Scheduling

When a program creates a new thread, the virtual machine places it onto a run queue where all threads are executed in a round-robin manner. In general, Limbo threads execute in priority-less order. Each thread is a given a quantum (a specified number of instructions) to complete before it is moved from the virtual machine and placed on the thread ready queue. The ready queue is a linked list of threads that are waiting for execution within the virtual machine.

The virtual machine ensures that Limbo threads are safe from execution concurrency issues. Neither the Limbo program, nor the programmer, need to be concerned with re-entrant code.