Beyond JVM

"Beyond JVM" as delivered at YOW! Brisbane 2013.

Transcript

1. Beyond JVM A tour of upcoming technologies
2. Me • Charles Oliver Nutter • Red Hat (yes, I have one; no, I don’t wear it) • JRuby and JVM languages • JVM hacking and spelunking • @headius
3. Goals • Get you excited about the future of JVM • Show you there are very few unsolvables • Convince you to get involved
4. What is “JVM”? • The JVM is software that runs JVM bytecode • Java, Scala, Groovy, JRuby, Clojure, … • OpenJDK contains Sun’s JVM “HotSpot” • Oracle’s JDK is based on OpenJDK • Many other JVMs exist for many platforms • Some just replace HotSpot
5. OSS JVMs • Avian • Azul Zulu • CACAO • Dalvik • GCJ • HaikuVM • HotSpot • IcedTea • IKVM.NET • Jamiga • JamVM • Jaos • Jato VM • Jelatine JVM • JESSICA • Jikes RVM (Jikes Research Virtual Machine) • JOP • Juice • Jupiter • JwiK • Kaffe • leDos • MateVM • Maxine • Mika VM • miniMV • Mysaifu • NanoVM • RoboVM • SableVM • Squawk virtual machine • SuperWaba • TakaTuka • TinyVM. • VM02
6. Why JVM?
7. Why Not JVM?
10. Startup Time
13. Java-Heavy JDK • + Less native code to maintain • + Easier portability • + Easier to swap out native side • – Takes longer to warm up
14. 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)
15. JRuby Startup -e 1 gem --help rake -T 0 2.5 5 7.5 10 C Ruby JRuby JRuby (best)
16. 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
17. $ export JAVACMD=`which drip` ! $ time jruby -e 1 ! real 0m1.655s user 0m4.486s sys 0m0.231s ! system ~/projects/jruby $ time jruby -e 1 ! real 0m0.577s user 0m0.052s sys 0m0.065s
18. $ export DRIP_INIT_CLASS=org.jruby.main.DripMain ! $ export DRIP_INIT="" ! $ time jruby -e 1 ! real 0m0.580s user 0m0.052s sys 0m0.063s ! system ~/projects/jruby $ time jruby -e 1 ! real 0m0.155s user 0m0.049s sys 0m0.058s
19. $ cat dripmain.rb # Preload some code Rails always needs require File.expand_path('../config/application', __FILE__)
20. JRuby Startup -e 1 gem --help rake -T 0 1.25 2.5 3.75 5 C Ruby JRuby (best) JRuby (drip) JRuby (drip init) JRuby (dripmain)
21. Native Interop
22. Native Interop
25. User Code JNI call JNI impl Target Library Java C/native
26. 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
27. /* 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
28. #include "com_headius_jnr_presentation_GetPidJNI.h"! ! jlong JNICALL Java_com_headius_jnr_1presentation_GetPidJNI_getpid! (JNIEnv *env, jclass c) {! ! return getpid();! } JNI
29. $ 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 JNI
30. Nobody enjoys calling native libraries...
31. ...but if you have to call native libraries, you might as well enjoy it.
32. 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 • Maven artifacts for everything
33. A Java API for binding native libraries and native memory
34. Justifications • 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, ...)
35. User Code JNI call JNI impl Target Library Java C/native
36. User Code JNI call JNI impl Target Library Java C/native
37. User Code JNR stub JNI call JNI impl libffi Target Library Java C/native
38. 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
39. Layered Runtime jffi jnr-ffi libffi jnr-posix jnr-constants ! jnr-enxio jnr-x86asm jnr-unixsocket etc etc
40. JNR 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
41. jnr-ffi • User-oriented API • Roughly equivalent to what JNA gives you • Functions, structs, callbacks, memory • https://github.com/jnr/jnr-ffi
42. 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-ffi
43. jnr-posix • Pre-bound set of POSIX functions • Mostly driven by what JRuby, Jython use • Goal: 100% of POSIX bound to Java
44. public int chmod(String string, int i);! public int chown(String string, int i, int i1);! public int execv(String string, String[] strings);! public int execve(String string, String[] strings, String[] strings1);! public int fork();! public int seteuid(int i);! public int getgid();! public String getlogin();! 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);! public Times times();! public int utimes(String string, long[] longs, long[] longs1);! public int waitpid(int i, int[] ints, int i1);! public int wait(int[] ints);! public int errno();! public void errno(int i);! public int posix_spawnp(String string, List<? extends SpawnFileAction> list, List<? extends CharSequence> list1, List<? extends CharSequence> list2);
45. POSIX posix = POSIXFactory.getPOSIX(! new MyPOSIXHandler(this),! isNativeEnabled);
46. 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();! }
47. 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
48. 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;! }
49. jnr-unixsocket • UNIX sockets for NIO • Built atop jnr-enxio • Fully selectable, etc • https://github.com/jnr/jnr-unixsocket
50. How Does It Perform?
51. getpid calls, 100M times 1ms 10ms 100ms 1000ms 10000ms 100000ms JNA getpid JNR getpid
52. 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
53. getpid calls, 100M times 0ms 500ms 1000ms 1500ms 2000ms JNR getpid JNR getpid @IgnoreError
54. getpid calls, 100M times 0ms 500ms 1000ms 1500ms 2000ms JNR getpid JNI JNR @IgnoreError GCC -O3 But There's More to Do
55. 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
56. Language Performance
57. 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
58. What is invokedynamic
59. 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
60. 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
61. +
    Method Pointers
    and Adapters Faster than reflection, with user-defined argument, flow, and exception handling A User-definable Bytecode You decide how the JVM implements it
62. invokedynamic user-def’d bytecode invokedynamic opcode method pointers MethodHandles
63. VM Operations Method Lookup Type Checking Branch Method Cache Method Invocation Target Object Object’s Class void foo() static void bar() instanceof obj.foo() JVM void foo() Call Site
64. // Static! System.currentTimeMillis()! Math.log(1.0)! ! // Virtual! "hello".toUpperCase()! System.out.println()! ! // Interface! myList.add("happy happy")! myRunnable.run()! ! // Special! new ArrayList()! super.equals(other)
65. // 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 invokestatic invokevirtual invokeinterface invokespecial
66. 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 invokespecial invokedynamic! 1. Call your bootstrap code 2. Bootstrap wires up a target function 3. Target function invoked directly until you change it
67. method handles invokedynamic bytecode bootstrap m ethod target method
68. How Do You Benefit?
69. Indy Languages • New language impls • JavaScript: Dyn.js and Nashorn • Redline Smalltalk • Improved language performance • JRuby, Groovy, Jython • Java features too!
70. Times Faster than Ruby 1.9.3 0 1.25 2.5 3.75 5 base64 richards neural redblack 4.32 3.66 3.44 2.658 1.565 1.914 1.538 1.346 JRuby/Java 6 JRuby/Java 7
71. red/black tree, pure Ruby versus native ruby-2.0.0 + Ruby ruby-2.0.0 + C ext jruby + Ruby Runtime per iteration 0 0.75 1.5 2.25 3 0.29s 0.51s 2.48s
72. Indy + JNR 100M getpid calls 0 675 1350 2025 2700 Ruby getpid Java getpid
73. 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…
74. All That C++
75. Out of our control Written in C++ JVM Bytecode JVM Language Bytecode Interpreter Bytecode JIT Native Code
76. 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
77. 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/
78. Graal Intermediate Representation JVM Language Graal Optimizer Native Code Your Transformations Your Optimizations Plain Java APIs Under your control
79. 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
80. The Dream • Design your language • ??? • PROFIT
81. Typical JVM Language • Design your language • Maybe write an interpreter • Compile to JVM bytecode • Pray that the JVM optimizes it right • PROFIT
82. What We Want • Design your language • Write an interpreter • PROFIT
83. 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
84. Truffle AST JVM Language Graal Intermediate Representation Graal Optimizer Native Code All we need
87. The Final Word • JVM is a powerful platform • Java and other languages are evolving • The JVM is adapting to our needs • New tools breaking JVM’s boundaries
88. Thank you! • Charles Oliver Nutter • @headius, headius@headius.com • http://blog.headius.com