Unified Optimistic and Pessimistic Concurrency Control for a Software Transactional Memory (STM) System

A method comprising:

• determining during runtime execution of program code including a first transaction that the first transaction is to be executed optimistically;
• determining during runtime execution of the program code including a second transaction that the second transaction is to be executed pessimistically;
• and
• executing, at least partially in parallel, the first transaction optimistically and the second transaction pessimistically, wherein executing, at least partially in parallel, the first transaction optimistically and the second transaction pessimistically comprises acquiring a pessimistic write lock and subsequently an optimistic write lock in a transaction record associated with a memory address referenced by an optimistic transactional write operation before performing the optimistic transactional write operation to the memory address.