A software transactional memory (STM) system allows the composition of traditional lock based synchronization with transactions in STM code. The STM system acquires each traditional lock the first time that a corresponding traditional lock acquire is encountered inside a transaction and defers all traditional lock releases until a top level transaction in a transaction nest commits or aborts. The STM system maintains state information associated with traditional lock operations in transactions and uses the state information to eliminate deferred traditional lock operations that are redundant. The STM system integrates with systems that implement garbage collection.