[Rcpp-devel] Struggling with cppFunction() and clusterExport()

[Matteo Fasiolo]

Dear Rcpp developers,

 I'm trying to parallelize some of my algorithms but I have encountered
the following problem:

# I have a cppFunction
cppFunction(' double inner_Cpp(double a){ return 1;  } ')

# And an R wrapper around it
wrapper_R<- function(input)
{
  inner_Cpp(input)
}

# And I want to call the wrappen in parallel within algorithm
algo <- function(input)
{
  cl <- makeCluster(2)
  clusterExport(cl, "inner_Cpp")
  a <- clusterApply(cl, 1:2, wrapper_R)
  stopCluster(cl)

  a
}

algo(2)

Error in checkForRemoteErrors(val) :
  2 nodes produced errors; first error: NULL value passed as symbol address

It seems that I'm unable to find the address of inner_Cpp.
If the inner function is an R function there is no problem:

inner_R <- function(input) 1

wrapper_R<- function(input)
{
  inner_R(input)
}

algo <- function(input)
{
  cl <- makeCluster(2)
  clusterExport(cl, "inner_R")

  a <- clusterApply(cl, 1:2, wrapper_R)

  stopCluster(cl)

  a
}

algo(2)

[[1]]
[1] 1

[[2]]
[1] 1

Do you have any idea about why this is happening?
Given that I have just started parallelizing my algorithms in this
way, any suggestion/criticism about the overall approach is
more then welcome!

Matteo
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