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Before the customer has a chance to make their reservation, another process makes a reservation for another customer, changing the number of available seats to zero. What if, for instance, a process reads the number of available seats on a flight, finds a value of one, and reports it to the customer. By the time a reading process displays the result of a request for information to the user, the actual data in the data base may have changed. If no constraints are put on access to the data base, data may change at any moment. The problem lies in writing information to the data base. Reading information from the data base will not cause a problem since no data is changed. There are two classes of threads which may access a. A practical example of a Readers and Writers problem is an airline reservation system consisting of a huge data base with many processes that read and write the data. The Readers/Writers problem is a modification of the mutual exclusion problem. The simplest one, referred to as the first readers-writers problem, requires that no reader will be kept waiting unless a writer has already obtained permission to use the shared object. As each Writer completes, however, it signals currently waiting Readers to allow them to be serviced in turn. The readers-writers problem has several variations, all involving priorities. It is acceptable to have multiple processes reading the database at the same time, if one process is. Imagine a big database, such as an airline reservation system, with many competing processes wishing to read and write. Operating System The Readers and Writers Problem. One, using the monitor construct Hoare 1974, also requires that newly arriving Readers remain queued if there is a waiting Writer. Operating System The Readers and Writers ProblemA +AA. The Readers and Writers problem is useful for modeling processes which are competing for a limited shared resource. Solutions to the Readers/Writers problem that satisfy the third criteria have also been developed.