Re: Nonblocking script execution

[Asko Kauppi <askok@...>]

Alexander Gladysh kirjoitti 25.2.2009 kello 1:59:

> On Wed, Feb 25, 2009 at 2:39 AM, Alex Davies  
> <alex.mania@iinet.net.au> wrote:
> > > I did a quick, nonreliable test, and it took about 14 times  
> > > longer  with a
> > > C hook.  Also, another problem I thought of: what if the script   
> > > makes an IO
> > > call?It'll still block...
> >
> > It is a problem - your whole C library needs to either have a  
> > guaranteed
> > worse case time (even Lua's standard library doesn't offer this,
> > string/io/table libraries can take a long time performing their  
> > various
> > functions) or check the debug hooks themselves.
>
> Yes, indeed.
>
> ("xyzzy"):rep(1e7):gsub("(z+)", "Z")
>
> This one takes 4 seconds on my box, and has just 9 instructions.
>
> While one can take away IO from untrusted code, string library is
> usually a requirement...
>
> Alexander.

Quite smart to think of this kind of issues; I've never realized them.

The only solution I'm aware of that currently offers cancellation of  
Lua states from the outside is Lanes. It will _really_ kill runaway  
cases, from the OS threading level, and then close their Lua states.

-asko