1. Dining Philosophers (Diners) Problem
7/1/2018
Dining Philosophers (Diners) Problem
definition
Chandy and Misra solution
extension to drinking philosophers

2. Definition extension to mutual exclusion arbitrary topology
7/1/2018
Definition
extension to mutual exclusion
arbitrary topology
each philosopher (process) proceeds through the following cycle
thinking (out of the CS) may remain indefinitely
hungry (requesting the CS)
eating (executing the CS) has to finish within finite time
solution properties
safety – no two neighbors eat at the same time
liveness – each hungry philosopher eventually eats
can a DMX solution be used to solve the diners problem? If yes, would this solution be efficient?

3. Chandy-Misra[84] (Hygenic) Solution Setup
7/1/2018
Chandy-Misra[84] (Hygenic) Solution Setup
each pair of diners share a fork
fork is clean before eating, fork is dirty during and after
diner cleans the fork only before giving it to neighbor
edge between diners u and v is oriented from u to v (u has higher priority) if
u holds clean fork
v holds dirty fork,
fork is in transition from v to u
initially, thus oriented graph is acyclic, all forks are dirty

4. Chandy-Misra[84] (Hygenic) Solution Details
7/1/2018
Chandy-Misra[84] (Hygenic) Solution Details
if diner does not have fork – it sends request to the neighbor
process gives up dirty forks and holds clean
diner can only wait for higher priority neighbor
Gets forks my sending a request for the fork – request for fork per CS request only sent once between a pair of procs
notice after eating, diner is a source (all his forks are dirty)
graph remains acyclic throughout operation
acyclic graph has a sink (lowest priority diner), that diner is guaranteed to eat

5. Extension to Drinking Philosophers
7/1/2018
Extension to Drinking Philosophers
definition
arbitrary topology
each pair of drinking philosophers share a bottle
philosopher alternates between being tranquil, thirsty and drinking
philosopher may be tranquil indefinitely but drinks only for finite amount of time
philosopher may request to drink from an arbitrary subset of adjacent bottles
properties
two neighbors cannot drink from the same bottle at the same time
each thirsty philosopher eventually drinks
relation to the other problems
can a solution to diners be used to solve the drinking philosophers problem? Can a DMX solution? If yes, are they going to be efficient?