1. JICOS A Java-Centric Distributed Computing Service
Computer Science Department
UC Santa Barbara

2. Introduction Project Goals
Minimize job completion time
despite large communication latency

3. Introduction Project Goals
Minimize job completion time
despite large communication latency
Jobs complete with high probability
despite faulty components

4. Introduction Project Goals
Minimize job completion time
despite large communication latency
Jobs complete with high probability
despite faulty components
Application program is oblivious to:
Number of processors
Inter-process communication
Hardware faults

5. Introduction Fundamental Issue: Heterogeneity…
OS1
OS2
OS3
OS4
OS5 M1 M2 M3 M4 M5
Heterogeneous
machine/OS
Functionally
Homogeneous
JVM 

6. JICOS Attributes Heterogeneous hardware & OS Easy to program
Fault tolerant compute servers (hosts)
Adaptively parallel
Small-grain parallel computation

7. Overview Computational model API Architecture Performance
Benefit summary
Plans

8. Computational Model DAC task graph
f(4)
f(3)
f(2)
f(2)
f(1)
f(1)
f(0)
f(1)
f(0) + + + +

9. Computational Model Embedded in an Environment
Read/Write shared object
f(4)
Read input object
f(3)
f(2)
f(2)
f(1)
f(1)
f(0)
f(1)
f(0) + + + +

10. Overview Computational model API Architecture Performance
Benefit summary
Plans

11. API
f(3)
f(2) +
f(1)
f(0)
f(4)
2 task classes: F
Sum

12. API f(4) public class F extends Task { private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(4)

13. API + f(4) f(3) f(2) public class F extends Task { private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(4)
f(3)
f(2) +

14. API + + f(3) f(2) f(2) f(1) public class F extends Task {
private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(3)
f(2)
f(2)
f(1) + +

15. API + + + f(2) f(2) f(1) f(1) f(0) public class F extends Task {
private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(2)
f(2)
f(1)
f(1)
f(0) + + +

16. API + + + + f(2) f(1) f(1) f(0) f(1) f(0)
public class F extends Task {
private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(2)
f(1)
f(1)
f(0)
f(1)
f(0) + + + +

17. API + + + + f(1) f(1) f(0) f(1) f(0) public class F extends Task {
private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(1)
f(1)
f(0)
f(1)
f(0) + + + +

18. API + + + + f(1) f(0) f(1) f(0) public class F extends Task {
private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(1)
f(0)
f(1)
f(0) + + + +

19. API + + + + f(0) f(1) f(0) public class F extends Task {
private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(0)
f(1)
f(0) + + + +

20. API + + + + f(1) f(0) public class Sum extends Task {
public Object execute(Env e) {
Integer I = ((Integer) getInput(0));
Integer J = ((Integer) getInput(1));
int sum = I.intValue() + J.intValue();
return new Integer( sum ); }
f(1)
f(0) + + + +

21. API + + + f(1) f(0) public class F extends Task { private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(1)
f(0) + + +

22. API + + + f(0) public class F extends Task { private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(0) + + +

23. API + + + public class Sum extends Task {
public Object execute(Env e) {
Integer I = ((Integer) getInput(0));
Integer J = ((Integer) getInput(1));
int sum = I.intValue() + J.intValue();
return new Integer( sum ); } + + +

24. API + + public class Sum extends Task { public Object execute(Env e) {
Integer I = ((Integer) getInput(0));
Integer J = ((Integer) getInput(1));
int sum = I.intValue() + J.intValue();
return new Integer( sum ); } + +

25. API + public class Sum extends Task { public Object execute(Env e) {
Integer I = ((Integer) getInput(0));
Integer J = ((Integer) getInput(1));
int sum = I.intValue() + J.intValue();
return new Integer( sum ); } +

26. API recap + + + + f(4) f(3) f(2) f(2) f(1) f(1) f(0) f(1) f(0)
public class F extends Task {
private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(4)
f(3)
f(2)
f(2)
f(1)
f(1)
f(0)
f(1)
f(0) + + + +

27. API recap + + + + f(4) f(3) f(2) f(2) f(1) f(1) f(0) f(1) f(0)
public class F extends Task {
private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(4)
f(3)
f(2)
f(2)
f(1)
f(1)
f(0)
f(1)
f(0) + + + +

28. API recap + + + + f(4) f(3) f(2) f(2) f(1) f(1) f(0) f(1) f(0)
public class F extends Task {
private int n;
public F(int n) { this.n = n; }
public Object execute(Env e) {
if ( n < 2 ) {
return new Integer( 1 );
else {
compute( new F( n-1 ) );
compute( new F( n-2 ) );
return new Sum(); }
f(4)
f(3)
f(2)
f(2)
f(1)
f(1)
f(0)
f(1)
f(0) + + + +

29. API recap + + + + f(4) f(3) f(2) f(2) f(1) f(1) f(0) f(1) f(0)
public class Sum extends Task {
public Object execute(Env e) {
int i = ((Integer) getInput(0));
int j = ((Integer) getInput(1));
return new Integer( I + j ); }
f(4)
f(3)
f(2)
f(2)
f(1)
f(1)
f(0)
f(1)
f(0) + + + +

30. Overview Computational model API Architecture Performance
Benefit summary
Plans

31. Architecture Goals Virtualize compute cycles
Store/coordinate partial results
Self-organizing
Independent of hardware/OS
Scale from LAN to Internet

32. Architecture … JICOS has 3 service component classes:
Hosting Service Provider (HSP):
clients interact solely with the HSP.
HSP manages other service components
Task server
A task space
Host
Executes tasks

33. Architecture …
Hosting
Service
Provider
Client

34. Architecture …
Adaptive parallelism
HSP
CLIENT

35. Architecture …
Tolerates faulty Hosts
HSP
CLIENT

36. Architecture Latency hiding/reduction1
Task caching
Task pre-fetch
Task server computation 2 5 3 8 6 7 4 9 10 11 12 13

37. Architecture Latency hiding/reduction1
Task caching 2 5 3 8 6 7 4 9 10 11 12 13

38. Architecture Latency hiding/reduction1
Task caching
Task pre-fetch
Issues pre-fetch 2 5 3 8 6 7 4 9 10 11 12 13

39. Architecture Latency hiding/reduction1
Root task
Task is cached
Task issues pre-fetch
Task is pre-fetched 2 5 3 8 6 7 4 9 10 11 12 13

40. Architecture Latency hiding/reduction1
Task caching
Task pre-fetch
Issues pre-fetch
Is pre-fetched
Task server computation 2 5 3 8 6 7 4 9 10 11 12 13

41. Overview Computational model API Architecture Performance
Benefit summary
Plans

42. JICOS Speedup:150-City TSP
1 processor: 6 hours, 18 minutes
52 processors: 8 minutes
16K Tasks, average task time: 1.5 seconds

43. Overview Computational model API Architecture Performance
Benefit summary
Plans

44. Benefit Summary API is easy to use Heterogeneous hardware & OS
Adaptive parallelism
Tolerates faulty hosts
Hides/reduces communication latency
Small-grain parallel computation

45. Overview Computational model API Architecture Performance
Benefit summary
Plans

46. Possible Projects Application as a Service
Non-Java
Program
Non-Java Interface
Jicos application
as web service:
allows non-Java programs to “use” Jicos.
XML-encoded TSP instance
WEB
SERVER
TSP
JAVA
JICOS

47. Possible Project Application Servers
SAT
TSP
JICOS ?
ILP

48. Possible Project Web Server Web Server Web Server TSP Server IP Server
SAT
Server
JICOS
JICOS
JICOS

49. Thanks! Questions? http://cs.ucsb.edu/projects/jicos

52. Introduction
“Listen to the technology!” Carver Mead

53. Introduction “Listen to the technology!” Carver Mead
What is the technology telling us?

54. Introduction “Listen to the technology!” Carver Mead
What is the technology telling us?
Internet’s idle cycles/sec growing rapidly

55. Introduction “Listen to the technology!” Carver Mead
What is the technology telling us?
Internet’s idle cycles/sec growing rapidly
Bandwidth is increasing & getting cheaper
Communication latency is not decreasing

56. Introduction “Listen to the technology!” Carver Mead
What is the technology telling us?
Internet’s idle cycles/sec growing rapidly
Bandwidth increasing & getting cheaper
Communication latency is not decreasing
Human technology is getting neither cheaper nor faster.

57. Introduction Fundamental Issue: Heterogeneity…
OS1
OS2
OS3
OS4
OS5 M1 M2 M3 M4 M5
Heterogeneous
machine/OS

58. Plans More performance experiments More NP-hard optimizations
Larger (SDSC Data Star 256 processor)
Heterogeneous
More NP-hard optimizations
Investigate upper & lower bounds
Use Jini to enable:
Secure communication (SSL)
Dynamic service discovery
Task Servers
Fault-tolerant
Adaptive network topology
More programming models