Optimize Compose Multiplatform Apps: Performance Monitoring in Jetpack Compose

Jetpack Compose has revolutionized Android UI development by offering a modern, declarative approach. Now, with Compose Multiplatform, developers can extend this paradigm to other platforms like iOS, web, and desktop. However, performance monitoring becomes even more crucial when targeting multiple platforms, as varying hardware and software environments can introduce platform-specific bottlenecks. This post delves into the techniques and tools for effectively monitoring the performance of your Compose Multiplatform applications.

Why is Performance Monitoring Important in Compose Multiplatform?

When building cross-platform applications with Compose Multiplatform, performance can vary significantly across different operating systems and devices. Optimizing for a single platform doesn’t guarantee optimal performance everywhere. Monitoring performance helps you to:

• Identify platform-specific issues.
• Ensure consistent user experience across all platforms.
• Detect memory leaks and inefficient code.
• Benchmark improvements after optimizations.

Key Areas for Performance Monitoring in Compose Multiplatform

Before diving into specific tools, let’s define the areas you need to monitor:

• UI Rendering: Measuring frame rates, UI thread responsiveness, and composition counts.
• Memory Usage: Monitoring memory consumption, garbage collection frequency, and identifying potential memory leaks.
• CPU Usage: Tracking CPU usage, particularly during computationally intensive tasks or animations.
• Network Performance: Analyzing network request times, data transfer rates, and error rates.
• Startup Time: Optimizing the time it takes for the application to start, which significantly impacts user experience.

Tools and Techniques for Performance Monitoring

1. Android Profiler

The Android Profiler, built into Android Studio, offers real-time data on your app’s CPU, memory, and network usage. It is an indispensable tool for any Android developer, and its benefits extend seamlessly to Compose Multiplatform projects on Android.

Using the Android Profiler with Compose Multiplatform

1. Connect your Android device or emulator: Ensure your test device is connected and recognized by Android Studio.
2. Run your Compose Multiplatform app: Build and run the Android target of your app.
3. Open the Android Profiler: Go to View > Tool Windows > Profiler in Android Studio.
4. Start Profiling: Choose the appropriate profiler (CPU, Memory, Network) to start monitoring.

Example: Monitoring CPU Usage

To monitor CPU usage:

1. Select the CPU profiler.
2. Choose a profiling configuration (e.g., Sampled Java Methods).
3. Interact with your app to trigger CPU-intensive operations.
4. Analyze the recorded data to identify hotspots.

// Sample CPU intensive operation in Kotlin
fun performComplexCalculation(): Double {
    var result = 0.0
    for (i in 1..1000000) {
        result += Math.sqrt(i.toDouble())
    }
    return result
}

// In your composable function
@Composable
fun MyComposable() {
    val result = remember { mutableStateOf(0.0) }

    Button(onClick = {
        // Start a coroutine to perform the calculation off the main thread
        CoroutineScope(Dispatchers.Default).launch {
            val calculatedResult = performComplexCalculation()
            withContext(Dispatchers.Main) {
                result.value = calculatedResult
            }
        }
    }) {
        Text("Calculate")
    }

    Text("Result: ${result.value}")
}

Run this on your Android device, and monitor the CPU profiler to see the impact of the performComplexCalculation function.

2. Instruments (for iOS)

On iOS, Instruments is the go-to tool for performance analysis. Instruments provides a wide array of instruments to profile different aspects of your app.

Using Instruments with Compose Multiplatform on iOS

1. Build your iOS app: Compile your Compose Multiplatform code into an iOS application.
2. Open Xcode: Launch Xcode and select Open Developer Tool > Instruments.
3. Choose a template: Select a profiling template (e.g., Allocations, Leaks, Time Profiler).
4. Record a profiling session: Launch your app on a physical iOS device or simulator and start the recording.

Example: Monitoring Memory Leaks with Instruments

Here’s how to use Instruments to detect memory leaks:

1. Select the Leaks template.
2. Run your app and perform actions that might lead to leaks.
3. Stop the recording and examine the identified leaks.

3. Compose Profiler

Jetpack Compose itself provides profiling tools to help analyze recompositions, which can be a major source of performance issues. It will let you inspect which parts of UI recompose often.

import androidx.compose.runtime.remember
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.Composable
import androidx.compose.material.Button
import androidx.compose.material.Text
import kotlinx.coroutines.*

@Composable
fun MyComposable(data: String) {
    val counter = remember { mutableStateOf(0) }

    // This button will trigger recomposition of this composable
    Button(onClick = { counter.value++ }) {
        Text("Increment")
    }

    // This Text composable will recompose when either 'data' or 'counter' changes
    Text("Data: $data, Counter: ${counter.value}")
}

To use the Compose Profiler:

1. Enable layout inspector and perform analysis
2. Run your app in debug mode
3. Inspect what triggered composition with help of recomposition highlights

4. Systrace

Systrace is a powerful command-line tool for analyzing system-wide performance. It allows you to visualize and identify bottlenecks in both kernel and user-space code on Android.

Using Systrace with Compose Multiplatform

1. Install Python and the Android SDK Platform-Tools: Make sure you have the necessary prerequisites installed.
2. Connect your Android device: Ensure your device is connected via ADB.
3. Run Systrace: Execute the Systrace command, specifying the categories and duration.

python systrace.py --time=10 -o my_trace.html gfx view input

Open the generated HTML file to analyze the trace. You can identify slow UI operations, blocking calls, and other performance issues.

5. Web Profilers

When targeting the web platform, browser developer tools become your primary performance monitoring resources.

Using Chrome DevTools with Compose Multiplatform

1. Run your Compose Multiplatform app in a browser.
2. Open Chrome DevTools: Right-click and select “Inspect.”
3. Use the Performance tab: Record a profiling session and analyze the results.

You can identify JavaScript performance bottlenecks, rendering issues, and network performance.

// JavaScript example: A slow function
function slowFunction() {
    let result = 0;
    for (let i = 0; i < 1000000; i++) {
        result += Math.sqrt(i);
    }
    return result;
}

6. Desktop Profilers

For desktop applications, platform-specific profilers or Java profilers can be utilized. YourKit, JProfiler, and VisualVM can connect to the JVM and inspect your application behavior.

Best Practices for Optimizing Performance in Compose Multiplatform

1. Minimize Recompositions:

   Avoid unnecessary recompositions by using stable data types, keys, and remember effectively. This includes usage of proper key in loop and using immutable data classes

2. Offload Work to Background Threads:

   Perform long-running or computationally intensive tasks in background threads to prevent blocking the UI thread.

3. Use Lazy Lists and Grids:

   For large datasets, use LazyColumn and LazyRow (or their multiplatform counterparts) to only compose items that are currently visible on the screen.

4. Optimize Images:

   Use optimized image formats and load them efficiently to reduce memory usage and improve rendering performance.

5. Use Hardware Acceleration:

   Ensure that hardware acceleration is enabled where available to improve rendering performance.

6. Profile Regularly:

   Make performance profiling a routine part of your development process. This will help catch issues early, before they become major bottlenecks.

7. Test on Multiple Devices:

   Testing your Compose Multiplatform application on a range of devices will give you a more accurate view of performance variations.

8. Use Inline Functions:

   In Kotlin, consider using inline functions for frequently called small functions to reduce overhead.

Code Examples and Implementation Tips

Efficient State Management

Avoid excessive recompositions by using stable state holders:

import androidx.compose.runtime.Composable
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember

// Good: Using remember to avoid re-initialization
@Composable
fun MyComposable() {
    val myState = remember { mutableStateOf(0) }
    Text("Value: ${myState.value}")
}

Use Keys in Loops

Always use unique keys when rendering lists of items. Without keys, Compose must re-compose the entire list even if only one item has changed.
This guarantees that Compose correctly identifies which items have changed, improving performance.

import androidx.compose.runtime.Composable
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.material.Text

data class ListItem(val id: Int, val text: String)

@Composable
fun MyList(items: List) {
    LazyColumn {
        items(items, key = { item -> item.id }) { item ->
            Text(text = item.text)
        }
    }
}

Conclusion

Performance monitoring in Compose Multiplatform applications requires a multifaceted approach. By leveraging platform-specific tools, adhering to best practices, and implementing targeted optimizations, you can ensure that your applications deliver a smooth and responsive user experience across all supported platforms. Embrace performance profiling as an integral part of your development lifecycle to identify and address bottlenecks proactively, resulting in high-quality Compose Multiplatform applications.