[Openmcl-devel] CCL is a mess

mikel evins mevins at mac.com
Wed May 27 10:25:11 PDT 2009

On May 27, 2009, at 11:59 AM, Rainer Joswig wrote:

> Question to the UI experts: is there an agreed way to use Cocoa from  
> a multi-threaded language/implementation (like CCL), in an  
> interactive development environment and in a robust way? Is that  
> even possible? That's a real question - it is not clear to me. What  
> good is a Lisp development environment if I can't really debug the  
> main thread interactively or when it is easy to screw up the main  
> thread which the whole IDE depends on - assuming Cocoa?

You've hit the nail on the head here. There is exactly one thread per  
app under Mac OS X that handles all events for that app. If you're  
accustomed to Lisp development, then you're probably thinking that  
what happens when there's an error is that you drop into a backtrace.  
But what if that error is on the Cocoa event thread? Well, then,  
dropping into a backtrace stops all event-processing (because that  
thread is busy being stopped in the backtrace, rather than handling  
events), so all you're going to see from the Cocoa app at that point  
is the spinning beachball of death.

It's kind of a hard problem to solve well. It's being worked on.


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