Marcus Lagergren | Oracle

Why dynamic languages on the JVM matter

Marcus Lagergren | Oracle

Why dynamic languages on the JVM matter

Marcus Lagergren | Oracle

Why dynamic languages on the JVM matter

Marcus Lagergren | Oracle

Why dynamic languages on the JVM matter

[and project Nashorn]

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Who am I?

@lagergren

I am here to talk about…

The Java Runtime: The JVM

I am here to talk about…

The Universal Meta-execution environment

I am here to talk about…

The Universal Meta-execution environment

I am here to talk about…

The JVM as a multi-language runtime

I am here to talk about…

The JVM as a multi-language runtime

(especially in the context of dynamic languages)

History (what is a runtime, anyway?)

LISP

LISP

1950s – First compiler in 1962

LISP

Just-in-time compilation

LISP

Just-in-time compilation

LISP

Also – Garbage Collection!

LISP

Also – Garbage Collection!

Smalltalk

Smalltalk

First class library.

Smalltalk

First class library. First visual GUI driven IDE.

Smalltalk

First class library. First visual GUI driven IDE. Bytecode.

Smalltalk

First class library. First visual GUI driven IDE. Bytecode.

Emerging (dynamic)

Languages

Dynamic languages

ActionScript Adenine APL BASIC BeanShell Clojure ColdFusion Dart Dylan Groovy E Fancy JavaScript

Julia Lua MATLAB Objective-C Perl PHP Powershell Python Qore R

REBOL REXX Ruby Scheme Smalltalk Snit Tcl VBScript Yoix etc

etc etc etc…

Dynamic languages

ActionScript Adenine APL BASIC BeanShell Clojure ColdFusion Dart Dylan Groovy E Fancy JavaScript

Julia Lua MATLAB Objective-C Perl PHP Powershell Python Qore R

REBOL REXX Ruby Scheme Smalltalk Snit Tcl VBScript Yoix etc

etc etc etc…

Dynamic languages •  Dynamic languages are hot today because

–  They are easy to use –  Have no explicit compile stage –  Have good code readability –  Allow short development time for small projects –  Performance is good enough

Trendy Dynamic Languages

Trendy Dynamic Languages

Trendy Dynamic Languages

Trendy Dynamic Languages

Trendy Dynamic Languages

Already on top of the JVM

…and of course

V8, Futhark, Carakan, SpiderMonkey, JägerMonkey, *Monkey, Nitro, Rhino, Nashorn, etc etc

Putting your language on top of

the JVM

Why? •  You get so much for free!

–  Automatic memory management –  State of the art JIT optimizations –  Native threading capability –  Hybridization (javax.scripting, JSR-223) –  Extending Java –  Man decades of high tech

Why?

0

100000

200000

300000

400000

500000

Code bases

Lines

Why?

0

100000

200000

300000

400000

500000

Code bases

Lines

If it were all about code complexity – TOTALLY WORTH IT!

“All problems in computer science can be solved

by another level of indirection” - David Wheeler

Sounds good – implement it! •  Just serve up some bytecode •  People have been doing it since 1996

They have been doing it a lot, actually…

Fantom

Fortress

BeanShell

Jaskell

ANTLR

JudoScript

ABCL

Erjang

X10

myForth

jdart

jgo

Nice

Gosu

Jacl

“All problems in computer science can be solved

by another level of indirection” - David Wheeler

“All problems in computer science can be solved

by another level of indirection” - David Wheeler

“Except for the problem of too many layers of

indirection” - Kevlin Henney

So why is it hard?

So why is it hard? •  “Java bytecode”

–  Notice the “Java”

•  There are “classes”, “methods”, size limitations, strong types

•  Languages can be much more dynamic than Java –  Different linkage –  Loose types

So why is it hard? •  Different levels of “hard” •  Square peg, round hole or round peg, oval

hole •  Scala is a fairly good fit •  Ruby or JavaScript are (at least at first

glance) pretty lousy ones

Not every language has exactly 5 strong types

int, float, long, double, Object

Not every language has exactly 5 strong types

int sum(int a, int b) { return a + b; }

int, float, long, double, Object

Not every language has exactly 5 strong types

int, float, long, double, Object

iload_1 iload_2 iadd ireturn

Not every language has exactly 5 strong types

int, float, long, double, Object

function sum(a, b) { return a + b; }

Not every language has exactly 5 strong types

int, float, long, double, Object

??? ??? ??? ???

Not every language has exactly 5 strong types

int, float, long, double, Object

??? ??? ??? ???

Also: It is hard to swap out code with other code

Also: It is hard to swap out code with other code

Applicability and Performance •  The extra layer also costs us performance •  How can we work around it?

Applicability and Performance •  The extra layer also costs us performance •  How can we work around it? •  Passive

–  Just wait –  JIT is getting better all the time, GC is getting

better all the time

Applicability and Performance •  The extra layer also costs us performance •  How can we work around it? •  Passive

–  Just wait –  JIT is getting better all the time, GC is getting

better all the time •  Active

–  Punch through the indirection layer –  There are tools these days

Punch through the indirection layer

invokedynamic is my ice pick

Invokedynamic •  Breaks the constraints of Java calls and

linkage •  Can implement calls that act like function

pointers •  More general: can implement custom data

access •  Makes it possible to efficiently swap out code

The whole point: The JVM can optimize this!

The Nashorn Project

(a Rhino for 2013)

Rationale •  Proof of concept: invokedynamic •  Does it provide all required functionality? •  Does it perform? •  Back in late 2010:

–  We must become the ultimate invokedynamic consumer and find out

–  Cross communication with other teams

Rationale – JavaScript? •  Extremely dynamic

–  All (well, most) getters, setters, calls have to be invokedynamics

•  Rhino is slow and old •  JSR-223

–  Should make it easy to provide POC apps for Nashorn

Full ECMAScript Compliance

Full ECMAScript Compliance

Performance

rhino 0

2000

4000

6000

8000

10000

12000

rhino

nashorn

Performance

rhino 0

2000

4000

6000

8000

10000

12000

rhino

nashorn

Further POC: node.jar •  A node.js implmentation in only Java and

JavaScript –  Forked the original node.js – threw out all native

code –  Async I/O implemented with Grizzly

•  Deploys fine on the ARM JVM on Raspberry PI

•  Might just as easy be a Java EE cloud offering

Nashorn already in OpenJDK 8

Now: more Nashorn & JVM performance enhancements

Now: more powerful hybrid proof of

concepts, e.g. node.jar, JavaFX

Contribute! 1.  Ask the community to contribute

functionality, testing, performance [analysis], bug fixes, library optimizations, browser simulation frameworks, kick-ass hybrid Java solutions. JVM optimizations

2.  … 3.  PROFIT!

blogs.oracle.com/nashorn nashorn-dev@openjdk.java.net

The Da Vinci Machine (MLVM)

Can we do better than the ice pick?

Reshape the hole!

Let’s continue building our “future VM”

•  An open source incubator for JVM futures

•  Contains code fragments (patches)

•  Migration to OpenJDK requires –  A standard –  A feature release plan

mlvm-dev@openjdk.java.net

It’s more than just invokedynamic

•  Unified type systems •  Pluggable frontends, “bytecode 2.0” •  Tail calls •  (delimited) Continuations / Coroutines •  Tuple types or C-style structs •  Tagged values •  Arrays 2.0 •  …

Da Vinci Machine Patches

It’s not just invokedynamic

The JVM is evolving to become the multi-language runtime

Danke!

[Hopefully, I’ll see you again at the Nashorn / invokedynamic deep dive 16.45 this

afternoon]

@lagergren