Software Transactional Memory Vladimir Sedach Andrew Seniuk

Software transactional memory (STM) is a shared-memory concurrency model, originally inspired by cache coherency protocols in hardware design, but having the flavour of version control systems such as CVS. The main idea is that a process initiates a transaction which obtains a private copy of the data to be modified, does local computation, and when finished attempts to commit the results back to shared memory. The commit will succeed only if validation checks ascertain that the transaction has seen a consistent view of memory; otherwise it must retry. The transaction appears to execute atomically at some point in time within its execution, or in other words STM is linearizable. Although lock-based code tends to run more efficiently, the STM approach has appeal in that locks need not be used, so that sequential code can in most cases be safely converted to concurrent simply be wrapping code into modular, composable transactions.