Glossary · Phase 7 · Software engineering
Semaphore
A counter of permits that limits how many tasks can do something at once. A task waits until a permit is free.
Try it now
Watch the ready list. Each task runs to its next yield, then goes to the back of the line. The log shows them interleaving.
Learn it properly
Concurrency and async · Do many things at once: processes, threads and the event loop. About 40 minutes.
Other terms from the same lesson
- coroutine: A function that can pause while it waits and resume later, written with async def in Python.
- event loop: The part of an async program that runs many tasks on one thread, switching whenever one is waiting.
- race condition: A bug where the result depends on the timing of tasks running at once, such as two updates where one gets lost.
Never trained an AI?
Teach a small one to write, right in your browser. It takes about 20 seconds and needs no account.