[prog] Passing data between modules

[Conor Daly]

On Tue, Jul 29, 2003 at 01:07:28PM +0100 or so it is rumoured hereabouts, 
Meredydd thought:
> On Tuesday 29 July 2003 12:26, Conor Daly wrote:
> > On Mon, Jul 28, 2003 at 11:01:59PM +0100 or thereabouts, Meredydd 
> wrote:
> > Last time we looked at dynamic libs programs (about 8 years ago), we
> > ended up with a 0.25x performance hit.  Whether that was down to
> > inexperience or inherent difficulties in libs.  We've been statically
> > linking ever since. It may be time to change but we'll have to learn
> > how...
> Hoo boy. That's...odd. In any case, as far as I can tell, dlopen() in C 
> puts the lib into the same address space as the executable, so they 
> behave just like normal functions. But anyway, if performance matters 
> that much, then interpreted and bytecoded languages are *definitely* 
> out of the window. In any case, the overhead from serialisation, 
> transmission and deserialisation is certain to be much greater than 
> that of dynamic loading.

I think performance mattered that much more when the DBMS and the
application servers were the same DEC workstation running ULTRIX which was
new 12 years ago.  The current Sunfire 8000 server should be able to
cope...
 
> One warning with recruits, though, although you almost certainly already 
> know this - look out for C novices! 

Like when I look in the mirror in the morning?  My C ability is only
reasonable though I'd be considered expert compared to most of my
colleagues.

> If someone has just learnt C, 
> especially if (s)he isn't moving up from something lower-level, you 
> really need to watch out for accidental clobberings, especially when 
> the subtleties of structure passing and serialisation start biting.

Again, these are reasons to carefully consider the way forward.  I _know_
we could do marvellous stuff but, when we move on, who will be able to
maintain it?

Conor
-- 
Conor Daly <conor.daly at oceanfree.net>

Domestic Sysadmin :-)
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