Memory Locking

Similarly to how database have locking mechanism, the operating system also has a locking mechanism for memory. The terminologies are exactly the same as the database locking, but the concept is a bit different.

1. Pessimistic Locking- Lock the memory first. Release it only after the work is done. Example - Mutex, Semaphores, Reentrant Locks.
2. Optimistic Locking - Do the work first. Check if the memory is still in the same state. If not, then retry or handle it based on the situation. Example - CAS (Compare and Swap) instruction, etc.