading + thumbnails  
Image(item.thumbnail) // Load low-res image first  
    .onAppear(async () => {  
        await loadHighResImage(); // Asynchronously load high-res image  
    })
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3. In-depth Analysis: DevEco Profiler

Purpose: Analyze time-consuming operations via trace files to accurately locate bottlenecks.

Practical Example: High page opening latency

  • Operation Process:
    1. Export perfdata file with the health check tool →
    2. Import into Profiler →
    3. View CPU Timeline

Problem Found:

// Synchronous time-consuming operation during page initialization  
aboutToAppear() {  
    initData(); // 2s synchronous operation  
}
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Optimization Solution:

// Split into asynchronous task  
aboutToAppear() {  
    TaskPool.execute(async () => {  
        await initData(); // Run in background  
        updateUI(); // Return to main thread to update UI  
    });  
}
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📊 2. Solutions to Common Performance Issues

Memory Leak Issue

Health Check Tool Tip:

❌ MemoryLeak: Detected unreleased Activity instance!

Typical Code:

// Global listener not unregistered  
sensor.on('acceleration', (data) => { ... });
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Fix Solution:

// Release resources when page exits  
aboutToDisappear() {  
    sensor.off('acceleration'); // Unregister listener  
}
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Overdraw Issue

Code Linter Warning:

⚠️ OverdrawWarning: Detected multiple overlapping draws!

Optimization Tip:

  • Use clip to crop overflow areas: 
Text("Hello")  
    .clip(true) // Prevent subcomponents from drawing outside
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🌟 Conclusion

This treasure hunt was really worth it! It turns out HarmonyOS has long prepared a full arsenal for performance optimization, just a bit hidden 😂 Quickly use the Code Linter + Health Check Tool + Profiler trio to avoid pitfalls from coding to testing. If you have more practical tips, feel free to share in the comments~

Performance optimization is not magic—use the right tools and your code will be silky smooth! 🚀

PS: For more cases, search for the keyword "Performance Best Practices" on the official website—there are more surprises in the official demo repository!

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