SKA South Africa, National Research Foundation of South Africa, Cape Town, South Africa
The KAT-7 and MeerKAT radio telescope control systems (www.ska.ac.za) are built on a rich Python architecture. At its core, we use KATCP (Karoo Array Telescope Communications Protocol), a text-based protocol that has served the projects very well. KATCP is supported by every device and connected software component in the system. However, its original implementation relied on threads to support asynchronous operations, and this has sometimes complicated the evolution of the software. Since MeerKAT (with 64 dishes) will be much larger and more complex than KAT-7, the Control and Monitoring (CAM) team investigated some alternatives to classical threading. We have adopted Tornado (www.tornadoweb.org) as the asynchronous engine for KATCP. Tornado, popular for Web applications, is built on a robust and very efficient coroutine paradigm that in turn is based on Python's generators. Co-routines avoid the complexity of thread re-entrancy and lifetime management, resulting in cleaner and more maintainable user code. This paper will describe our migration to a Tornado co-routine architecture, highlighting the benefits and some of the pitfalls and implementation challenges we have met.
*www.tornadoweb.org.
