In which situations is it advisable to use pessimistic locking to manage access to resources?

Pessimistic locking is used when the likelihood of conflicts during concurrent access to a resource is high and the consequences of such conflicts are critical. This is relevant in systems with high competition for data, where it is important to guarantee integrity and consistency, for example, when updating bank accounts or inventory in real-time.

In such situations, the resource is locked immediately when work begins with it, preventing access by other threads or transactions until the operation is complete. This reduces the risk of errors but may lead to decreased performance due to waiting for locks.

Example: in Java using ReentrantLock or database locks with an isolation level of "Serializable".