Presented at JAX London 2013
Worried about the future of Java? Want to see it keep moving forward? Don't be concerned. The transformation of Java is already underway. Driven by new technologies and new opportunities Java and the JVM are entering uncharted worlds and challenging old approaches. In this session learn about one such expedition in the form of an introductory talk to technology being developed by IBM. This experimental technology is exploring a new way to share data between the JVM and other runtimes.
2. Important Disclaimers
THE INFORMATION CONTAINED IN THIS PRESENTATION IS PROVIDED FOR
INFORMATIONAL PURPOSES ONLY.
WHILST EFFORTS WERE MADE TO VERIFY THE COMPLETENESS AND ACCURACY OF THE
INFORMATION CONTAINED IN THIS PRESENTATION, IT IS PROVIDED “AS IS”, WITHOUT
WARRANTY OF ANY KIND, EXPRESS OR IMPLIED.
ALL PERFORMANCE DATA INCLUDED IN THIS PRESENTATION HAVE BEEN GATHERED IN A
CONTROLLED ENVIRONMENT. YOUR OWN TEST RESULTS MAY VARY BASED ON
HARDWARE, SOFTWARE OR INFRASTRUCTURE DIFFERENCES.
ALL DATA INCLUDED IN THIS PRESENTATION ARE MEANT TO BE USED ONLY AS A GUIDE.
IN ADDITION, THE INFORMATION CONTAINED IN THIS PRESENTATION IS BASED ON IBM’S
CURRENT PRODUCT PLANS AND STRATEGY, WHICH ARE SUBJECT TO CHANGE BY IBM,
WITHOUT NOTICE.
IBM AND ITS AFFILIATED COMPANIES SHALL NOT BE RESPONSIBLE FOR ANY DAMAGES
ARISING OUT OF THE USE OF, OR OTHERWISE RELATED TO, THIS PRESENTATION OR
ANY OTHER DOCUMENTATION.
NOTHING CONTAINED IN THIS PRESENTATION IS INTENDED TO, OR SHALL HAVE THE
EFFECT OF:
- CREATING ANY WARRANT OR REPRESENTATION FROM IBM, ITS AFFILIATED
COMPANIES OR ITS OR THEIR SUPPLIERS AND/OR LICENSORS
3. Steve Poole
!
Works at IBM’s Hursley Laboratory in the UK
Involved in IBM Java VM development since before Java was 1
Currently leading IBM’s OpenJDK technical engagement
4. What this talk is about
“Packed Objects”
aka
“Compact Off-Heap Structures in the Java Language”
!
This technology is being developed to help address
important pressures on Java
!
This talk focuses on how to improve Java interop to Non
Java applications
5. You’ll learn
“Compact Off-Heap Structures in the Java Language”
1. An overview of this technology
2. Why we need your input and support
3. How to get started with using this technology yourself
7. Interoperability - why is it important?
Java is built on talking native
!
Operating Systems
Processor Architectures
File Systems
User interfaces
Network Interfaces
!
Java keeps the WORA
monsters away
!
!
8. WORA - the components
JDK Java code
JVM
JIT
native
Class Library
Native code
Your JNI code
Your Java application
9. 2013 - Not so Java-centric
JVM
JIT
Class
Library
native
Your Native code
JDK Java code
Your JNI code
Your Java application
10. 2013 - clusters and new processors
non Java
Runtime
High speed memory channels (RDMA etc)
Specialised Processors (GPUs etc)
11. 2013 - Can we survive with JNI 1.1?
JIT
?
Other runtime
JVM
Class
Library
Your Native code
JDK Java code
Your JNI code
Your Java application
native
High speed memory channels (RDMA etc)
Specialised Processors (GPUs etc)
?
?
12. 2013 - we can’t survive with JNI 1.1
• 1997 - JNI 1.1
• Designed for independence
• Version independence
• Platform Independence
• VM Independence
• Java at the centre of the world
• Not performance focused
13. Packed Objects to the rescue
• What we need is
• To be able to share data between Java and
other runtimes with minimal overhead
• To not require a Java centric data view
• and share data off-heap too!
• Can we do that?
• Time for a demo.
15. A simple demo
Draw 100 000 random sized rectangles using SDL
!
Move them around the screen and get them to change direction if they hit the
sides
!
RGB colour elements
!
typedef struct {
int red,green,blue;
float vx,vy;
SDL_Rect rec;
float x,y;
!
} RECT;
!15
position adjustment
vectors
SDL structure contains
location , height and
width
float version of location - makes
it easier to handle different h/w
speeds
16. A simple demo
Draw 100 000 random sized rectangles using SDL
!
Move them around the screen and get them to change direction if they hit the
sides
!
Initialise
Per frame
Update rectangle locations
Draw rectangles with SDL
terminate
!16
17. More than one demo
Demo
Standard - all C code calling the
SDL graphics routines
Mixed C and JNI. Java updates
the location of each element
Mixed C with PackedObjects Java updates the location of
each element
!17
Frames per second
number of JNI calls
per frame
18. Demo 1 - all C
Draw 100 000 random sized rectangles using SDL
!
Move them around the screen and get them to change direction if they hit the
sides
!
Initialise
Per frame
Update rectangle locations
Draw rectangles with SDL
terminate
!18
19. Results
Demo
Standard - all C code calling the
SDL graphics routines
Mixed C and JNI. Java updates
the location of each element
Mixed C with PackedObjects Java updates the location of
each element
!19
Frames per second
20
number of JNI calls
per frame
0
20. Demo 2- Mixed JNI and C
Draw 100 000 random sized rectangles using SDL
!
Move them around the screen and get them to change direction if they hit the
sides
!
Initialise
Per frame
Update rectangle locations
Draw rectangles with SDL
terminate
!20
21. Results
Demo
Standard - all C code calling the
SDL graphics routines
Mixed C and JNI. Java updates
the location of each element
Mixed C with PackedObjects Java updates the location of
each element
!21
Frames per second
20
number of JNI calls
per frame
0
22. er frame)
Results
Demo
Frames per second
Standard - all C code calling the
SDL graphics routines
20
Mixed C and JNI. Java updates
the location of each element
11
number of JNI calls
per frame
0
200000
(~4MB per frame)
Mixed C with PackedObjects Java updates the location of
each element
200 000 JNI calls per frame.
Copying data, validating data everytime.
AND ensuring there is no chance of
optimization by the JIT.
!22
23. Demo 2- Details
Draw 100 000 random sized rectangles using SDL
!
Move them around the screen and get them to change direction if they hit the
sides
!
Initialise
Per frame
Update rectangle locations
Draw rectangles with SDL
terminate
!23
24. Demo 2- Details
Draw 100 000 random sized rectangles using SDL
!
Move them around the screen and get them to change direction if they hit the
sides
!
for every rectangle…
C function calls Java method via JNI
passes in x,y, vx and vy (by copy)
Java method updates the rectangles new position
Java native calls native method passing in
new x,y, vx and vy values (by copy)
C native method returns
Java method returns
C function returns
!24
25. Demo 3 - Packed Objects
Draw 100 000 random sized rectangles using SDL
!
Move them around the screen and get them to change direction if they hit the
sides
!
Initialise
Per frame
Update rectangle locations
Draw rectangles with SDL
terminate
!25
26. er frame)
Results
Demo
Frames per second
Standard - all C code calling the
SDL graphics routines
20
Mixed C and JNI. Java updates
the location of each element
11
Mixed C with PackedObjects Java updates the location of
each element
!26
number of JNI calls
per frame
0
200000
(~4MB per frame)
27. er frame)
Results
Demo
Frames per second
number of JNI calls
per frame
Standard - all C code calling the
SDL graphics routines
Mixed C and JNI. Java updates
the location of each element
11
200000
(~4MB per frame)
Mixed C with PackedObjects Java updates the location of
each element
!27
20
18
1
(4 bytes per frame)
0
28. Demo 3 - Packed Objects
Draw 100 000 random sized rectangles using SDL
!
Move them around the screen and get them to change direction if they hit the
sides
!
Initialise
Per frame
Update rectangle locations
Draw rectangles with SDL
terminate
!28
29. Demo 3 - Packed Objects
Draw 100 000 random sized rectangles using SDL
!
Move them around the screen and get them to change direction if they hit the
sides
!
once per frame..
Java method updates each rectangle’s position directly
!
}
!29
for(Rectangle r: rectangles) {
r.x=r.x+r.vx;
r.y=r.y+r.vy;
…
30. Today Java only speaks Java
• Getting data into and out of Java has always required some form of marshaling or
serialization process
!
• Interaction with native data structures in memory is particularly problematic
• JNI is the slowest but safest
– But you need good C / C++ knowledge
• Unsafe and NIO are faster but more challenging to use
– They both have their own programming ‘model’
• If the Java side is in control of storage layouts it’s easier
• When mapping existing native structures it’s much, much, much more difficult
!
• Ironically the JVM is completely aware of native data formats
31. Tomorrow, with Packed Objects..
Java will let you reference data stored like this
!
typedef struct {
int red,green,blue;
float vx,vy;
SDL_Rect rec;
float x,y;
!
} RECT;
C structure
32. Tomorrow, with Packed Objects..
as if it looked like this
!
!
typedef struct {
public class Rectangle {
!
int red,green,blue;
float vx,vy;
SDL_Rect rec;
float x,y;
!
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
!
} RECT;
C structure
}
Java structure
33. Tomorrow, with Packed Objects..
!
!
typedef struct {
public class Rectangle {
!
int red,green,blue;
float vx,vy;
SDL_Rect rec;
float x,y;
!
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
without
copying
!
} RECT;
C structure
}
Java structure
34. Tomorrow, with Packed Objects..
!
!!
! typedef struct {
!
int red,green,blue;
!
float vx,vy;
!
SDL_Rect rec;
!
float x,y;
!!
! } RECT;
!
!
‘C’ runtime
And off
!
!
!
public class Rectangle {
!
!
!
int red,green,blue;
!
float vx,xy;
!
heap SDLRect rec;
!
float x,y;
!
!
!
}
!
!
Java heap
36. Under the covers
!
public class Rectangle {
Let’s look at these
classes from a JVM
point of view..
!
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
!
}
public class SDLRect {
short x,y
int width,height
}
37. Under the covers
!
!
!
!
!
!
!
!
!
!
!
int red
int green
int blue
float vx
float vy
SLDRect ptr
float x
float y
Java heap
!
public class Rectangle {
!
short x
short y
int width
int height
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
!
}
public class SDLRect {
short x,y
int width,height
}
Java structure
!37
J
38. !
!
!
!
!
!
!
!
!
!
!
Questions
!
int red
int green
int blue
float vx
float vy
SLDRect ptr
float x
float y
Java heap
!38
1 - How does a JVM ‘know’
the class of these objects?
!
!
short x
short y
int width
int height
2 - What are the data format
rules for these types?
!
!
3 - When synchonizing on a
object - where is the monitor
stored?
39. !
!
!
!
!
!
!
!
!
!
!
int red
int green
int blue
float vx
float vy
SLDRect ptr
float x
float y
Java heap
!39
Answers
class ptr
monitor
!
class ptr
monitor
short x
short y
int width
int height
1 - How does a JVM ‘know’
the class of these objects?
Additional internal ptr
!
2 - What are the data format
rules for these types?
JVM impl specific (including
ordering)
3 - When synchonizing on a
object - where is the monitor
stored?
Additional internal field
40. How to add the metadata
!
!
!
!
!
!
!
!
!
!
!
class ptr
monitor
int red
int green
int blue
float vx
float vy
SLDRect ptr
float x
float y
Java heap
!40
class ptr
monitor
short x
short y
int width
int height
!
!
!
!
!
!
!
!
!
!
!
[4] red
[4] green
[4] blue
[4] vx
[4] vy
[2] rect.x
[2] rect.y
[4] rect.width
[4] rect.height
[4] x
[4] y
‘C’ runtime
No space
No space
for the extra
for the extra
Java fields -Java fields
what do we
what do we
do?
do?
41. Under the covers
!
!
!
!
!
!
!
!
!
!
!
Java heap
!41
!
!
!
!
!
!
!
!
!
!
!
public class Rectangle {
[4] red
[4] green
[4] blue
[4] vx
[4] vy
[2] rect.x
[2] rect.y
[4] rect.width
[4] rect.height
[4] x
[4] y
‘C’ runtime
!
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
}
public class SDLRect {
short x,y
int width,height
}
42. Under the covers
!
!
!
!
!
!
!
!
!
!
!
Java heap
!
!
!
!
!
!
!
!
!
!
!
public class Rectangle {
[4] red
[4] green
[4] blue
[4] vx
[4] vy
[2] rect.x
[2] rect.y
[4] rect.width
[4] rect.height
[4] x
[4] y
‘C’ runtime
!
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
}
public class SDLRect {
short x,y
int width,height
}
Rectangle r=PackedObject.newNativePackedObject(Rectangle.class,0x******);
!42
43. Under the covers
!
!
!
!
!
!
!
!
!
!
!
class ptr
monitor
data ptr
“r”
Java heap
!43
!
!
!
!
!
!
Constructor
!
was not !
called!
!
!
!
public class Rectangle {
[4] red
[4] green
[4] blue
[4] vx
[4] vy
[2] rect.x
[2] rect.y
[4] rect.width
[4] rect.height
[4] x
[4] y
‘C’ runtime
!
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
}
public class SDLRect {
short x,y
int width,height
}
44. Rectangle r=PackedObject.newNativePackedObject(Rectangle.class,0x******);
Under the covers
!
!
!
!
!
!
!
!
!
!
!
class ptr
monitor
data ptr
“r”
Java heap
SDLRect s=r.rect;
!
!44
!
!
!
!
!
!
!
!
!
!
!
public class Rectangle {
[4] red
[4] green
[4] blue
[4] vx
[4] vy
[2] rect.x
[2] rect.y
[4] rect.width
[4] rect.height
[4] x
[4] y
‘C’ runtime
!
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
}
public class SDLRect {
short x,y
int width,height
}
45. Rectangle r=PackedObject.newNativePackedObject(Rectangle.class,0x******);
Under the covers
!
!
!
!
!
!
!
!
!
!
!
class ptr
monitor
data ptr
“r”
“s”
class ptr
monitor
data ptr
Java heap
SDLRect s=r.rect;
!
!45
!
!
!
!
!
!
!
!
!
!
!
public class Rectangle {
[4] red
[4] green
[4] blue
[4] vx
[4] vy
[2] rect.x
[2] rect.y
[4] rect.width
[4] rect.height
[4] x
[4] y
‘C’ runtime
!
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
}
public class SDLRect {
short x,y
int width,height
}
46. Rectangle r=PackedObject.newNativePackedObject(Rectangle.class,0x******);
Under the covers
!
!
!
!
!
!
!
!
!
!
!
class ptr
monitor
data ptr
“r”
“s”
class ptr
monitor
data ptr
Java heap
SDLRect s=r.rect;
SDLRect t=r.rect;
!46
!
!
!
!
!
!
!
!
!
!
!
public class Rectangle {
[4] red
[4] green
[4] blue
[4] vx
[4] vy
[2] rect.x
[2] rect.y
[4] rect.width
[4] rect.height
[4] x
[4] y
‘C’ runtime
!
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
}
public class SDLRect {
short x,y
int width,height
}
47. Rectangle r=PackedObject.newNativePackedObject(Rectangle.class,0x******);
Under the covers
!
!
!
!
!
!
!
!
!
!
!
class ptr
monitor
data ptr
“r”
“s”
class ptr
monitor
data ptr
“t”
class ptr
monitor
data ptr
Java heap
SDLRect s=r.rect;
SDLRect t=r.rect;
!47
!
!
!
!
!
!
!
!
!
!
!
public class Rectangle {
[4] red
[4] green
[4] blue
[4] vx
[4] vy
[2] rect.x
[2] rect.y
[4] rect.width
[4] rect.height
[4] x
[4] y
‘C’ runtime
!
int red,green,blue;
float vx,xy;
SDLRect rec;
float x,y;
}
public class SDLRect {
short x,y
int width,height
}
49. Design considerations
• Off heap Packed Objects are considered to already exist so
constructors are not called.
• Since there is limited opportunity to store the vital metadata it is
constructed when needed.
• The assumption is that creating new objects when accessing
embedded data is confusing and dangerous.
• How does ‘==‘ work?
• What about synchronization?
• The idea of ‘identityless’ objects is being discussed.
• Something that PackedObjects has in common with ValueTypes
• Could you handle Objects of this style?
50. The way forward?
• This approach offers Java a way forward in the multi
environment world
• Almost zero cost data interop will benefit Java when
exploiting new processors and memory systems.
• There are additional use cases that ‘fall out’ from this design.
• Low cost r/w of files
• Instant application startup
• Basic unmanaged memory capabilities
• Under the covers heap usage benefits through better
control for ‘locality of reference’
51. Is this the right or only way?
• IBM and Oracle have been discussing these
sorts of concepts for some time
• We need your input. How important are
these use cases to you? What’s missing, not
needed? What do you hate?
• We are trying to keep clear of syntax
discussions at this point - it’s too early and just
distracting.
52. You too can use Packed Objects
• Google for “IBM Java 8 Beta”
53. Hard hats must be worn…
The current prototype implementation surfaces a lot of the
internals that will eventually just disappear
This approach makes it easier
for us to quickly revise the
design but means users of the
prototype have to work harder.
!
AND
!
it avoids syntax wars :-)
picture courtesy http://www.flickr.com/people/karen_od/
54. Wrap up -hopefully you now:
“Compact Off-Heap Structures in the Java Language”
1. Have a basic understanding of this technology
2. Know why we need your input and support
3. Know how to get started with using this technology
Thank You