R parallel rbindlist not working

Question

I have a function that uses rbindlist, and I would like to call this function using parLapply. Simplified version below:

func <- function(x){
  df1 <- data.frame(a = c(x,2), b = c(3,4))
  df2 <- data.frame(a = c(x,2), b = c(4,4))
  rbindlist(list(df1,df2))
}

cl <- makeCluster(getOption('cl.cores', detectCores()))
tmp <- parLapply(cl,c(1,2),func)
stopCluster(cl)

However, I get the error message:

Error in checkForRemoteErrors (val): 2 nodes caused errors; first error: could not find function "rbindlist"

Answer 1

If using other libraries with, parlapplymake sure that you loaded them correctly on each node. You can do

clusterEvalQ(cl, library(data.table))

Before running your commands or enable

require(data.table)

in your function.