R: Options for parallel support

set.mcOption {spatialreg} | R Documentation

## Options for parallel support

### Description

Provides support for the use of parallel computation in the parallel package.

### Usage

    set.mcOption(value)
    get.mcOption()
    set.coresOption(value)
    get.coresOption()
    set.ClusterOption(cl)
    get.ClusterOption()

### Arguments

`value` | valid replacement value
`cl` | a cluster object created by `makeCluster` in parallel

### Details

Options in the spatialreg package are held in an environment local to the package namespace and not exported. Option values are set and retrieved with pairs of access functions, get and set. The `mc` option is set by default to FALSE on Windows systems, as they cannot fork the R session; by default it is TRUE on other systems, but may be set FALSE. If `mc` is FALSE, the `Cluster` option is used: if `mc` is FALSE and the `Cluster` option is NULL no parallel computing is done, or the `Cluster` option is passed a “cluster” object created by the parallel or snow package for access without being passed as an argument. The `cores` option is set to NULL by default, and can be used to store the number of cores to use as an integer. If `cores` is NULL, facilities from the parallel package will not be used.

### Value

The option access functions return their current settings, the assignment functions usually return the previous value of the option.

### Note

An extended example is shown in the documentation of `mom_calc`, including treatment of seeding of RNG for multicore/cluster.

### Author(s)

Roger Bivand Roger.Bivand@nhh.no

### Examples

    ls(envir=spatialreg:::.spatialregOptions)
    library(parallel)
    nc <- detectCores(logical=FALSE)
    nc
    # set nc to 1L here
    if (nc > 1L) nc <- 1L
    #nc <- ifelse(nc > 2L, 2L, nc)
    coresOpt <- get.coresOption()
    coresOpt
    if (!is.na(nc)) {
     invisible(set.coresOption(nc))
     print(exists("mom_calc"))
     if(.Platform$OS.type == "windows") {
    # forking not permitted on Windows - start cluster
    # removed for Github actions 210502
    ## Not run:
      print(get.mcOption())
      cl <- makeCluster(get.coresOption())
      print(clusterEvalQ(cl, exists("mom_calc")))
      set.ClusterOption(cl)
      clusterEvalQ(get.ClusterOption(), library(spatialreg))
      print(clusterEvalQ(cl, exists("mom_calc")))
      clusterEvalQ(get.ClusterOption(), detach(package:spatialreg))
      set.ClusterOption(NULL)
      print(clusterEvalQ(cl, exists("mom_calc")))
      stopCluster(cl)

    ## End(Not run)
     } else {
      mcOpt <- get.mcOption()
      print(mcOpt)
      print(mclapply(1:get.coresOption(), function(i) exists("mom_calc"),
       mc.cores=get.coresOption()))
      invisible(set.mcOption(FALSE))
      cl <- makeCluster(nc)
      print(clusterEvalQ(cl, exists("mom_calc")))
      set.ClusterOption(cl)
      clusterEvalQ(get.ClusterOption(), library(spatialreg))
      print(clusterEvalQ(cl, exists("mom_calc")))
      clusterEvalQ(get.ClusterOption(), detach(package:spatialreg))
      set.ClusterOption(NULL)
      print(clusterEvalQ(cl, exists("mom_calc")))
      stopCluster(cl)
      invisible(set.mcOption(mcOpt))
     }
     invisible(set.coresOption(coresOpt))
    }

[Package spatialreg version 1.2-1 Index]