Mark Murphy

There are four main dispatchers (or sources of dispatchers) that you will find yourself using… if you are working in Kotlin/JVM.

If you do not provide a dispatcher to the stock implementations of launch() or async(), your dispatcher will be Dispatchers.Default. This dispatcher is for generic background work.

Dispatchers.IO. This is designed for background work that may potentially block, such as disk I/O or network I/O.

In Kotlin/JVM, this dispatcher does not have its own thread pool. Instead, it shares a thread pool with Dispatchers.Default. However, Dispatchers.IO has different logic at the level of the dispatcher for using that thread pool, taking into account the limited actual parallelism that may be going on due to the blocking nature of the work.