Helllo All, Need some help understanding parallel processing. ?I set-up DoParallel and worked perfectly. ?I tried to set-up using parallel package following the book Parallel R but I get the following error: Error in checkForRemoteErrors(val) :? ? 4 nodes produced errors; first error: 'what' must be a character string or a function? I have read some posts on the internet suggesting the issue may be related to S4 class and I have tried parse() to no avail. ?I have read Snow and Parallel documentation but I am not getting the issue. Glenn ? library(parallel) library(foreach) library(doParallel) From Parallel R and Internet set up the following ============ DoParallel 4 seconds (perfect) took about 10 mins to set-up =============ptm <- proc.time() Cluster <- makeCluster(detectCores()) registerDoParallel(Cluster) clusterSetRNGStream(cl = Cluster, set.seed(100)) OAS <- foreach(i = 1:4, .packages = c("BondLab"), .combine = cbind) %dopar%? ? Mortgage.OAS(bond.id = "bondlabMBS4", trade.date = "01-10-2013", settlement.date = "01-13-2013", ? original.bal = 100000, price = 105.75, sigma = .23/sqrt(240), paths = 50)@OAS mean(OAS) proc.time() - ptm hist(OAS * 100, breaks = 20) stopCluster(Cluster) ============== followed the book example fails with the following message: Error in checkForRemoteErrors(val) :? ? 4 nodes produced errors; first error: 'what' must be a character string or a function =========== ptm <- proc.time() RNGkind("L'Ecuyer-CMRG") cl <- makeCluster(detectCores()) clusterSetRNGStream(cl, set.seed(100)) clusterEvalQ(cl, library(BondLab)) OAS <- clusterApply(cl = cl, 1:4, Mortgage.OAS(bond.id = "bondlabMBS4",? ? ? ? ? ? trade.date = "01-10-2013", settlement.date = "01-13-2013", ? ? ? ? ? original.bal = 100000, price = 105.75, sigma = .23/sqrt(240), paths = 50)@OAS)? proc.time() - ptm mean(OAS) hist(OAS * 100, breaks = 20) stopCluster(cl)