Beyond JVM - YOW! Sydney 2013

Beyond JVM
or, How to Boil the Ocean in Seven Years

No platform-speciﬁc
compilation needed.

No native library
dependencies

Magical black box that
runs our code

Things We Like About

JVM
• Bytecode intermediate form

• Freedom from native libraries

• Optimizing JIT

• It just works (usually)

Things That Make

JRuby Difﬁcult
• Bytecode intermediate form

• Optimizing JIT

• Freedom from native libraries

• It just works (usually)

Things That Make

JRuby Difﬁcult
• Startup time sucks

• JNI is a massive pain to use

• Hard to get unusual languages to optimize

• Core is in C++ that we can’t touch

Java-Heavy JDK
• + Less native code to maintain

• + Easier portability

• + Easier to swap out native side

• – Takes longer to warm up

JVM
Language

JVM
Bytecode

Bytecode
Interpreter

Bytecode
JIT
Time

Native
Code

JVM
Language

JVM
Bytecode

Bytecode
Interpreter

Bytecode
JIT

Native
Code

Save JITed Code?
• Code will change across runs

• Often has speciﬁc memory addresses

• May optimize object layout differently

• Which JIT output?

• Client, Server, Tiered (1-4)

JRuby Startup
C Ruby

JRuby

-e 1

gem --help

rake -T

0

2.5

5

7.5

10

Tweaking Flags
• -client mode

• -XX:+TieredCompilation -XX:TieredStopAtLevel=1

• -X-C to disable JRuby’s compiler

• Heap sizes, code veriﬁcation, etc etc

JRuby Startup
C Ruby

JRuby

JRuby (best)

-e 1

gem --help

rake -T

0

2.5

5

7.5

10

Nailgun?
• Keep a single JVM running in background

• Toss commands over to it

• It stays hot, so code starts faster

• Hard to clean up all state (e.g. threads)

• Can’t get access to user’s terminal

Drip
• Start a new JVM after each command

• Pre-boot JVM plus optional code

• Analyze command line for differences

• Age out unused instances

• https://github.com/ﬂatland/drip

$ export JAVACMD=`which drip`
!
$ time jruby -e 1
!
real 0m1.655s
user 0m4.486s
sys 0m0.231s
!
$ time jruby -e 1
!
real 0m0.577s
user 0m0.052s
sys 0m0.065s

JRuby Startup
C Ruby

JRuby

JRuby (best)

JRuby (drip)

-e 1

gem --help

rake -T

0

2.5

5

7.5

10

$ export DRIP_INIT_CLASS=org.jruby.main.DripMain
!
$ export DRIP_INIT=""
!
$ time jruby -e 1
!
real 0m0.580s
user 0m0.052s
sys 0m0.063s
!
$ time jruby -e 1
!
real 0m0.155s
user 0m0.049s
sys 0m0.058s

public class DripMain {!
    public static RubyInstanceConfig DRIP_CONFIG;!
    public static Ruby DRIP_RUNTIME;!

!

    public static final String JRUBY_DRIP_WARMUP_ENV = "JRUBY_DRIP_WARMUP";!
    public static final String JRUBY_DRIP_WARMUP_DEFAULT = "1 + 1";!
    public static final String JRUBY_DRIP_PREBOOT_FILE = "./dripmain.rb";!

!

    public static void main(String[] args) throws IOException {!
        // warmup JVM first!
        Ruby ruby = Ruby.newInstance();!

!

        String envWarmup = System.getenv(JRUBY_DRIP_WARMUP_ENV);!
        if (envWarmup != null && envWarmup.length() > 0) {!
            ruby.evalScriptlet(envWarmup);!
        } else {!
            ruby.evalScriptlet(JRUBY_DRIP_WARMUP_DEFAULT);!
        }!

!

        // preboot actual runtime!
        Ruby.clearGlobalRuntime();!
        File dripMain = new File(JRUBY_DRIP_PREBOOT_FILE);!

!

        RubyInstanceConfig config = new RubyInstanceConfig();!
        ruby = Ruby.newInstance(config);!

!

        if (dripMain.exists()) {!
            FileInputStream fis = new FileInputStream(dripMain);!
            try {!
                ruby.getLoadService().load(dripMain.getAbsolutePath(), false);!
            } finally {!
                fis.close();!
            }!
        }!

!

        // use config and runtime from preboot process!
        DRIP_CONFIG = config;!
        DRIP_RUNTIME = ruby;!
    }!
}!

public static final String JRUBY_DRIP_WARMUP_ENV = "JRUBY_DRI
public static final String JRUBY_DRIP_WARMUP_DEFAULT = "1 + 1
public static final String JRUBY_DRIP_PREBOOT_FILE = "./dripm

public static void main(String[] args) throws IOException {!
     // warmup JVM first!
     Ruby ruby = Ruby.newInstance();!

     String envWarmup = System.getenv(JRUBY_DRIP_WARMUP_ENV);!
     if (envWarmup != null && envWarmup.length() > 0) {!
         ruby.evalScriptlet(envWarmup);!
     } else {!
         ruby.evalScriptlet(JRUBY_DRIP_WARMUP_DEFAULT);!
     }!





     if (dripMain.exists()) {!
         FileInputStream fis = new FileInputStream(dripMain);!
         try {!
             ruby.getLoadService().load(dripMain.getAbsolutePa
         } finally {!
             fis.close();!
         }!
     }!

     // use config and runtime from preboot process!
     DRIP_CONFIG = config;!
     DRIP_RUNTIME = ruby;!
}!

JRuby Startup
C Ruby
JRuby (drip init)

JRuby

JRuby (best)

JRuby (drip)

-e 1

gem --help

rake -T

0

2.5

5

7.5

10

$ cat dripmain.rb
# Preload some code Rails always needs
require File.expand_path('../config/application', __FILE__)

JRuby Startup
C Ruby
JRuby (drip)

JRuby
JRuby (drip init)

JRuby (best)
JRuby (dripmain)

rake -T

0

2.5

5

7.5

10

JRuby Startup
C Ruby

JRuby (dripmain)

rake -T

0

0.275

0.55

0.825

1.1

User Code

Java

JNI call

C/native

JNI impl
Target Library

JNI
public class GetPidJNI {!
public static native long getpid();!
!
public static void main( String[] args ) {!
getpid();!
}!
!
static {!
System.load(!
System.getProperty("user.dir") +!
"/getpidjni.dylib");!
}!
}

JNI
/* DO NOT EDIT THIS FILE - it is machine generated */!
#include <jni.h>!
/* Header for class com_headius_jnr_presentation_GetPidJNI */!
!
#ifndef _Included_com_headius_jnr_presentation_GetPidJNI!
#define _Included_com_headius_jnr_presentation_GetPidJNI!
#ifdef __cplusplus!
extern "C" {!
#endif!
/*!
* Class:
com_headius_jnr_presentation_GetPidJNI!
* Method:
getpid!
* Signature: ()J!
*/!
JNIEXPORT jlong JNICALL Java_com_headius_jnr_1presentation_GetPidJNI_getpid!
(JNIEnv *, jclass);!
!
#ifdef __cplusplus!
}!
#endif!
#endif

JNI
#include "com_headius_jnr_presentation_GetPidJNI.h"!
!
jlong JNICALL Java_com_headius_jnr_1presentation_GetPidJNI_getpid!
(JNIEnv *env, jclass c) {!
!
return getpid();!
}

JNI
$ gcc -I $JAVA_HOME/include -I
$JAVA_HOME/include/darwin -L
$JAVA_HOME/jre/lib/ -dynamiclib -ljava
-o getpidjni.dylib
com_headius_jnr_presentation_GetPidJNI.
c!
!

$ java -Djava.library.path=`pwd` -cp
target/jnr_presentation-1.0SNAPSHOT.jar
com.headius.jnr_presentation.GetPidJNI

Java Native Runtime
• Java API

• for calling Native code

• supported by a rich Runtime library

• You may be familiar with JNA

• Foreign Function Interface (FFI)

• https://github.com/jnr

User Code
JNR stub

Java

JNI call

C/native

JNI impl
libfﬁ
Target Library

JNR
import jnr.ffi.LibraryLoader;!
import jnr.ffi.annotations.IgnoreError;!
!
public class GetPidJNRExample {!
public interface GetPid {!
long getpid();!
}!
!
GetPid getpid = LibraryLoader!
.create(GetPid.class)!
.load("c");!
!
getpid.getpid();!
}!
}

Layered Runtime
etc etc
jnr-posix

jnr-unixsocket!
jnr-enxio

jnr-constants

jnr-ffi
jffi
libffi

jnr-x86asm

jfﬁ Platforms
• Darwin (OS X): universal (+ppc?)

• Linux: i386, x86_64, arm, ppc, ppc64, s390x

• Windows: i386, x86_64

• FreeBSD, OpenBSD: i386, x86_64

• SunOS: i386, x86_64, sparc, sparcv9

• AIX: ppc

• OpenVMS, AS/400: builds out there somewhere

• If your platform isn't here, contribute a build

jnr-fﬁ
• User-oriented API

• Roughly equivalent to what JNA gives you

• Functions, structs, callbacks, memory

• https://github.com/jnr/jnr-fﬁ

jnr-posix
• Pre-bound set of POSIX functions

• Mostly driven by what JRuby, Jython use

• Goal: 100% of POSIX bound to Java

public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
public
List<?

int chmod(String string, int i);!
int chown(String string, int i, int i1);!
int execv(String string, String[] strings);!
int execve(String string, String[] strings, String[] strings1);!
int fork();!
int seteuid(int i);!
int getgid();!
String getlogin();!
int getpgid();!
int getpgid(int i);!
int getpgrp();!
int getpid();!
int getppid();!
Passwd getpwent();!
Passwd getpwuid(int i);!
Passwd getpwnam(String string);!
Group getgrgid(int i);!
Group getgrnam(String string);!
int getuid();!
boolean isatty(FileDescriptor fd);!
int kill(int i, int i1);!
int symlink(String string, String string1);!
int link(String string, String string1);!
String readlink(String string) throws IOException;!
String getenv(String string);!
int setenv(String string, String string1, int i);!
int unsetenv(String string);!
int getpriority(int i, int i1);!
int setpriority(int i, int i1, int i2);!
int setuid(int i);!
FileStat stat(String string);!
int stat(String string, FileStat fs);!
int umask(int i);!
Times times();!
int utimes(String string, long[] longs, long[] longs1);!
int waitpid(int i, int[] ints, int i1);!
int wait(int[] ints);!
int errno();!
void errno(int i);!
int posix_spawnp(String string, List<? extends SpawnFileAction> list,
extends CharSequence> list1, List<? extends CharSequence> list2);

POSIX posix = POSIXFactory.getPOSIX(!
new MyPOSIXHandler(this),!
isNativeEnabled);

public interface POSIXHandler {!
public void error(Errno errno, String string);!
public void unimplementedError(String string);!
public void warn(WARNING_ID wrngd, String string, Object[] os);!
public boolean isVerbose();!
public File getCurrentWorkingDirectory();!
public String[] getEnv();!
public InputStream getInputStream();!
public PrintStream getOutputStream();!
public int getPID();!
public PrintStream getErrorStream();!
}

public
public
public
public
public
public
public
public
public

int chmod(String string, int i);!
int chown(String string, int i, int i1);!
int kill(int i, int i1);!
int getpriority(int i, int i1);!
int setpriority(int i, int i1, int i2);!
int waitpid(int i, int[] ints, int i1);!
int wait(int[] ints);!
int errno();!
void errno(int i);

jnr-constants
• C/preprocessor constants in enum form

• Generator code to run on each platform

• Several pregenerated sets for jnr-posix

public int open(String string, int flags, int mode);!
public int socket(int i, int i1);

jnr-enxio
• Extended Native X-platform IO

• NIO-compatible JNR-backed IO library

• Read, write, select (kqueue, epoll, etc)

• Low-level fcntl control

• https://github.com/jnr/jnr-enxio

public class NativeSocketChannel!
extends AbstractSelectableChannel!
implements ByteChannel, NativeSelectableChannel {!
public NativeSocketChannel(int fd);!
public NativeSocketChannel(int fd, int ops);!
public final int validOps();!
public final int getFD();!
public int read(ByteBuffer dst) throws IOException;!
public int write(ByteBuffer src) throws IOException!
public void shutdownInput() throws IOException;!
public void shutdownOutput() throws IOException;!
}

jnr-unixsocket
• UNIX sockets for NIO

• Built atop jnr-enxio

• Fully selectable, etc

• https://github.com/jnr/jnr-unixsocket

What Else?
• NIO, NIO.2

• Native IO, symlinks, FS-walking,

• Unmanaged memory

• Selectable stdio, process IO

• Low-level or other sockets (UNIX, ICMP, ...)

• New APIs (graphics, crypto, OS, ...)

Performance
• Generated code leading to JNI call

• Generated assembly version of native part

• jnr-x86asm: Generate and link ASM

• Used internally by jnr

• https://github.com/jnr/jnr-x86asm

JNA getpid

JNR getpid

getpid calls, 100M times
100000ms

10000ms

1000ms

100ms

10ms

1ms

@IgnoreError
import jnr.ffi.LibraryLoader;!
import jnr.ffi.annotations.IgnoreError;!
!
public class GetPidJNRExample {!
public interface GetPid {!
@IgnoreError!
long getpid();!
}!
!
GetPid getpid = LibraryLoader!
.create(GetPid.class)!
.load("c");!
!
getpid.getpid();!
}!
}

JNR getpid

JNR getpid @IgnoreError

2000ms

1500ms

1000ms

500ms

0ms

But There's More to Do
JNR getpid

JNI

JNR @IgnoreError

2000ms

1500ms

1000ms

500ms

0ms

GCC -O3

JVM Help is Coming
• Standard FFI API in JDK

• JIT intelligence

• Drop JNI overhead where possible

• Bind native call directly at call site

• Security policies, segv protection, etc

• Time for an FFI JSR

History
• JVM authors mentioned non-Java languages

• Language authors have targeted JVM

• Hundreds of JVM languages now

• But JVM was a mismatch for many of them

• Usually required tricks that defeated JVM
optimizations

• Or required features JDK could not provide

JVM
Opcodes
Invocation

Field Access

invokevirtual!
invokeinterface!
invokestatic!
invokespecial

getfield!
setfield!
getstatic!
setstatic

Stack

Flow Control

Boolean and Numeric

Array Access

*aload!
*astore!
b,s,c,i,l,d,f,a

Local Vars

Allocation

Goals of JSR 292
• A user-definable bytecode

• Full freedom to define VM behavior

• Fast method pointers + adapters

• Optimizable like normal Java code

• Avoid future modifications

Invoke

// Static!
System.currentTimeMillis()!
Math.log(1.0)

Invoke

// Static!
Math.log(1.0)!
!
// Virtual!
"hello".toUpperCase()!
System.out.println()

Invoke

// Static!
Math.log(1.0)!
!
// Virtual!
System.out.println()!
!
// Interface!
myList.add("happy happy")!
myRunnable.run()

Invoke

// Static!
Math.log(1.0)!
!
// Virtual!
System.out.println()!
!
// Interface!
myList.add("happy happy")!
myRunnable.run()!
!
// Constructor and super!
new ArrayList()!
super.equals(other)

// Static!
invokestatic java/lang/System.currentTimeMillis:()J!
invokestatic java/lang/Math.log:(D)D!
!
// Virtual!
invokevirtual java/lang/String.toUpperCase:()Ljava/lang/String;!
invokevirtual java/io/PrintStream.println:()V!
!
// Interface!
invokeinterface java/util/List.add:(Ljava/lang/Object;)Z!
invokeinterface java/lang/Runnable.add:()V!
!
// Special!
invokespecial java/util/ArrayList.<init>:()V!
invokespecial java/lang/Object.equals:(java/lang/Object)Z

invokevirtual!
1. Confirm object is of correct type

2. Confirm arguments are of correct type

3. Look up method on Java class

invokestatic
4. Cache method

5. Invoke method

invokestatic!


3. Cache method

4. Invoke method

invokevirtual
invokeinterface!
1. Confirm object’s type implements interface



invokeinterface
4. Cache method

5. Invoke method

invokespecial!
1. Confirm object is of correct type


3. Confirm target method is visible


5. Cache method

6. Invoke method

invokespecial
invokedynamic!
1. Call your bootstrap code

2. Bootstrap wires up a target function

3. Target function invoked directly until you change it

invokedynamic bytecode
target method

bo
ot
st

ra
p

m

et
ho
d

method handles

Indy Languages
• New language impls

• JavaScript: Dyn.js and Nashorn

• Redline Smalltalk

• Improved language performance

• JRuby, Groovy, Jython

• Java features too!

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

1.25

0

1.346

base64

1.565

1.538

richards

neural

redblack

red/black tree, pure Ruby versus native

ruby-2.0.0 + Ruby

2.48s

ruby-2.0.0 + C ext

0.51s

jruby + Ruby

0.29s

0

0.75

1.5
Runtime per iteration

2.25

3

Caveat Emptor
• Indy was really slow in ﬁrst Java 7 release

• Got fast in 7u2...and turned out broken

• Rewritten for 7u40

• Slow to warm up

• Still some issues (memory use, etc)

• Java 8 due in March…

JVM
Language

JVM
Bytecode

Out of our control

Written in C++

Bytecode
Interpreter

Bytecode
JIT

Native
Code

What If…
• The JVM’s JIT optimizer were written in Java

• You could customize how the JIT works for
your language or library

• JITed code could directly make native calls

Graal
• A 100% Java-based JIT framework

• Grew out of the 100% Java “Maxine” JVM

• Backends to assembly or HotSpot IR

• Directly control code generation

• Build a language without using JVM bytecode

• http://openjdk.java.net/projects/graal/

JVM
Language
Plain Java APIs

Graal

Intermediate
Representation

Graal
Optimizer

Your
Optimizations
Under your control

Native
Code

However…
• Not everyone is a compiler writer

• Graal’s IR is low-level and nontrivial

• Need to understand JVM internals

• Need some understanding of CPU

The Dream
• Design your language

• ???

• PROFIT

What We Want
• Design your language

• Write an interpreter

• PROFIT

Truffle
• Language framework built on Graal

• Designed to fulfill the dream

• Implement interpreter

• Truffle feeds that to backend

• No compiler expertise needed

• https://wiki.openjdk.java.net/display/Graal/Truffle+FAQ+and+Guidelines

JVM
Language

Trufﬂe

AST
All we need

Graal
Intermediate
Representation

Graal
Optimizer

Native
Code

The JVM has its
problems, but we can
ﬁx them.

OpenJDK and all these
solutions are really,
truly, open source.

Thank you!
• Charles Oliver Nutter

• @headius, headius@headius.com

• http://blog.headius.com

Beyond JVM - YOW! Sydney 2013

Beyond JVM - YOW! Sydney 2013

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