Module sync 

Synchronization primitives.

Mutex and RwLock are re-exports of std::sync’s implementations: the uncontended path is just an atomic CAS, and the contended path is made scheduler-safe by wrapping .lock() with the M’s syscall-handoff shim (see [crate::runtime::syscall]). Porting Go’s sync.Mutex plus runtime.sema would add hundreds of lines for no measurable win.

WaitGroup and Cond are ported because they benefit from goroutine-level parking: waiters yield to the scheduler rather than blocking an OS thread.

Structs

Cond

A goroutine-aware condition variable.

Mutex

A mutual exclusion primitive useful for protecting shared data

RwLock

A reader-writer lock

WaitGroup

A synchronisation barrier: wait for a set of goroutines to complete.