Worker clusters with the running package builds

JAGS_runtime_cluster() starts a PSOCK cluster for parallel computation whose workers run the package builds of the calling session, as the workers of parallel JAGS_fit() do. Packages built on BayesTools use it for their own parallel computation. JAGS_runtime_cluster_stop() stops such a cluster.

JAGS_runtime_cluster(
  cores,
  packages = "BayesTools",
  runtime_setup = NULL,
  options = list(),
  operation = "Parallel computation"
)

JAGS_runtime_cluster_stop(cl)

Arguments

cores

number of worker processes.

packages

packages that every worker loads. Each worker must load the same build (version, R code, and native libraries; see JAGS_package_builds()) as the calling session.

runtime_setup

NULL or a function of one context argument, as in JAGS_fit(). It runs in the calling process and on every worker when the cluster starts (context$phase "start"), and in the calling process after the workers stopped ("finish"). The context counts one chain per worker (context$chains equals cores).

options

named list of options set on every worker, in addition to all current BayesTools.* options of the calling session; an entry of options takes precedence over a current option of the same name.

operation

description of the computation used in error messages.

cl

cluster returned by JAGS_runtime_cluster().

Value

JAGS_runtime_cluster() returns the cluster (as created by parallel::makePSOCKcluster()), for use with the functions of the parallel package. JAGS_runtime_cluster_stop() returns NULL invisibly.

Details

Workers start with Rscript --vanilla, so no user or site startup file runs, and with the library paths of the calling session. Setting the options precedes loading the packages. If the start fails, the workers are stopped (and a started runtime setup finished) before the error is signalled. JAGS_runtime_cluster_stop() stops the workers first and then finishes the runtime setup in the calling process; further calls have no effect.

See also

JAGS_fit() JAGS_package_builds()

Examples

if (FALSE) { # \dontrun{
cl <- JAGS_runtime_cluster(2, packages = "BayesTools")
on.exit(JAGS_runtime_cluster_stop(cl), add = TRUE)
parallel::parLapply(cl, 1:2, function(i) i^2)
} # }