The document discusses the effectiveness of Java applications, focusing on code quality, performance measurement, and optimization techniques. It highlights the importance of factors like CPU utilization and memory usage while introducing JMH as a micro-benchmarking framework for performance measurement. Various code samples and their measurement results are provided to illustrate the performance implications of different coding practices.

1. Effective Java
applications
Sergey Morenets, morenets@mail.ru
October, 27 2015

2. About author
• Works in IT since 2000
• 12 year of Java SE/EE experience
• Regular speaker at Java conferences
• Author of “Development of Java applications” and
“Main errors in Java programming ”books
• Founder of http://it-simulator.com

3. Agenda

4. Agenda
• What is effectiveness?
• Code samples
• Measurements
• Optimization

5. Ideal code
Concise Readable
Self-describing Reusable
Testable Modern
Flexible Scalable
Effective

6. Effectiveness
• Hard to determine on code/design review stages or
in unit-tests
• Is relevant for the specific project configuration
• Cannot be defined in development environment
• Depends on the application environment
• Premature optimization is evil
• Hardware-specific

7. Effectiveness
CPU
utilization
Memory
utilization
Network I/O
utilization
Disk I/O
utilization

8. Effectiveness
• Can be measured
• Can be static and dynamic
• Can be tuned

9. Tuning
• JVM options
• Metaspace/heap/stack size
• Garbage collector options
• http://blog.sokolenko.me/2014/11/javavm-options-
production.html

10. Measurements
• JMH is micro benchmarking framework
• Developed by Oracle engineers
• First release in 2013
• Requires build tool(Maven, Gradle)
• Can measure throughput or average time
• Includes warm-up period

11. Warm-up

12. Environment
• JMH 1.11.1
• Maven 3.3.3
• JDK 1.8.0.65
• Intel Core i7, 4 cores, 16 GB

13. Sample

14. Samples

15. Measurements
Type Time(ns)
Addiction 2,06
Incrementation 2,06

16. Samples

17. Measurements
Type Time(ns)
Standard 2,10
Addiction 2,08
XOR 2,04

18. Samples

19. Measurements
Type Time(ns)
Ternary operation 2,05
If operator 2,03

20. Samples

21. Measurements
Type Time(ns)
Long usage(small numbers) 3
Long usage(average numbers) 19
Long usage(big numbers) 33
Long usage (not a number) 849
Regexp (small numbers) 58
Regexp (average numbers) 75
Regexp (big numbers) 82
Regexp (not a number) 47

22. Samples

23. Measurements
Type Time(ns)
+ 7,62
Concat 13,4
StringBuffer 7,32
StringBuilder 7,24

24. Samples

25. Measurements
Type Time(ns)
Entries (10 pairs) 30
Keys/Values(10 pairs) 70
Entries (1000 pairs) 2793
Keys/Values(1000 pairs) 8798
Entries (200 000 pairs) 237652
Keys/Values(200 000 pairs) 350821

26. Samples

27. Measurements
Type Time(ns)
For (10 elements) 4,9
For-each (10 elements) 5,1
For (1000 elements) 260
For-each (1000 elements) 259,9
For (50000 elements) 12957
For-each (50000 elements) 12958

28. Samples

29. Measurements
Type Time(ns)
For (10 elements) 5,04
For optimized(10 elements) 5,07
For (1000 elements) 258,9
For-each (1000 elements) 258,7

30. Samples

31. Measurements
Type Time(ns)
Sequential (10 elements) 5
Parallel (10 elements) 6230
Sequential (1000 elements) 263
Parallel (1000 elements) 8688
Sequential (50000 elements) 13115
Parallel (50000 elements) 34695

32. Measurements
Type Time(ns)
Sequential (10 elements) 5
Parallel (10 elements) 6230
Sequential (1000 elements) 263
Parallel (1000 elements) 8688
Sequential (50000 elements) 13115
Parallel (50000 elements) 34695
Sequential (5 000 000 elements) 1 765 206
Parallel (5 000 000 elements) 2 668 564
Sequential (500 000 000) 183 ms
Parallel (500 000 000) 174 ms

33. Samples

34. Samples

35. Measurements
Type Time(ns)
Parse(1000 tokens) 12239
Parse with intern(1000 tokens) 72814

36. Samples

37. Samples

38. Measurements
Type Time(ns)
Fill array (1000 elements) 148
Fill bit set(1000 elements) 1520
Fill array (50 000 elements) 4669
Fill bit set(50 000 elements) 71395

39. Samples

40. Measurements
Type Time(ns)
Fill array (1000 elements) 148
Fill bit set(1000 elements) 261
Fill array (50 000 elements) 4669
Fill bit set(50 000 elements) 12758

41. Samples

42. Samples

43. Measurements
Type Time(ns)
New ArrayList() 3,6
emptyList() 2,4

44. LIFO

45. LIFO
Stack
LinkedList
ArrayDeque

46. Samples

47. Measurements
Type Time(ns)
Stack(1000 elements) 5729
LinkedList(1000 elements) 7928
ArrayDeque(1000 elements) 4366
Stack(100 000 elements) 588770
LinkedList(100 000 elements) 773684
ArrayDeque(100 000 elements) 484280

48. Samples

49. Measurements
Type Time(ns)
New object 3,0
Reflection 5,4

50. Samples

51. Measurements
Type Time(ns)
Method call 0,3
Reflection 232

52. Measurements
Type Time(ns)
Method call 0,3
Reflection (cached) 3,1

53. Sample

54. Sample

55. Measurements
Type Time(ns)
ArrayList (1000 elements) 4766
ArrayList (100 000 elements) 381707
LinkedList (1000 elements) 5504
LinkedList (100 000 elements) 504231

56. Theory

57. Q&A
• Sergey Morenets, morenets@mail.ru