The trace (english tracing ) refers to programming a function to analyze or troubleshoot programs. It is a cross-cutting concern.
In this case, a message is displayed, for example, at every entry point in a function, and when leaving, so the programmer can keep track of when and where the function is called. The messages may also contain the arguments to the function.
Together with other diagnostic issues can the program flow of a faulty program often quickly traced back to the error-causing function.
In multithreaded environments tracing is more helpful than debugging with setting breakpoints, since in this case the current thread is not stopped, which would otherwise cause the context is distorted and thus the same program error may not be able to reproduce as desired.