Now argument 'workers' for plan(multisession) defaults to availableCores(constraints = "connections-16") [#797]

Author: HenrikBengtsson

DESCRIPTION

@@ -1,5 +1,5 @@
 Package: future
-Version: 1.58.0-9012
+Version: 1.58.0-9013
 Title: Unified Parallel and Distributed Processing in R for Everyone
 Depends:
     R (>= 3.2.0)

NEWS.md

@@ -1,5 +1,12 @@
 # Version (development version)
 
+## Significant Changes
+
+ * Now argument `workers` for `plan(multisession)` defaults to
+   `availableCores(constraints = "connections-16")`. This will make
+   `plan(multisession)` work also on computers with a large number of
+   CPU cores, e.g. 192 and 256 cores.
+
 ## Performance
 
  * The pre-validation of the cluster worker allotted to a future when

R/backend_api-13.MultisessionFutureBackend-class.R

@@ -13,7 +13,7 @@
 #' @keywords internal
 #' @rdname FutureBackend
 #' @export
-MultisessionFutureBackend <- function(workers = availableCores(), rscript_libs = .libPaths(), interrupts = TRUE, gc = FALSE, earlySignal = FALSE, ...) {
+MultisessionFutureBackend <- function(workers = availableCores(constraints = "connections-16"), rscript_libs = .libPaths(), interrupts = TRUE, gc = FALSE, earlySignal = FALSE, ...) {
   debug <- isTRUE(getOption("future.debug"))
   if (debug) {
     mdebugf_push("MultisessionFutureBackend(workers = <workers>, interrupts = %s, ...) ...", interrupts)
@@ -129,7 +129,7 @@ print.MultisessionFutureBackend <- function(x, validate = TRUE, ...) {
 #'
 #' @aliases MultisessionFuture
 #' @export
-multisession <- function(..., workers = availableCores(), lazy = FALSE, rscript_libs = .libPaths(), gc = FALSE, earlySignal = FALSE, envir = parent.frame()) {
+multisession <- function(..., workers = availableCores(constraints = "connections-16"), lazy = FALSE, rscript_libs = .libPaths(), gc = FALSE, earlySignal = FALSE, envir = parent.frame()) {
   stop("INTERNAL ERROR: The future::multisession() must never be called directly")
 }
 class(multisession) <- c("multisession", "cluster", "multiprocess", "future", "function")