What other options for solving the problem of concurrent write-offs exist (pessimistic locking, optimistic locking, serializable isolation)?

In addition to pessimistic and optimistic locking, as well as serializable isolation, there are other approaches to solving the problem of concurrent updates:

• Multiversion Concurrency Control (MVCC) — allows transactions to work with different versions of data, reducing locking.
• Timestamps and conflict control — transactions check if data has changed since it was read, and roll back in case of conflicts.
• Use of specialized data structures and lock-free, wait-free algorithms — increase performance in multi-threaded environments.
• Compensating transactions — perform rollback and reapplication operations in case of conflicts.
• Application-level isolation — for example, using distributed locks or semaphores.

Each method has its pros and cons and is chosen depending on the requirements for performance, consistency, and system complexity.