C.R.a.C in Spring - I Froze My Server! (15 Minute Session For NLJUG Speaker Academy)

Starting up complex enterprise Java applications may take a long time and you may not want to wait that long when scaling or deploying. Project CRaC, meaning Coordinated Restore at Checkpoin…
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1. C.R.a.C in Spring I just froze my service! By João Esperancinha 23rd October 2024 Master speaker academy
2. Who am I ? • João Esperancinha • ISEL (Instituto Superior de Engenharia de Lisboa) • Telecommunications and Computers Engineering • OCP11 - VMWare Spring Professional 2021 - Kong Champion • Plants, Furniture making, Nature • JESPROTECH channel on YouTube
3. What is C.R.a.C? Coordinated Restore at Checkpoint https://wiki.openjdk.org/display/crac
4. What do we need to solve? Startup times! and everything related to it…
5. History • 2010s ◦ CRIU (Checkpoint Restore in Userspace) - Linux ◦ Mitigation of fault tolerance and processes • 2021 ◦ CRaC started with coordinated checkpoint and restore operations ◦ Prepare checkpoint ◦ Save state ◦ Restore later • 2022 - 2023 ◦ Experimentation and tests in frameworks like Spring and Quarkus • 2023 ◦ In April Azul releases the first JDK 17 supporting C.R.a.C.
6. Coordinated Restore at Checkpoint • Application resources and JDK coordinated at checkpoints • Close files, connections and dump cache before checkpoint • Restores, files, connections and cache after checkpoint • A checkpoint is where we freeze the service • The restore doesn’t start the runtime from the checkpoint
7. What do we need for it? • CRAC library: org.crac:crac:<latest version>, 1.4.0 • Spring Framework : ◦ Spring web: org.springframework.boot:spring-boot-starter-web:<latest_version> ◦ Spring boot maven plugin: org.spring.framework:spring-boot-maven-plugin:<latest_version> • A JDK that supports project C.R.a.C.: openjdk version "21.0.4" 2024-07-16 LTS OpenJDK Runtime Environment Zulu21.36+19-CRaC-CA (build 21.0.4+7-LTS) OpenJDK 64-Bit Server VM Zulu21.36+19-CRaC-CA (build 21.0.4+7-LTS, mixed mode, sharing)
8. What do we need to configure for it? • The JDK itself: ◦ sudo chown root:root $(JAVA_HOME)/lib/criu ◦ sudo chmod u+s $(JAVA_HOME)/lib/criu • The jar MUST be compiled with CRaC compatible JDK • The jar MUST run with CRaC compatible Runtime
9. How can we create a checkpoint? • Programmatically: ◦ Core.checkpointRestore(); • Or via the command line: ◦ jcmd target/crac-service-java.jar JDK.checkpoint • Start the service indicating the target dump directory: ◦ java -XX:CRaCCheckpointTo=./tmp_checkpoint -jar target/crac-service-java.jar • Use a tool to make requests to the application ◦ siege -c 1 -r 100000 -b http://localhost:8080
10. How can we monitor the start and restore? • Monitoring can be done with Resource: public class CracRunner implements Resource { public CracRunner() { Core.getGlobalContext().register(this); } @Override public void beforeCheckpoint(Context<? extends Resource> context) throws Exception { System.out.println("Before Checkpoint!"); } @Override public void afterRestore(Context<? extends Resource> context) throws Exception { System.out.println("After Restore!"); } }
11. How can we restore a checkpoint ? • It has to be via the command line: ◦ java -XX:CRaCRestoreFrom=./tmp_checkpoint ◦ java -XX:CRaCRestoreFrom=./tmp_checkpoint -cp target/crac-runner-java.jar org.jesperancinha.smtd.CracRunner
12. Why would we need this? • Faster Startup Times • Reduced Warm-Up Time for JVM • Cost Savings in Cloud Environments • Improved Elasticity for Microservices • Enabling Stateful Workloads
13. Questions? I am an inquisitive cat
14. Resources • https://mbien.dev/blog/entry/crac-coordinated-restore-at-checkpoint • https://spring.io/blog/2023/10/16/runtime-efficiency-with-spring • https://wiki.openjdk.org/display/crac • https://foojay.io/today/springboot-3-2-crac/ • https://en.wikipedia.org/wiki/CRIU • https://openjdk.org/projects/crac/ • https://www.youtube.com/watch?v=sVXUx_Y4hRU • https://foojay.io/today/how-to-run-a-java-application-with-crac-in-a-docker-container/
15. Source code and other media • https://github.com/jesperancinha/jeorg-spring-master-test-drives • https://github.com/jesperancinha/asnsei-the-right-waf • 1 CRaC for Spring unexpected behaviour: https://youtu.be/TEviStU4188
16. The lost presentations • Could Virtual Threads cast away the usage of Kotlin Coroutines? What experience can tell us • Integrating Arrow Optics in a Real Life Scenario, my personal life experience in a parallel world • Kotlin Mysteries found from years working with Kotlin • Finally, we can simplify our code with Java Virtual Threads and do away with Kotlin Coroutines! • Improve startup times with Spring CRaC by freezing your spring service!
17. Thank you! See you next time!
18. About me • Homepage - https://joaofilipesabinoesperancinha.nl • Threads - https://www.threads.net/@joaofisaes • LinkedIn - https://www.linkedin.com/in/joaoesperancinha/ • YouTube - https://www.youtube.com/@jesprotech • Bluesky - https://bsky.app/profile/jesperancinha.bsky.social • Mastodon - https://masto.ai/@jesperancinha • GitHub - https://github.com/jesperancinha • Hackernoon - https://hackernoon.com/u/jesperancinha • DevTO - https://dev.to/jofisaes • Medium - https://medium.com/@jofisaes