Package 'doMC'

The doMC Package

Description

The doMC package provides a parallel backend for the foreach/%dopar% function using the multicore functionality of the parallel package.

Details

Further information is available in the following help topics:

registerDoMC	register doMC to be used by foreach/%dopar%

To see a tutorial introduction to the doMC package, use vignette("gettingstartedMC"). To see a tutorial introduction to the foreach package, use vignette("foreach").

To see a demo of doMC computing the sinc function, use demo(sincMC).

Some examples (in addition to those in the help pages) are included in the “examples” directory of the doMC package. To list the files in the examples directory, use list.files(system.file("examples", package="doMC")). To run the bootstrap example, use source(system.file("examples", "bootMC.R", package="doMC")). This is a simple benchmark, executing both sequentally and in parallel. There are many more examples that come with the foreach package, which will work with the doMC package if it is registered as the parallel backend.

For a complete list of functions with individual help pages, use library(help="doMC").

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registerDoMC

Description

The registerDoMC function is used to register the multicore parallel backend with the foreach package.

Usage

registerDoMC(cores=NULL, ...)

Arguments

cores	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.

Details

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.

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