Владимир Иванов (Oracle): Java: прошлое и будущее

1
Copyright © 2015, Oracle and/or its affiliates. All rights reserved
20 years of Java
Vladimir Ivanov
HotSpot JVM Compiler
Oracle Corp.
Twitter: @iwan0www
OpenJDK: vlivanov
28.11.2015

2
20 years of Java (The Platform)
Vladimir Ivanov
HotSpot JVM Compiler
Oracle Corp.
Twitter: @iwan0www
OpenJDK: vlivanov

3
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.

4
About me
1996 2002 2010 20152005
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

5
1991: Project Green

6
1991: *7 (StarSeven)
Oak programming language

7
1991: *7 (StarSeven)
Duke

8
1994: WebRunner/HotJava browser

9
1995: First release: 1.0a2

10
Intel Pentium
P54CS, 0.35µm, 200MHz, 66MHz FSB

11
Sun Enterprise 10000
64 UltraSPARC II CPUs, 400 MHz, 16x4GB RAM

12
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

13
1996: picoJava

14
1997: JDK 1.1
February, 19

15
1998: J2SE 1.2
December, 8

16
1999: J2SE, J2ME, J2EE

17
1999: J2SE, J2ME, J2EE

18
2000: J2SE 1.3
May, 8

19
1998: JCP

20
2002
February, 6

21
First release
1995 1997 2002
Java Releases
1996 1998
JDK 1.0
JDK 1.1
J2SE 1.2
2000
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
March
AWT
Network
I/O

22
2004: J2SE 5.0
September, 30

23
2004: J2SE 5.0
September, 30

24
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

25
Java SE 6u
§  Escape analysis in C2
–  6u23
§  NUMA GC Enhancements
–  Java SE 6u2
§  Compressed OOPs
–  6u23
§  Tiered compilation
HotSpot Express

26
2007
May, 8

27
2007: May
JavaFX 1.0 on December, 2008

28

29
2010

30
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

31
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

32
2014: Java SE 8
March, 18

33
2016: Java SE 9
ETA: September, 22
Project
Jigsaw

Scalability

Performance

Security

http://openjdk.java.net

34
Project Jigsaw
Scalability

35
Java 8
4 Copyright © 2014, Oracle and/or its afﬁliates. All rights reserved.
auth
jdbc
jaxpnaming
jaxws
compiler
rowset
xmldsig
crypto
corba
desktop
tools.jre
httpserver
tools
tools.jaxws tools.base
devtools
javafx
prefssctp jx.annotations
instrument
54MB 30 16 11 nashorn
rmi
compact1
JRE
compact3
compact2
JDK

36
naming.rmi

base

charsets

se

compact3

compact2

compact1

logging
scrip:ng

security.acl

security.sasl

sql

rmi

xml
xml.crypto

prefs
desktop

ac:va:on

corba

compiler
management

sql.rowset

security.jgss

instrument

naming

xml.ws

xml.soap

xml.bind

annota:ons.common

hBpserver

rmic

javadoc

xml.ws

xml.bind

compiler

hotspot.agent

jconsole
jcmd
jdi

aBach

jvmstat

naming

smartcardio

crypto.ec

crypto.pkcs11

hprof.agent

jdwp.agent

localedata

sctp

zipfs

security.auth

scripting.
nashorn
Project Jigsaw
Performance

37
Project Jigsaw
tls
logging
auth
jdbc
jta
jaxpnaming
jaxws
compiler
rowset
kerberos
management
xmldsig
crypto
cosnaming
management.iiop
corba
desktop
tools.jre
httpserver
tools
devtools
javafx
nashorn
instrument base
script
rmi

38
Project Jigsaw
tls
logging
auth
jdbc
jta
jaxpnaming
jaxws
compiler
rowset
kerberos
management
xmldsig
crypto
cosnaming
management.iiop
corba
desktop
tools.jre
httpserver
tools
devtools
javafx
nashorn
instrument base
script
rmi

39
Project Jigsaw
tls
logging
auth
jdbc
jta
jaxpnaming
jaxws
compiler
rowset
kerberos
management
xmldsig
crypto
cosnaming
management.iiop
corba
desktop
tools.jre
httpserver
tools
devtools
javafx
nashorn
instrument base
script
rmi

40
Project Jigsaw
crypto
javafx
nashorn
base
script

41
jlink
*.jmod
$JRE/bin/java
/ l i b / . . .
*.jar
*.class
JVM image
. j a r
.jmod
Fat binary

42
Project Jigsaw
Opportunities for performance improvements
rt.jar
nashorn.jar, jfxrt.jar,
sunjce_provider.jar
myapp.jar
crypto
javafx
nashorn
base
script

43
Project Jigsaw
§  Improved class loading architecture
–  fast class lookup
crypto
javafx
nashorn
base
script

44
Project Jigsaw
crypto
javafx
nashorn
base
script

45
Project Jigsaw
§  Aggressive inlining
crypto
javafx
nashorn
base
script

46
Project Jigsaw
§  Ahead-Of-Time compilation
crypto
javafx
nashorn
base
script

47
Project Jigsaw
§  JVM-specific memory images
–  e.g. Application Class Data Sharing (AppCDS)
crypto
javafx
nashorn
base
script

48
Project Jigsaw
§  JVM-specific memory images
–  e.g. Application Class Data Sharing (AppCDS)
§  Removal of unused fields/methods/classes
crypto
javafx
nashorn
base
script

49
sun.*
*.internal.*
Project Jigsaw
Security

50
sun.misc.Unsafe?!
Project Jigsaw
Security

51
- How many of you have used the Unsafe API?
…
John Rose
JVM Architect, Oracle Corporation
Project Jigsaw & sun.misc.Unsafe
@ JVM Language Summit 2014

52
- 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

53

54
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

55
Critical Internal APIs
§  sun.misc.Cleaner
§  sun.misc.{Signal,SignalHandler}
§  sun.misc.Unsafe
§  sun.reflect.Reflection::getCallerClass
§  sun.reflect.ReflectionFactory

56
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)

57
sun.misc.Unsafe
Use case Replacement
Concurrency primitives JEP 193 Variable Handles
Serialization
Reboot JEP 187 Serialization
Improvements
layout, and access
Project Panama, Project Valhalla,
Arrays 2.0, Better GC
boundary
Project Panama,
JEP 191 Foreign Function Interface

58
sun.misc.Unsafe (JDK 9)
Use case Replacement
Concurrency primitives JEP 193 Variable Handles
Serialization
Reboot JEP 187 Serialization
Improvements
layout, and access
Project Panama, Project Valhalla,
Arrays 2.0, Better GC
boundary
Project Panama,
JEP 191 Foreign Function Interface

59

60
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

61
Charles Oliver Nutter
JRuby Lead Developer
“The most fundamental change to Java since its
inception.”
Java 7: Method Handles

62
Method Handles

63
(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

64
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”

65
(1) Variable Handles

66
(2) Memory Fences
a = ?, b = ?
Thread #1 Thread #2

67
(2) Memory Fences
[a,b] = [0,0], [0,1], [1,0], [1,1]
Thread #1 Thread #2

68
(2) Memory Fences
Thread #1 Thread #2
[a,b] = [0,0], [0,1], [1,0], [1,1]

69
(3) Finalization

70
(3) Premature Finalization

71
(3) Premature Finalization

72
Beyond Java 9

73
Project Valhalla
Project Panama
Specialized Generics
Value Types
Foreign Function Interface
Data Layout Control
Arrays 2.0

74
Project Valhalla
“The hall of valor value”

75
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

76
Value-based Class
Point[] points =
Arrays
hheader
x y
x y
x y
x y
x y
x y

77
Value-based Class
Point[] points =
Arrays
hheader
x y
x y
x y
x y
x y
x y
for
(Point
p
:
points)
{

sum
+=
p.x
+
p.y;

}

78
Value-based Class
int[]
xPoints
=

Arrays
hheader
assert(xPoints.length
==
yPoints.length);

for
(int
i
=
0;
i
<
xPoints.length;
i++)
{

sum
+=
xPoint[i]
+
yPoint[i];

}

hheader
x x x x x x
y y y y y yint[]
yPoints
=

79
Value-based Class
int[]
points
=

Arrays
hheader
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

80
“Codes like a class, works like an int!”
John Rose, Brian Goetz, Guy Steele
“State of the Values”

81
Value Types
Arrays
value
class
Point
{

public
final
int
x;

public
final
int
y;

}

Point[]
points
=
hheader x y x y x y x y x y x y
for
(Point
p
:
points)
{

sum
+=
points.x
+
points.y;

}

82
Motivation
§  Smaller footprint
–  no object header
§  Better locality
–  no dereference
§  Simpler semantics
–  no identity, no aliasing
§  No object allocation
Value Types

83
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 yhheader

Rectangle
r
=

x y
x y
hheader

Rectangle
r
=

84
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 yhheader

Rectangle
r
=

x y
x y
hheader

Rectangle
r
=

85
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

86
Selected details
Point[] <:? Object[]

87
Selected details
Point[] <: Object[]
Point[]
points
=
hheader x y x y x y x y x y x y

88
Generic Specialization
Motivation
ArrayList<Integer>

89
Motivation
ArrayList<int>

90
Objects
§  Object, String, …, MyClass, …,
Integer, Long, …
–  8 primitive types (+ reference)
§  boolean, byte, short, char, int, long,
float, double
vs Primitives

91
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

92
Motivation
ArrayList<Point>

93
class
Box<T>

{

T

val;

public
Box(T

val)
{
this.val
=
val;
}

public
T

get()

{
return
val;
}

}

94
class
Box<T>

{

T

val;

public
Box(T

val)
{
this.val
=
val;
}

public
T

get()

{
return
val;
}

}

95
class
Box<Object>

{

Object
val;

public
Box(Object
val)
{
this.val
=
val;
}

public
Object
get()

{
return
val;
}

}

96
class
Box<

int>

{

int

val;

public
Box(int

val)
{
this.val
=
val;
}

public
int

get()

{
return
val;
}

}

97
class
Box<any
T>

{

T

val;

public
Box(T

val)
{
this.val
=
val;
}

public
T

get()

{
return
val;
}

}

98
class
Box
extends
Object
{

private
final
Object
t;

public
Object
get()
{

0:
aload_0

1:
getfield
#2
//Field
t:LObject;

4:
areturn

}

}

99
class
Box
extends
Object
{

private
final

int
t;

public

int
get()
{

0:
aload_0

1:
getfield
#2
//Field
t:I;

4:
ireturn

}

}

100
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

}

}

101
Box<Integer> :> Box

102
Box<int> :>? Box

103
Box<int> :> Box
Box<int> :> Box<?>
Box<Object> :> Box<?>
Box :> Box<?>

104
Project Panama
“Bridging the gap”

105
“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

106
JNI
@since 1.1

107
JNI
A victim of its own success?

108
JNI
Usage scenario

109
JNI
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();
}

110
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

111
Better JNI
Easier, safer, faster!

112
sun.misc.Unsafe
§ Anti-JNI

113
Unsafe.getUnsafe().
putInt(new Object(), 0, 0)

114
Unsafe.getUnsafe().
putInt(null, 0, 0)

115
Better JNI
Easier, safer, faster!

116
Better JNI
pid_t get_pid();

117
Better JNI
public
interface
GetPid
{

long
getpid();

}

Easier

118
Better JNI
public
interface
GetPid
{

long
getpid();

}

GetPid
getpid
=
Library.load(GetPid.class,
“c”
/*
lib_name
*/
);

Easier

119
Better JNI
public
interface
GetPid
{

long
getpid();

}

GetPid
getpid
=
Library.load(GetPid.class,
“c”
/*lib_name*/
);

getpid.getpid();

Easier

120
Better JNI
Faster
callq 0x1057b2eb0 ; getpid entry

121
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;

122
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);

}

123
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();

}

124
Better JNI
Resources
Timeval
tval;

try
{

tval
=
lib.create(Timeval.class);

int
res
=
null);

if
(res
==
0)
{

long
tv_sec

=
tval.tv_sec$get();

long
tv_usec
=
tval.tv_usec$get();

}

}
finally
{

lib.free(tval);

tval
=
null;

}

125
Better JNI
Resources
try
(Timeval
tval
=
lib.create(Timeval.class))
{

int
res
=
null);

if
(res
==
0)
{

long
tv_sec

=
tval.tv_sec$get();

long
tv_usec
=
tval.tv_usec$get();

}

}

126
Better JNI
§  no crashes
§  no leaks
§  no hangs
§  no privilege escalation
§  no unguarded casts
Safer

127
Better JNI

128
Project Valhalla

Project Panama
Specialized Generics
Value Types
Foreign Function Interface
Data Layout Control
Arrays 2.0

129
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

130
Duke
1995 2015

131

132
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.

133
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Владимир Иванов (Oracle): Java: прошлое и будущее

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