Re: Cocoa/Windows parallel dvlpmt

[Nicola Pero]

> There's another point I must mention - an app compiled with GnuStep under Red 
> Hat
> is an order of magnitude slower, in some areas, than one compiled using 
> XCode.  The Gnu ObjC runtime appears to be very slow, contrary to what 
> it's maintainers claim.  For the two projects I've considered using 
> GnuStep for, the performance was simply too poor.
>
> [...]
>
> I never really narrowed it down properly, but the basic scenario was 
> that I had homogenous NSArray's containing tens/hundreds of thousands of 
> items, and I was stepping through those arrays, calling certain 
> predictable methods on each, removing/adding items here and there, etc 
> etc.
> 
> It seems the two biggest bottlenecks were NSArray performance and 
> messaging speed.  I would have been sending millions of messages a 
> second (ideally; in reality I didn't meet this).  The NSArray 
> performance didn't seem that much worse than Apple's - i.e. slow anyway
> - so I can only imagine it was the messaging speed that was the problem.  
> I didn't really use any other classes, and I of course subtracted the
> performance of the C-based core from my measurements.
>
> The end result was that the comparative performance was at least 5 times 
> worse than simplying compiling with Apple's gcc and runtime.  Using the 
> same compiler flags of course (-g -O2 -Wall, from memory).  This 
> translated to about half the performance of the entire app, given that most
> of the app's time was spent in non-ObjC areas.
>
> I wish I could release the source, but of course it's owned by my 
> employer.  It's a simple scientific tool, and I'm just a summer temp, so 
> hopefully they'll release it as open source in a few weeks, at the end 
> of my employment.  If they do I'll make sure to tell you.
>
> Wade Tregaskis
>
> P.S.  I tried a few things to improve performance, like resolving 
> methods to IMP's and so forth, which did help, but not significantly for 
> either 
> GnuStep nor Apple's runtime.

If resolving methods to IMPs did not help significantly the performance, I
would argue that the problem is *not* the runtime. :-)

It might be the compiler (in general).  Difficult to say without seeing
the code.  If you can extract an excerpt which demonstrates where you are
having performance problems (without sending us the whole project), it
would be easier to diagnose what's wrong, and if something can be done to
cure it in the libraries, to cure it.