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Beyond JVM - YOW! Sydney 2013

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Charles Nutter

The document discusses strategies for improving the startup performance of JRuby. It describes how the JRuby team optimized startup by using a Java-heavy JDK instead of native code, tweaking JVM flags, and implementing Drip - a technique that pre-boots the JVM and caches runtime configurations between runs. Drip reduced JRuby startup times from over 10 seconds to under 1 second for many common tasks. Later, it discusses challenges with JNI and how the Java Native Runtime (JNR) provides a better alternative for interfacing Java with native code and libraries.

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Beyond JVM or, How to Boil the Ocean in Seven Years
Beyond JVM - YOW! Sydney 2013
Beyond JVM - YOW! Sydney 2013
+
We Like the JVM
No platform-specific compilation needed.
No native library dependencies
Optimizing JIT compiler
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
Beyond JVM - YOW! Sydney 2013
Beyond JVM - YOW! Sydney 2013
Beyond JVM - YOW! Sydney 2013
Beyond JVM - YOW! Sydney 2013
Beyond JVM - YOW! Sydney 2013
There must be a way!
Startup Time
Beyond JVM - YOW! Sydney 2013
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);!      }!      // preboot actual runtime!      Ruby.clearGlobalRuntime();!      File dripMain = new File(JRUBY_DRIP_PREBOOT_FILE);!      RubyInstanceConfig config = new RubyInstanceConfig();!      ruby = Ruby.newInstance(config);!
 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);!      }!      // preboot actual runtime!      Ruby.clearGlobalRuntime();!      File dripMain = new File(JRUBY_DRIP_PREBOOT_FILE);!      RubyInstanceConfig config = new RubyInstanceConfig();!      ruby = Ruby.newInstance(config);!
 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);!      }!      // preboot actual runtime!      Ruby.clearGlobalRuntime();!      File dripMain = new File(JRUBY_DRIP_PREBOOT_FILE);!      RubyInstanceConfig config = new RubyInstanceConfig();!      ruby = Ruby.newInstance(config);!
     // 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.getAbsolutePa          } finally {!              fis.close();!          }!      }!      // use config and runtime from preboot process!      DRIP_CONFIG = config;!      DRIP_RUNTIME = ruby;!  }!
     // 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.getAbsolutePa          } finally {!              fis.close();!          }!      }!      // use config and runtime from preboot process!      DRIP_CONFIG = config;!      DRIP_RUNTIME = ruby;!  }!
     // 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.getAbsolutePa          } finally {!              fis.close();!          }!      }!      // use config and runtime from preboot process!      DRIP_CONFIG = config;!      DRIP_RUNTIME = ruby;!  }!
     // 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.getAbsolutePa          } finally {!              fis.close();!          }!      }!      // use config and runtime from preboot process!      DRIP_CONFIG = config;!      DRIP_RUNTIME = ruby;!  }!
     // 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.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
Native Interop
JVM World ???? Native World
Beyond JVM - YOW! Sydney 2013
Beyond JVM - YOW! Sydney 2013
JNI
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
There Must Be A Better Way
User Code Java JNI call C/native JNI impl Target Library
User Code Java JNI call C/native JNI impl Target Library
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();! }! ! public static void main( String[] args ) {! 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, ...)
How Does It Perform?
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();! }! ! public static void main( String[] args ) {! GetPid getpid = LibraryLoader! .create(GetPid.class)! .load("c");! ! getpid.getpid();! }! }
JNR getpid JNR getpid @IgnoreError getpid calls, 100M times 2000ms 1500ms 1000ms 500ms 0ms
But There's More to Do JNR getpid JNI JNR @IgnoreError getpid calls, 100M times 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
Language Performance
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! System.currentTimeMillis()! Math.log(1.0)!  ! // Virtual! "hello".toUpperCase()! System.out.println()
Invoke // Static! System.currentTimeMillis()! Math.log(1.0)!  ! // Virtual! "hello".toUpperCase()! System.out.println()!  ! // Interface! myList.add("happy happy")! myRunnable.run()
Invoke // Static! System.currentTimeMillis()! Math.log(1.0)!  ! // Virtual! "hello".toUpperCase()! 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! 1. Confirm arguments are of correct type 2. Look up method on Java class 3. Cache method 4. Invoke method invokevirtual invokeinterface! 1. Confirm object’s type implements interface 2. Confirm arguments are of correct type 3. Look up method on Java class invokeinterface 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 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
Does It Work?
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…
All That C++
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
Beyond JVM - YOW! Sydney 2013
Beyond JVM - YOW! Sydney 2013
What Have We Learned?
The JVM has its problems, but we can fix them.
OpenJDK and all these solutions are really, truly, open source.
Nothing is impossible.
Thank you! • Charles Oliver Nutter • @headius, headius@headius.com • http://blog.headius.com

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Beyond JVM - YOW! Sydney 2013

  • 1. Beyond JVM or, How to Boil the Ocean in Seven Years
  • 4. +
  • 9. Magical black box that runs our code
  • 10. Things We Like About JVM • Bytecode intermediate form • Freedom from native libraries • Optimizing JIT • It just works (usually)
  • 11. Things That Make JRuby Difficult • Bytecode intermediate form • Optimizing JIT • Freedom from native libraries • It just works (usually)
  • 12. 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
  • 18. There must be a way!
  • 21. Java-Heavy JDK • + Less native code to maintain • + Easier portability • + Easier to swap out native side • – Takes longer to warm up
  • 24. 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)
  • 25. JRuby Startup C Ruby JRuby -e 1 gem --help rake -T 0 2.5 5 7.5 10
  • 26. Tweaking Flags • -client mode • -XX:+TieredCompilation -XX:TieredStopAtLevel=1 • -X-C to disable JRuby’s compiler • Heap sizes, code verification, etc etc
  • 27. JRuby Startup C Ruby JRuby JRuby (best) -e 1 gem --help rake -T 0 2.5 5 7.5 10
  • 28. 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
  • 29. 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
  • 30. $ 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
  • 31. JRuby Startup C Ruby JRuby JRuby (best) JRuby (drip) -e 1 gem --help rake -T 0 2.5 5 7.5 10
  • 32. $ 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
  • 33. 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;!     }! }!
  • 34.  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);!      }!      // preboot actual runtime!      Ruby.clearGlobalRuntime();!      File dripMain = new File(JRUBY_DRIP_PREBOOT_FILE);!      RubyInstanceConfig config = new RubyInstanceConfig();!      ruby = Ruby.newInstance(config);!
  • 35.  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);!      }!      // preboot actual runtime!      Ruby.clearGlobalRuntime();!      File dripMain = new File(JRUBY_DRIP_PREBOOT_FILE);!      RubyInstanceConfig config = new RubyInstanceConfig();!      ruby = Ruby.newInstance(config);!
  • 36.  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);!      }!      // preboot actual runtime!      Ruby.clearGlobalRuntime();!      File dripMain = new File(JRUBY_DRIP_PREBOOT_FILE);!      RubyInstanceConfig config = new RubyInstanceConfig();!      ruby = Ruby.newInstance(config);!
  • 37.      // 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.getAbsolutePa          } finally {!              fis.close();!          }!      }!      // use config and runtime from preboot process!      DRIP_CONFIG = config;!      DRIP_RUNTIME = ruby;!  }!
  • 38.      // 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.getAbsolutePa          } finally {!              fis.close();!          }!      }!      // use config and runtime from preboot process!      DRIP_CONFIG = config;!      DRIP_RUNTIME = ruby;!  }!
  • 39.      // 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.getAbsolutePa          } finally {!              fis.close();!          }!      }!      // use config and runtime from preboot process!      DRIP_CONFIG = config;!      DRIP_RUNTIME = ruby;!  }!
  • 40.      // 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.getAbsolutePa          } finally {!              fis.close();!          }!      }!      // use config and runtime from preboot process!      DRIP_CONFIG = config;!      DRIP_RUNTIME = ruby;!  }!
  • 41.      // 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.getAbsolutePa          } finally {!              fis.close();!          }!      }!      // use config and runtime from preboot process!      DRIP_CONFIG = config;!      DRIP_RUNTIME = ruby;!  }!
  • 42. 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
  • 43. $ cat dripmain.rb # Preload some code Rails always needs require File.expand_path('../config/application', __FILE__)
  • 44. JRuby Startup C Ruby JRuby (drip) JRuby JRuby (drip init) JRuby (best) JRuby (dripmain) rake -T 0 2.5 5 7.5 10
  • 45. JRuby Startup C Ruby JRuby (dripmain) rake -T 0 0.275 0.55 0.825 1.1
  • 50. JNI
  • 52. 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");! }! }
  • 53. 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
  • 54. JNI #include "com_headius_jnr_presentation_GetPidJNI.h"!  ! jlong JNICALL Java_com_headius_jnr_1presentation_GetPidJNI_getpid! (JNIEnv *env, jclass c) {!  ! return getpid();! }
  • 55. 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
  • 56. There Must Be A Better Way
  • 59. 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
  • 60. User Code JNR stub Java JNI call C/native JNI impl libffi Target Library
  • 61. JNR 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();! }! }
  • 63. 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
  • 64. jnr-ffi • User-oriented API • Roughly equivalent to what JNA gives you • Functions, structs, callbacks, memory • https://github.com/jnr/jnr-ffi
  • 65. jnr-posix • Pre-bound set of POSIX functions • Mostly driven by what JRuby, Jython use • Goal: 100% of POSIX bound to Java
  • 66. 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);
  • 67. POSIX posix = POSIXFactory.getPOSIX(! new MyPOSIXHandler(this),! isNativeEnabled);
  • 68. 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();! }
  • 69. 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);
  • 70. jnr-constants • C/preprocessor constants in enum form • Generator code to run on each platform • Several pregenerated sets for jnr-posix
  • 71. public int open(String string, int flags, int mode);! public int socket(int i, int i1);
  • 72. 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
  • 73. 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;! }
  • 74. jnr-unixsocket • UNIX sockets for NIO • Built atop jnr-enxio • Fully selectable, etc • https://github.com/jnr/jnr-unixsocket
  • 75. 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, ...)
  • 76. How Does It Perform?
  • 77. 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
  • 78. JNA getpid JNR getpid getpid calls, 100M times 100000ms 10000ms 1000ms 100ms 10ms 1ms
  • 79. @IgnoreError 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();! }! }
  • 80. JNR getpid JNR getpid @IgnoreError getpid calls, 100M times 2000ms 1500ms 1000ms 500ms 0ms
  • 81. But There's More to Do JNR getpid JNI JNR @IgnoreError getpid calls, 100M times 2000ms 1500ms 1000ms 500ms 0ms GCC -O3
  • 82. 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
  • 84. 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
  • 86. 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
  • 90. Invoke // Static! System.currentTimeMillis()! Math.log(1.0)!  ! // Virtual! "hello".toUpperCase()! System.out.println()!  ! // Interface! myList.add("happy happy")! myRunnable.run()!  ! // Constructor and super! new ArrayList()! super.equals(other)
  • 91. // 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
  • 92. 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! 1. Confirm arguments are of correct type 2. Look up method on Java class 3. Cache method 4. Invoke method invokevirtual invokeinterface! 1. Confirm object’s type implements interface 2. Confirm arguments are of correct type 3. Look up method on Java class invokeinterface 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 invokespecial invokedynamic! 1. Call your bootstrap code 2. Bootstrap wires up a target function 3. Target function invoked directly until you change it
  • 95. Indy Languages • New language impls • JavaScript: Dyn.js and Nashorn • Redline Smalltalk • Improved language performance • JRuby, Groovy, Jython • Java features too!
  • 96. 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
  • 97. 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
  • 98. 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…
  • 100. JVM Language JVM Bytecode Out of our control Written in C++ Bytecode Interpreter Bytecode JIT Native Code
  • 101. 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
  • 102. 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/
  • 104. 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
  • 105. The Dream • Design your language • ??? • PROFIT
  • 106. What We Want • Design your language • Write an interpreter • PROFIT
  • 107. 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
  • 111. What Have We Learned?
  • 112. The JVM has its problems, but we can fix them.
  • 113. OpenJDK and all these solutions are really, truly, open source.
  • 115. Thank you! • Charles Oliver Nutter • @headius, headius@headius.com • http://blog.headius.com