What are the main difficulties that may arise when using transactions in systems?

The main challenges when using transactions in systems can include:

• Data consistency: it is important to ensure that a transaction either completes fully or does not affect the data at all (atomicity).

• Locks and contention: transactions can lock resources, leading to reduced performance and potential deadlocks.

• Isolation management: choosing the level of transaction isolation affects data visibility between transactions and can lead to issues such as "dirty reads" or "phantom reads".

• Error handling: transactions must be correctly rolled back in case of exceptions or failures.

• Performance: frequent or long transactions can negatively impact the overall system performance.

In Java, transaction management often uses APIs such as JTA or Spring Transaction Management, which help abstract these complexities, but understanding their nature is important for proper application design and debugging.