Below are the R options and environment variables that are used by the future.batchtools package. See future::future.options for additional ones that apply to futures in general.

WARNING: Note that the names and the default values of these options may change in future versions of the package. Please use with care until further notice.

## Settings for batchtools futures

future.batchtools.workers:

(a positive numeric or +Inf) The default number of workers available on HPC schedulers with job queues. (Default: 100)

future.batchtools.output:

(logical) If TRUE, batchtools will produce extra output. If FALSE, such output will be disabled by setting batchtools options batchtools.verbose and batchtools.progress to FALSE. (Default: getOption("future.debug", FALSE))

future.batchtools.expiration.tail:

(a positive numeric) When a batchtools job expires, the last few lines will be relayed by batchtools futures to help troubleshooting. This option controls how many lines are displayed. (Default: 48L)

future.cache.path:

(character string) An absolute or relative path specifying the root folder in which batchtools registry folders are stored. This folder needs to be accessible from all hosts ("workers"). Specifically, it must not be a folder that is only local to the machine such as file.path(tempdir(), ".future" if an job scheduler on a HPC environment is used. (Default: .future in the current working directory)

future.delete:

(logical) Controls whether or not the future's batchtools registry folder is deleted after the future result has been collected. If TRUE, it is always deleted. If FALSE, it is never deleted. If not set or NULL, the it is deleted, unless running in non-interactive mode and the batchtools job failed or expired, which helps to troubleshoot when running in batch mode. (Default: NULL (not set))

## Environment variables that set R options

All of the above R future.batchtools.* options can be set by corresponding environment variable R_FUTURE_BATCHTOOLS_* when the future.batchtools package is loaded. This means that those environment variables must be set before the future.batchtools package is loaded in order to have an effect. For example, if R_FUTURE_BATCHTOOLS_WORKERS="200" is set, then option future.batchtools.workers is set to 200 (numeric).

## Examples

# Set an R option:
options(future.cache.path = "/cluster-wide/folder/.future")