Advanced Programming: Concurrency, Lab 7

Look at the following examples from Chapter 6:
Compile/compose each of these systems; then Run them and do Safety and Progress checks on them. Make sure you understand the results of these checks. The first one deadlocks: thus there is bound to be a progress violation too. The second one has no deadlocks, and no progress violations with the default progress check. The third has no deadlocks, but with the given ProgressCheck in place there is a progress violation: note that here the ProgressCheck in effect biases some of the choices (in favour of Time Outs) and there are no progress violations for the default progress check (which assumes fair choices)
Look at the Dining Philosophers, in both versions:
- Dining Philosophers
- DeadlockFree Philosophers
A different way to break the deadlock in the first version is to have a doorman who will only allow up to four philosophers into the room where the eating takes place. Write a DOORMAN process which simply counts philosophers in and out of the room (obviously PHIL must now perform actions enter and leave in addition to all previous actions). Compose this DOORMAN with the existing DINERS composition -- call it NEWDINERS, for example -- and then see what happens. (Note: in this version, DINERS will be using your amended version of PHIL)