Improving Android Build Performance Cédric Champeau, Gradle Inc.

About Gradle

| 3 What is Gradle? - Gradle != Gradle plugin for Android != Android Studio - Gradle is a build and automation tool - JVM based - 100% Free Open Source - Apache Standard License 2.0 - Multi-ecosystem - JVM: Java, Kotlin, Groovy, Scala, … - Native: C/C++, Go… - Android - …

| 4 Gradle, Inc. The company behind Gradle. • Build Happiness • Employs full time engineers • Providing Gradle Build Scans and Gradle Enterprise • (Gradle consulting, support, development services etc.) • (Training: online, public and in-house)

| 5 We’re hiring • Fully distributed development team • Exciting project used by millions • Build tool team and Gradle enterprise positions If anything you hear from now on sounds like a great problem to solve, Talk to us! https:/ /gradle.com/careers/

The Cost of Builds

| 7 60s waste * 50 builds per day * 50 developers = 42h wasted per day … and that’s not even considering lost focus Fast Builds Matter

General Advice

| 9 Process 1. Define scenario to improve 2. Profile scenario 3. Identify biggest bottleneck 4. Fix bottleneck 5. Verify fix by measurement 6. Repeat

|10 Automate your measurements github.com/gradle/gradle-profiler configurationTime { tasks = ["help"] } sync { tasks = ["generateDebugSources"] } cleanBuild { tasks = ["build"] cleanup-tasks = ["clean"] } cachedCleanBuild { tasks = ["build"] cleanup-tasks = ["clean"] gradle-args = ["--build-cache"] } configurationTime { tasks = ["help"] } sync { tasks = ["generateDebugSources"] } cleanBuild { tasks = ["build"] cleanup-tasks = ["clean"] } cachedCleanBuild { tasks = ["build"] cleanup-tasks = ["clean"] gradle-args = ["--build-cache"] }

|11 Stay Up-To-Date ./gradlew wrapper --gradle-version 4.10.2 buildscript { repositories { google() } dependencies { classpath ‘com.android.tools.build:gradle:3.1.2' } } buildscript { repositories { google() } dependencies { classpath ‘com.android.tools.build:gradle:3.1.2' } }

|12 JVM tuning Provide enough heap space Other tweaks often do more harm than good Spend your time on structural improvements

|13 The Gradle Daemon The Gradle Daemon is enabled by default Provides a number of in-memory caches Useful for repeated builds Do not disable it!

Where is the Problem?

|15 Build Scans

|16 The Build Lifecycle

|17 Red Flags Startup/Settings/buildSrc > 1s Configuration time >10ms/project Single-line change ≅ clean build No-op build doing any work at all High GC time

Startup, buildSrc, Settings

|19 Startup, buildSrc, Settings Use the Daemon, keep it healthy

Configuration Time

|21 Configuration Time Applying plugins Evaluating build scripts Running afterEvaluate {} blocks

|22 Configuration Time When running any task Even gradle help/gradle tasks Android Studio sync

|23 Resolution at Configuration Time

|24 Eager resolution task uberJar(type:Jar) { from sourceSets.main.output from configurations.runtime.collect { it.directory ? it : zipTree(it) } classifier "uber-jar" } task uberJar(type:Jar) { from sourceSets.main.output from configurations.runtime.collect { it.directory ? it : zipTree(it) } classifier "uber-jar" } Resolution at Configuration Time

|25 Use lazy evaluation instead task uberJar(type:Jar) { inputs.files configurations.runtime from sourceSets.main.output from { configurations.runtime.collect { it.directory ? it : zipTree(it) } } classifier "uber-jar" } task uberJar(type:Jar) { inputs.files configurations.runtime from sourceSets.main.output from { configurations.runtime.collect { it.directory ? it : zipTree(it) } } classifier "uber-jar" } Resolution at Configuration Time

|26 This build script seems expensive I/O at Configuration Time

|27 task projectStats() { def statsFile = new File(buildDir, 'stats.txt') statsFile.parentFile.mkdirs() statsFile.text = "Source files: ${sourceSets.main.java.size()}" } task projectStats() { def statsFile = new File(buildDir, 'stats.txt') statsFile.parentFile.mkdirs() statsFile.text = "Source files: ${sourceSets.main.java.size()}" } I/O at Configuration Time Careful when writing custom tasks!

|28 I/O at Configuration Time task projectStats() { def statsFile = new File(buildDir, 'stats.txt') inputs.files sourceSets.main.java outputs.file statsFile doLast { statsFile.parentFile.mkdirs() statsFile.text = "Source files: ${sourceSets.main.java.size()}" } } task projectStats() { def statsFile = new File(buildDir, 'stats.txt') inputs.files sourceSets.main.java outputs.file statsFile doLast { statsFile.parentFile.mkdirs() statsFile.text = "Source files: ${sourceSets.main.java.size()}" } } Don’t forget doLast {}

|29 task projectStats(type: ProjectStats) { statsFile = new File(buildDir, 'stats.txt') sources = sourceSets.main.java } class ProjectStats extends DefaultTask { @InputFiles FileCollection sources @OutputFile File statsFile @TaskAction def stats() { statsFile.text = "Source files: ${sources.size()}" } } task projectStats(type: ProjectStats) { statsFile = new File(buildDir, 'stats.txt') sources = sourceSets.main.java } class ProjectStats extends DefaultTask { @InputFiles FileCollection sources @OutputFile File statsFile @TaskAction def stats() { statsFile.text = "Source files: ${sources.size()}" } } I/O at Configuration Time

|30 Inefficient Plugins

|31 Expensive logic for each project def out = new ByteArrayOutputStream() exec { commandLine 'git', 'rev-parse', "HEAD" standardOutput = out workingDir = rootDir } version = new String(out.toByteArray()) def out = new ByteArrayOutputStream() exec { commandLine 'git', 'rev-parse', "HEAD" standardOutput = out workingDir = rootDir } version = new String(out.toByteArray()) subprojects { apply from: "$rootDir/gradle/version-from-status.gradle" } subprojects { apply from: "$rootDir/gradle/version-from-status.gradle" } Inefficient Plugins

|32 Reuse expensive calculations def out = new ByteArrayOutputStream() exec { commandLine 'git', 'rev-parse', "HEAD" standardOutput = out workingDir = rootDir } version = new String(out.toByteArray()) subprojects { version = rootProject.version } def out = new ByteArrayOutputStream() exec { commandLine 'git', 'rev-parse', "HEAD" standardOutput = out workingDir = rootDir } version = new String(out.toByteArray()) subprojects { version = rootProject.version } Inefficient Plugins

|33 Variant Explosion Use variantFilter {} to exclude useless flavor/buildType combinations

Optimising Build Logic

|35 Extract Script Plugins Makes finding issues easier apply from: "$rootDir/gradle/environment.gradle" apply from: "gradle/chuck-norris-fact.gradle" apply from: "$rootDir/gradle/version-from-status.gradle" subprojects { apply plugin: 'java' apply from: "$rootDir/gradle/test-fixtures.gradle" apply from: "$rootDir/gradle/compiler-settings.gradle" } apply from: "$rootDir/gradle/environment.gradle" apply from: "gradle/chuck-norris-fact.gradle" apply from: "$rootDir/gradle/version-from-status.gradle" subprojects { apply plugin: 'java' apply from: "$rootDir/gradle/test-fixtures.gradle" apply from: "$rootDir/gradle/compiler-settings.gradle" }

|36 Extract Binary Plugins Use buildSrc Use static compilation Keep build scripts declarative

|37 Optimise on the Algorithmic Level gradle-profiler --profile jfr

Execution Time

|39 Execution Time Executing selected tasks Incremental Cacheable Parallelizable

|40 Incremental Builds Nothing changed? Executed tasks should be zero!

|41 Incremental Builds Find volatile inputs

|42 Example: Crashlytics Unique IDs are the bane of local dev performance apply plugin: 'io.fabric' android { buildT ypes { debug { ext.alwaysUpdateBuildId = false } } } apply plugin: 'io.fabric' android { buildT ypes { debug { ext.alwaysUpdateBuildId = false } } }

|43 Faster Compilation Modularization => Compile avoidance Decoupled code => Faster incremental compilation Careful with Kotlin migration (for now)

|44 Incremental Annotation Processing Since Gradle 4.7 Early adopters: Lombok, Android-State, Dagger, Parceller Others: github.com/gradle/gradle/issues/5277

|45 Caching

|46 Parallelism Serial execution

|47 Parallelism --parallel and small, decoupled projects

Keeping track of performance

|50 Gradle Enterprise

|51 See all Builds Find out what colleagues are struggling with

|52 Get Deep Insights

|53 Watch Performance over Time

Resources

|55 Gradle performance guide https://guides.gradle.org/performance Android performance guide https://developer.android.com/studio/build/optimize-your-build.html Plugin development guide https://guides.gradle.org/implementing-gradle-plugins Structuring build logic guide https://docs.gradle.org/current/userguide/organizing_build_logic.html Guides

|56 scans.gradle.com

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