[PATCH 2/2] lib/core/fiber: Allow to extend default stack size

[Cyrill Gorcunov]

On Tue, Apr 02, 2019 at 10:14:11AM +0300, Konstantin Osipov wrote:
> * Cyrill Gorcunov <gorcunov at gmail.com> [19/04/02 01:09]:
> > > I don't think we should bother with making sure the stack is right
> > > for all fibers. You set the stack size, then you start fibers
> > > which depend on it.
> > 
> > Kostja, "require('fiber').cfg{stack_size=value})" implies that
> > lua read and parse it, but lua *itself* runs inside a fiber where
> > we've the stack size already allocated and what is worse its size
> > is compiled in. Next time when "readline" developers increase *own*
> > stack size we hit the same bug. Users simply won't have a chance to
> > run tarantool, instead they will have to wait us to increase default
> > stack size and rebuild the program.
> 
> Yes. We could remedy this by making the first (REPL or script)
> fiber stack sufficiently large at once.

It is true that we can make stack size for the "interactive" fiber
big enough but you know it looks somehow fishy for me -- we simply
hope that size gonne be enough not giving a way to customize these
early sizes. I won't insist though. Need to figure out how to
work with our cfg engine.