When using a DB connection pool like HikariCP. Should one opt for

<http://Dispatchers.IO|Dispatchers.IO>

or a

newFixedThreadPoolContext

with the number of threads being the max DB pool size?

I would go with

<http://Dispatchers.IO|Dispatchers.IO>

and switch to own

DB

dispatcher when https://github.com/Kotlin/kotlinx.coroutines/issues/261 resolved

You could also use the worker pool pattern to limit concurrency, you don’t need a dedicated dispatcher.