Thread state transitions

A non-transitory machine-readable storage medium comprising instructions that upon execution cause a system to:

• transition a first thread in its kernel persona to a wait state to wait for an event, wherein in the wait state the first thread remains active;
• transition the first thread from the wait state to a blocked state in which the first thread is blocked on the event, wherein a time interval exists between when the first thread is in the wait state and when the first thread is in the blocked state;
• responsive to a second thread delivering the event:
• transition the first thread from the wait state to an active state if the first thread is in the wait state and has not yet transitioned to the blocked state, and
• transition the first thread from the blocked state to a ready state if the first thread is in the blocked state;
• and
• responsive to a cancellation of the first thread's waiting or blocking on the event:
• transition the first thread from the wait state to a wait and cancel state in which the cancellation is pending, if the first thread has not yet transitioned to the blocked state, and
• transition the first thread from the blocked state to a ready and cancel state in which the cancellation is pending, if the first thread has transitioned to the blocked state.

A method of a system including a hardware processor, comprising:

• receiving, by a scheduling executive that is separate from a micro-kernel, a first indication that a first thread is to wait for an event, wherein the first thread has transitioned to a wait state while the first thread remains active, wherein the scheduling executive and the micro-kernel are part of an operating system (OS) kernel;
• receiving, by the scheduling executive, a second indication that the first thread has transitioned to a blocked state in which the first thread is blocked on the event;
• receiving, by the scheduling executive, a third indication from a second thread delivering the event, the third indication to unblock the first thread;
• in response to the third indication, the scheduling executive:
• causing a transition of the first thread from the wait state to an active state if the first thread is in the wait state and has not yet transitioned to the blocked state, and
• causing a transition of the first thread from the blocked state to a ready state if the first thread is in the blocked state;
• and
• in response to a cancellation of the first thread's waiting or blocking on the event:
• transition the first thread from the wait state to a wait and cancel state in which the cancellation is pending, if the first thread has not yet transitioned to the blocked state, and
• transition the first thread from the blocked state to a ready and cancel state in which the cancellation is pending, if the first thread has transitioned to the blocked state.