Multicore frozen at 0% in the presence of many system R processes

[cfhammill]

Today I ran in to an issue with multicore batch jobs freezing at zero. Ctrl-C yeilded the error code "r" which I tracked down to getWorkerSchedulerStatus, the check was:

    if (worker$status$n.rprocs >= 3 * worker$ncpus) 
        return("r")

which is a sensible check, however my system had a number of active R sessions and enough defunct ones to cause multicore to freeze. Would it be possible to make this check more obvious, perhaps issuing a message or warning to alert the user that the hang is due to too many process?