Publication

Title of proceedings	Proceedings of the International Workshop on Smalltalk Technologies
DOI	10.1145/2991041.2991059

URL	http://scg.unibe.ch/archive/papers/Lesk16b.pdf
Type of Open Access	Website

Promises are synchronization constructs that hide the complexity of process synchronisation from the developer by providing a placeholder for the result of a potentially incomplete computation performed in a concurrent process. Promises evaluated by remote processes pose challenges for debugging when the remote computation raises an exception. Current debuggers are either unaware that there is a problem in the remote computation or give developers access only to the context of the remote process. This does not allow developers to interact at the same time with the process that launched the promise and the remote process that executed the promise's computation. To improve debugging of remote promises, in this paper we propose a debugger interface that presents a unified view of both the original and the remote process, by merging the call chains of the two processes at the point where the promise was created. We exemplify our approach, discuss challenges for making it practical, and illustrate through an initial prototype that it can improve debugging of exceptions in remote promises.