Add BlockHound support

[OliverO2]

kotlinx-coroutines-debug supports a BlockHound integration. However, Kotest currently does not.

Using Kotest in conjunction with BlockHound is usually fine. The following issue is an exception. Kotest uses ThreadPoolExecutor by default in FixedThreadCoroutineDispatcherFactory (via Executors.newSingleThreadExecutor().asCoroutineDispatcher()), which briefly blocks for thread queue management:

• BlockHound false positive in ThreadPoolExecutor.execute · Issue #3540 · Kotlin/kotlinx.coroutines

If that's OK, I could prepare a PR with a BlockHound integration solving the above issue.

[sksamuel]

Feel free to raise a PR for us to look at. BlockHound seems reactor specific?

[OliverO2]

While BlockHound is a reactor project, it provides the same benefits with coroutines when used with the kotlinx-coroutines-debug module:

It reports blocking calls from threads that are part of the coroutine thread pool and currently execute a CPU-bound coroutine computation. It helps to detect thread-blocking early, e.g. when calling a blocking I/O library function. In a case like this, one can decide whether to

• replace the call with a non-blocking one (using a coroutine-aware library), or
• schedule the calling coroutine to run on a separate I/O thread, or
• add an exception if the blocking is harmless.

I'll prepare a PR.