GOTO Night with Charles Nutter Slides
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These are Charles Nutter's Slides for his presentation at GOTO Chicago's second annual GOTO Night.
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GOTO Night with Charles Nutter Slides
- 1. What’s Next for the JVM Charles Oliver Nutter @headius
- 2. Background
- 4. Java • Released in 1995 • Major library enhancements in 1.2 (1998) • JIT compiler in 1.3 (2000) • Two-year cycle…until 1.6 (2006)
- 5. Sun Versus Apache • Apache wanted TCK to test Harmony • Sun could/would not release TCK • Apache retaliated by voting no on Java 7 • Java was stuck at 1.6 for five years
- 6. •OPurshaesc Jlaeva 7T tharokugeh JsC PO, agvaiensrt Apache • Oh noes…they are evil like we thought! • Doubles down on OpenJDK • Ok, more support, more resources ++ • Back to two-year cycle, aggressive features • Invokedynamic, lambda, modules, generics
- 8. OpenJDK Community • Dozens of companies contributing now • Most JVMs are OpenJDK-based • Former competitors enhancing OpenJDK • It’s a big ol’ OSS love-fest
- 9. kbarrett kbr kcr kevinw khazra kizune klooney klward kmiller kmo kselle kshefov ksrini kurosaki kurt kvn kwwong lagergren lana lancea landonf
- 12. We Like the JVM
- 13. No platform-specific compilation needed.
- 14. No native library dependencies
- 16. Magical black box that runs our code
- 17. Things We Like About JVM • Bytecode intermediate form • Freedom from native libraries • Optimizing JIT • It just works (usually)
- 18. Things That Make JRuby Difficult • JVM bytecode tailored to Java features • Native libraries too hard to use • Black box forces us to guess and pray
- 20. InvokeDynamic
- 21. 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
- 22. JVM Opcodes Invocation invokevirtual invokeinterface invokestatic invokespecial Field Access getfield setfield getstatic setstatic Array Access *aload *astore b,s,c,i,l,d,f,a Stack Local Vars Flow Control Allocation Boolean and Numeric
- 23. "In the future, we will consider bounded extensions to the Java Virtual Machine to provide better support for other languages." - JVM Specification First Edition (1997), preface
- 24. Goals of JSR 292 • A user-definable bytecode • Full freedom to define VM behavior • Fast method pointers + adapters • Caching and invalidation • Avoid future modifications
- 25. Invoke // Static System.currentTimeMillis() Math.log(1.0)
- 26. Invoke // Static System.currentTimeMillis() Math.log(1.0) // Virtual "hello".toUpperCase() System.out.println()
- 27. Invoke // Static System.currentTimeMillis() Math.log(1.0) // Virtual "hello".toUpperCase() System.out.println() // Interface myList.add("happy happy") myRunnable.run()
- 28. Invoke // Static System.currentTimeMillis() Math.log(1.0) // Virtual "hello".toUpperCase() System.out.println() // Interface myList.add("happy happy") myRunnable.run() // Constructor and super
- 29. // Static invokestatic java/lang/System.currentTimeMillis:()J invokestatic java/lang/Math.log:(D)D invokestatic // Virtual invokevirtual java/lang/String.toUpperCase:()Ljava/lang/String; invokevirtual invokevirtual java/io/PrintStream.println:()V // Interface invokeinterface invokeinterface java/util/List.add:(Ljava/lang/Object;)Z invokeinterface java/lang/Runnable.add:()V invokespecial // Special invokespecial java/util/ArrayList.<init>:()V invokespecial java/lang/Object.equals:(java/lang/Object)Z
- 30. invokestatic 1. Confirm arguments are of correct type 2. Look up method on Java class 3. Cache method 4. Invoke method invokevirtual 1. Confirm object is of correct type 2. Confirm arguments are of correct type 3. Look up method on Java class 4. Cache method 5. Invoke method invokeinterface 1. Confirm object’s type implements interface 2. Confirm arguments are of correct type 3. Look up method on Java class 4. Cache method 5. Invoke method invokespecial 1. Confirm object is of correct type 2. Confirm arguments are of correct type 3. Confirm target method is visible 4. Look up method on Java class 5. Cache method 6. Invoke method invokestatic invokevirtual invokeinterface invokespeciianlvokedynamic 1. Call your bootstrap code 2. Bootstrap wires up a target function 3. Target function invoked directly until you change it
- 31. invokedynamic bytecode target method method handles
- 32. What Can It Do?
- 33. Indy Languages • New language impls • JavaScript: Dyn.js and Nashorn • Redline Smalltalk • Improved language performance • JRuby, Groovy, Jython • Java features too!
- 34. Indy in JRuby • Method dispatch • Look up method, cache, invalidate if class changes or a new type is seen • Constant lookup • Retrieve constant, cache, invalidate if redefined
- 35. 1.346071 JRuby/Java 6 JRuby/Java 7 Times Faster than Ruby 1.9.3 1.537647 1.913565 1.565463 2.658063 3.439953 3.660331 4.32043 5 3.75 2.5 1.25 0 base64 richards neural redblack
- 36. 2.48 red/black tree, pure Ruby versus native 0.51 0.29 0 0.75 1.5 2.25 3 ruby-2.0.0 + Ruby ruby-2.0.0 + C ext jruby + Ruby Runtime per iteration
- 37. Lambda (8) • Long-awaited closure support for Java • Similar to inner classes, but… • Lazily generate function class • Single object constructed, cached • All shared state passed on call stack
- 38. Collections.sort(input, (a,b)->Integer.compare(a.length(), b.length())); 0: aload_0 1: invokedynamic #36, 0 6: invokestatic #37 // Comparator.sort:(…) 9: return 0: aload_0 1: invokevirtual #53 // String.length:()I 4: aload_1 5: invokevirtual #53 // String.length:()I 8: invokestatic #54 // Integer.compare:(II)I 11: ireturn
- 39. Generic Specialization (9) • ArrayList<int> that actually uses int • Indy call site requests int-specialization • int version of class generated lazily • Working prototypes now in Valhalla
- 40. What Else? • JRuby working to pre-optimize more code • JVM folks working on startup time issues • What about non-JVM languages?
- 41. Native Interop
- 42. JVM World ???? Native World
- 43. “If non-Java programmers find some library useful and easy to access, it should be similarly accessible to Java programmers.” - John Rose
- 46. JNI
- 47. User Code JNI call JNI impl Target Library Java C/native
- 48. 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
- 49. /* 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 } JNI
- 50. #include "com_headius_jnr_presentation_GetPidJNI.h" jlong JNICALL Java_com_headius_jnr_1presentation_GetPidJNI_getpid (JNIEnv *env, jclass c) { return getpid(); } JNI
- 51. 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-1.0- SNAPSHOT.jar com.headius.jnr_presentation.GetPidJNI
- 52. There Must Be A Better Way
- 53. User Code JNI call JNI impl Target Library Java C/native
- 54. User Code JNR stub JNI call JNI impl libffi Target Library Java C/native
- 55. 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
- 56. import jnr.ffi.LibraryLoader; import jnr.ffi.annotations.IgnoreError; public class GetPidJNRExample { public interface GetPid { long getpid(); } public static void main( String[] args ) { GetPid getpid = LibraryLoader .create(GetPid.class) .load("c"); getpid.getpid(); } } JNR
- 57. Layered Runtime etc etc jnr-ffi jffi libffi jnr-posix jnr-constants jnr-enxio jnr-x86asm jnr-unixsocket
- 58. 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
- 59. jnr-ffi • User-oriented API • Roughly equivalent to what JNA gives you • Functions, structs, callbacks, memory • https://github.com/jnr/jnr-ffi
- 60. jnr-posix • Pre-bound set of POSIX functions • Mostly driven by what JRuby, Jython use • Goal: 100% of POSIX bound to Java
- 61. public int getpgid(); public int getpgid(int i); public int getpgrp(); public int getpid(); public int getppid(); public Passwd getpwent(); public Passwd getpwuid(int i); public Passwd getpwnam(String string); public Group getgrgid(int i); public Group getgrnam(String string); public int getuid(); public boolean isatty(FileDescriptor fd); public int kill(int i, int i1); public int symlink(String string, String string1); public int link(String string, String string1); public String readlink(String string) throws IOException; public String getenv(String string); public int setenv(String string, String string1, int i); public int unsetenv(String string); public int getpriority(int i, int i1); public int setpriority(int i, int i1, int i2); public int setuid(int i); public FileStat stat(String string); public int stat(String string, FileStat fs); public int umask(int i);
- 62. POSIX posix = POSIXFactory.getPOSIX( new MyPOSIXHandler(this), isNativeEnabled);
- 63. 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
- 64. 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; }
- 65. jnr-unixsocket • UNIX sockets for NIO • Built atop jnr-enxio • Fully selectable, etc • https://github.com/jnr/jnr-unixsocket
- 66. 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, ...)
- 67. 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
- 68. 100000 10000 1000 100 10 1 JNA getpid JNR getpid getpid calls, 100M times
- 69. import jnr.ffi.LibraryLoader; import jnr.ffi.annotations.IgnoreError; public class GetPidJNRExample { public interface GetPid { @IgnoreError long getpid(); } public static void main( String[] args ) { GetPid getpid = LibraryLoader .create(GetPid.class) .load("c"); getpid.getpid(); } @IgnoreError
- 70. 2500 2000 1500 1000 500 0 JNR getpid JNR getpid @IgnoreError getpid calls, 100M times
- 71. But There's More to 2500 2000 1500 1000 500 0 Do JNR getpid JNI JNR @IgnoreError GCC -O3 getpid calls, 100M times
- 72. Project Panama • JEP-191: FFI for the JVM • Native interop at platform level • JIT intelligence • Security • Native method handles • Native memory layout and manipulation
- 74. Out of our control Written in C++ JVM Language JVM Bytecode Bytecode Interpreter Bytecode JIT Native Code
- 75. 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
- 76. Graal • A 100% Java-based JIT framework • Grew out of the 100% Java “Maxine” JVM • Emits assembly or HotSpot IR • Directly control code generation • Route around JVM bytecode • http://openjdk.java.net/projects/graal/
- 77. Language Plain Java APIs Under your control JVM Graal Intermediate Representati on Graal Optimizer Native Code Your Optimizations
- 78. 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
- 79. The Dream • Design your language • ??? • PROFIT
- 80. What We Want • Design your language • Write an interpreter • PROFIT
- 81. 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+Guid elines
- 82. JVM Language Truffle AST Graal Intermediate Representatio n Graal Optimize r Native Code All we need
- 85. The Payoff • RubyTruffle now part of JRuby • Released in JRuby 9k • Many languages in the works • May become part of OpenJDK releases? • Forcing Hotspot folks to push harder
- 86. What Have We Learned?
- 87. The JVM has its problems, but we can fix them.
- 88. This is all open source…you can help
- 90. Thank you! • Charles Oliver Nutter • @headius, headius@headius.com • http://blog.headius.com