6 ms·

What's the difference with RR?

by ognarb 1y ago

leni536 1y ago
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 1y ago
  rr does support multithreaded and multi-process applications, via, like Undo[1], allowing only a single thread to run at a time. (edit note - that's only about multithreading; Undo might have parallel multi-process recording) [1]: https://undo.io/resources/undo-performance-benchmarks/ https://undo.io/resources/undo-performance-benchmarks/ - "Undo serializes their execution"
  - leni536 1y ago
    I stand corrected, not sure where I heard this then.
    - dzaima 1y ago
      https://undo.io/resources/undo-vs-rr/ https://undo.io/resources/undo-vs-rr/ does note parallel recording for multi-process (not multi-threaded), so perhaps that.
kristopolous 1y ago
[flagged]
- 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 our marketing, but no-one is going to spend a bunch of money with us just because of that. So there must be something else in it I guess ;-)
deleted 1y ago
[deleted]
roca 1y ago
[rr developer here] Undo has cool features like Live Recording that we don't have in rr. They don't need access to the hardware PMU which is a big advantage in some situations. They can handle accesses to shared memory in cases where rr can't. https://undo.io/resources/undo-vs-rr/ https://undo.io/resources/undo-vs-rr/ is a good resource.
- sidkshatriya 1y ago
  If you don't have access to the hardware PMU then you can try https://github.com/sidkshatriya/rr.soft https://github.com/sidkshatriya/rr.soft (which is a modification of the rr debugger). It may not be commercial quality but its open source and free :) [I built rr.soft]
mark_undoio 1y ago
Undo (where I'm CTO) has existed for longer than RR and its real benefit is that it scales to use cases where RR (for one reason or another) isn't a fit. Technically: * Doesn't need hardware performance counters - runs on more CPUs and on cloud systems (where performance counters are often blocked). * Can attach and detach at any time - means you get to record just a subset of program execution that's interesting. * You can our ship recording tech with your application and control it by API, so you can grab crash recordings on customer systems. * Supports programs that share memory with non-recorded processes. * Supports direct device access (e.g. DPDK). * Accelerated debugging features - searching with recordings using parallel processing, accelerated conditional breakpoints a few thousand times faster than native GDB. * We provide a stable, patched fork of GDB that we're occasionally told is more stable than the default. For many people's use cases none of these really matter - they should use RR if they're not already. But if you need any of these things then Undo can give you time travel debugging. In practice, it's usually big software organisations that we deal with because they have development pain and the extreme requirements we can match.
- db48x 1y ago
  > * You can our ship recording tech with your application and control it by API, so you can grab crash recordings on customer systems. That’s actually pretty neat.
hugograffiti 1y ago
Undo also support Java and Scala: https://docs.undo.io/java/index.html https://docs.undo.io/java/index.html

What's the difference with RR?

by ognarb 1y ago

What's the difference with RR?

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 1y ago
rr does support multithreaded and multi-process applications, via, like Undo[1], allowing only a single thread to run at a time. (edit note - that's only about multithreading; Undo might have parallel multi-process recording) [1]: https://undo.io/resources/undo-performance-benchmarks/ https://undo.io/resources/undo-performance-benchmarks/ - "Undo serializes their execution"
- leni536 1y ago
  I stand corrected, not sure where I heard this then.
  - dzaima 1y ago
    https://undo.io/resources/undo-vs-rr/ https://undo.io/resources/undo-vs-rr/ does note parallel recording for multi-process (not multi-threaded), so perhaps that.

kristopolous 1y ago

[flagged]

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 our marketing, but no-one is going to spend a bunch of money with us just because of that. So there must be something else in it I guess ;-)

deleted 1y ago

[deleted]

roca 1y ago

[rr developer here] Undo has cool features like Live Recording that we don't have in rr. They don't need access to the hardware PMU which is a big advantage in some situations. They can handle accesses to shared memory in cases where rr can't. https://undo.io/resources/undo-vs-rr/ https://undo.io/resources/undo-vs-rr/ is a good resource.

sidkshatriya 1y ago
If you don't have access to the hardware PMU then you can try https://github.com/sidkshatriya/rr.soft https://github.com/sidkshatriya/rr.soft (which is a modification of the rr debugger). It may not be commercial quality but its open source and free :) [I built rr.soft]

mark_undoio 1y ago

Undo (where I'm CTO) has existed for longer than RR and its real benefit is that it scales to use cases where RR (for one reason or another) isn't a fit. Technically: * Doesn't need hardware performance counters - runs on more CPUs and on cloud systems (where performance counters are often blocked). * Can attach and detach at any time - means you get to record just a subset of program execution that's interesting. * You can our ship recording tech with your application and control it by API, so you can grab crash recordings on customer systems. * Supports programs that share memory with non-recorded processes. * Supports direct device access (e.g. DPDK). * Accelerated debugging features - searching with recordings using parallel processing, accelerated conditional breakpoints a few thousand times faster than native GDB. * We provide a stable, patched fork of GDB that we're occasionally told is more stable than the default. For many people's use cases none of these really matter - they should use RR if they're not already. But if you need any of these things then Undo can give you time travel debugging. In practice, it's usually big software organisations that we deal with because they have development pain and the extreme requirements we can match.

db48x 1y ago
> * You can our ship recording tech with your application and control it by API, so you can grab crash recordings on customer systems. That’s actually pretty neat.

hugograffiti 1y ago

Undo also support Java and Scala: https://docs.undo.io/java/index.html https://docs.undo.io/java/index.html