CLI options --parallel=n now sets a 'multisession' plan; was 'multipr…

…ocess' [#420]
futureverse · Oct 29, 2020 · 4d0b765 · 4d0b765
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diff --git a/NEWS b/NEWS
@@ -1,7 +1,7 @@
 Package: future
 ===============
 
-Version: 1.19.1-9000 [2020-10-24]
+Version: 1.19.1-9000 [2020-10-29]
 
 SIGNIFICANT CHANGES:
 
@@ -10,6 +10,10 @@ SIGNIFICANT CHANGES:
    will give an informative deprecation warning when 'multiprocess' is used.
    This warning is given only once per R session.
 
+ * Launching R or Rscript with command-line option --parallel=n, where n > 1,
+   will now use 'multisession' as future strategy.  Previously, it would use
+   'multiprocess', which is now deprecated.
+
  * Support for 'local = FALSE' is deprecated.  For the time being, it remains
    supported for 'transparent' futures and 'cluster' futures that use
    'persistent = TRUE'.  However, note that 'persistent = TRUE' will also

diff --git a/R/options.R b/R/options.R
@@ -29,7 +29,7 @@
 #'
 #' @section Options for controlling futures:
 #' \describe{
-#'  \item{\option{future.plan}:}{(character string or future function) Default future strategy plan used unless otherwise specified via [plan()]. This will also be the future plan set when calling `plan("default")`.  If not specified, this option may be set when the \pkg{future} package is _loaded_ if command-line option `--parallel=ncores` (short `-p ncores`) is specified; if `ncores > 1`, then option \option{future.plan} is set to `multiprocess` otherwise `sequential` (in addition to option \option{mc.cores} being set to `ncores`, if `ncores >= 1`).  If system environment variable \env{R_FUTURE_PLAN} is set, then that overrides the future plan set by the command-line option. (Default: `sequential`)}
+#'  \item{\option{future.plan}:}{(character string or future function) Default future strategy plan used unless otherwise specified via [plan()]. This will also be the future plan set when calling `plan("default")`.  If not specified, this option may be set when the \pkg{future} package is _loaded_ if command-line option `--parallel=ncores` (short `-p ncores`) is specified; if `ncores > 1`, then option \option{future.plan} is set to `multisession` otherwise `sequential` (in addition to option \option{mc.cores} being set to `ncores`, if `ncores >= 1`).  If system environment variable \env{R_FUTURE_PLAN} is set, then that overrides the future plan set by the command-line option. (Default: `sequential`)}
 #'
 #'  \item{\option{future.globals.maxSize}:}{(numeric) Maximum allowed total size (in bytes) of global variables identified. Used to prevent too large exports. If set of `+Inf`, then the check for large globals is skipped. (Default: `500 * 1024 ^ 2` = 500 MiB)}
 #'

diff --git a/R/zzz.R b/R/zzz.R
@@ -87,8 +87,8 @@
       if (debug) mdebug(" => options(future.plan = sequential)")
       options(future.plan = sequential)
     } else {
-      if (debug) mdebugf(" => options(future.plan = tweak(multiprocess, workers = %s))", p)
-      options(future.plan = tweak(multiprocess, workers = p))
+      if (debug) mdebugf(" => options(future.plan = tweak(multisession, workers = %s))", p)
+      options(future.plan = tweak(multisession, workers = p))
     }
   }
 

diff --git a/man/future.options.Rd b/man/future.options.Rd
diff --git a/vignettes/future-5-startup.md.rsp b/vignettes/future-5-startup.md.rsp
@@ -56,7 +56,7 @@ then future will interpret this as we wish to resolve futures in parallel using
 mc.cores
        2
 > class(future::plan())
-[1] "tweaked"      "multisession" "future"       "function"
+[1] "FutureStrategy" "tweaked"        "multisession"   "future"         "function"
 ```
 
 We can use this command-line option also with `Rscript`, which provides a convenient mechanism for launching future-enhanced R scripts such that they run in parallel, e.g.