Set the number of threads used by DVS operations

Description

Controls the thread pool size for parallel file operations (add, get, status). The value is stored as the dvs.num_threads option and synced to the Rust backend before each operation.

Details

Can also be set via .Rprofile or temporarily with withr::with_options().

Each add, get and status operation takes its thread count from the first rule that applies:

1. A thread count set here or in the dvs.num_threads option: that many threads, at most 32.
2. The DVS_NUM_THREADS environment variable, when it is a whole number above 0: that many threads, at most 32. Any other value is ignored.
3. Otherwise 4 threads per CPU, at most 16.

An operation never uses more threads than it has files. NULL and 0 set no thread count, so the operation falls through to DVS_NUM_THREADS or to 4 threads per CPU. --threads 0 in the CLI does the same.

Usage

set_dvs_threads(threads)

Arguments

Argument	Description
threads	A whole number of threads, or NULL or 0 to set no thread count. NA, a negative or fractional number, TRUE, FALSE, a string or more than one value raises a dvs_error_argument condition.

Value

The previous value of dvs.num_threads (invisibly).

Examples

# Not run:
set_dvs_threads(4)

# Temporarily use 2 threads
withr::with_options(list(dvs.num_threads = 2), {
  dvs_add(paths = "big_data.csv")
})