Information Technology Reference
In-Depth Information
MacOS and preemptive scheduling
Until 2002, Apple's MacOS operating system lacked the ability to force a process
to yield the processor back to the kernel. Instead, all application programmers were
told to design their systems to periodically call into the operating system to check if
there was other work to be done. The operating system would then save the state of
the original process, switch control to another application, and return back only when
it again became the original process's turn. This has a drawback: if a process fails to
yield, e.g., because it has a bug and enters an infinite loop, the operating system kernel
has no recourse. The user needed to reboot the machine to give control back to the
operating system. This happened frequently enough that it was given its own name: the
“spinning cursor of death.”
