Here is an example:
use ::std::{
iter::FromIterator,
thread,
};
/// Maximum number of threads
const N: usize = 8;
fn main ()
{
let slice: &mut [i32] =
&mut Vec::from_iter(0 .. 128)[..]
;
::crossbeam::scope(|scope| {
slice
.chunks_mut(
// At most N threads
(slice.len() as f64 / (N as f64))
.ceil()
as usize
)
.for_each(|sub_slice: &mut [i32]| {
scope.spawn(move |_| {
println!(
"{:?} doubling {:3?}",
thread::current().id(),
sub_slice,
);
sub_slice
.iter_mut()
.for_each(|at_elem: &mut i32|
*at_elem *= 2
)
});
})
;
}).expect("Some thread panicked");
println!("slice = {:?}", slice);
}
Printing:
ThreadId(1) doubling [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
ThreadId(2) doubling [ 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31]
ThreadId(5) doubling [ 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79]
ThreadId(4) doubling [ 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63]
ThreadId(3) doubling [ 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47]
ThreadId(6) doubling [ 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95]
ThreadId(7) doubling [ 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111]
ThreadId(8) doubling [112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127]
slice = [0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46 ...