InvokeDynamic - You Ain't Seen Nothin Yet
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Invokedynamic allows for more dynamic method dispatch at runtime. It works by adding a new bytecode called invokedynamic that defers method lookup to a bootstrap method specified by the developer. This gives developers control over how methods are looked up and invoked, enabling use cases like dynamic language implementation, lazy constants, delegates, multi-dispatch, and more. Languages like JRuby have seen significant performance improvements by using invokedynamic.
![Field Access
Call Site
Field Name
Signature
Target [+ Value]](https://image.slidesharecdn.com/jax2012-invokedynamickeynote-120420172559-phpapp01/85/InvokeDynamic-You-Ain-t-Seen-Nothin-Yet-49-320.jpg)
![Field Access
Call Site VM Operations
Field Name Get Field Offset
Signature Type Check
Target [+ Value] Access Field](https://image.slidesharecdn.com/jax2012-invokedynamickeynote-120420172559-phpapp01/85/InvokeDynamic-You-Ain-t-Seen-Nothin-Yet-50-320.jpg)
![Array Access
Call Site
Target + Offset [+ Value]](https://image.slidesharecdn.com/jax2012-invokedynamickeynote-120420172559-phpapp01/85/InvokeDynamic-You-Ain-t-Seen-Nothin-Yet-52-320.jpg)
![Array Access
Call Site VM Operations
Target + Offset [+ Value] Type Check
Access Element](https://image.slidesharecdn.com/jax2012-invokedynamickeynote-120420172559-phpapp01/85/InvokeDynamic-You-Ain-t-Seen-Nothin-Yet-53-320.jpg)
InvokeDynamic - You Ain't Seen Nothin Yet
- 1. invokedynamic You Ain’t Seen Nothin’ Yet
- 2. Me
- 6. @headius
- 7. JRuby Guy
- 8. JVM Guy
- 9. I KNOW π
- 12. Invoke?
- 13. Invoke? That’s one use, but there are many others
- 14. Dynamic?
- 15. Dynamic? Dynamic typing is a common reason, but there are many others
- 16. User-defined Data Endpoint
- 17. User-defined Data Endpoint Hä ?!
- 18. JVM 101
- 20. JVM 101 200 opcodes Ten (or 16) “data endpoints”
- 21. JVM 101 200 opcodes Ten (or 16) “data endpoints” Invocation invokevirtual invokeinterface invokestatic invokespecial
- 22. JVM 101 200 opcodes Ten (or 16) “data endpoints” Invocation Field Access invokevirtual getfield invokeinterface setfield invokestatic getstatic invokespecial setstatic
- 23. JVM 101 200 opcodes Ten (or 16) “data endpoints” Invocation Field Access Array Access invokevirtual getfield *aload invokeinterface setfield *astore invokestatic getstatic b,s,c,i,l,d,f,a invokespecial setstatic
- 24. JVM 101 200 opcodes Ten (or 16) “data endpoints” Invocation Field Access Array Access invokevirtual getfield *aload invokeinterface setfield *astore invokestatic getstatic b,s,c,i,l,d,f,a invokespecial setstatic All Java code revolves around these endpoints Remaining ops are stack, local vars, flow control allocation, and math/boolean/bit operations
- 25. JVM Opcodes
- 26. JVM Opcodes Invocation Field Access Array Access invokevirtual getfield *aload invokeinterface setfield *astore invokestatic getstatic b,s,c,i,l,d,f,a invokespecial setstatic
- 27. JVM Opcodes Invocation Field Access Array Access invokevirtual getfield *aload invokeinterface setfield *astore invokestatic getstatic b,s,c,i,l,d,f,a invokespecial setstatic Stack Local Vars Flow Control Allocation Boolean and Numeric
- 28. JVM Opcodes Invocation Field Access Array Access invokevirtual getfield *aload invokeinterface setfield *astore invokestatic getstatic b,s,c,i,l,d,f,a invokespecial setstatic Stack Local Vars Flow Control Allocation Boolean and Numeric
- 29. JVM Opcodes Invocation Field Access Array Access invokevirtual getfield *aload invokeinterface setfield *astore invokestatic getstatic b,s,c,i,l,d,f,a invokespecial setstatic Stack Local Vars Flow Control Allocation Boolean and Numeric
- 32. Invocation
- 33. Invocation
- 34. Invocation Call Site VM Operations
- 35. Invocation Call Site VM Operations Method Name Signature Target + Args
- 36. Invocation Call Site VM Operations Method Name Method Lookup Signature Type Checking Target + Args Branch Method Cache
- 37. Invocation Target Object instanceof obj.foo() JVM Object’s Class void foo() static void bar()
- 38. Invocation VM Operations Target Object instanceof obj.foo() JVM Object’s Class Call Site void foo() static void bar()
- 39. Invocation VM Operations Target Object instanceof obj.foo() JVM Object’s Class Call Site void foo() static void bar()
- 40. Invocation VM Operations Method Lookup Target Object instanceof obj.foo() JVM Object’s Class Call Site void foo() void foo() static void bar()
- 41. Invocation VM Operations Method Lookup Type Checking Target Object instanceof obj.foo() JVM Object’s Class Call Site void foo() void foo() static void bar()
- 42. Invocation VM Operations Method Lookup Type Checking Target Branch Object instanceof obj.foo() JVM Object’s Class Call Site void foo() void foo() static void bar()
- 43. Invocation VM Operations Method Lookup Type Checking Target Branch Object Method Cache instanceof obj.foo() JVM Object’s Class void foo() Call Site void foo() static void bar()
- 44. Invocation
- 45. Invocation Virtual Interface Method Lookup Method Lookup Type Checking Type Checking Branch Branch Method Cache Method Cache
- 46. Invocation Virtual Interface Method Lookup Method Lookup Type Checking Type Checking Branch Branch Method Cache Method Cache Static Method Lookup Branch Method Cache
- 47. Invocation Virtual Interface Method Lookup Method Lookup Type Checking Type Checking Branch Branch Method Cache Method Cache Static Special Method Lookup Method Lookup Access Checking Branch Branch Method Cache Method Cache
- 48. Field Access
- 49. Field Access Call Site Field Name Signature Target [+ Value]
- 50. Field Access Call Site VM Operations Field Name Get Field Offset Signature Type Check Target [+ Value] Access Field
- 51. Array Access
- 52. Array Access Call Site Target + Offset [+ Value]
- 53. Array Access Call Site VM Operations Target + Offset [+ Value] Type Check Access Element
- 54. Deja Vu? • Similar call site • Similar VM operations • Why can’t we compose our own?
- 56. invokedynamic
- 58. Call Site VM Operations invokedynamic
- 59. bytecode + Site Call bootstrap Method Handles VM Operations invokedynamic
- 60. bytecode
- 61. bytecode • invokedynamic • like invokevirtual, invokestatic, etc • Name and signature, like the others • Additional bootstrap method • JVM defers to you
- 62. Method Handles • Function/field/array pointers • Argument manipulation • Flow control • Optimizable by the JVM • This is very important
- 65. invokedynamic bytecode bo ot stra p m et ho d
- 66. invokedynamic bytecode bo ot stra p m et ho d method handles
- 67. invokedynamic bytecode target method bo ot stra p m et ho d method handles
- 68. invokedynamic bytecode target method bo ot stra p m et ho d method handles
- 69. invokedynamic bytecode target method bo ot stra p m et ho d method handles
- 70. You Decide How to reach some data endpoint
- 71. You Decide What transformations to perform on arguments
- 72. You Decide When and why the endpoint should change
- 73. You Decide How to make the JVM work for you!
- 74. Use Cases
- 75. Dynamic Invocation • The obvious one • Method lookup based on runtime types • Potentially mutable types • Type check specific to language
- 76. Dynamic Invocation Target Object associated with obj.foo() JVM Method Table def foo ... def bar ...
- 77. Dynamic Invocation VM Operations Target Object associated with obj.foo() JVM Method Table Call Site def foo ... def bar ...
- 78. Dynamic Invocation VM Operations Target Object associated with obj.foo() JVM Method Table Call Site def foo ... def bar ...
- 79. Dynamic Invocation VM Operations Method Lookup Target Object associated with obj.foo() JVM Method Table Call Site def foo ... def foo ... def bar ...
- 80. Dynamic Invocation VM Operations Method Lookup Target Branch Object associated with obj.foo() JVM Method Table Call Site def foo ... def foo ... def bar ...
- 81. Dynamic Invocation VM Operations Method Lookup Target Branch Method Cache Object associated with obj.foo() JVM def foo ... Method Table Call Site def foo ... def bar ...
- 82. Lazy Constants • Call site just produces a value • Value calculated once • Subsequent access is direct, optimizable
- 83. Lazy Constant JVM Lazy LAZY_CONST Computation Call Site
- 84. Lazy Constant VM Operations JVM Lazy LAZY_CONST Computation Call Site
- 85. Lazy Constant VM Operations JVM Lazy LAZY_CONST Computation Call Site
- 86. Lazy Constant VM Operations Calculate Value JVM Lazy LAZY_CONST Computation value Call Site
- 87. Lazy Constant VM Operations Calculate Value Bind Permanently JVM Lazy LAZY_CONST value Computation Call Site
- 88. Delegates • Arbitrary function pointers • No anon inner classes • No bridge methods • Java 8 “Lambda” will do this
- 89. Lambda Expression Surrounding String s -> JVM Class toString() lambda body Call Site
- 90. Lambda Expression VM Operations Surrounding String s -> JVM Class toString() lambda body Call Site
- 91. Lambda Expression VM Operations Surrounding String s -> JVM Class toString() lambda body Call Site
- 92. Lambda Expression VM Operations Retrieve Lambda Obj Surrounding String s -> lambda JVM Class body toString() Call Site
- 93. Lambda Expression VM Operations Retrieve Lambda Obj Bind and Invoke Surrounding String s -> lambda JVM Class body toString() Call Site
- 94. Multi-dispatch • Dispatch based on runtime types • Java is single-dispatch • Call site looks like normal invoke • VM side examines target, args • Multiple targets cached with branches
- 95. How Do You Benefit?
- 96. Future • New language impls • JavaScript: Dyn.js and Nashorn • Redline Smalltalk • Improved language performance • JRuby, Groovy, Jython, Clojure, Scala • Java features too!
- 97. JRuby/Java 6 JRuby/Java 7
- 98. JRuby/Java 6 JRuby/Java 7 Times Faster than Ruby 1.9.3 5 3.75 2.5 1.25 0 base64 richards neural redblack
- 99. JRuby/Java 6 JRuby/Java 7 Times Faster than Ruby 1.9.3 5 3.75 2.5 1.914 1.538 1.565 1.25 1.346 0 base64 richards neural redblack
- 100. JRuby/Java 6 JRuby/Java 7 Times Faster than Ruby 1.9.3 5 4.32 3.75 3.66 3.44 2.5 2.658 1.914 1.538 1.565 1.25 1.346 0 base64 richards neural redblack
- 101. invokedynamic is the future of Java!
- 102. Thank You! • @headius • blog.headius.com • invokedynamic post coming soon • [email protected] • Come to my deep dive at 16:00 • Have fun with invokedynamic!
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