Suspend-Less Debugging for Interactive and/or Realtime Programs

Programs with interactive and/or realtime activities, such as GUI programs, action game programs, network-based programs, and sensor information processing programs, are not suitable for traditional breakpoint-based debugging, in which execution of the target program is suspended, for two reasons. First, since the timings and order of input event occurrences such as user operations are quite important, such programs do not behave as expected if execution is suspended at a breakpoint. Second, suspending a program to observe its internal states significantly degrades the efficiency of debugging. A debugging method is presented that resolves these problems. It keeps track of both the currently executing statement in a program and the changes in value of expressions of interest, and visualizes them in realtime. The proposed method was implemented as SLDSharp, a debugger for C# programs, by means of a program transformation technique. Through a case study of debugging a practical game program created by using the Unity game engine, it is shown in that SLDSharp makes it possible to efficiently debug.