Benchmarking in AndroidX

The public documentation at d.android.com/benchmark explains how to use the library - this page focuses on specifics to writing libraries in the AndroidX repo, and our continuous testing / triage process.

Writing the benchmark

Benchmarks are just regular instrumentation tests! Just use the BenchmarkRule provided by the library:

Kotlin {.new-tab}

@RunWith(AndroidJUnit4::class)
class ViewBenchmark {
    @get:Rule
    val benchmarkRule = BenchmarkRule()

    @Test
    fun simpleViewInflate() {
        val context = InstrumentationRegistry
                .getInstrumentation().targetContext
        val inflater = LayoutInflater.from(context)
        val root = FrameLayout(context)

        benchmarkRule.measure {
            inflater.inflate(R.layout.test_simple_view, root, false)
        }
    }
}

Java {.new-tab}

@RunWith(AndroidJUnit4.class)
public class ViewBenchmark {
    @Rule
    public BenchmarkRule mBenchmarkRule = new BenchmarkRule();

    @Test
    public void simpleViewInflate() {
        Context context = InstrumentationRegistry
                .getInstrumentation().getTargetContext();
        final BenchmarkState state = mBenchmarkRule.getState();
        LayoutInflater inflater = LayoutInflater.from(context);
        FrameLayout root = new FrameLayout(context);

        while (state.keepRunning()) {
            inflater.inflate(R.layout.test_simple_view, root, false);
        }
    }
}

Project structure

As in the public documentation, benchmarks in the AndroidX repo are test-only library modules. Differences for AndroidX repo:

1. Module name must end with -benchmark in settings.gradle.
2. You do not need to apply the benchmark plugin (it's pulled in automatically from source)

I'm lazy and want to start quickly

Start by copying one of the following projects:

• navigation-benchmark
• recyclerview-benchmark

Compose

Compose builds the benchmark from source, so usage matches the rest of the AndroidX project. See existing Compose benchmark projects:

• Compose UI benchmarks
• Compose Runtime benchmarks

Profiling

Command Line

The benchmark library supports capturing profiling information - sampled and method - from the command line. Here's an example which runs the androidx.ui.benchmark.test.CheckboxesInRowsBenchmark#draw method with MethodSampling profiling:

./gradlew compose:integ:bench:cC \
    -P android.testInstrumentationRunnerArguments.androidx.benchmark.profiling.mode=MethodSampling \
    -P android.testInstrumentationRunnerArguments.class=androidx.ui.benchmark.test.CheckboxesInRowsBenchmark#draw

The command output will tell you where to look for the file on your host machine:

04:33:49 I/Benchmark: Benchmark report files generated at
/androidx-main/out/ui/ui/integration-tests/benchmark/build/outputs/connected_android_test_additional_output

To inspect the captured trace, open the appropriate *.trace file in that directory with Android Studio, using File > Open.

For more information on the MethodSampling and MethodTracing profiling modes, see the Studio Profiler configuration docs, specifically Java Sampled Profiling, and Java Method Tracing.

Advanced: Simpleperf Method Sampling

Simpleperf offers more accurate profiling for apps than standard method sampling, due to lower overhead (as well as C++ profiling support). Simpleperf support will be simplified and improved over time.

Simpleperf app profiling docs.

Device

Get an API 28+ device (Or a rooted API 27 device). The rest of this section is about why those constraints exist, skip if not interested.

Simpleperf has restrictions about where it can be used - Jetpack Benchmark will only support API 28+ for now, due to platform/simpleperf constraints (see last subsection titled “If you want to profile Java code”). Summary is:

• <=23 (M): Unsupported for Java code.

• 24-25 (N): Requires compiled Java code. We haven't investigated support.

• 26 (O): Requires compiled Java code, and wrapper script. We haven't investigated support.

• 27 (P): Can profile all Java code, but requires userdebug/rooted device

• >=28 (Q): Can profile all Java code, requires profileable (or userdebug/rooted device)

We aren‘t planning to support profiling debuggable APK builds, since they’re misleading for profiling.

Initial setup

Currently, we rely on Python scripts built by the simpleperf team. We can eventually build this into the benchmark library / gradle plugin. Download the scripts from AOSP:

# copying to somewhere outside of the androidx repo
git clone https://android.googlesource.com/platform/system/extras ~/simpleperf

Next configure your path to ensure the ADB that the scripts will use matches the androidx tools:

export PATH=$PATH:<path/to/androidx>/prebuilts/fullsdk-<linux or darwin>/platform-tools

Now, setup your device for simpleperf:

~/simpleperf/simpleperf/scripts/api_profiler.py prepare --max-sample-rate 10000000

Build and Run, Option 1: Studio (slightly recommended)

Running from Studio is simpler, since you don't have to manually install and run the APKs, avoiding Gradle.

Add the following to the benchmark module's build.gradle:

android {
    defaultConfig {
        // DO NOT COMMIT!!
        testInstrumentationRunnerArgument 'androidx.benchmark.profiling.mode', 'MethodSamplingSimpleperf'
        // Optional: Control freq / duration.
        testInstrumentationRunnerArgument 'androidx.benchmark.profiler.sampleFrequency', '1000000'
        testInstrumentationRunnerArgument 'androidx.benchmark.profiler.sampleDurationSeconds', '5'
    }
}

And run the test or tests you'd like to measure from within Studio.

Build and Run, Option 2: Command Line

Note - this will be significantly simplified in the future

Since we‘re not using AGP to pull the files yet, we can’t invoke the benchmark through Gradle, because Gradle uninstalls after each test run. Instead, let's just build and run manually:

./gradlew compose:integration-tests:benchmark:assembleReleaseAndroidTest

adb install -r ../../../out/ui/compose/integration-tests/benchmark/build/outputs/apk/androidTest/release/benchmark-release-androidTest.apk

# run the test (can copy this line from Studio console, when running a benchmark)
adb shell am instrument -w -m --no-window-animation -e androidx.benchmark.profiling.mode MethodSamplingSimpleperf -e debug false -e class 'androidx.ui.benchmark.test.CheckboxesInRowsBenchmark#toggleCheckbox_draw' androidx.ui.benchmark.test/androidx.benchmark.junit4.AndroidBenchmarkRunner

Pull and open the trace

# move the files to host
# (Note: removes files from device)
~/simpleperf/simpleperf/scripts/api_profiler.py collect -p androidx.ui.benchmark.test -o ~/simpleperf/results

# create/open the HTML report
~/simpleperf/simpleperf/scripts/report_html.py -i ~/simpleperf/results/CheckboxesInRowsBenchmark_toggleCheckbox_draw\[1\].data

Advanced: Studio Profiling

Profiling for allocations and simpleperf profiling requires Studio to capture.

Studio profiling tools require debuggable=true. First, temporarily override it in your benchmark's androidTest/AndroidManifest.xml.

Next choose which profiling you want to do: Allocation, or Sampled (SimplePerf)

ConnectedAllocation will help you measure the allocations in a single run of a benchmark loop, after warmup.

ConnectedSampled will help you capture sampled profiling, but with the more detailed / accurate Simpleperf sampling.

Set the profiling type in your benchmark module's build.gradle:

android {
    defaultConfig {
        // Local only, don't commit this!
        testInstrumentationRunnerArgument 'androidx.benchmark.profiling.mode', 'ConnectedAllocation'
    }
}

Run File > Sync Project with Gradle Files, or sync if Studio asks you. Now any benchmark runs in that project will permit debuggable, and pause before and after the test, to allow you to connect a profiler and start recording, and then stop recording.

Running and Profiling

After the benchmark test starts, you have about 20 seconds to connect the profiler:

1. Click the profiler tab at the bottom
2. Click the plus button in the top left, <device name>, <process name>
3. Next step depends on which you intend to capture

Allocations

Click the memory section, and right click the window, and select Record allocations. Approximately 20 seconds later, right click again and select Stop recording.