dispatch_semaphore_create(3) on macOS
The text f63c3422de37, as macOS 10.13.6, macOS 10.13.5, macOS 10.13.4, macOS 10.13.3, macOS 10.13.2, macOS 10.13.1, macOS 10.13, macOS 10.12.6, macOS 10.12.5, macOS 10.12.4 shipped it.
synchronized counting semaphore