yo-yo leader election lijie wang 6982704 1. using spin used to detect design error in applications;...

YO-YO Leader Election

Lijie Wang6982704

1

Using SPIN Used to detect design error in

applications; descriptions of distributed

algorithms.

2

YO-YO Algorithm Minimum finding

Leader(smallest id node) Consists two parts

Preprocessing Iterations

3

Basic Components Node

Id Neighbor

s

4

Edge Between nodes Voting through

Preprocessing Node

Exchange its id with neighbors

5

Edge Direction

Small->large (id)

DAG

6

Direction goes down

using different ico

7

Candidates Local minima

->source ->candidate

8

Preprocessing completed

Second part start…

Iteration Remove candidates

Leave the only one

9

Two phases YO- -YO

10

Source: ⊙->id-> out neighbors Internal: ->all in neighbors-> ⊙->min->out neighbors Sink: ->all in neighbors-> ⊙

All sink done -> YO- end…

11

-YO start… Sink: ⊙->Y ->min; ⊙-> N->others Internal: ->all out neighbors-> ⊙

Receive at least one N: ⊙->N-> all in neighbors Receive all Y: ⊙->Y->min; ⊙->N->others

Source: all out neighbors -> ⊙

Eliminate candidates

Receive at least one N No longer a candidate

How?...

12

Receive all Y Survives (this

time)

Reverse N-edge Receive at least one N

No longer a candidate Become sink or

internal

13

Modify DAG Flip the link

with N

With reversing Sink and internal not

become candidate

less candidate

Drag down the dead candidates

14

And start over…

YO- [2]

15

-YO [2]

16

Flip [2]

17

Termination?

18

Count the only one candidate Become the leader

Pruning

To reduce the message To detect termination

Only left one source

Additional mechanism

Pruning

19

Eliminate leaf

Eliminate redundant route

20Pruning [1]

21

Pruning [2]

22

Pruning more [2]

23

Pruning [3]

Complexity

24

Without pruning Each phase: 2 messages each link Number of phase: log (number of sources) Total: 2*m*log(s)

With pruning Though we do not know the exact number

of reduced message in each iteration. Surely, the communication cost will be less

remarkable Total: 2*

For the spin result

25

Fail to intall Ispin on the 64-bit system Try to use the Virtual Machine with a 32-

bit system

Ispin result will be show in the final report

THANK YOU