I'm running my script using mpirun -mp 4 and using snowfall+Rmpi on Linux 64bits. I receive the following error, but apparently without consequences on the results. Any idea? I'm able to reproduce it with a minimal script (below). Seems the critical issue is the for loop. Without it no error. Thanks for your help! TERM: Undefined variable. TERM: Undefined variable. TERM: Undefined variable. TERM: Undefined variable. Loading required package: utils Loading required package: utils Loading required package: utils Loading required package: utils Library Rmpi loaded. snowfall 1.70 initialized: parallel execution on 3 CPUs. Error in unserialize(obj) : unknown input format Calls: sfExport ... mpi.recv.Robj -> .mpi.unserialize -> unserialize -> .Call Execution halted MPI Application rank 0 exited before MPI_Finalize() with status 1 /users/mvalle/snow/snow/inst/RMPISNOW: line 40: 15028 Terminated R --no-save $* /users/mvalle/snow/snow/inst/RMPISNOW: line 40: 23906 Terminated R --no-save $* /users/mvalle/snow/snow/inst/RMPISNOW: line 40: 22094 Terminated R --no-save $* --- script ------------------------------------ library('Rmpi', verbose=FALSE) library('snowfall', verbose=FALSE) # Initialize cluster sfInit(parallel=TRUE, cpus=3, type="MPI") for(i in 1:2) { # Prepare fake data n <- 46000 x <- runif(n, 0.02, 0.54) logx <- log(x) sfExport("logx") # Compute fake function computeTakens <- function(r0idx) { if(r0idx == 1) return(NA) return(1/(logx[r0idx] - sum(logx[1:(r0idx-1)])/(r0idx-1))) } res <- sfClusterApplyLB(n:1, computeTakens) } sfStop() -- Ing. Mario Valle Data Analysis and Visualization Group | http://www.cscs.ch/~mvalle Swiss National Supercomputing Centre (CSCS) | Tel: +41 (91) 610.82.60 v. Cantonale Galleria 2, 6928 Manno, Switzerland | Fax: +41 (91) 610.82.82