PetersonAlgorithmen

The Peterson algorithm is a classic software solution to the critical section problem in concurrent programming, specifically designed for two processes. It was developed by Gary L. Peterson in 1981 and is notable for its simplicity and effectiveness in ensuring mutual exclusion and progress in a two-process system.

The critical section problem arises when multiple processes need access to a shared resource, and it is essential to prevent simultaneous access to avoid data corruption or inconsistency. The Peterson algorithm addresses this by using a combination of shared variables to coordinate access to the critical section. These variables include a pair of flags, one for each process, indicating whether the process wants to enter the critical section, and a turn variable that determines which process is allowed to proceed.

The algorithm works as follows: each process sets its own flag to indicate its intention to enter the critical section. It then sets the turn variable to the other process, yielding the right of way. If the other process is also trying to enter the critical section, the turn variable ensures that only one process can proceed. Once a process exits the critical section, it resets its flag to allow the other process to enter.

The Peterson algorithm guarantees mutual exclusion, ensuring that only one process can be in the critical section at any time. It also ensures progress, as no process is indefinitely postponed from entering the critical section. However, it is important to note that the algorithm is only suitable for two processes. For systems with more than two processes, other algorithms such as the Bakery algorithm or the use of semaphores are more appropriate.