Increase test processes to start in parallel

[Goooler]

More context see detekt/detekt#5944.

https://docs.gradle.org/7.6/userguide/performance.html#execute_tests_in_parallel

[Goooler]

Or we can read dokka_integration_test_parallelism like

dokka/build-logic/src/main/kotlin/org/jetbrains/conventions/dokka-integration-test.gradle.kts

Lines 54 to 56 in 3ea4142

	project.properties["dokka_integration_test_parallelism"]?.toString()?.toIntOrNull()?.let { parallelism ->
	maxParallelForks = parallelism
	}

[Goooler]

There are more cores in TeamCity runners, maybe we can use

    maxParallelForks = if (System.getenv("GITHUB_ACTIONS") != null) {
        Runtime.getRuntime().availableProcessors()
    } else {
        (Runtime.getRuntime().availableProcessors() / 2).takeIf { it > 0 } ?: 1
    }

for both tests and integrationTests, get rid of dokka_integration_test_parallelism property.

[Goooler]

5facf7e

[IgnatBeresnev]

Finally set out some time to test it.

I think it makes perfect sense to do this for unit tests, absolutely no questions here. But I wasn't sure what sort of an impact it would have on our integration tests.

I have a totally overspec'd workstation (16C, 32T, 128GB RAM) to draw any conclusions, but running the integrationTest task multiple times with caching disabled:

• With maxParallelForks = 2 it takes ~17 minutes, max RAM consumed throughout each run is ~20GB
• With maxParallelForks = 16 (i.e with changes from this PR) it takes ~10 minutes, max RAM consumed throughout each run is ~50GB.

I actually wonder what would happen if I didn't have enough memory - would the integration tests fail, or would the time increase drastically because of GC problems?

I'm trying to trigger integration tests on teamcity for this PR, but teamcity is not picking up the branch changes like it did before... Our admins might've introduced some security policies, so I'll have to resolve that first, which might take time...

I'd be happy to merge this change for unit tests only though, if you open a separate PR or change this one

[IgnatBeresnev]

(looks like TeamCity was simply lagging yesterday, integration tests work now)

[IgnatBeresnev]

Thank you!

I'm still interested in having (or at least testing) this change for integration tests, so @Goooler if you want and have the time, feel free to open a separate PR :)