Disruptor - using high performance, low latency technology in the CERN control system

Accelerator control systems process thousands of concurrent events per second, which adds complexity to their implementation. The Disruptor library provides an innovative single-threaded approach, which combines high performance event processing with a simplified software design, implementation and maintenance. This open-source library was originally developed by a financial company to build a low latency trading exchange. In 2014 the high-level control system for CERN experimental areas (CESAR) was renovated. CESAR calculates the states of thousands of devices by processing more than 2500 asynchronous event streams. The Disruptor was used as an event-processing engine. This allowed the code to be greatly simplified by removing the concurrency concerns. This paper discusses the benefits of the programming model encouraged by the Disruptor (simplification of the code base, performance, determinism), the design challenges faced while integrating the Disruptor into CESAR as well as the limitations it implies on the architecture. (author)