[casept]

Does anything like the Antithesis hypervisor exist as open source?

The closest I've seen is Qemu record/replay, but that's very slow (no KVM acceleration, no multicore), and broken in current Qemu versions (replayed system just gets stuck).

[eatonphil]

https://github.com/facebookexperimental/hermit but it hasn't worked for me and is now unmaintained.

[spencerflem]

There's languages that support time travel debugging, like RR for GDB, or smalltalk, but no open source system wide thing like Antithesis that I know of yet.

[dzaima]

rr can record process trees; i.e. basically any part/descendant of a process you spawn will be recorded and can be replayed (userspace CPU & memory, that is); won't record the entire OS though.

[casept]

My experience with RR is that the chance of it working without hitting a missing syscall or desync is only about 50%, which is why I want a different solution that doesn't rely on the fragile syscall recording approach.

[dzaima]

Huh. In my experience it works nearly flawlessly, certainly far above 50%. And even when there are spurious failures in replaying it's easy enough to just re-replay (though I do wish there was some way to export the current position & checkpoints with instruction-level precision to import in a fresh replay). I suppose it depends massively on the recorded program (most of mine are simple C programs, but also a decent bit of Java for JIT inspection or FFI, and I've also recorded an Electron app a couple times, and for fun Factorio)

[vlovich123]

Same, I haven't had it have too many problems but it's not perfect & missing support for io_uring is a problem (they'll add it eventually I suspect once someone ponies up the money for it).