Debugging is an essential yet often tedious part of
the software development process. Omniscient debuggers have
long aimed to make debugging easier by recording execution
traces, enabling more direct debugging interactions. Although the
concept of omniscient debugging has been explored extensively in
research, it has seen limited adoption in industry until recently.
The emergence of new commercial tools like Replay presents an
opportunity to reevaluate the impact of omniscient debugging. In
this paper, we conducted a controlled experiment with 20 participants
with a commercial omniscient debugger, Replay, and a traditional
debugger, Chrome DevTools. We investigated whether the
omniscient debugger improved developer productivity and how it
influenced debugging behavior. We coded developers’ navigation,
rerun, and runtime value collection behaviors and summarized
their debugging strategies. Our results show that developers with
the omniscient debugger were not more successful or faster than
those using the traditional debugger. Omniscient debugger users
reran the program less, but there was no significant difference
in the number of files or functions they explored or the number
of runtime values they collected. Omniscient debugger users
faced navigation and runtime value collection challenges, which
may have hindered their effectiveness. Our results suggest that
commercial omniscient debuggers must include more of the
high-level support for interacting with traces found in research
prototypes to successfully help developers in debugging tasks.