Multi-threading (was Re: HTTP-ng, Anonymous and mSQL-Auth)

[David Robinson <dr...@ast.cam.ac.uk>]

> > On Sat, 6 Jan 1996, sameer wrote:
> > >     Is there a good reference on MT that I can look at? I don't
> > > have a very good clue on what multi-threadedness is all about.
> > 
> > Dunno either.  Who on the list has experience with writing multithreaded 
> > applications?
> 
> I have. Amongst others I have written an MT protocol stack, which seems kind
> of relevant.

Me too; I've written some MT multi-CPU numerical code.

> >  Should we make a public call-out for help?  I know there 
> > are platform issues too, not all OS's do threading so Apache suddenly 
> > becomes harder to port.
> 
> Actually, in my experience, it isn't too hard to make an MT program work on
> an ST platform - if care is taken. So long as one is happy with the ST doing
> things sequentially, that is.
>
> Another alternative is to simulate threads with children on ST platforms.
> This would be the only way to get a nice HTTP-NG implementation on ST. It
> would mean abstracting the interface between threads, which is generally a
> good idea anyway, as it tends to avoid the nastier problems of MT.
> 
> If Apache were MT, it wouldn't have to spawn children, would it?

Actually, it would. For reliability and security, it would always have
a parent and one child. It would be simple to allow more children; this
would be a good idea as there will be a limit on how many requests can be
handled in one process (a limit on file descriptors, for example), 

It seems to me that NG would be optimally implemented as a UNIX device
driver; after setting up the connection you would use NG_accept() to wait
for a new request...

 David.