Gradle Performance Optimization

Table of Contents

• [Purpose](#purpose)
• [When to Use](#when-to-use)
• [Quick Start](#quick-start)
• [Instructions](#instructions)
• [Examples](#examples)
• [Commands Reference](#commands-reference)
• [Troubleshooting](#troubleshooting)
• [Performance Optimization Checklist](#performance-optimization-checklist)
• [See Also](#see-also)

Purpose

Dramatically improve Gradle build speed through intelligent caching, parallel execution, and configuration optimization. Properly configured projects can see 50-80% reduction in build times.

When to Use

Use this skill when you need to:

• Speed up slow Gradle builds (>2 minutes for medium projects)
• Optimize CI/CD pipeline build times
• Configure caching for multi-module projects
• Enable configuration cache for faster configuration phase
• Set up parallel execution for independent subprojects
• Tune JVM memory settings for large projects
• Generate build scans to identify performance bottlenecks
• Implement dependency locking for reproducible builds

Quick Start

Add these lines to gradle.properties:

# Enable caching (87% faster with cache hits)
org.gradle.caching=true
org.gradle.configuration-cache=true

# Enable parallel execution
org.gradle.parallel=true

# Configure memory (4GB for most projects)
org.gradle.jvmargs=-Xmx4g -XX:MaxMetaspaceSize=1g -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8

# Keep daemon running (enabled by default)
org.gradle.daemon=true

Then run:

./gradlew build --build-cache --parallel

Instructions

Step 1: Enable Build Cache

The build cache stores task outputs and reuses them when inputs haven't changed.

Enable local cache in gradle.properties:

org.gradle.caching=true

Results: 87% faster builds on cache hits (35s down to 4.5s example)

Configure remote cache for CI (optional but recommended for teams):

// settings.gradle.kts
buildCache {
    local {
        isEnabled = true
    }
    remote<HttpBuildCache> {
        url = uri("https://build-cache.company.com/cache/")
        isEnabled = true
        isPush = System.getenv("CI") == "true"  // Only CI pushes
        credentials {
            username = System.getenv("CACHE_USERNAME")
            password = System.getenv("CACHE_PASSWORD")
        }
    }
}

Step 2: Enable Configuration Cache

Configuration cache skips the entire configuration phase when inputs haven't changed. Gradle 8.11+ gives 65% median time reduction.

Enable in gradle.properties:

org.gradle.configuration-cache=true
org.gradle.configuration-cache.problems=warn  # Start with warnings

Verify compatibility:

./gradlew help --configuration-cache

Check configuration cache report:

build/reports/configuration-cache/<hash>/configuration-cache-report.html

Step 3: Enable Parallel Execution

Execute tasks from different projects simultaneously.

Enable in gradle.properties:

org.gradle.parallel=true
org.gradle.workers.max=4  # Adjust based on CPU cores (default: num cores)

Effectiveness: 30-50% faster for multi-module projects

Note: Requires independent subprojects; tasks within same project run sequentially unless using configuration cache.

Step 4: Configure Memory Settings

Proper JVM heap allocation is critical for large projects.

For most projects (up to 30 modules) in gradle.properties:

org.gradle.jvmargs=-Xmx4g -XX:MaxMetaspaceSize=1g -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8

For large projects (30+ modules):

org.gradle.jvmargs=-Xmx8g -XX:MaxMetaspaceSize=2g -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8

Memory allocation guidelines:

• Small projects (1-10 modules): 2-4 GB (-Xmx2g to -Xmx4g)
• Medium projects (10-30 modules): 4-6 GB (-Xmx4g to -Xmx6g)
• Large projects (30+ modules): 6-8 GB (-Xmx6g to -Xmx8g)

Step 5: Configure Daemon Settings

Gradle daemon is enabled by default but can be optimized.

In gradle.properties:

org.gradle.daemon=true
org.gradle.daemon.idletimeout=3600000  # 1 hour (default: 3 hours)

Manage daemon:

./gradlew --status              # Show running daemons
./gradlew --stop                # Stop all daemons
./gradlew build --no-daemon     # Run without daemon (for debugging)

Step 6: Dependency Resolution Optimization

Lock dependency versions for reproducible, faster builds.

Generate lock files:

./gradlew dependencies --write-locks

Result: gradle.lockfile and configuration-specific lock files created

Verify against locks:

./gradlew dependencies --verify-locks

Step 7: Enable Build Scans

Visualize build performance and identify bottlenecks.

One-time scan:

./gradlew build --scan

Automatic scanning in builds:

// build.gradle.kts
plugins {
    id("com.gradle.build-scan") version "3.17"
}

buildScan {
    termsOfServiceUrl = "https://gradle.com/terms-of-service"
    termsOfServiceAgree = "yes"
    publishAlways()
}

Step 8: Optimize CI/CD Configuration

Detect CI environment and adjust behavior:

// build.gradle.kts
val isCi = System.getenv("CI") != null

if (isCi) {
    // CI-specific build scan
    buildScan {
        termsOfServiceUrl = "https://gradle.com/terms-of-service"
        termsOfServiceAgree = "yes"
        publishAlways()
        tag("CI")
        tag(System.getenv("CI_COMMIT_REF_NAME") ?: "unknown")
    }
}

Examples

Example 1: Complete Optimized gradle.properties

# Gradle Optimization Configuration

# === CACHING ===
# Build cache - stores task outputs for reuse (87% faster on hits)
org.gradle.caching=true

# Configuration cache - skip configuration phase (65% faster median time)
org.gradle.configuration-cache=true
org.gradle.configuration-cache.problems=warn

# === EXECUTION ===
# Parallel execution - run tasks from different projects simultaneously
org.gradle.parallel=true
org.gradle.workers.max=4

# Daemon - long-running JVM process (enabled by default)
org.gradle.daemon=true
org.gradle.daemon.idletimeout=3600000

# === MEMORY ===
# JVM heap for Gradle daemon (adjust for project size)
org.gradle.jvmargs=-Xmx4g -XX:MaxMetaspaceSize=1g -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8

# === DEBUGGING ===
# Uncomment if needed
# org.gradle.logging.level=info
# org.gradle.debug=true

Example 2: Enabling Configuration Cache with Warnings

Start with warnings to identify incompatible plugins:

# gradle.properties
org.gradle.configuration-cache=true
org.gradle.configuration-cache.problems=warn  # Shows warnings instead of failing

Monitor output:

./gradlew build 2>&1 | grep -i "configuration-cache"

Fix issues, then switch to strict mode:

# Once all issues are fixed
org.gradle.configuration-cache=true
org.gradle.configuration-cache.problems=fail  # Now strict

Example 3: CI/CD GitHub Actions with Optimization

# .github/workflows/build.yml
name: Optimized Build

on: [push, pull_request]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v4

    - name: Set up JDK 21
      uses: actions/setup-java@v4
      with:
        java-version: '21'
        distribution: 'temurin'

    - name: Setup Gradle (official action with caching)
      uses: gradle/actions/setup-gradle@v4
      with:
        cache-encryption-key: ${{ secrets.GRADLE_ENCRYPTION_KEY }}

    - name: Build with Gradle (optimized)
      run: ./gradlew build --parallel --build-cache --configuration-cache --scan
      env:
        CI: true

    - name: Upload build scans
      if: always()
      uses: actions/upload-artifact@v4
      with:
        name: build-scans
        path: build/reports/

Example 4: GitLab CI/CD with Performance Tuning

# .gitlab-ci.yml
image: gradle:8.11-jdk21-alpine

variables:
  GRADLE_OPTS: "-Dorg.gradle.daemon=false -Dorg.gradle.caching=true -Dorg.gradle.parallel=true"
  GRADLE_USER_HOME: "$CI_PROJECT_DIR/.gradle"

cache:
  key: "$CI_COMMIT_REF_SLUG"
  paths:
    - .gradle/wrapper
    - .gradle/caches

build:
  stage: build
  script:
    - chmod +x ./gradlew
    - ./gradlew assemble --parallel --build-cache --configuration-cache
  artifacts:
    paths:
      - build/libs/*.jar
    expire_in: 1 day

test:
  stage: test
  script:
    - ./gradlew test --parallel --build-cache --configuration-cache
  artifacts:
    when: always
    reports:
      junit: build/test-results/test/TEST-*.xml

Example 5: Measuring Build Performance Improvement

# Before optimization
time ./gradlew clean build
# Real    2m 30s

# After optimization
time ./gradlew build --parallel --build-cache --configuration-cache
# Real    0m 45s (82% improvement!)

# Generate build scan for detailed analysis
./gradlew build --scan
# Opens scan at https://scans.gradle.com

Example 6: Dependency Locking for Consistency

# Generate lock files
./gradlew dependencies --write-locks

# Verify locks in CI
./gradlew dependencies --verify-locks

# Update lock files (controlled)
./gradlew dependencies --write-locks --refresh-dependencies

Commands Reference

See [references/commands-and-troubleshooting.md](references/commands-and-troubleshooting.md) for complete command reference, troubleshooting guide, and optimization checklist.

See Also

• [gradle-dependency-management](../gradle-dependency-management/SKILL.md) - Optimize dependency resolution
• [gradle-troubleshooting](../gradle-troubleshooting/SKILL.md) - Diagnose slow builds
• Gradle Build Scans - Analyze build performance
• Gradle Performance Guide