Run a pipeline of targets in parallel with transient future workers.

This function is like tar_make() except that targets run in parallel with transient future workers. It requires that you declare your future::plan() inside the target script file (default: _targets.R). future is not a strict dependency of targets, so you must install future yourself.

Usage

tar_make_future(
  names = NULL,
  shortcut = targets::tar_config_get("shortcut"),
  reporter = targets::tar_config_get("reporter_make"),
  workers = targets::tar_config_get("workers"),
  callr_function = callr::r,
  callr_arguments = targets::tar_callr_args_default(callr_function, reporter),
  envir = parent.frame(),
  script = targets::tar_config_get("script"),
  store = targets::tar_config_get("store")
)

Arguments

names

Names of the targets to build or check. Set to NULL to check/build all the targets (default). Otherwise, you can supply tidyselect helpers like any_of() and starts_with(). Because tar_make() and friends run the pipeline in a new R session, if you pass a character vector to a tidyselect helper, you will need to evaluate that character vector early with !!, e.g. tar_make(names = any_of(!!your_vector)). Applies to ordinary targets (stem) and whole dynamic branching targets (patterns) but not to individual dynamic branches.

shortcut

Logical of length 1, how to interpret the names argument. If shortcut is FALSE (default) then the function checks all targets upstream of names as far back as the dependency graph goes. shortcut = TRUE increases speed if there are a lot of up-to-date targets, but it assumes all the dependencies are up to date, so please use with caution. It relies on stored metadata for information about upstream dependencies. shortcut = TRUE only works if you set names.

reporter

Character of length 1, name of the reporter to user. Controls how messages are printed as targets run in the pipeline. Defaults to tar_config_get("reporter_make"). Choices:

• "silent": print nothing.

• "summary": print a running total of the number of each targets in each status category (queued, started, skipped, build, canceled, or errored). Also show a timestamp ("%H:%M %OS2" strptime() format) of the last time the progress changed and printed to the screen.

• "timestamp": same as the "verbose" reporter except that each .message begins with a time stamp.

• "timestamp_positives": same as the "timestamp" reporter except without messages for skipped targets.

• "verbose": print messages for individual targets as they start, finish, or are skipped. Each individual target-specific time (e.g. "3.487 seconds") is strictly the elapsed runtime of the target and does not include steps like data retrieval and output storage.

• "verbose_positives": same as the "verbose" reporter except without messages for skipped targets.

workers

Positive integer, maximum number of transient future workers allowed to run at any given time.

callr_function

A function from callr to start a fresh clean R process to do the work. Set to NULL to run in the current session instead of an external process (but restart your R session just before you do in order to clear debris out of the global environment). callr_function needs to be NULL for interactive debugging, e.g. tar_option_set(debug = "your_target"). However, callr_function should not be NULL for serious reproducible work.

callr_arguments

A list of arguments to callr_function.

envir

An environment, where to run the target R script (default: _targets.R) if callr_function is NULL. Ignored if callr_function is anything other than NULL. callr_function should only be NULL for debugging and testing purposes, not for serious runs of a pipeline, etc.

The envir argument of tar_make() and related functions always overrides the current value of tar_option_get("envir") in the current R session just before running the target script file, so whenever you need to set an alternative envir, you should always set it with tar_option_set() from within the target script file. In other words, if you call tar_option_set(envir = envir1) in an interactive session and then tar_make(envir = envir2, callr_function = NULL), then envir2 will be used.

script

Character of length 1, path to the target script file. Defaults to tar_config_get("script"), which in turn defaults to _targets.R. When you set this argument, the value of tar_config_get("script") is temporarily changed for the current function call. See tar_script(), tar_config_get(), and tar_config_set() for details about the target script file and how to set it persistently for a project.

store

Character of length 1, path to the targets data store. Defaults to tar_config_get("store"), which in turn defaults to _targets/. When you set this argument, the value of tar_config_get("store") is temporarily changed for the current function call. See tar_config_get() and tar_config_set() for details about how to set the data store path persistently for a project.

Value

NULL except if callr_function = callr::r_bg(), in which case a handle to the callr background process is returned. Either way, the value is invisibly returned.

Details

To configure tar_make_future() with a computing cluster, see the future.batchtools package documentation.

See also

Other pipeline: tar_make_clustermq(), tar_make()

Examples

if (identical(Sys.getenv("TAR_EXAMPLES"), "true")) {
tar_dir({ # tar_dir() runs code from a temporary directory.
tar_script({
  future::plan(future::multiprocess, workers = 2)
  list(
    tar_target(x, 1 + 1),
    tar_target(y, 1 + 1)
  )
}, ask = FALSE)
tar_make_future()
})
}