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by Veserv 843 days ago
If you are okay with single-threaded Linux native as a debug platform (i.e. you have a build that you reproduce bugs on) then you can probably use rr. undo.io has also been in the field for a long time. I hear they can also do multithreaded Linux native in some capacity as well. One of the people from undo frequently pops into time travel debugging threads when they appear, so they could give you more info if they drop by.

If you are on Windows, Microsoft has some form of time travel debugging, but I am pretty sure they do a instrumented emulator which is a 10-20x slowdown approach. I do not know of anything else on Windows.

The only efficient multithreaded time travel debugging I am aware of is all in the embedded field, so unlikely to be applicable. Most of the “multithreading” solutions otherwise available work by serializing your execution to a single thread, so they do not really count. Maybe there is something else out there, but not really sure.
1 comments
roca 843 days ago
rr and Undo are about the same here: they support multiple threads but run all threads on a single core.
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Veserv 843 days ago
Hm, thought they did more than standard replay. Do you know anybody outside of embedded that can do true multithreaded time travel debugging? I do not keep too much up to date on Linux native solutions. Most of the new ones I see are either just wrappers around rr or really hacky replay-based and should really just be wrappers around rr.
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roca 837 days ago
Microsoft's TTD handles multiple threads on multiple cores, because they instrument reads. But that's high overhead.

I'd like to know more about what the embedded tools do. I see SourcePoint supports multicore x86, but the data volume looks high so I suspect they can't handle workloads that run for minutes or hours. Also it's not clear to me which of these tools can reproduce the state of memory at every point in the past.

Basically I don't think you can do low-overhead record and replay without hardware support like Intel's QuickRec project. "Capture all memory traffic" is not going to scale.

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