crew (version 0.5.0)

crew_controller_local: Create a controller with a local process launcher.

Description

Create an R6 object to submit tasks and launch workers on local processes.

Usage

crew_controller_local(
  name = NULL,
  workers = 1L,
  host = "127.0.0.1",
  port = NULL,
  tls = crew::crew_tls(),
  tls_enable = NULL,
  tls_config = NULL,
  seconds_interval = 0.25,
  seconds_timeout = 10,
  seconds_launch = 30,
  seconds_idle = Inf,
  seconds_wall = Inf,
  seconds_exit = 1,
  tasks_max = Inf,
  tasks_timers = 0L,
  reset_globals = TRUE,
  reset_packages = FALSE,
  reset_options = FALSE,
  garbage_collection = FALSE,
  launch_max = 5L
)

Arguments

name

Name of the client object. If NULL, a name is automatically generated.

workers

Integer, maximum number of parallel workers to run.

host

IP address of the mirai client to send and receive tasks. If NULL, the host defaults to the local IP address.

port

TCP port to listen for the workers. If NULL, then an available ephemeral port is automatically chosen.

tls

A TLS configuration object from crew_tls().

tls_enable

Deprecated on 2023-09-15 in version 0.4.1. Use argument tls instead.

tls_config

Deprecated on 2023-09-15 in version 0.4.1. Use argument tls instead.

seconds_interval

Number of seconds between polling intervals waiting for certain internal synchronous operations to complete. If space_poll is TRUE, then this is also the minimum number of seconds between calls to mirai::daemons() for the purposes of checking worker status.

seconds_timeout

Number of seconds until timing out while waiting for certain synchronous operations to complete.

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

Number of seconds to wait for NNG websockets to finish sending large data (when a worker exits after reaching a timeout or having completed a certain number of tasks). See the exitlinger argument of mirai::daemon().

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.

See Also

Other user: crew-package, crew_clean(), crew_controller_group(), crew_tls()

Examples

if (identical(Sys.getenv("CREW_EXAMPLES"), "true")) {
controller <- crew_controller_local()
controller$start()
controller$push(name = "task", command = sqrt(4))
controller$wait()
controller$pop()
controller$terminate()
}