Create a launcher with local process workers.

Create an R6 object to launch and maintain local process workers.

Usage

crew_launcher_local(
  name = NULL,
  seconds_interval = 0.5,
  seconds_timeout = 60,
  seconds_launch = 30,
  seconds_idle = Inf,
  seconds_wall = Inf,
  seconds_exit = NULL,
  tasks_max = Inf,
  tasks_timers = 0L,
  reset_globals = TRUE,
  reset_packages = FALSE,
  reset_options = FALSE,
  garbage_collection = FALSE,
  launch_max = 5L,
  tls = crew::crew_tls(),
  r_arguments = c("--no-save", "--no-restore"),
  local_log_directory = NULL,
  local_log_join = TRUE
)

Arguments

name

Name of the launcher.

seconds_interval

Number of seconds between polling intervals waiting for certain internal synchronous operations to complete, such as checking mirai::status().

seconds_timeout

Number of seconds until timing out while waiting for certain synchronous operations to complete, such as checking mirai::status().

seconds_launch

Seconds of startup time to allow. A worker is unconditionally assumed to be alive from the moment of its launch until seconds_launch seconds later. After seconds_launch seconds, the worker is only considered alive if it is actively connected to its assign websocket.

seconds_idle

Maximum number of seconds that a worker can idle since the completion of the last task. If exceeded, the worker exits. But the timer does not launch until tasks_timers tasks have completed. See the idletime argument of mirai::daemon(). crew does not excel with perfectly transient workers because it does not micromanage the assignment of tasks to workers, so please allow enough idle time for a new worker to be delegated a new task.

seconds_wall

Soft wall time in seconds. The timer does not launch until tasks_timers tasks have completed. See the walltime argument of mirai::daemon().

seconds_exit

Deprecated on 2023-09-21 in version 0.5.0.9002. No longer necessary.

tasks_max

Maximum number of tasks that a worker will do before exiting. See the maxtasks argument of mirai::daemon(). crew does not excel with perfectly transient workers because it does not micromanage the assignment of tasks to workers, it is recommended to set tasks_max to a value greater than 1.

tasks_timers

Number of tasks to do before activating the timers for seconds_idle and seconds_wall. See the timerstart argument of mirai::daemon().

reset_globals

TRUE to reset global environment variables between tasks, FALSE to leave them alone.

reset_packages

TRUE to unload any packages loaded during a task (runs between each task), FALSE to leave packages alone.

reset_options

TRUE to reset global options to their original state between each task, FALSE otherwise. It is recommended to only set reset_options = TRUE if reset_packages is also TRUE because packages sometimes rely on options they set at loading time.

garbage_collection

TRUE to run garbage collection between tasks, FALSE to skip.

launch_max

Positive integer of length 1, maximum allowed consecutive launch attempts which do not complete any tasks. Enforced on a worker-by-worker basis. The futile launch count resets to back 0 for each worker that completes a task. It is recommended to set launch_max above 0 because sometimes workers are unproductive under perfectly ordinary circumstances. But launch_max should still be small enough to detect errors in the underlying platform.

tls

A TLS configuration object from crew_tls().

r_arguments

Optional character vector of command line arguments to pass to Rscript (non-Windows) or Rscript.exe (Windows) when starting a worker. Example: r_arguments = c("--vanilla", "--max-connections=32").

local_log_directory

Either NULL or a character of length 1 with the file path to a directory to write worker-specific log files with standard output and standard error messages. Each log file represents a single instance of a running worker, so there will be more log files if a given worker starts and terminates a lot. Set to NULL to suppress log files (default).

local_log_join

Logical of length 1. If TRUE, crew will write standard output and standard error to the same log file for each worker instance. If FALSE, then they these two streams will go to different log files with informative suffixes.

See also

Other plugin_local: crew_class_launcher_local, crew_controller_local()

Examples

if (identical(Sys.getenv("CREW_EXAMPLES"), "true")) {
client <- crew_client()
client$start()
launcher <- crew_launcher_local(name = client$name)
launcher$start(sockets = client$summary()$socket)
launcher$launch(index = 1L)
task <- mirai::mirai("result", .compute = client$name)
mirai::call_mirai_(task)
task$data
client$terminate()
}