scholarly journals Multi-Version-Pulsating STM: A Multi-Version Optimistic Concurrency Control Scheme for Highly Parallel in-Memory Workload in a Multi Core Environment

2019 ◽  
Vol 9 (1) ◽  
pp. 1973-1979
Keyword(s):  
Data Structures ◽  
Energy Efficient ◽  
Concurrency Control ◽  
Control Algorithm ◽  
Software Transactional Memory ◽  
Optimistic Concurrency Control ◽  
Control Scheme ◽  
Memory Dynamic ◽  
Time And Energy ◽  
Better Than

Large in-memory data structures have a significant application in the fields of graphics, gaming, military and all the possible areas where Big Data can be employed. Their fame in the area of science and technology is attributable to fast in-memory access by the processor as compared to on-disk data structures. These enormous data structures can be accessed still fast and efficiently through parallel computing. For employing highly parallel computations, equally parallel algorithms are required. One of the most desirable attributes of such algorithms is their ability to control concurrency and avoid any deadlocks while being time and energy efficient. This paper presents a multi-version optimistic concurrency control algorithm based on timestamping. This algorithm is lock free and is tested on 64 simulated CPU cores on a multi core simulator. The algorithm is a Software Transactional Memory approach employing 16, 32, 40 and 50 threads in different tests running on the simulator. Half of the threads are doing reading and half are doing writing operation in each case while accessing an in-memory dynamic array. Being lock free and employing lazy timestamp calculations, this approach is better than other existing concurrency control approaches.

scholarly journals Pulsating STM – The in-memory Optimistic Concurrency Control Technique for Multi Core Systems

2019 ◽  
Vol 9 (1) ◽  
pp. 1966-1972
Keyword(s):  
Artificial Intelligence ◽  
Deep Learning ◽  
Embedded System ◽  
Concurrency Control ◽  
Control Technique ◽  
Software Transactional Memory ◽  
Optimistic Concurrency Control ◽  
The World ◽  
Data Source ◽  
Better Than

In the world of ever increasing parallelism, the problem of deadlock-free concurrency control is inevitable. As the number of processing cores is increasing, the number of processing threads is also increasing, and with this increase in the number of processing threads, there is a good chance of problems arising due to lack of proper concurrency control. The application areas under the domain of advanced graphics, cryptography, deep learning, embedded system programming, artificial intelligence and networking are prone to the problems of heavy uncontrolled concurrency of threads. This paper presents a novel Software Transactional Memory (STM) based optimistic concurrency control technique that is deadlock free for threads accessing the in-memory data structure for the purpose of reading as well as writing. The technique is lock free and is based upon timestamping. Threads involved in the proposed approach possess the transactional properties of atomicity, concurrency and isolation. Durability is not expected as the threads are working on an in-memory data source. The approach involves lazy conflict detection that ensures minimum aborts and restarts as well as maximum concurrency among transactions. Being lock free, the algorithm is better than the existing lock-based techniques. The technique is tested on Sniper-6.1 multi core simulator simulating 64 CPU cores and running 16, 32, 40 and 50 threads in our case. The results show significant improvement in throughput with the increasing number of threads over the existing lock-based techniques as well as other STM techniques based on optimistic concurrency control.

scholarly journals Cigarette-Smokers’ Problem with STM

2017 ◽  
pp. 130-135
Author(s):  
Rup Kamal ◽  
Ryan Saptarshi Ray ◽  
Utpal Kumar Ray ◽  
Parama Bhaumik
Keyword(s):  
Parallel Processing ◽  
Concurrency Control ◽  
Transactional Memory ◽  
Performance Comparison ◽  
Critical Section ◽  
Parallel Programs ◽  
Software Transactional Memory ◽  
Complex Interactions ◽  
Processor Speed ◽  
Better Than

The past few years have marked the start of a historic transition from sequential to parallel computation. The necessity to write parallel programs is increasing as systems are getting more complex while processor speed increases are slowing down. Current parallel programming uses low-level programming constructs like threads and explicit synchronization using locks to coordinate thread execution. Parallel programs written with these constructs are difficult to design, program and debug. Also locks have many drawbacks which make them a suboptimal solution. One such drawback is that locks should be only used to enclose the critical section of the parallel-processing code. If locks are used to enclose the entire code then the performance of the code drastically decreases. Software Transactional Memory (STM) is a promising new approach to programming shared-memory parallel processors. It is a concurrency control mechanism that is widely considered to be easier to use by programmers than locking. It allows portions of a program to execute in isolation, without regard to other, concurrently executing tasks. A programmer can reason about the correctness of code within a transaction and need not worry about complex interactions with other, concurrently executing parts of the program. If STM is used to enclose the entire code then the performance of the code is the same as that of the code in which STM is used to enclose the critical section only and is far better than code in which locks have been used to enclose the entire code. So STM is easier to use than locks as critical section does not need to be identified in case of STM. This paper shows the concept of writing code using Software Transactional Memory (STM) and the performance comparison of codes using locks with those using STM. It also shows why the use of STM in parallel-processing code is better than the use of locks.

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