hw4 - 4. (25 points) In the dining philosophers protocol,...

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CSE586 (Spring 2010): Homework 4 Due by Mar 24 Wednesday, in class. 1. (15 points) In Lamport’s logical clock based mutual exclusion protocol (Chapter 7), give an example that shows a safety violation if we omit the following check for a process i entering the critical section. For all other j , knownT [ j ] must be larger than the timestamp of req i . 2. (15 points) Show that in Lamport’s mutual exclusion protocol, if a process i is executing the critical section, then i ’s request need not be at the top of the request queue ( reqQ ) at another process j . Is this still true when there are no messages in transit? 3. (20 points) Prove the progress property (by showing a suitable variant function) for Raymond’s Token Tree algorithm for mutual exclusion.
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Unformatted text preview: 4. (25 points) In the dining philosophers protocol, what kind of undesirable scenario may happen if, instead of starting with dirty forks in the initial state, all processes were to start with clean forks? 5. (25 points) Answer the following questions for the hygenic dining philosophers protocol in Chapter 8: 1. In the worst case, how much of the neighborhood processes are aected (i.e., starve), when an eating node fails by crushing? (Hint: think about whether it is possible to construct long dependency chains using the priority concept.) 2. In the worst case, how much of the neighborhood processes are aected (i.e., starve), when a thinking node fails by crushing? 1...
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