search for: jobname1

...you have to collect them twice to free used resources -- at least on unix systems. Here is a small example to illustrate the current behavior: library(parallel) f = function(x) { Sys.sleep(x); sprintf("job with x = %i", x) } jobs = integer() jobs = c(jobs, mcparallel(f(10), name = "jobname1")$pid) jobs = c(jobs, mcparallel(f(3), name = "jobname2")$pid) for (i in 1:13) { message("\ni = ", i) print(mccollect(jobs, wait = FALSE, timeout = 0)) Sys.sleep(1) } I've created a small patch (<https://gist.github.com/mllg/82410d0f564a7a24251e9e747e210b39&g...