Thursday, February 09, 2006

6. Sleeping Barber - continued

I would like to continue this thread, but am busy at the moment. I just want to point out the provably false statement in Tanenbaum. Consider page 130:

page 130. "Our solution uses three semaphores: customers, which counts waiting customers (excluding the customer who is in the barber chair, who is not waiting) , barbers, the number of barbers (0 or 1) who are idle, waiting for customers, and mutex, which is used for mutual exclusion. We need also a variable, waiting, which also counts the waiting customers."

The fact is that the barbers semaphore is _not_ restricted to having values 0 or 1 as Tanenbaum states, and as is suggested by his meaning given to the semaphore. The semaphore may take arbitrarily large values.



Anonymous Anonymous said...

How Can I run this sleeping in windows?

1:46 AM  

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