In my career, I could help some companies to solve many application performance issues. After several suggestions from colleagues, I have tried to put together in this presentation the main points that I think Java developer should take into account to fix and prevent performance issues.

1. Java Performance
What Developers Must Know
Diego Lemos

2. We care about performance...
(credit: http://www.morguefile.com/)
...when things go bad.

3. Panic Driven Actions
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Add more hardware
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Work on ugly code
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Long Meetings (?!)
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Blame somebody

4. Milliseconds Matter
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Amazon:
–
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Increase 100ms in load time decreased sales by 1%
Google:
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From loading a 10-result page in 0.4 seconds to a 30result page loading in 0.9 seconds decreased traffic and
ad revenues by 20%

5. Measure Don’t Guess
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Support decisions by measurements
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Tune what matters
(credit: http://xkcd.com)

6. Generic Application Stack
Application
Profiling
JVM
Heap Analysis
Operating System
Monitor System
Hardware

7. Tools
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vmstat, iostat, netstat
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JMeter, Gatling
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HPjmeter
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VisualVM, jconsole

8. Demo :

9. Any problem here?
Java heap space

10. And here?
Everything is OK!

11. What happened here?
"catalina-exec-8190-104" - Thread t@135
java.lang.Thread.State: BLOCKED
at com.google.code.morphia.Morphia.mapPackage(Morphia.java:72)

12. Performance Best Practices
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●
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Test one build a day for performance issues
(continuous integration)
Monitoring (production env.) for compliance
Keep users at the center of performance
tuning efforts
Devs + Ops

13. Performance Tests on CI

14. Follow Coding Best Practices
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KISS
–
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complex code is hard to optimize
Loose coupling
–
–
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Optimize without fear of breaking anything else
Avoid contamination (external applications)
Let your objects die young

15. Performance myths
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Tune by default (early tuning)
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Optimize by precaution (over-engineer)
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The architecture cannot change
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Hardware will solve the problem

16. Conclusion
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Think performance before problems come
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Devs + ops working together
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Monitor your application

17. More on this
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http://java.dzone.com/kirk-dominating-consumer
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https://github.com/dlresende/spring-petclinic
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http://jmeter.apache.org/usermanual/glossary.html
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http://www.oracle.com/technetwork/java/javase/gc-tunin
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http://munchweb.com/effect-of-website-speed
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http://www.javaworld.com/article/2073905/build-ci-sdlc