Question about rr alternative design

Robert O'Callahan robert at
Thu Feb 22 21:13:15 UTC 2018

On Fri, Feb 23, 2018 at 9:59 AM, Yichun Zhang (agentzh) <agentzh at>

> Hope these tips help. That was exactly what I did last year when I
> used rr to successfully track down a deep bug in LuaJIT's JIT compiler
> while recording the whole nginx process (with our ngx_lua module
> compiled in).

You should publish something about that so I can read it :-).

> To Robert: The ability of attaching rr to any running process would be
> really awesome, which makes online recording possible. Is there any
> concrete plan on that yet? ;)

I have other priorities right now.

Like I said above, it is doable but it is challenging, especially to
support syscall buffering after attach.

Su ot deraeppa sah dna Rehtaf eht htiw saw hcihw, efil lanrete eht uoy ot
mialcorp ew dna, ti ot yfitset dna ti nees evah ew; deraeppa efil eht. Efil
fo Drow eht gninrecnoc mialcorp ew siht - dehcuot evah sdnah ruo dna ta
dekool evah ew hcihw, seye ruo htiw nees evah ew hcihw, draeh evah ew
hcihw, gninnigeb eht morf saw hcihw taht.
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