Debugging distributed C programs by real time reply

TL;DR: The Bugnet project is testing how well existing multiprocess C programs can be debugged without special hardware features that make porting difficult, and making the implementation easier to port.

Abstract: Bugnet is a portable Unix system designed to debug C programs distributed within a local area network. A graphics interface allows the user of a Sun workstation to manage process groups and monitor process interactions very conveniently. Bugnet gives information about interprocess communication, I/O events, and execution traces for each component process. It allows the user to detect an error visually, to roll global program state back to a time before the error, and to replay events almost exactly as they previously occurred. Current work on Bugnet is making the implementation easier to port, seeing if replay accuracy can be improved by minor adjustments in the Unix process scheduler, linking it with Unix dbx to control individual processes, and determining useful tools for filtering of long event strings and for detecting errors. The Bugnet project is testing how well existing multiprocess C programs can be debugged without special hardware features that make porting difficult. An initial version is running on a network of Suns. It currently reproduces real time execution sequences with an accuracy of 0.01 to 0.10 seconds.