Debugging: Difference between revisions

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* ''{{visible anchor|Remote debugging}}'' is the process of debugging a program running on a system different from the debugger. To start remote debugging, a debugger connects to a remote system over a communications link such as a local area network. The debugger can then control the execution of the program on the remote system and retrieve information about its state.

* ''Post-mortem debugging'' is debugging of the program after it has already [[crash (computing)|crashed]]. Related techniques often include various tracing techniques like examining log files, outputting a [[call stack]] on the crash,<ref>{{cite web|url=https://www.drdobbs.com/tools/postmortem-debugging/185300443|title=Postmortem Debugging|access-date=2019-12-17|archive-date=2019-12-17|archive-url=https://web.archive.org/web/20191217045909/https://www.drdobbs.com/tools/postmortem-debugging/185300443|url-status=live}}</ref> and analysis of [[memory dump]] (or [[core dump]]) of the crashed process. The dump of the process could be obtained automatically by the system (for example, when the process has terminated due to an unhandled exception), or by a programmer-inserted instruction, or manually by the interactive user.

* ''"Wolf fence" algorithm:'' Edward Gauss described this simple but very useful and now famous algorithm in a 1982 article for [[Communications of the ACM]] as follows: "There's one wolf in Alaska; how do you find it? First build a fence down the middle of the state, wait for the wolf to howl, determine which side of the fence it is on. Repeat process on that side only, until you get to the point where you can see the wolf."<ref>{{cite journal |url=https://dl.acm.org/citation.cfm?id=358690.358695 |title=Pracniques: The 'Wolf Fence' Algorithm for Debugging |author=E. J. Gauss |journal=Communications of the ACM |year=1982 |volume=25 |issue=11 |page=780 |doi=10.1145/358690.358695|s2cid=672811 |doi-access=free }}</ref> This is implemented e.g. in the [[Git (software)|Git]] [[version control system]] as the command ''git bisect'', which uses the above algorithm to determine which [[commit (data management)|commit]] introduced a particular bug.

* ''[[Record and replay debugging]]'' is the technique of creating a program execution recording (e.g. using Mozilla's free [[rr (debugging)|rr]] debugging tool; enabling reversible debugging/execution), which can be replayed and interactively debugged. Useful for remote debugging and debugging intermittent, non-deterministic, and other hard-to-reproduce defects.

* ''[[Time travel debugging]]'' is the process of stepping back in time through source code (e.g. using [[Undo (company)|Undo LiveRecorder]]) to understand what is happening during execution of a computer program; to allow users to interact with the program; to change the history if desired and to watch how the program responds.