Calling a function that includes foreach %dopar% construct from optim causes an error:
> workers <- startWorkers(6) # 6 cores
>
> registerDoSMP(workers)
>
> t0 <- Sys.time()
>
> optim(w,maxProb2,control=list(fnscale=-1))
>
> Error in { : task 1 failed - "unused argument(s) (isPrebuilt = TRUE)"
>
> Sys.time()-t0
>
> Time difference of 2.032 secs
>
> stopWorkers(workers)
The called function looks like that:
> maxProb2 <- function(wp) {
>
> r <- foreach (i=s0:s1, .combine=c) %dopar% { pf(i,x[i,5],wp,isPrebuilt=TRUE) }
>
> cat("w=",wp,"max=",sum(r),"\n")
>
> sum(r)
>
> }
pf is some other function, x is a static table of pre-computed elements.
Also calling the function to be optimized just once causes the same error:
> workers <- startWorkers(6) # 6 cores
>
> Warning message:
> In startWorkers(6) : there is an existing doSMP session using doSMP1
>
> registerDoSMP(workers)
>
> maxProb2(w)
> Error in { : task 1 failed - "unused argument(s) (isPrebuilt = TRUE)"
>
> stopWorkers(workers)
What's strange, the identical code works fine when called directly a single time (optim calles the same function many times):
> workers <- startWorkers(6) # 6 - ilosc rdzeni
>
> Warning message:
> In startWorkers(6) : there is an existing doSMP session using doSMP1
>
> registerDoSMP(workers)
>
> r <- foreach (i=s0:s1, .combine=c) %dopar% { pf(i,x[i,5],w,isPrebuilt=TRUE) }
>
> sum(r)
> [1] 187.1781
>
> stopWorkers(workers)
The called function (maxProb2) works fine, when %do% is used instead of %dopar%.
How can I correctly call a function including a foreach %dopar% construction?
UPDATE 2011-07-17:
I have renamed the pf function into probf but the problem remains.
probf functions is defined in the script, not in some external package.
Two notes: OS: Windows 7, IDE: Revolution Analytics Enterprise 4.3
> workers <- startWorkers(workerCount = 3)
>
> registerDoSMP(workers)
>
> maxProb2(w)
>
Error in { : task 1 failed - "could not find function "probf""