[R] R hangs when connected via VPN [incl. minimal example]

[Marius Hofert]

Dear expeRts,

This is a similar post as on R-SIG-MAC [I didn't receive an answer there; not sure if it was the right place to post either]. 

I'm running R version 2.12.1 (Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit))
on a MacBook Pro under Mac OS X 10.6.6. The following minimal example runs fine
under this setup. However, if I am connected to a server via a VPN client 
[Cisco AnyConnect; same with Apple's internal VPN connection], then the minimal 
example hangs and just does not do anything. The "red button" in the R Console 
is dark red [normal behavior if R is running], so R tries to do something, but 
cannot succeed. CPU goes up to 100%... Same happens if I start the job from the 
command line via R CMD BATCH. What's going on? Is this a known issue? 

Cheers,

Marius

library(doSNOW) 
library(Rmpi) 
library(rlecuyer) 
library(foreach)

cl <- makeCluster(mpi.universe.size(), type ="MPI") 
tmp <- clusterSetupRNG(cl, seed=rep(1,6)) 
registerDoSNOW(cl)

counter <- 0
res <- foreach(k = 1:1000) %do% {
    counter <- counter + 1
}
tmp <- stopCluster(cl)

unlist(res)