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Effectiveness and code optimization in Java
- 1. Effectiveness and code optimization in Java Sergey Morenets, [email protected] December, 4 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. Preface
- 4. Agenda
- 5. Agenda • What is effectiveness? • Code optimization • JVM optimization • Code samples • Measurements
- 6. Ideal code Concise Readable Self-describing Reusable Testable Modern Flexible Scalable Effective
- 7. 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 • The only aspect of the ideal code that affects users
- 14. Effectiveness • Can be measured • Can be static or dynamic • Can be tuned
- 15. Tuning • JVM options • Metaspace/heap/stack size • Garbage collector options • http://blog.sokolenko.me/2014/11/javavm-options- production.html • http://www.javaspecialists.eu/
- 16. Code optimization Java compiler JIT compiler JVM
- 18. Code optimization public int execute(); Code: 0: iconst_2 1: istore_1 2: iinc 1, 1 5: iconst_1 6: ireturn
- 20. Code optimization public int execute(); Code: 0: iconst_2 1: istore_1 2: iconst_1 3: ireturn
- 22. Code optimization public void execute(); Code: 0: return
- 24. Code optimization public static boolean get(); Code: 0: iconst_1 1: ireturn
- 26. Code optimization public void execute(); Code: 0: return
- 28. Code optimization public int execute(); Code: 0: iconst_2 1: istore_1 2: iconst_4 3: istore_2 4: iload_1 5: iload_2 6: iadd 7: ireturn
- 30. Code optimization public int execute(); Code: 0: bipush 6 2: ireturn
- 32. Code optimization public int execute(); Code: 0: bipush 12 2: ireturn
- 33. Javacompiler Dead code elimination Constant folding Fixed expression calculation
- 34. 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
- 35. Warm-up
- 36. Environment • JMH 1.11.1 • Maven 3.3.3 • JDK 1.8.0.65 • Intel Core i7, 4 cores, 16 GB
- 37. Measurements Type Time(ns) Multiply 4 2,025 Shift 2,024
- 38. Measurements Type Time(ns) Multiply 17 2,04 Shift 2,04
- 39. Sample
- 40. Method vs Field
- 44. Increment
- 46. Swap
- 47. Measurements Type Time(ns) Standard 2,10 Addiction 2,08 XOR 2,04
- 48. Conditions
- 49. Measurements Type Time(ns) Ternary operation 2,05 If operator 2,03
- 50. Parsing
- 51. 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
- 52. Copying arrays
- 53. Measurements Type Time(ns) Loop(1000 elements) 52,6 arrayCopy(1000 elements) 45,6 Loop(100 000 elements) 21666 arrayCopy(100 000 elements) 21707 Loop(10 000 000 elements) 6432557 arrayCopy(10 000 000 elements) 6616976
- 55. Measurements Type Time(ns) Rows(10 elements) 37 Columns(10 elements) 67 Rows(100 elements) 2954 Columns(100 elements) 5567 Rows(1000 elements) 264340 Columns(1000 elements) 1300244 Rows(5000 elements) 9,6(ms) Columns(5000 elements) 387(ms)
- 56. Strings
- 57. Measurements Type Time(ns) + 7,62 Concat 13,4 StringBuffer 7,32 StringBuilder 7,24
- 58. Maps
- 59. 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
- 60. Arrays
- 61. 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
- 62. Arrays
- 63. 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
- 64. Arrays
- 65. 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
- 66. 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
- 67. Exceptions
- 69. Strings
- 70. Strings
- 71. Measurements Type Time(ns) Parse(1000 tokens) 12239 Parse with intern(1000 tokens) 72814
- 72. Arrays
- 73. Bitset
- 74. 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
- 75. Bitset
- 76. 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
- 77. Collections
- 78. Collections
- 79. Measurements Type Time(ns) New ArrayList() 3,6 emptyList() 2,4
- 80. Autoboxing
- 81. Measurements Type Time(ns) Array(100 elements) 58 List(100 elements) 390 Array(10 000 elements) 4776 List(10 000 elements) 48449
- 82. LIFO
- 84. Stack
- 85. 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
- 86. Collections
- 87. Collections Type Time(ns) Fill HashMap(1000 elements) 16000 Fill TreeMap(1000 elements) 40115 Fill HashMap(100 000 elements) 2 027 116 Fill TreeMap(100 000 elements) 11 195 422 Iteration HashMap(1000 elements) 3086 Iteration TreeMap(1000 elements) 5038
- 88. Reflection
- 89. Reflection Type Time(ns) instanceof 2,266 isAssignableFrom 2,146 == 2,401
- 90. Reflection
- 91. Measurements Type Time(ns) New object 3,0 Reflection 5,4
- 92. Reflection
- 93. Measurements Type Time(ns) Method call 0,3 Reflection 232
- 94. Measurements Type Time(ns) Method call 0,3 Reflection (cached) 3,1
- 95. Cloning
- 96. Measurements Type Time(ns) Clone 6,5 Direct copying 3,8
- 97. Sample
- 98. Lists
- 99. Measurements Type Time(ns) ArrayList (1000 elements) 4766 ArrayList (100 000 elements) 381707 LinkedList (1000 elements) 5504 LinkedList (100 000 elements) 504231
- 100. JIT optimization • Inline methods • Eliminate locks • Replace interface with direct method calls • Join synchronized blocks • Eliminate dead code • Drop memory write for non-volatile variables
- 101. Theory