ThreadId generation fallback path: avoid spurious yields

Author: RalfJung

library/std/src/thread/id.rs

@@ -70,7 +70,9 @@ impl ThreadId {
 
                 // Acquire lock.
                 let mut spin = 0;
-                while COUNTER_LOCKED.compare_exchange_weak(false, true, Ordering::Acquire, Ordering::Relaxed).is_err() {
+                // Miri doesn't like it when we yield here as it interferes with deterministically
+                // scheduling threads, so use `compare_exchange` to avoid spurious yields.
+                while COUNTER_LOCKED.compare_exchange(false, true, Ordering::Acquire, Ordering::Relaxed).is_err() {
                     if spin <= 3 {
                         for _ in 0..(1 << spin) {
                             spin_loop();