[R-SIG-Mac] Strange error message with mclapply

[Simon Urbanek]

Guillaume,

please read ?multicore -- especially the section "Warning".

Cheers,
Simon


On Jan 15, 2010, at 9:42 , Guillaume Chapron wrote:

> Hello,
>
> I have this test function:
>
> onerun <- function(j) {
> 	
> 	p <- numeric(10)	
> 	for (i in 1:9) {	
> 		p[i+1] <- j + p[i]	
> 	}	
> 	return(p)
>
> }
>
> Then I can call:
>
> lapply(1:100, onerun)
>
> I would like to multi-thread this, so I do:
>
> library(multicore)
> mclapply(1:100, onerun)
>
> and it works.
>
> But when I increase the size of the computations, i.e.
>
> mclapply(1:10000, onerun)
>
> it crashes with this error message:
>
> The process has forked and you cannot use this CoreFoundation  
> functionality safely. You MUST exec().
> Break on  
> __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__ 
> () to debug.
>
> What do I do wrong? I have a dual core MBP.
>
> Thanks!
>
> Guillaume
>
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