Gradle Summit
Gradle 3.0: Unleash the Daemon!
Eric Wendelin
2016

Eric Wendelin
@eriwen

Long-lived Background Process
Client/Server communicating over TCP locally
Listens for and executes Build Actions
Daemon in a nutshell

Daemonstration

2nd build typically
15-75% faster

faster the more
you use it
Progressive runtime optimizations
Higher class cache hit rate
More effective task I/O caching

"Discovered the beauty of the
@gradle daemon, and now reaping the
benefits of sub-second builds"
@tylerjharden

"Enabling the #gradle daemon took
my build from 13s to 1.1s. This should
be the default."
@GDBolinger

5th build typically
30-90% faster

Smokin'
fast!

Daemon in Gradle 3.0

Daemon in Gradle 3.0
Enabled by default
Resource-aware
More robust, especially on Windows
Better UX
Integrated with Gradle Build Scans

Daemon in Gradle 3.0
Enabled by default
Resource-aware
More robust, especially on Windows
Better UX
Integrated with Gradle Build Scans

--daemon
org.gradle.daemon=true

Daemon in Gradle 3.0
Enabled by default
Resource-aware
More robust, especially on Windows
Better UX
Integrated with Gradle Build Scans

Resource Awareness
System Memory
Daemon JVM Memory
GC Activity
Other Daemons

What we've built is a
framework for making the
Daemon more intelligent

Daemon in Gradle 3.0
Enabled by default
Resource-aware
More robust, especially on Windows
Better UX
Integrated with Gradle Build Scans

GRADLE-3018*
GRADLE-3481*
GRADLE-2803
GRADLE-3265
GRADLE-3315
GRADLE-2828
GRADLE-2275*
GRADLE-2415
GRADLE-2629
GRADLE-2367
GRADLE-2273
GRADLE-2271
Reasons not to use the Daemon
* In Progress

Daemon in Gradle 3.0
Enabled by default
Resource-aware
More robust, especially on Windows
Better UX
Integrated with Gradle Build Scans

Better UX

Daemon in Gradle 3.0
Enabled by default
Resource-aware
More robust, especially on Windows
Better UX
Integrated with Gradle Build Scans

Gradle Build Scans

Everyday Daemon Use

When should I use the Daemon?
All projects, everywhere
except possibly CI

Daemon in IDEs
All IDEs always use the Daemon
through the Gradle Tooling API

Reusing Daemons across projects
Same Gradle version
Same $JAVA_HOME
Compatible JVM Args

How do I score one of those sweet,
rare Gradlephant transfer stickers?
Bribery

Maximizing
Performance

Effective Daemon Reuse
gradle --status
gradle --info shows Daemon stopped reasons
org.gradle.daemon.idletimeout

Daemon Performance Logging
org.gradle.daemon.performance.logging=true
~/.gradle/daemon/$VERSION/daemon-$PID.out.log

Daemon Performance Tuning
org.gradle.daemon.
performance.tenured-usage-expire-at=90
org.gradle.daemon.
performance.tenured-rate-expire-at=1.2
org.gradle.daemon.
performance.permgen-usage-expire-at=80
~/.gradle/daemon/$VERSION/daemon-$PID.out.log

Build slow, even with Daemon?
Gradle Build Scans to the rescue

gradle.github.io/performance-guide
Gradle Performance Guide

None of these?

News Flash: You're at the freakin' Gradle Summit
Tweet @gradle
discuss.gradle.org
None of these?

Maximizing Performance
Reuse Daemon as much as possible
Use Build Scans
Gradle Performance Guide
discuss.gradle.org

Beyond Gradle 3.0

Beyond Gradle 3.0
Cross-version Daemon Registry
More intelligent caching
Better cache eviction for longer-running
Daemons

Beyond Gradle 3.0
Warms itself up while idle
Automatically adjusts for user behavior
through machine learning
Speculative dependency resolution and
execution

The Daemon is the vehicle
through which Gradle can
become proactive

two more things...

Try it today
gradle wrapper
--gradle-version 3.0-milestone-2

Give feedback
discuss.gradle.org

gradle.org/jobs
Have ideas?

@eriwen
Thank You
@mbarnath@ghhale @lhotari
Eric Wendelin and the Daemon Team

Learn more at www.gradle.org