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rr – record and replay debugger for C/C++

rr-project.org

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Re: rr – record and replay debugger for C/C++

#2

Post by rtpg »

rr is really cool, but almost every time I have decided to pull it out as one of the "big guns" it turns out that I have a concurrency bug and so rr is unable to reproduce it.

Despite that, it would be very, very, very cool if some languages built rr directly into their tooling. Obviously you can always "just" use rr/gdb, but imagine if rr invocations were as easy to set up and do as pdb is in Python!

Re: rr – record and replay debugger for C/C++

#4

Post by angus-g »

rtpg wrote: post #2

rr is really cool, but almost every time I have decided to pull it out as one of the "big guns" it turns out that I have a concurrency bug and so rr is unable to reproduce it. Despite that, it would be very, very, very cool if some languages built rr directly into their tooling. Obviously you can always "just" use rr/gdb, but imagine if rr invocations were as easy to set up and do as pdb is in Python!

I actually had a concurrency bug that I was able to capture with rr: an MPI job where I only ran rr on rank 0 and managed to figure out where a different send/recv ordering was causing issues. In fact, it was also a Python model that ties in with a lot of native code generation, so quite a complex issue.

Re: rr – record and replay debugger for C/C++

#5

Post by IshKebab »

rtpg wrote: post #2

rr is really cool, but almost every time I have decided to pull it out as one of the "big guns" it turns out that I have a concurrency bug and so rr is unable to reproduce it. Despite that, it would be very, very, very cool if some languages built rr directly into their tooling. Obviously you can always "just" use rr/gdb, but imagine if rr invocations were as easy to set up and do as pdb is in Python!

Yeah same for me. Actually the time I really wanted it was on Mac and unfortunately it only works on Linux.

There is Undodb which works on Mac and maybe with multithreading (not sure about that), but unfortunately it costs about $50k.

Re: rr – record and replay debugger for C/C++

#6

Post by suby »

Perhaps worth mentioning is that someone attempted to port this to Rust and got about 60,000 lines of code into it before archiving the project. I feel like comparing these two efforts would be an interesting case study on the impacts / benefits / limitations or difficulties, etc involved in rewriting from C++ to Rust.

https://github.com/sidkshatriya/rd/

Re: rr – record and replay debugger for C/C++

#7

Post by dwattttt »

suby wrote: post #6

Perhaps worth mentioning is that someone attempted to port this to Rust and got about 60,000 lines of code into it before archiving the project. I feel like comparing these two efforts would be an interesting case study on the impacts / benefits / limitations or difficulties, etc involved in rewriting from C++ to Rust. https://github.com/sidkshatriya/rd/

It would be a good but difficult analysis; at a quick check, rr 1.0 took 3 years and signficant contributions from around 3 or 4 people (I saw at least 5 people contributing), and the rr we have today is 10 years further work on that.

Re: rr – record and replay debugger for C/C++

#9

Post by tarruda »

suby wrote: post #6

Perhaps worth mentioning is that someone attempted to port this to Rust and got about 60,000 lines of code into it before archiving the project. I feel like comparing these two efforts would be an interesting case study on the impacts / benefits / limitations or difficulties, etc involved in rewriting from C++ to Rust. https://github.com/sidkshatriya/rd/

I don't understand the "rewrite X/Y/Z in Rust" trend that has been going for a few years.

I'm not familiar with Rust, but I'm almost sure it has a good C interoperability. If a certain piece of software is working well, what is the benefit of rewriting it in Rust?

Re: rr – record and replay debugger for C/C++

#10

Post by borodi »

rtpg wrote: post #2

rr is really cool, but almost every time I have decided to pull it out as one of the "big guns" it turns out that I have a concurrency bug and so rr is unable to reproduce it. Despite that, it would be very, very, very cool if some languages built rr directly into their tooling. Obviously you can always "just" use rr/gdb, but imagine if rr invocations were as easy to set up and do as pdb is in Python!

Chaos mode is an option when invoking rr that can expose some concurrency issues. Basically it switches which thread is executing a bunch to try and simulate multiple cores executing. It has found some race conditions for me but it’s of course limited
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