pub fn set_kernel_threads(n: i32)Expand description
Process-global interpreter worker-thread count
(src/interp/parallel.cpp:16, one std::atomic<int>; setter at :24).
A free function, never a ScriptBuilder method, because there is one
setting per process and it changes timing, never values — nobody should be
able to write builder.threads(4) and expect isolation.
Rust-specific footgun: a program already running rayon at
num_cpus that also calls set_kernel_threads(num_cpus) oversubscribes
multiplicatively, and the symptom is a slowdown with no error anywhere
(hazard 8).