RDMA Optimization Technology for Two-Phase Locking Concurrency Control

Abstract

Performance optimization of distributed transactions is one of the hottest topics in academic and industry community. Concurrency control technology based on two-phase locking can guarantee the correctness of concurrent transaction scheduling, thus it is widely implemented in mainstream commercial and open source distributed data-bases. However, existing works show that the performance bottleneck of distributed transaction processing tech-nology, based on traditional TCP/IP protocol and Share-Nothing architecture, comes from low CPU utilization of transaction scheduler and high network latency between transaction scheduler and storage nodes. To address the above two problems, an optimization technology of two-phase locking (2PL) concurrency control based on new hardware RDMA (remote direct memory access) is proposed to improve the performance of distributed transactions by using RDMA??s characteristics, e.g., high bandwidth, low latency and kernel bypass (eliminating the CPU overhead caused by TCP/IP protocol stack). The main technical contributions of this paper include the rewriting and opti-mization of network communication operators based on RDMA, and the atomicity guarantee when using RDMA one-sidedly to acquire and release read-write locks. Experimental results based on YCSB benchmark show that: one-sided mutex lock algorithm and one-sided mutex/shared lock algorithm have relative advantages under low and high contention workload respectively; 2PL concurrency control protocols with RDMA achieve up to 5.3x and 10.6x performance gain for NO WAIT and WAIT DIE respectively under high contention workload.

Keywords

• remote direct memory access (rdma); two-phase locking (2pl); distributed database; concurrency control