pub fn rayon_threads(default: usize) -> usizeExpand description
Worker count for the global Rayon pool, from XDG parallelism.rayon_threads.
GAP-SG-92: the pool used to be sized by writing RAYON_NUM_THREADS into the
process environment at startup, which made an env var the configuration
channel and required an unsafe block. Reading the XDG key and handing the
number to ThreadPoolBuilder keeps the policy inside the documented
precedence and removes the mutation entirely.
A value of 0 is rejected in favour of default: Rayon treats zero as
“detect the host CPU count”, which silently discards the cap this knob
exists to enforce.