Debugging in the Multiverse

Does anything like the Antithesis hypervisor exist as open source?<p>The closest I&#x27;ve seen is Qemu record&#x2F;replay, but that&#x27;s very slow (no KVM acceleration, no multicore), and broken in current Qemu versions (replayed system just gets stuck).

Would love to hear a technical comparison between this and King et al.&#x27;s classic paper on Time-Traveling VMs from USENIX ATC 2006: &quot;Debugging operating systems with time-traveling virtual machines&quot; (<a href="https:&#x2F;&#x2F;www.usenix.org&#x2F;legacy&#x2F;events&#x2F;usenix05&#x2F;tech&#x2F;general&#x2F;king&#x2F;king.pdf" rel="nofollow">https:&#x2F;&#x2F;www.usenix.org&#x2F;legacy&#x2F;events&#x2F;usenix05&#x2F;tech&#x2F;general&#x2F;k...</a>, 505 citations).

It is really interesting to me that this sort of thing didn’t come from programming language folks like I’d expect. You’d think PLs are in the absolute perfect spot to implement things, because they define the semantics and runtime. And there are a few PLs who have time-travel demos, but they’ve never really been seen as more than a cool tech demo.<p>Perhaps the language is too small a vantage point to really get into what’s happening when debugging.

I&#x27;ve enjoyed reading many of the blog posts by Antithesis, really cool work.<p>I don&#x27;t really see a fit for the automated testing product in our stack at the moment, but I would love to use a time traveling hypervisor that I can hop into whenever I&#x27;d like.<p>Currently, it seems your pricing is pretty focused on the automated testing service. Do you have pricing or plans that offer just the deterministic dev environment?

How do you handle side effects that interact with third party systems? In my own tests, I use network request mocks. Do you need to provide a test mode flag to indicate that mocks should be used?

I was once working in a company producing software &#x2F; operating systems for smart cards (such as the chips on your credit cards). We developed a simulator for the hardware that logged all changes to registers, memory and other states in a very large ring buffer, allowing us to undo &#x2F; step backwards through code. With RAM being large, those chips being slow, and some snapshotting, we were usually able to undo back to the reset of the card. That was a game changer regarding debugging the OS.

Antithesis employee here. Happy to jump in and answer any burning questions people might have about multiverse debugging.

There&#x27;s a binary analysis time travel debugger similar to this, Qira [0][1].<p>[0]: <a href="https:&#x2F;&#x2F;www.usenix.org&#x2F;conference&#x2F;enigma2016&#x2F;conference-program&#x2F;presentation&#x2F;hotz" rel="nofollow">https:&#x2F;&#x2F;www.usenix.org&#x2F;conference&#x2F;enigma2016&#x2F;conference-prog...</a><p>[1]: <a href="https:&#x2F;&#x2F;qira.me&#x2F;" rel="nofollow">https:&#x2F;&#x2F;qira.me&#x2F;</a>

This looks very interesting! Is it possible to implement this in a node.js web app? Does it work with any build tool? How much latency does it add to a production server?

&gt;Seems obvious enough. But maybe, just maybe, the brake lines were cut by somebody who wanted the driver dead. Or what if he was drugged? Can we distinguish that scenario from him being sleepy?<p>If this is prod, your job is going to be finding what combination of these things caused it this time.

Pretty much no software, even when run deterministically, is bijective. There are almost always cases where two different states map to the same state.<p>How does this tooling deal with that?

Is this like UndoDB[0]?<p>[0]: <a href="https:&#x2F;&#x2F;undo.io&#x2F;products&#x2F;udb&#x2F;" rel="nofollow">https:&#x2F;&#x2F;undo.io&#x2F;products&#x2F;udb&#x2F;</a>

I know I&#x27;m taking the wrong thing from this - but I really struggle to read this site. Something about the contrast and aggro gradients.

Is this designed to be run in production?