my int $b; await (^5).map: { start { ++$b for ^100000 } } say $b; # something like 419318 my int $a; my $l = Lock.new; await (^5).map: { start { for ^100000 { $l.protect( { ++$a } ) } } } say $a; # 500000 my atomicint $c; await (^5).map: { start { ++⚛$c for ^100000 } } say $c; # 500000