What's the difference between a Dispatcher and a S...

# coroutines

[CLOVIS]

What's the difference between a Dispatcher and a Scheduler?

I see that <http://Dispatchers.IO|Dispatchers.IO> is a DefaultIoSchduler . Are these just synonyms?

Does <http://Dispatchers.IO|Dispatchers.IO> + testScheduler make any sense?

[Oliver.O]

IIRC, a dispatcher is an entity that processes job queues and distributes jobs across threads. A scheduler does time keeping (for delay). (Just from the top of my head.)

[Oliver.O]

TestCoroutineScheduler docs say

Test dispatchers are parameterized with a scheduler. Several dispatchers can share the same scheduler, in which case their knowledge about the virtual time will be synchronized. When the dispatchers require scheduling an event at a later point in time, they notify the scheduler, which will establish the order of the tasks.

[Oliver.O]

But admittedly, the notion of DefaultIoScheduler doesn't fit into this concept. Why should IO have a different idea of time?

[Oliver.O]

Seems like with DefaultIoScheduler (which is a ExecutorCoroutineDispatcher) and others, the names "dispatcher" and "scheduler" are used interchangeably. Possibly something to clean up.

[Oliver.O]

Other than that, using a test scheduler with anything else than a test dispatcher doesn't seem to make sense: The test dispatcher relies on single-threading to skip time when scheduling jobs. This cannot (easily) work on a multithreaded dispatcher, which would probably not honor a separate scheduler for time keeping anyway.