AFAIK it records multithreaded applications on multiple threads and CPU, rr records them on a single OS thread, AFAIK. Not sure about replay. Never used undo though, so not sure how much better it is.
dzaima · 1h ago
rr does support multithreaded and multi-process applications, via, like Undo[1], allowing only a single thread to run at a time.
I was in talks with them recently because I kept running into limitations with rr. The main advantages for my use case were that undo doesn't have the same dependency on hardware timers, which means the ARM support is much better, you can run it in a VM (e.g. a cloud machine) and you can do replays on different systems.
Veserv · 1h ago
Well, if you have a Google L5 making ~365k [1] then it would need to make them ~2.2% more productive overall to be worth it when just considering direct pay. If we consider a Google L3 at ~187k then it would need to make them ~4.2% more productive overall.
This, of course, ignores employee benefits and overhead which usually amount to ~100% extra costs over direct pay. So that is now ~1.1% and ~2.1%, respectively.
And that ignores the fact that you need to pay people less than they produce to be profitable which probably drops us down to ~0.5% and ~1.0%, respectively.
edit: Incorrectly linked to product designer instead of software engineer levels.
dima55 · 1h ago
OK... Most of us don't know what a "google l5" is, so I guess we can safely ignore this. Heh.
esafak · 1h ago
No-one is going to speed $8K out of pocket to A/B test this on themselves. Of all the things you could be doing to improve your productivity, this is some high hanging fruit.
Veserv · 57m ago
If you have a US employer who is unwilling to spend 8 k$ on software engineering productivity then they are pennywise, pound foolish. It literally costs 10x that for a single junior engineer. And, as I pointed out, the net productivity improvement you need to see to justify that expense is miniscule.
If your employer really is skeptical, then they can run a A/B test over a small group of engineers to prove out changes in productivity. But not even being willing to run that test when it is so cheap is just management incompetence.
Engineers are ridiculously expensive. In electrical engineering, where the engineers are generally less well-paid than in software, employers routinely spend multiple hundreds of thousands of dollars per engineer per year in tooling. Not being willing to spend 8 k$ on a test of well known technology and attempting to identify mere single digit percentage improvements is just stupid.
ranger_danger · 27m ago
Not everyone is Google. Some people work for themselves, or have very small teams, or live in a developing country, and don't have lots of spare cash laying around.
Please try to understand that the world is not as simple and black and white as you'd like.
Veserv · 3m ago
Ugh, it appears I was not utterly pedantic enough even though I did, quite clearly, make my statements conditional in a way far beyond what is normally expected when talking about generalities that any normal person would assume are meant to apply in cases representative of the median situation.
Very well, a software engineering employer in the US who employs over 10 software engineers in the US at above the 20th percentile of wages, which constitutes the employers of a significant fraction of total software engineers above the 20th percentile of wages, would be foolish to not spend 8 K$ on software development tooling that would result in a 10% productivity improvement. It would be further foolish to not investigate such potential improvements given a reasonably credible belief that such a productivity improvement is possible. Outright dismissal without even considering the potential cost-benefit or making a incorrect cost-benefit analysis requiring significantly in excess of 10% is also foolish.
Please try to understand that when people are not being utterly pedantic to the point of insanity it is because they assume people will use their judgement to interpret the applicability to their situation rather than because they can only see in black and white.
more-nitor · 7m ago
this
if someone's bringing "google payscale" for comparison... well that's not some average joe...
why not just bring Bill Gates and say "everything -- including private jet -- is dirt cheap" ?
$8k per year simply doesn't make sense for 95% of the programmers. For a lot of developing countries, that's more than a well-paying programmer's annual salary...
[1]: https://undo.io/resources/undo-performance-benchmarks/ - "Undo serializes their execution"
Pricing & Licensing
A UDB floating license costs $7,900 per year.
I was in talks with them recently because I kept running into limitations with rr. The main advantages for my use case were that undo doesn't have the same dependency on hardware timers, which means the ARM support is much better, you can run it in a VM (e.g. a cloud machine) and you can do replays on different systems.
This, of course, ignores employee benefits and overhead which usually amount to ~100% extra costs over direct pay. So that is now ~1.1% and ~2.1%, respectively.
And that ignores the fact that you need to pay people less than they produce to be profitable which probably drops us down to ~0.5% and ~1.0%, respectively.
[1] https://www.levels.fyi/companies/google/salaries/software-en...
edit: Incorrectly linked to product designer instead of software engineer levels.
If your employer really is skeptical, then they can run a A/B test over a small group of engineers to prove out changes in productivity. But not even being willing to run that test when it is so cheap is just management incompetence.
Engineers are ridiculously expensive. In electrical engineering, where the engineers are generally less well-paid than in software, employers routinely spend multiple hundreds of thousands of dollars per engineer per year in tooling. Not being willing to spend 8 k$ on a test of well known technology and attempting to identify mere single digit percentage improvements is just stupid.
Please try to understand that the world is not as simple and black and white as you'd like.
Very well, a software engineering employer in the US who employs over 10 software engineers in the US at above the 20th percentile of wages, which constitutes the employers of a significant fraction of total software engineers above the 20th percentile of wages, would be foolish to not spend 8 K$ on software development tooling that would result in a 10% productivity improvement. It would be further foolish to not investigate such potential improvements given a reasonably credible belief that such a productivity improvement is possible. Outright dismissal without even considering the potential cost-benefit or making a incorrect cost-benefit analysis requiring significantly in excess of 10% is also foolish.
Please try to understand that when people are not being utterly pedantic to the point of insanity it is because they assume people will use their judgement to interpret the applicability to their situation rather than because they can only see in black and white.
if someone's bringing "google payscale" for comparison... well that's not some average joe...
why not just bring Bill Gates and say "everything -- including private jet -- is dirt cheap" ?
$8k per year simply doesn't make sense for 95% of the programmers. For a lot of developing countries, that's more than a well-paying programmer's annual salary...