gregthelaw

6 ms·

1.
by gregthelaw 1y ago
If you'll excuse the shameless self promotion, I gave a talk at C++Now last year on how time travel debuggers work: https://www.youtube.com/watch?v=NiGzdv84iDE (Warning: contains me trying to play Doom :)
2.
by gregthelaw 1y ago
Undo founder here. I just got a slack from one of our marketing team who is thrilled you appreciate their work. :-) Our customers are top tier tech companies and our users are among the smartest engineers on the planet. I'm proud of ou
3.
by gregthelaw 1y ago
Undo co-founder here. rr is indeed awesome. If it works for your use-case, you should use it! Undo is mostly used by companies whose world is complex enough that rr doesn't work for them, and they understand how powerful time travel de
4.
by gregthelaw 1y ago
Undo founder here. We've been at this for getting on 20 years now. Originally it cost $295 for a perpetual license. Eventually we understood that the majority of developers (actually employers of developers) will pay $0. But some are h
5.
by gregthelaw 2y ago
If it's been a long time I recommend taking another look. TBF you can tell it hasn't had the millions of dollars of investment that the Microsoft debuggers have, but still it's come a long way over the last 5-10 years. e.g. i
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by gregthelaw 2y ago
Exactly right. Undo has "thread fuzzing" which is similar concept to chaos mode, but more targeted.
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by gregthelaw 2y ago
Co-founder of Undo here. This is a common misunderstanding, and just not true -- neither for Undo nor rr. Most races will reproduce at least as easily in Undo, especially if you use our "thread fuzzing" feature (rr has something s
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by gregthelaw 2y ago
Congrats on this work -- writing a debugger from scratch is a big job. I have cloned the repo, will take a proper look this w/e.
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by gregthelaw 2y ago
I haven't tried UScope yet (I shall), but I don't agree with you about GDB. I don't find it especially buggy unless doing niche things like non-stop debugging -- I guess you may well have a different experience though. I thin
10.
by gregthelaw 2y ago
I would say yes, your CI should accumulate all of those regression tests. Where I work we now have many, many thousands of regression test cases. There's a subset to be run prior to merge which runs in reasonable time, but the full CI
11.
by gregthelaw 2y ago
But if you don't squash, doesn't this render git bisect almost useless? I think every commit that gets merged to main should be an atomic believed-to-work thing. Not only does this make bisect way more effective, but it's a m
12.
by gregthelaw 2y ago
I've spent the past two decades working on a time travel debugger so obviously I'm massively biassed, but IMO most programmers are not nearly as proficient in the available debug tooling as they should be. Consider how long it tak
13.
by gregthelaw 2y ago
Related: write down what you're seeing (or rather, what you _think_ you're seeing), and so with pen and paper, not the keyboard. You can type way faster than you can write, and the slowness of writing makes you think harder about
14.
by gregthelaw 2y ago
I love the "if you didn't fix it, it ain't fixed". It's too easy to convince yourself something is fixed when you haven't fully root-caused it. If you don't understand exactly how the thing your seeing man
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by gregthelaw 2y ago
It's a great talk! I have stolen your "if you smell smoke, find the source" advice and put it in some of my own talks on the subject.
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by gregthelaw 2y ago
I have a bunch of (36 if you're counting :) short videos and blog posts introducing the advanced features of GDB: https://undo.io/resources/gdb-watchpoint/
17.
by gregthelaw 2y ago
Just yesterday I gave a talk at MeetingC++ in Berlin on debugging multithreaded code. It's amazing how few developers know anything beyond the very basic of their debugger. If all you know is print, break, continue, next and then you d
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by gregthelaw 2y ago
You need a time travelling debugger! https://undo.io/ https://rr-project.org/ https://learn.microsoft.com/en-us/windows-hardware/drivers/d...
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by gregthelaw 3y ago
Sometimes printf debugging is all you have available. But printf can be lousy for debugging race conditions because it's pretty slow and worse, libc's printf takes a lock and so introduces a synchronisation point. So I made a simp
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No more Heisenbugs: lock-free fast logging library(github.com)
2 points by gregthelaw 3y ago|1 comments
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by gregthelaw 3y ago
> Indeed, that fixes the part about it only marching forward. But still, it wouldn't be sufficient in cases where the ultimate cause is near neither the start nor the obvious error, but (e.g.) in the 50th of 100 entries. Not true. r
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by gregthelaw 3y ago
This is super cool.
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by gregthelaw 10y ago
Great to see. I'm biassed of course, but reversible debugging is the future (or should that be the past? Sorry.) If you'll excuse the shameless plug, http://undo.io/ for the same with C/C++. I'd like to
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by gregthelaw 13y ago
I'm a co-founder of the company. Lots of stability improvements over the past year or so: I'd urge you to try it again. Particularly v4 beta. Send email to beta@undo-software.com to get a beta license. I'd never claim it&#x27