Static SLEEPINESS 

pub static SLEEPINESS: AtomicU32

Facilitates delay injection. If you set this to something other than 0, the fallible! macro will randomly call std::thread::yield_now(), with the nubmer of times being multiplied by this value. You should not need to set it very high to get a lot of delays, but you’ll need to play with the number sometimes for specific concurrent systems under test.