Why does my R program use more RAM when run via “qsub” than it does when run within a “qrsh” session.

Some R programs, such a “randomForestSRC” or programs that use “libgomp”, rely on OpenMP, which may try to use multiple cores on the node it is running on, and will subsequently require more RAM to run.

To restrict your program to a single core, set mc.cores and rf.cores to “1”.

options(rf.cores=1, mc.cores=1)

Thanks to Kasper Hansen and Jacob Fiksel for their work on identifying the issue and finding a fix for it.