Re: [Tarantool-patches] [PATCH 2/5] lua/fio: Add lbox_fio_push_error as a separate helper

[Cyrill Gorcunov <gorcunov@gmail.com>]

On Fri, Nov 29, 2019 at 02:22:03PM +0300, Konstantin Osipov wrote:
> > Because there could be calls with higher priority. coio
> > keeps requests in prio-heap (or similar) so we should
> > follow the scheme and every call to popen should be
> > dispatched in compare with other calls.
> 
> I don't think you should bother with this. I don't see any
> practical implication of doing it through coio, except
> overhead/complexity it brings.

OK, thanks!

> > > Isn't it sufficient to only wrap vfork, everything else 
> > > can be done in the main thread, what do you think?
> > 
> > You mean to call popen_helpers directly? From programming
> > pov I would love to make it so, the code base would shrink
> > a lot but I fear this won't be looking as a solid design.
> 
> > Currently all our i/o goes via coio and scheduled. To be
> > honest I don't know yet which solution would be better.
> 
> Don't mix up coio and eio please. coio is
> cooperative-wihtin-the-same-thread. eio is async via a thread
> pool. Eio should be killed altogether now that asyncio in linux is
> mature enough, and there is io_uring.

OK, so the longterm plans are to get rid of eio and
use io_uring instead? I'm both hands for this kind of
async io, except we will get a huge problems on FreeBSD/MachO
I think (or we will have to keep eio for them).

> eio is just a legacy from the times when there was no good non-blocking
> file io on linux.

Thanks for explanation!