RC-OCP: Reverse coordinated optimized commit protocol

Abstract

With the growth of trends in computing and requirement for developing a reliable computing environment the need for performing tasks in distributed manner has gained much importance. Atomic commit protocols (ACP) are used to preserve the ACID property in distributed systems. Two-Phase Commit (2PC) is most widely used but the blocking of sites is undesirable as these sites may be holding locks on the resources. As alternative, non-blocking ACP has been suggested: This nonblocking protocol is Three-Phase Commit (3PC) protocol which requires an extra phase (pre-commit) to remove blocking state. The existing protocols require so many messages transfer from the coordinator to participants and vice versa during different phases and corresponding increase communication and time complexity and hold the locks acquire by different participants till the end of last phase, forcing other transactions also to be blocked just because of the objects that are locked. All the existing protocols give the same performance for both deferred and immediate consistency constraints databases. Lots of protocols are being proposed and mainly the concentration was to make the 2PC protocol non-blocking or to minimize the blocking possibilities in 2PC. There has been a renewed interest in developing and optimization of more efficient ACPs. This paper is an effort to propose a new technique to optimize atomic commit protocols by optimizing voting phase based on deferred and immediate consistency constraints. Also an attempt has been made to propose reduction in communication complexity which will require less number of messages to be shared between coordinator and participants, the cost of execution as well as time delays.