10.5 Threads

The module Thread provides operations on first class threads.

Threads may be in one of three states, namely runnable, blocked, or terminated. Orthogonally, a thread may be suspended.

Runnable and non-suspended threads are scheduled according to their priorities, which may be low, medium, or high. The default priority is medium. The priority of a thread may influence its time share for execution, where threads with medium priority obtain at least as long a time share as threads with low priority and at most as long as threads with high priority. Implementations may also choose not to schedule a thread at all if a thread with higher priority is runnable.

A newly created thread inherits its priority from its parent if the latter has either medium or low priority. Otherwise, the new thread gets default (i. e., medium) priority.

IsThread

{Thread.is +X ?B}

test whether X is a thread.

this

{Thread.this ?Thread}

returns the current thread.

state

{Thread.state +Thread ?A}

returns one of the atoms runnable, blocked, terminated according to the current state of Thread.

resume

{Thread.resume +Thread}

resumes Thread. Resumption undoes suspension.

suspend

{Thread.suspend +Thread}

suspends Thread such that it cannot be further reduced.

isSuspended

{Thread.isSuspended +Thread ?B}

tests whether Thread is currently suspended.

injectException

{Thread.injectException +Thread +X}

raises X as exception on Thread. If Thread is terminated, an error exception is raised in the current thread.

terminate

{Thread.terminate +Thread}

raises an exception kernel(terminate ...) on Thread.

getPriority

{Thread.getPriority +Thread ?A}

returns one of them atoms low, medium, or high according to the current priority of Thread.

setPriority

{Thread.setPriority +Thread +A}

sets priority of thread Thread to the priority described by atom A. A must be one of low, medium, or high.

getThisPriority

{Thread.getThisPriority ?A}

returns one of them atoms low, medium, or high according to the priority of the current thread.

setThisPriority

{Thread.setThisPriority +A}

sets priority of the current thread to the priority described by atom A. A must be one of low, medium, or high.

preempt

{Thread.preempt +Thread}

preempts the current thread, i. e., immediately schedules another runnable thread (if there is one). Thread stays runnable.