This document shows best practices to help diagnose problems and ensure your Baseline Profiles work correctly to provide the most benefit.

## Build issues

If you have copied the Baseline Profiles example in the[Now in Android](https://github.com/android/nowinandroid)sample app, you might encounter test failures during the Baseline Profile task stating that the tests cannot be run on an emulator:  

    ./gradlew assembleDemoRelease
    Starting a Gradle Daemon (subsequent builds will be faster)
    Calculating task graph as no configuration cache is available for tasks: assembleDemoRelease
    Type-safe project accessors is an incubating feature.

    > Task :benchmarks:pixel6Api33DemoNonMinifiedReleaseAndroidTest
    Starting 14 tests on pixel6Api33

    com.google.samples.apps.nowinandroid.foryou.ScrollForYouFeedBenchmark > scrollFeedCompilationNone[pixel6Api33] FAILED
            java.lang.AssertionError: ERRORS (not suppressed): EMULATOR
            WARNINGS (suppressed):
            ...

The failures occur because Now in Android uses a Gradle-managed device for Baseline Profile generation. The failures are expected, because you generally shouldn't run performance benchmarks on an emulator. However, since you're not collecting performance metrics when you generate Baseline Profiles, you can run Baseline Profile collection on emulators for convenience. To use Baseline Profiles with an emulator, perform the build and installation from the command-line, and set an argument to enable Baseline Profiles rules:  

    installDemoRelease -Pandroid.testInstrumentationRunnerArguments.androidx.benchmark.enabledRules=BaselineProfile

Alternatively, you can create a custom run configuration in Android Studio to enable Baseline Profiles on emulators by selecting**Run \> Edit Configurations**:
![Add a custom run configuration to create Baseline Profiles in Now in Android](https://developer.android.com/static/topic/performance/images/studio/run-config-nowinandroid-baselineprofiles.png)**Figure 1.**Add a custom run configuration to create Baseline Profiles in Now in Android.**Note:** Creating a custom run configuration isn't necessary when you add Baseline Profiles using the Baseline Profile module wizard in Android Studio, which is recommended. The wizard creates a run configuration for you.

## Installation issues

Check that the APK or AAB you're inspecting is from a build variant that includes Baseline Profiles:

1. In Android Studio select**Build \> Analyze APK**.
2. Open your AAB or APK.
3. If you're inspecting an AAB, the profile is at`/BUNDLE-METADATA/com.android.tools.build.profiles/baseline.prof`. If you're inspecting an APK, the profile is at`/assets/dexopt/baseline.prof`.

![Check for a Baseline Profile using APK Viewer in Android Studio](https://developer.android.com/static/topic/performance/images/studio/baseline-profile-in-apk.png)**Figure 2.**Check for a Baseline Profile using APK Viewer in Android Studio.

Baseline Profiles need to be compiled on the device running the app. When you install the app using the Play store, Android Studio, or the Gradle Wrapper command line tool, the on-device compilation happens automatically. When the app is installed using other tools, the Jetpack[`ProfileInstaller`](https://developer.android.com/jetpack/androidx/releases/profileinstaller)library is responsible for enqueueing the profiles for compilation during the next background DEX optimization process. In those cases, if you want to ensure your Baseline Profiles are being used, you might need to[force compilation of Baseline Profiles](https://developer.android.com/topic/performance/baselineprofiles/debug-baseline-profiles#force_compilation_of_baseline_profiles).[`ProfileVerifier`](https://developer.android.com/reference/androidx/profileinstaller/ProfileVerifier)lets you query the status of the profile installation and compilation, as shown in the following example:
**Note:** If you're using an AGP version lower than 8.4 and installing the app using Android Studio or the Gradle Wrapper command line tool (or tools other than the Play store), the Baseline Profile compilation doesn't happen automatically. For more information, see the release updates at[Minimum recommended stable versions](https://developer.android.com/topic/performance/baselineprofiles/overview#recommended-versions).  

### Kotlin

```kotlin
private const val TAG = "MainActivity"

class MainActivity : ComponentActivity() {
  ...
  override fun onResume() {
    super.onResume()
    lifecycleScope.launch {
      logCompilationStatus()
    }
  }

  private suspend fun logCompilationStatus() {
     withContext(Dispatchers.IO) {
        val status = ProfileVerifier.getCompilationStatusAsync().await()
        when (status.profileInstallResultCode) {
            RESULT_CODE_NO_PROFILE ->
                Log.d(TAG, "ProfileInstaller: Baseline Profile not found")
            RESULT_CODE_COMPILED_WITH_PROFILE ->
                Log.d(TAG, "ProfileInstaller: Compiled with profile")
            RESULT_CODE_PROFILE_ENQUEUED_FOR_COMPILATION ->
                Log.d(TAG, "ProfileInstaller: Enqueued for compilation")
            RESULT_CODE_COMPILED_WITH_PROFILE_NON_MATCHING ->
                Log.d(TAG, "ProfileInstaller: App was installed through Play store")
            RESULT_CODE_ERROR_PACKAGE_NAME_DOES_NOT_EXIST ->
                Log.d(TAG, "ProfileInstaller: PackageName not found")
            RESULT_CODE_ERROR_CACHE_FILE_EXISTS_BUT_CANNOT_BE_READ ->
                Log.d(TAG, "ProfileInstaller: Cache file exists but cannot be read")
            RESULT_CODE_ERROR_CANT_WRITE_PROFILE_VERIFICATION_RESULT_CACHE_FILE ->
                Log.d(TAG, "ProfileInstaller: Can't write cache file")
            RESULT_CODE_ERROR_UNSUPPORTED_API_VERSION ->
                Log.d(TAG, "ProfileInstaller: Enqueued for compilation")
            else ->
                Log.d(TAG, "ProfileInstaller: Profile not compiled or enqueued")
        }
    }
}
```

### Java

```java
public class MainActivity extends ComponentActivity {

    private static final String TAG = "MainActivity";

    @Override
    protected void onResume() {
        super.onResume();

        logCompilationStatus();
    }

    private void logCompilationStatus() {
         ListeningExecutorService service = MoreExecutors.listeningDecorator(
                Executors.newSingleThreadExecutor());
        ListenableFuture<ProfileVerifier.CompilationStatus> future =
                ProfileVerifier.getCompilationStatusAsync();
        Futures.addCallback(future, new FutureCallback<>() {
            @Override
            public void onSuccess(CompilationStatus result) {
                int resultCode = result.getProfileInstallResultCode();
                if (resultCode == RESULT_CODE_NO_PROFILE) {
                    Log.d(TAG, "ProfileInstaller: Baseline Profile not found");
                } else if (resultCode == RESULT_CODE_COMPILED_WITH_PROFILE) {
                    Log.d(TAG, "ProfileInstaller: Compiled with profile");
                } else if (resultCode == RESULT_CODE_PROFILE_ENQUEUED_FOR_COMPILATION) {
                    Log.d(TAG, "ProfileInstaller: Enqueued for compilation");
                } else if (resultCode == RESULT_CODE_COMPILED_WITH_PROFILE_NON_MATCHING) {
                    Log.d(TAG, "ProfileInstaller: App was installed through Play store");
                } else if (resultCode == RESULT_CODE_ERROR_PACKAGE_NAME_DOES_NOT_EXIST) {
                    Log.d(TAG, "ProfileInstaller: PackageName not found");
                } else if (resultCode == RESULT_CODE_ERROR_CACHE_FILE_EXISTS_BUT_CANNOT_BE_READ) {
                    Log.d(TAG, "ProfileInstaller: Cache file exists but cannot be read");
                } else if (resultCode
                        == RESULT_CODE_ERROR_CANT_WRITE_PROFILE_VERIFICATION_RESULT_CACHE_FILE) {
                    Log.d(TAG, "ProfileInstaller: Can't write cache file");
                } else if (resultCode == RESULT_CODE_ERROR_UNSUPPORTED_API_VERSION) {
                    Log.d(TAG, "ProfileInstaller: Enqueued for compilation");
                } else {
                    Log.d(TAG, "ProfileInstaller: Profile not compiled or enqueued");
                }
            }

            @Override
            public void onFailure(Throwable t) {
                Log.d(TAG,
                        "ProfileInstaller: Error getting installation status: " + t.getMessage());
            }
        }, service);
    }
}
```

The following result codes provide hints for the cause of some issues:

`RESULT_CODE_COMPILED_WITH_PROFILE`
:   The profile is installed, compiled, and is used whenever the app is run. This is the result you want to see.

`RESULT_CODE_ERROR_NO_PROFILE_EMBEDDED`
:   No profile is found in the APK being run. Ensure that you're using a build variant that includes Baseline Profiles if you see this error, and that the APK contains a profile.

`RESULT_CODE_NO_PROFILE`
:   No profile was installed for this app when installing the app through app store or package manager. The main reason for this to error code is that profile installer did not run due to[`ProfileInstallerInitializer`](https://developer.android.com/reference/androidx/profileinstaller/ProfileInstallerInitializer)being disabled. Note that when this error is reported an embedded profile was still found in the application APK. When an embedded profile is not found, the error code returned is`RESULT_CODE_ERROR_NO_PROFILE_EMBEDDED`.

`RESULT_CODE_PROFILE_ENQUEUED_FOR_COMPILATION`
:   A profile is found in the APK or AAB and is enqueued for compilation. When a profile is installed by`ProfileInstaller`, it is queued for compilation the next time background DEX optimization is run by the system. The profile isn't active until compilation completes. Don't attempt to benchmark your Baseline Profiles until compilation is complete. You might need to[force compilation of Baseline Profiles](https://developer.android.com/topic/performance/baselineprofiles/debug-baseline-profiles#force_compilation_of_baseline_profiles). This error won't occur when app is installed from the app store or package manager on devices running Android 9 (API 28) and higher, because compilation is performed during installation.

`RESULT_CODE_COMPILED_WITH_PROFILE_NON_MATCHING`
:   A non-matching profile is installed and the app has been compiled with it. This is the result of installation through Google Play store or package manager. Note that this result differs from`RESULT_CODE_COMPILED_WITH_PROFILE`because the non-matching profile will only compile any methods that are still shared between the profile and the app. The profile is effectively smaller than expected, and fewer methods will be compiled than were included in the Baseline Profile.

`RESULT_CODE_ERROR_CANT_WRITE_PROFILE_VERIFICATION_RESULT_CACHE_FILE`
:   `ProfileVerifier`can't write the verification result cache file. This can either happen because something is wrong with the app folder permissions or if there isn't enough free disk space on the device.

`RESULT_CODE_ERROR_UNSUPPORTED_API_VERSION`
:   ProfileVerifier`is running on an unsupported API version of Android.
    ProfileVerifier`supports only Android 9 (API level 28) and higher.

`RESULT_CODE_ERROR_PACKAGE_NAME_DOES_NOT_EXIST`
:   A[`PackageManager.NameNotFoundException`](https://developer.android.com/reference/android/content/pm/PackageManager.NameNotFoundException)is thrown when querying the[`PackageManager`](https://developer.android.com/reference/android/content/pm/PackageManager)for the app package. This should rarely happen. Try uninstalling the app and reinstalling everything.

`RESULT_CODE_ERROR_CACHE_FILE_EXISTS_BUT_CANNOT_BE_READ`
:   A previous verification result cache file exists, but it can't be read. This should rarely happen. Try uninstalling the app and reinstalling everything.

### Use ProfileVerifier in production

In production, you can use`ProfileVerifier`in conjunction with analytics-reporting libraries, such as[Google Analytics for Firebase](https://firebase.google.com/products/analytics), to generate analytics events indicating the profile status. For example, this alerts you quickly if a new app version is released that doesn't contain Baseline Profiles.

### Force compilation of Baseline Profiles

If the compilation status of your Baseline Profiles is`RESULT_CODE_PROFILE_ENQUEUED_FOR_COMPILATION`, you can force immediate compilation using[`adb`](https://developer.android.com/tools/adb):  

    adb shell cmd package compile -r bg-dexopt <var translate="no">PACKAGE_NAME</var>

### Check compilation state without ProfileVerifier

If you aren't using`ProfileVerifier`, you can check the compilation state using`adb`, although it doesn't give as deep insights as`ProfileVerifier`:  

    adb shell dumpsys package dexopt | grep -A 2 <var translate="no">PACKAGE_NAME</var>

Using`adb`produces something similar to the following:  

      [com.google.samples.apps.nowinandroid.demo]
        path: /data/app/~~dzJiGMKvp22vi2SsvfjkrQ==/com.google.samples.apps.nowinandroid.demo-7FR1sdJ8ZTy7eCLwAnn0Vg==/base.apk
    arm64: \[status=speed-profile\] \[reason=bg-dexopt\] \[primary-abi\]
            [location is /data/app/~~dzJiGMKvp22vi2SsvfjkrQ==/com.google.samples.apps.nowinandroid.demo-7FR1sdJ8ZTy7eCLwAnn0Vg==/oat/arm64/base.odex]

The status value indicates the profile compilation status and is one of the following values:

| Compilation status |                   Meaning                    |
|--------------------|----------------------------------------------|
| `speed‑profile`    | A compiled profile exists and is being used. |
| `verify`           | No compiled profile exists.                  |

A`verify`status doesn't mean that the APK or AAB doesn't contain a profile, because it can be queued for compilation by the next background DEX optimization task.

The reason value indicates what triggers the compilation of the profile and is one of the following values:

|    Reason    |                                                                  Meaning                                                                  |
|--------------|-------------------------------------------------------------------------------------------------------------------------------------------|
| `install‑dm` | A Baseline Profile was compiled manually or by Google Play when the app is installed.                                                     |
| `bg‑dexopt`  | A profile was compiled while your device was idle. This might be a Baseline Profile, or it might be a profile collected during app usage. |
| `cmdline`    | The compilation was triggered using adb. This might be a Baseline Profile, or it might be a profile collected during app usage.           |

## Performance issues

This section shows some best practices for correctly defining and benchmarking your Baseline Profiles to get the most benefits from them.

### Correctly benchmark startup metrics

Your Baseline Profiles will be more effective if your startup metrics are well-defined. The two key metrics are[time to initial display (TTID)](https://developer.android.com/topic/performance/vitals/launch-time#time-initial)and[time to full display (TTFD)](https://developer.android.com/topic/performance/vitals/launch-time#time-full).

TTID is when the app draws its first frame. It's important to keep this as short as possible because displaying something shows the user that the app is running. You can even display an indeterminate progress indicator to show that the app is responsive.

TTFD is when the app can actually be interacted with. It's important to keep this as short as possible to avoid user frustration. If you correctly signal TTFD, you're telling the system that the code that's run on the way to TTFD is part of app startup. The system is more likely to place this code in the profile as a result.

Keep both TTID and TTFD as low as possible to make your app feel responsive.

The system is able to detect TTID, display it in Logcat, and report it as part of startup benchmarks. However, the system is unable to determine TTFD, and it's the app's responsibility to report when it reaches a fully drawn interactive state. You can do this by calling[`reportFullyDrawn()`](https://developer.android.com/reference/androidx/activity/ComponentActivity#reportFullyDrawn()), or[`ReportDrawn`](https://developer.android.com/reference/kotlin/androidx/activity/compose/package-summary#ReportDrawn())if you're using Jetpack Compose. If you have multiple background tasks that all need to complete before the app is considered fully drawn, then you can use[`FullyDrawnReporter`](https://developer.android.com/reference/androidx/activity/FullyDrawnReporter), as described in[Improve startup timing accuracy](https://developer.android.com/topic/performance/benchmarking/macrobenchmark-metrics#startup-accuracy).

#### Library profiles and custom profiles

When benchmarking the impact of profiles, it can be difficult to separate the benefits of your app's profiles from profiles contributed by libraries, such as Jetpack libraries. When you build your APK the Android Gradle plugin adds any profiles in library dependencies as well as your custom profile. This is good for optimizing overall performance, and is recommended for your release builds. However, it makes it hard to measure how much additional performance gain comes from your custom profile.

A quick way to manually see the additional optimization provided by your custom profile is to remove it, and run your benchmarks. Then replace it and run your benchmarks again. Comparing the two will show you the optimizations provided by the library profiles alone, and the library profiles plus your custom profile.

An automatable way of comparing profiles is by creating a new build variant that contains only the library profiles and not your custom profile. Compare benchmarks from this variant to the release variant that contains both the library profiles and your custom profiles. The following example shows how to set up the variant that includes only library profiles. Add a new variant named`releaseWithoutCustomProfile`to your profile consumer module, which is typically your app module:  

### Kotlin

```kotlin
android {
  ...
  buildTypes {
    ...
    // Release build with only library profiles.
    create("releaseWithoutCustomProfile") {
      initWith(release)
    }
    ...
  }
  ...
}
...
dependencies {
  ...
  // Remove the baselineProfile dependency.
  // baselineProfile(project(":baselineprofile"))
}

baselineProfile {
  variants {
    create("release") {
      from(project(":baselineprofile"))
    }
  }
}
```

### Groovy

```groovy
android {
  ...
  buildTypes {
    ...
    // Release build with only library profiles.
    releaseWithoutCustomProfile {
      initWith(release)
    }
    ...
  }
  ...
}
...
dependencies {
  ...
  // Remove the baselineProfile dependency.
  // baselineProfile ':baselineprofile"'
}

baselineProfile {
  variants {
    release {
      from(project(":baselineprofile"))
    }
  }
}
```

The preceding code example removes the`baselineProfile`dependency from all variants and selectively applies it to only the`release`variant. It might seem counterintuitive that the library profiles are still being added when the dependency on the profile producer module is removed. However, this module is only responsible for generating your custom profile. The Android Gradle plugin is still running for all variants, and is responsible for including library profiles.

You also need to add the new variant to the profile generator module. In this example the producer module is named`:baselineprofile`.  

### Kotlin

```kotlin
android {
  ...
    buildTypes {
      ...
      // Release build with only library profiles.
      create("releaseWithoutCustomProfile") {}
      ...
    }
  ...
}
```

### Groovy

```groovy
android {
  ...
    buildTypes {
      ...
      // Release build with only library profiles.
      releaseWithoutCustomProfile {}
      ...
    }
  ...
}
```

When you run the benchmark from Android Studio, select a`releaseWithoutCustomProfile`variant to measure performance with only library profiles, or select a`release`variant to measure performance with library and custom profiles.

### Avoid I/O-bound app startup

If your app is performing a lot of I/O calls or networks calls during startup, it can negatively affect both app startup time and the accuracy of your startup benchmarking. These heavyweight calls can take indeterminate amounts of time that can vary over time and even between iterations of the same benchmark. I/O calls are generally better than network calls, because the latter can be affected by factors external to the device and on the device itself. Avoid network calls during startup. Where using one or other is unavoidable, use I/O.

We recommend making your app architecture support app startup without network or I/O calls, even if only to use it when benchmarking startup. This helps ensure the lowest possible variability between different iterations of your benchmarks.

If your app uses Hilt, you can provide fake I/O-bound implementations when benchmarking in[Microbenchmark and Hilt](https://github.com/android/performance-samples/tree/main/MacrobenchmarkSample).

### Cover all important user journeys

It's important to accurately cover all of the important user journeys in your Baseline Profile generation. Any user journeys that aren't covered won't be improved by Baseline Profiles. The most effective baseline profiles include all common startup user journeys as well as performance-sensitive in-app user journeys such as scrolling lists.