The document outlines the steps and tools required for visualizing garbage collection (GC) in Java applications using Visual VM and its GC plugin. It aims to demonstrate the impact of different GC configurations on application performance rather than benchmarking. Various VM arguments for testing different GC behaviors are provided, along with links for further reading.

1. VISUALISING GARBAGE
COLLECTION USING VISUAL VM
LUIZ TESTON, WWW.FRACTA.CC

2. BEFORE
WE START

3. MANDATORY ITEMS TO REPRODUCE THE STEPS ON THE GC WORKSHOP
▸ JDK >= 1.5
▸ Visual VM + Visual GC plugin
▸ Jetty (or any other Java application to measure)
▸ Apache Bench “ab” or any other stress application
▸ credentials: cam20jan16 / AJtmN5d3

4. DISCLAIMER
▸ The objective is to visualise different GC configurations and
how they affect the application execution and the GC
behaviour itself.
▸ The stress tools are here just to help objects being created
and destroyed by the application.
▸ We are not benchmarking jetty.
▸ We are not benchmarking http.
▸ We are not benchmarking at all.

5. RECIPES TO TRY

6. RUN YOUR APP
STRESS IT
VISUALISE IT

7. VM ARGUMENTS TO TRY
▸ -Xmx<size>[m|g]
▸ -Xms<size>[m|g]
▸ -XX:NewSize=<size>[m|g]
▸ -XX:+UseSerialGC
▸ -XX:+UseParallelOldGC
▸ -XX:+UseConcMarkSweepGC
▸ -XX:+UseParallelGC -XX:+UseNUMA
▸ -XX:+UseG1GC

8. SCREENSHOTS

9. <no args>

10. -Xmx2G -Xms2G

11. -Xmx7G -Xms7G

12. -Xmx1G -Xms1G -XX:NewSize=800m

13. -Xmx1G -Xms1G -XX:NewSize=800m -XX:+UseSerialGC

14. -Xmx1G -Xms1G -XX:UseParallelOldGC

15. -Xmx1G -Xms1G -XX:+UseConcMarkSweepGC

16. -Xmx1G -Xms1G -XX:+UseParallelGC -XX:+UseNUMA

17. -Xmx1G -Xms1G -XX:+UseG1GC

18. QUESTIONS? THANKS FOR YOUR TIME!
▸ http://docs.oracle.com/javase/8/docs/technotes/guides/
vm/gctuning/index.html
▸ mechanical-sympathy.blogspot.com/2013/07/java-
garbage-collection-distilled.html
▸ https://visualvm.java.net
▸ fotos: Dani Teston