Bill

Career

• 32% // Solutions Engineering
• 60% // Systems Architecture
• 5% // Wireless Spectrum Research
• 3% // Embedded Sofware Development

📷 Photographer ・ 👨‍👩‍👦‍👦 Father ・ 🇨🇳 Mandarin Learner

🤓 Self-Hoster ・ 👨‍💻 Go Developer ・ 📝 Letter Writer

🏠 London ・ 🗺️ China

Contact

👨‍💻 bill.dev
🗓️ meet.bill.dev

Sustainability

Sustainability

“meeting the needs of the present without compromising the ability of future generations to meet their own needs.”

Sustainability

“Resource efficiency means using the Earth’s limited resources in a sustainable manner while minimising environmental impacts. It allows us to create more with less and to deliver greater value with less input.”

Practically Speaking

• Create real value (for now and the future)
• Use only what’s needed, and no more.

Why should you care?

🌍

💸

But I write code

Source: iea.org

Trends

• Industrialisation & cheap energy
• Moore’s Law
• Globalisation
• Always on, always connected
• Infrastructure as code
• Fast response times
• Big data, analytics

Software Development Lifecycle

Sustainability Throughout

• idea
• development
• iteration
• test
• runtime
• decommission

Three Things

1. Spring
2. Architecture
3. Cloud Foundry

One Caveat

All apps are different

1. Spring

Spring continues to evolve

Spring Boot requires at least Java 17

spring.io

As does Java

8 → 11 → 17 → 21 → 25

• Project Graal - native images, AOT - Java 21
• Project Loom - virtual threads - Java 21
• Project CRaC - reduced start/warm times - EA
• Project Leyden - improve start, peak perf, mem - EA

Learn More

What can we optimise for?

• Startup – scale to zero
• Memory – more apps on fewer servers
• Warmup – reach peak performance faster
• Utilisation – get the most out of hardware

Spring Boot 2.7.3 and Java 8

sdk use java 8.0.452-librca
./mvnw clean package -DskipTests
java -jar target/spring-petclinic-2.7.3.jar

Upgrade JDK / JVM to Java 24

sdk use java 24.0.1-librca
./mvnw clean package -DskipTests
java -jar target/spring-petclinic-2.7.3.jar

Use Java 24 and Spring Boot 3.5.0

git checkout 3.5.0
sdk use java 24.0.1-librca
./mvnw clean package -DskipTests
java -jar target/spring-petclinic-2.7.3.jar

Use Java 24 and Spring Boot 3.5.0 - Extracted

git checkout 3.5.0
sdk use java 24.0.1-librca
./mvnw clean package -DskipTests
java -Djarmode=tools \
  -jar target/spring-petclinic-3.5.0-SNAPSHOT.jar \
	extract --destination application
java -jar application/spring-petclinic-3.5.0-SNAPSHOT.jar

Use Virtual Threads

spring.threads.virtual.enabled=true

Class Data Sharing (CDS)

java -XX:ArchiveClassesAtExit=application.jsa \
	-Dspring.context.exit=onRefresh \
	-jar application/spring-petclinic-3.5.0-SNAPSHOT.jar

java -XX:SharedArchiveFile=application.jsa \
-jar application/spring-petclinic-3.5.0-SNAPSHOT.jar

Use Spring AOT

java -Djarmode=tools \
  -jar target/spring-petclinic-3.5.0-SNAPSHOT.jar \
  extract --destination application

java -Dspring.aot.enabled=true \
  -jar application/spring-petclinic-3.5.0-SNAPSHOT.jar

Use GraalVM for Native Image Building

sdk use java 24.0.1-graalce
./mvnw -q -Pnative clean native:compile \
  -DskipTests -Dcheckstyle.skip

./target/spring-petclinic

2. Architecture

Long tail

• 20% of your APIs handle 80% of the traffic
• 80% sit idle the majority of the time

The curse of non-functional side-effects

• “must be deployed in both sites”
• “must have three instances”
• “must respond within [fast]ms”

Missing?

Must do all the above while minimising environmental footprint

scale to zero

*not currently in Cloud Foundry

3. Cloud Foundry

🦸

Multi-Tenancy

Puzzle Pieces

1. Foundation
2. Org
3. Space
4. Isolation Segment

Foundation

Org

Space

Isolation Segment

Small Footprint

New Upgrade to full foundations!
Idea Reduced minimum install footprint