Net-dbx: a web-based debugger of MPI programs over low-bandwidth lines

This paper describes Net-dbx, a tool that utilizes Java and other World Wide Web tools for the debugging of MPI programs from anywhere in the Internet. Net-dbx is a source-level interactive debugger with the full power of gdb (the GNU Debugger) augmented with the debug functionality of the public-domain MPI implementation environments. The main effort was on a low overhead, yet powerful, graphical interface supported by low-bandwidth connections. The portability of the tool is of great importance as well because it enables the tool to be used on heterogeneous nodes that participate in an MPI multicomputer. Both needs are satisfied a great deal by the use of WWW browsing tools and the Java programming language. The user of our system simply points his/her browser to the Net-dbx page, logs in to the destination system, and starts debugging by interacting with the tool, just as with any GUI environment. The user can dynamically select which MPI processes to view/debug. A special WWW-based environment has been designed and implemented to host the system prototype.