20 years of java - oraclecr.openjdk.java.net/~vlivanov/talks/2015_java_20_years_minsk.pdfjava...

20 years of Java

Vladimir Ivanov HotSpot JVM Compile r Oracle Corp.

Twitter: @iwan0www OpenJDK: vlivanov

28.11.2015

20 years of Java (The Platform)

Vladimir Ivanov HotSpot JVM Compile r Oracle Corp.

Twitter: @iwan0www OpenJDK: vlivanov

Safe Harbor Statement

The preceding is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle.

About me

1996 2002 2010 2015 2005

JDK 1.0

Wrote my first program in Java.

Joined Sun Microsystems

(SPBDC) to work on HotSpot JVM Now

Became part of Oracle Corp.

after acquisition

1991: Project Green

1991: *7 (StarSeven) Oak programming language

1991: *7 (StarSeven) Duke

1994: WebRunner/HotJava browser

1995: First release: 1.0a2

Intel Pentium P54CS, 0.35µm, 200MHz, 66MHz FSB

Sun Enterprise 10000 64 UltraSPARC II CPUs, 400 MHz, 16x4GB RAM

1996: JDK 1.0

§ 6 packages –  java.applet –  java.awt –  java.io –  java.lang –  java.net –  java.util

January, 23

§ # of classes –  java/ 225 –  sun/ 379

1996: picoJava

1997: JDK 1.1 February, 19

1998: J2SE 1.2 December, 8

1999: J2SE, J2ME, J2EE

2000: J2SE 1.3 May, 8

1998: JCP

2002 February, 6

First release

1995 1997 2002

Java Releases

1996 1998

JDK 1.0

JDK 1.1

J2SE 1.2

J2SE 1.3

J2SE 1.4

Inner classes JavaBeans

JDBC RMI

Reflection JNI

Swing JIT compiler Java Plug-in Collections

HotSpot JVM JNDI

Java Sound JVMDI JVMPI

Regular Expressions IPv6 support

Logging XML, XSLT

Java Web Start

January, 23

February, 19

December, 8

May, 8

February, 6

AWT Network

2004: J2SE 5.0 September, 30

2006: Java SE 6

§ Scripting Language Support (JSR 223) §  Java Compiler API (JSR 199) § Support for pluggable annotations (JSR 269) § Numerous performance improvements

–  C1: new linear register allocator –  C1: IR in SSA form

December, 11

Java SE 6u

§ Escape analysis in C2 –  6u23

§ NUMA GC Enhancements –  Java SE 6u2

§ Compressed OOPs –  6u23

§ Tiered compilation

HotSpot Express

2007 May, 8

2007: May JavaFX 1.0 on December, 2008

2011: Java SE 7

§  JVM support for dynamic languages (JSR 292) § Small language changes

–  e.g. strings in switch, try-with-resources § New file I/O library (defined by JSR 203)

July, 28

2014: Java SE 8

§  JSR 335: Language-level support for lambda expressions

§  JSR 223: Project Nashorn, a JavaScript runtime §  JSR 308: Annotation on Java Types §  JSR 310: Date and Time API §  JEP 122: Remove the permanent generation

March, 18

2014: Java SE 8 March, 18

2016: Java SE 9 ETA: September, 22

Project Jigsaw Scalability Performance Security

http://openjdk.java.net

Project Jigsaw Scalability

Java 8

authjdbc jaxpnaming

jaxwscompiler

rowsetxmldsig

crypto

desktop

tools.jre

httpserver

tools.jaxws tools.base

devtools

javafx

prefssctp jx.annotationsinstrument

54MB 30 16 11 nashorn

compact1

compact3

compact2

naming.rmi

base charsets

compact3

compact2

compact1

logging scrip:ng

security.acl

security.sasl

sql rmi

xml xml.crypto

prefs desktop

ac:va:on

compiler management

sql.rowset

security.jgss

instrument

naming

xml.ws

xml.soap

xml.bind

annota:ons.common

hBpserver

javadoc

xml.ws

xml.bind

compiler

hotspot.agent

jconsole jcmd jdi

jvmstat

naming

smartcardio crypto.ec

crypto.pkcs11

hprof.agent jdwp.agent

localedata sctp

zipfs security.auth

scripting. nashorn

Project Jigsaw Performance

Project Jigsaw

tlslogging

authjdbc

jaxpnaming

jaxwscompiler

rowset

kerberosmanagement

xmldsig

crypto

cosnaming management.iiop

desktop

tools.jre

httpserver

devtools

javafx

prefssctp jx.annotations

nashorn

instrument base

script

Project Jigsaw

tlslogging

authjdbc

jaxpnaming

jaxwscompiler

rowset

kerberosmanagement

xmldsig

crypto

desktop

tools.jre

httpserver

devtools

javafx

nashorn

instrument base

script

Project Jigsaw

tlslogging

authjdbc

jaxpnaming

jaxwscompiler

rowset

kerberosmanagement

xmldsig

crypto

desktop

tools.jre

httpserver

devtools

javafx

nashorn

instrument base

script

Project Jigsaw

crypto

javafx

nashorn

script

j l i n k

*.jmod $JRE/bin/java

/ l i b / . . .

* . j a r

* .c lass

JVM image

. j a r

Fat binary

Project Jigsaw Opportunities for performance improvements

rt.jar

nashorn.jar, jfxrt.jar,sunjce_provider.jar

myapp.jar

crypto

javafx

nashornbase

script

Project Jigsaw

§  Improved class loading architecture –  fast class lookup

Opportunities for performance improvements crypto

javafx

nashornbase

script

Project Jigsaw

javafx

nashornbase

script

Project Jigsaw

§ Aggressive inlining

javafx

nashornbase

script

Project Jigsaw

§ Aggressive inlining § Ahead-Of-Time compilation

javafx

nashornbase

script

Project Jigsaw

§ Aggressive inlining § Ahead-Of-Time compilation §  JVM-specific memory images

–  e.g. Application Class Data Sharing (AppCDS)

javafx

nashornbase

script

Project Jigsaw

§ Aggressive inlining § Ahead-Of-Time compilation §  JVM-specific memory images

–  e.g. Application Class Data Sharing (AppCDS)

§ Removal of unused fields/methods/classes

javafx

nashornbase

script

sun.* * . in te rna l .*

Project Jigsaw Security

sun.misc.Unsafe?!

Project Jigsaw Security

- How many of you have used the Unsafe API? …

John Rose JVM Architect, Oracle Corporation

Project Jigsaw & sun.misc.Unsafe

@ JVM Language Summit 2014

- How many of you have used the Unsafe API? …

- A lot of you. Gosh, I'm sorry.

John Rose JVM Architect, Oracle Corporation

Project Jigsaw & sun.misc.Unsafe

@ JVM Language Summit 2014

JEP 260: Encapsulate Most Internal APIs

§ Replacement exists in JDK 8 –  Encapsulate/remove the method in JDK 9

§ Replacement exists in JDK 9 –  Deprecate in JDK9

§ No replacement exists in JDK 9 –  (For widely used internal API) Leave accessible

Critical Internal APIs

§  sun.misc.Cleaner §  sun.misc.{Signal,SignalHandler} §  sun.misc.Unsafe §  sun.reflect.Reflection::getCallerClass §  sun.reflect.ReflectionFactory

sun.misc.Unsafe

Use case Example methods

Concurrency primitives Unsafe.compareAndSwap*

Serialization Unsafe.allocateInstance (ReflectionFactory.newConstructorForSerialization)

Efficient memory management, layout, and access

Unsafe.allocate/freeMemory Unsafe.get*/put* (and JNI)

Interoperate across the JVM boundary

Unsafe.get*/put* (and JNI)

sun.misc.Unsafe

Use case Replacement

Concurrency primitives JEP 193 Variable Handles

Serialization Reboot JEP 187 Serialization Improvements

Project Panama, Project Valhalla, Arrays 2.0, Better GC

Project Panama, JEP 191 Foreign Function Interface

sun.misc.Unsafe (JDK 9)

Use case Replacement

Concurrency primitives JEP 193 Variable Handles

Serialization Reboot JEP 187 Serialization Improvements

Project Panama, Project Valhalla, Arrays 2.0, Better GC

Project Panama, JEP 191 Foreign Function Interface

JEP 193: Variable Handles

1.  Safe, performant, enhanced atomics –  access to field and array elements

2.  Fence operations for fine-grained control of memory ordering –  replacements for Unsafe::{full,store,load}Fence and more

3.  Reachability fence –  java.lang.ref.Reference::reachabilityFence

Charles Oliver Nutter JRuby Lead Developer

“The most fundamental change to Java since its inception.”

Java 7: Method Handles

Method Handles

(1) Variable Handles

§  like method handles for data –  Abstracts over location

§  static fields, instance fields, arrays, off heap –  Supports explicit fences and atomic operations

§ Safer than Unsafe, as fast as method handles

Are sun.misc.Unsafe methods really fast?

§ Not necessarily… –  public native Object allocateInstance(Class<?> cls) throws …;

–  Array index vs raw offset long[] base = new long[…]; int idx = …; long offset = (((long) idx) << SCALE + OFFSET) long value = Unsafe.getLong(base, offset);

–  JDK-8078629: “VM should constant fold Unsafe.get*() loads from final fields”

(1) Variable Handles

(2) Memory Fences

a = ?, b = ?

Thread #1 Thread #2

(2) Memory Fences

[a,b] = [0,0], [0,1], [1,0], [1,1]

Thread #1 Thread #2

(2) Memory Fences

Thread #1 Thread #2

[a,b] = [0,0], [0,1], [1,0], [1,1]

(3) Finalization

(3) Premature Finalization

Beyond Java 9

Project Valhalla

Project Panama

Specialized Generics Value Types

Foreign Function Interface Data Layout Control Arrays 2.0

Project Valhalla “The hall of valor value”

Value-based Class

final class Point { public final int x; public final int y; }

@since 8

“Use of identity-sensitive operations on instances of value-based classes may have unpredictable effects and should be avoided.”

ValueBased javadoc

Value-based Class

Point[] points =

Arrays

h header

Value-based Class

Point[] points =

Arrays

h header

for (Point p : points) { sum += p.x + p.y; }

Value-based Class

int[] xPoints =

Arrays

h header

assert(xPoints.length == yPoints.length); for (int i = 0; i < xPoints.length; i++) { sum += xPoint[i] + yPoint[i]; }

h header

x x x x x x

y y y y y y int[] yPoints =

Value-based Class

int[] points =

Arrays

h header

assert(points.length % 2 == 0); for (int i = 0; i < points.length; i+=2) { sum += points[i] + points[i+1]; }

x y x y x y x y x y x y

“Codes like a class, works like an int!”

John Rose, Brian Goetz, Guy Steele

“State of the Values”

Value Types Arrays

value class Point { public final int x; public final int y; }

Point[] points = h header x y x y x y x y x y x y

for (Point p : points) { sum += points.x + points.y; }

Motivation

§ Smaller footprint –  no object header

§ Better locality –  no dereference

§ Simpler semantics –  no identity, no aliasing

§ No object allocation

Value Types

value class Point { public final int x; public final int y; } class Rectangle { public final Point corner1; public final Point corner2; }

Concurrent side effects

x xy yh header

Rectangle r =

h header

Rectangle r =

Value Types

value class Point { public final int x; public final int y; } class Rectangle { public Point corner1; public volatile Point corner2; }

Concurrent side effects

x xy yh header

Rectangle r =

h header

Rectangle r =

Use cases

§ Numerics: complex, decimal, rarely-big-num, etc. § Native types: int128_t, vectors, unsigned, safe native pointers § Algebraic data: optional (no box), choice-of, unit (no bits) § Tuples: multiple-value return! (requires specialization machinery also) § Cursors: unboxed iterators, STL-style bounds § Flat data: values naturally represent pointer-poor data structures

Selected details

Point[] <:? Object[]

Selected details

Point[] <: Object[]

Point[] points = h header x y x y x y x y x y x y

Generic Specialization Motivation

ArrayList<Integer>

ArrayList<int>

Objects

§ Object, String, …, MyClass, …, Integer, Long, …

–  8 primitive types (+ reference)

§  boolean, byte, short, char, int, long, float, double

vs Primitives

Objects

§ Object, String, …, MyClass, …, Integer, Long, …

–  8 primitive types (+ reference)

§  boolean, byte, short, char, int, long, float, double

–  Value types

§  User-defined (!!!)

vs Non-objects

ArrayList<Point>

Generic Specialization

class Box<T> { T val; public Box(T val) { this.val = val; } public T get() { return val; } }

class Box<Object> { Object val; public Box(Object val) { this.val = val; } public Object get() { return val; } }

class Box< int> { int val; public Box(int val) { this.val = val; } public int get() { return val; } }

class Box<any T> { T val; public Box(T val) { this.val = val; } public T get() { return val; } }

class Box extends Object { private final Object t; public Object get() { 0: aload_0 1: getfield #2 //Field t:LObject; 4: areturn } }

class Box extends Object { private final int t; public int get() { 0: aload_0 1: getfield #2 //Field t:I; 4: ireturn } }

class Box extends Object { private final Object*T t; public Object*T get() { 0: aload_0 1: getfield #2 //Field t:Lobject*T; 4: areturn*T } }

Box<Integer> :> Box

Box<int> :>? Box

Box<int> :> Box

Box<int> :> Box<?> Box<Object> :> Box<?>

Box :> Box<?>

Project Panama “Bridging the gap”

“If non-Java programmers find some library useful and easy to access, it should be similarly accessible to Java programmers.”

John Rose, JVM Architect,

Oracle Corporation

JNI @since 1.1

A victim of its own success?

JNI Usage scenario

Java: public class GetPid { public static native long getpid(); }

C/C++:

get_pid.h: JNIEXPORT jlong JNICALL Java_GetPid_getpid (JNIEnv *, jclass); get_pid.c: jlong JNICALL Java_GetPidJNI_getpid(JNIEnv *env, jclass c) {

return getpid(); }

JNI: Method Invocation

1.  if (GC_locker::needs_gc()) SharedRuntime::block_for_jni_critical()

2.  transition to thread_in_native 3.  unpack array arguments

4.  call native entry point

Runtime checks before and after native call

1.  call native entry point 2.  check for safepoint in progress

3.  check if any thread suspend flags are set –  call into JVM and possibly unlock the

JNI critical if a GC was suppressed while in the critical native

4.  transition to thread_in_Java

5.  return

Better JNI Easier, safer, faster!

sun.misc.Unsafe § Anti-JNI

Unsafe.getUnsafe().

putInt(new Object(), 0, 0)

Unsafe.getUnsafe().

putInt(null, 0, 0)

Better JNI Easier, safer, faster!

Better JNI

pid_t get_pid();

Better JNI

public interface GetPid { long getpid(); }

Easier

Better JNI

public interface GetPid { long getpid(); } GetPid getpid = Library.load(GetPid.class, “c” /* lib_name */ );

Easier

Better JNI

public interface GetPid { long getpid(); } GetPid getpid = Library.load(GetPid.class, “c” /*lib_name*/ ); getpid.getpid();

Easier

Better JNI Faster

callq 0x1057b2eb0 ; getpid entry

Better JNI gettimeofday

/* time.h */ struct { time_t tv_sec; suseconds_t tv_usec; } timeval;

int gettimeofday(struct timeval* tv, struct timezone* tz);

struct { int tz_minuteswest; int tz_dsttime; } timezone;

Better JNI $ jextract time.h

interface Time { interface Timeval { long tv_sec$get(); void tv_sec$set(long); long tv_usec$get(); void tv_usec$set(long); }

int gettimeofday(Timeval, Timezone);

interface Timezone { long tz_...$get(); void tz_...$set(long); long tz_...$get(); void tz_...$set(long); }

Better JNI Runtime Library lib = Library.create(“c”); Time time = lib.create(Time.class); Timeval tval = lib.create(Timeval.class); Timezone tzone = null; int res = time.gettimeofday(tval, tzone); if (res == 0) { long tv_sec = tval.tv_sec$get(); long tv_usec = tval.tv_usec$get(); }

Better JNI Resources

Timeval tval; try { tval = lib.create(Timeval.class); int res = time.gettimeofday(tval, null); if (res == 0) { long tv_sec = tval.tv_sec$get(); long tv_usec = tval.tv_usec$get(); } } finally { lib.free(tval); tval = null; }

Better JNI Resources

try (Timeval tval = lib.create(Timeval.class)) { int res = time.gettimeofday(tval, null); if (res == 0) { long tv_sec = tval.tv_sec$get(); long tv_usec = tval.tv_usec$get(); } }

Better JNI

§ no crashes § no leaks § no hangs § no privilege escalation § no unguarded casts

Better JNI

Project Valhalla

Project Panama

Specialized Generics Value Types

Foreign Function Interface Data Layout Control Arrays 2.0

Project Valhalla

valhalla-‐dev@openjdk.java.net http://hg.openjdk.java.net/valhalla/valhalla

Project Panama panama-‐dev@openjdk.java.net http://hg.openjdk.java.net/panama/panama

1995 2015

Safe Harbor Statement

The following is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle.

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