The registerDoMC function is used to register the multicore
parallel backend with the foreach package.
registerDoMC(cores=NULL, …)The number of cores to use for parallel execution. If not
specified, the number of cores is set to the value of
options("cores"), if specified, or to approximately half
the number of cores detected
by the parallel package.
Package options. Currently, only the nocompile option
is supported. If nocompile is set to TRUE, compiler
support is disabled.
The multicore functionality, originally written by Simon Urbanek and
subsumed in the parallel package in R 2.14.0, provides functions
for parallel execution of R code on machines with multiple cores or
processors, using
the system fork call to spawn copies of the current process. The
multicore functionality, and therefore registerDoMC, should
not be used
in a GUI environment, because multiple processes then share the same GUI.