| 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. |
That’s actually pretty neat.