The Nevercrash Operating System Company has been receiving complaints from some of its customers about its latest release, which includes semaphore operations. They feel it is immoral for processes to block (they call it ‘‘sleeping on the job’’). Since it is company policy to give the customers what they want, it has been proposed to add a third operation, peek, to supplement up and down. peek simply examines the semaphore without changing it or blocking the process. In this way, programs that feel it is immoral to block can first inspect the semaphore to see if it is safe to do a down. Will this idea work if three or more processes use the semaphore? If two processes use the semaphore?
