Thread starvation is still very much a thing on a lot of devices. macOS and iOS even have a Quality Of Service implementation in the kernel specifically to ensu

Thread starvation is still very much a thing on a lot of devices. macOS and iOS even have a Quality Of Service implementation in the kernel specifically to ensure that high-priority threads get to run when they'd otherwise be starved, and this can lead to low-priority threads being suspended for many seconds at a time under high workload. In fact, it's now really dangerous to use a regular spinlock on iOS and macOS because you can get into a priority inversion livelock if threads from different QoS levels are contending the same lock. The Obj-C runtime was seeing delays of tens of seconds in some cases when using spinlocks, so it now uses a private "os_lock" which is a spinlock that uses SPI to "donate" the QoS of the waiting thread to the one that holds the spinlock.