snow-startstop {snow}R Documentation

Starting and Stopping SNOW Clusters


Functions to start and stop a SNOW cluster and to set default cluster options.


makeCluster(spec, type = getClusterOption("type"), ...)


makeSOCKcluster(names, ..., options = defaultClusterOptions)
makePVMcluster(count, ..., options = defaultClusterOptions)
makeMPIcluster(count, ..., options = defaultClusterOptions)


spec cluster specification
count number of nodes to create
names character vector of node names
options cluster options object
cl cluster object
... cluster option specifications
type character; specifies cluster type.


makeCluster starts a cluster of the specified or default type and returns a reference to the cluster. Supported cluster types are "SOCK", "PVM", and "MPI". For "PVM" and "MPI" clusters the spec argument should be an integer specifying the number of slave nodes to create. For "SOCK" clusters spec should be a character vector naming the hosts on which slave nodes should be started; one node is started for each element in the vector.

stopCluster should be called to properly shut down the cluster before exiting R. If it is not called it may be necessary to use external means to ensure that all slave processes are shut down.

setDefaultClusterOptions can be used to specify alternate values for default cluster options. There are many options. The most useful ones are type and homogeneous. The default value of the type option is currently set to "PVM" if the rpvm package is available; otherwise, it is set to "MPI" if Rmpi is available, and it is set to "SOCK" if neither of these packages is found.

The homogeneous option should be set to FALSE to specify that the startup procedure for inhomogeneous clusters is to be used; this requires some additional configuration. The default setting is TRUE unless the environment variable R_HOME_LIB is defined on the master host with a non-empty value.

The optionoutfile can be used to specify the file to which slave node output is to be directed. The default is /dev/null; during debugging of an installation it can be useful to set this to a proper file.

The functions makeSOCKcluster, makePVMcluster, and makeMPIcluster can be used to start a cluster of the corresponding type.

In MPI configurations where process spawning is not available and something like mpirun is used to start a master and a set of slaves the corresponding cluster will have been pre-constructed and can be obtained with getMPIcluster. This interface is still experimental and subject to change.

For more details see


  ## Not run: 
cl <- makeCluster(c("localhost","localhost"), type = "SOCK")
clusterApply(cl, 1:2, get("+"), 3)
## End(Not run)

[Package snow version 0.2-1 Index]