School of Computing

Virtual Machine Based Debugging for occam-pi

Carl G. Ritson and Jonathan Simpson

In Peter H. Welch, Susan Stepney, Fiona A.C. Polack, Frederick R.M. Barnes, Alistair A. McEwan, Gardner S. Stiles, Jan F. Broenink, and Adam T. Sampson, editors, Communicating Process Architectures 2008, volume 66 of Concurrent Systems Engineering Series, pages 182-196, Amsterdam, The Netherlands, September 2008. IOS Press.


While we strive to create robust language constructs and design patterns which prevent the introduction of faults during software development, an inevitable element of human error still remains. We must therefore endeavor to ease and accelerate the process of diagnosing and fixing software faults, commonly known as 'debugging'.

Current support for debugging occam-pi programs is fairly limited. At best the developer is presented with a reference to the last known code line executed before their program abnormally terminated. This assumes the program does in fact terminate, and does not instead live-lock. In cases where this support is not sufficient, developers must instrument their own tracing support, ``printf style''. An exercise which typically enlightens one as to the true meaning of concurrency...

In this paper we explore previous work in the field of debugging occam programs and introduce a new method for run-time monitoring of occam-pi applications, based on the Transterpreter virtual machine interpreter. By adding a set of extensions to the Transterpreter, we give occam-pi processes the ability to interact with their execution environment. Use of a virtual machine allows us to expose program execution state which would otherwise require non-portable or specialised hardware support. Using a model which bears similarities to that applied when debugging embedded systems with a JTAG connection, we describe debugging occam-pi by mediating the execution of one execution process from another.

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Bibtex Record

author = {Carl G. Ritson and Jonathan Simpson},
title = {{Virtual Machine Based Debugging for occam-pi}},
month = {September},
year = {2008},
pages = {182-196},
keywords = {determinacy analysis, Craig interpolants},
note = {},
doi = {},
url = {},
    publication_type = {inproceedings},
    submission_id = {2719_1234151280},
    ISBN = {978-1-58603-907-3},
    booktitle = {Communicating Process Architectures 2008},
    editor = {Peter H. Welch and Susan Stepney and Fiona A.C. Polack and Frederick R.M. Barnes and Alistair A. McEwan and Gardner S. Stiles and Jan F. Broenink and Adam T. Sampson},
    volume = {66},
    series = {Concurrent Systems Engineering Series},
    address = {Amsterdam, The Netherlands},
    publisher = {IOS Press},
    ISSN = {1383-7575},
    refereed = {yes},

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Last Updated: 21/03/2014