Achieving Starvation-Freedom with Greater Concurrency in Multi-Version Object-based Transactional Memory Systems

Abstract

To utilize the multi-core processors properly concurrent programming is needed. The main challenge is to design a correct and efficient concurrent program. Software Transactional Memory Systems (STMs) provide ease of multithreading to the programmer without worrying about concurrency issues as deadlock, livelock, priority inversion, etc. Most of the STMs work on read-write operations known as RWSTMs. Some STMs work at higher-level operations and ensure greater concurrency than RWSTMs. Such STMs are known as Single-Version Object-based STMs (SVOSTMs). The transactions of SVOSTMs can return commit or abort. Aborted SVOSTMs transactions retry. But in the current setting of SVOSTMs, transactions may starve. So, we propose a Starvation-Freedom in SVOSTM as SF-SVOSTM that satisfies the correctness criteria conflict-opacity. Databases and STMs say that maintaining multiple versions corresponding to each shared data-item (or key) reduces the number of aborts and improves the throughput. So, to achieve greater concurrency further, we propose Starvation-Freedom in Multi-Version OSTM as SF-MVOSTM algorithm. The number of versions maintains by SF-MVOSTM either be unbounded with garbage collection as SF-MVOSTM-GC or bounded with latest K-versions as SF-KOSTM. SF-MVOSTM satisfies the correctness criteria as local opacity and shows the performance benefits as compared with state-of-the-art STMs.

A Novel Multi Granularity Locking Scheme Based on Concurrent Multi -Version Hierarchical Structure

“…In case of read-write conflicts (IS-X,IX-S,S-SIX,S-X) mode unlike MGL,CGVL avoids synchronous waiting for data item reclamation by providing suitable version for each data item [31].It works on timestamp ordering principle to provide a consistent snapshot of each data item. Each requesting thread selects the suitable version of the data item by using the last committed timestamp of each version(when the version was committed).This is well known approach that exist in multi version control database scheme [14][15][16][17][18] that provide multiple version for each transactional operations to perform their work.…”