And as for why you might want to spawn processes in these cases - it helps isolate memory corruption, other unrecoverable process failures, or even just issues like memory fragmentation to a specific unit test / file build - so that issues building/testing X don't show up as intermitent failures that get misattributed to building/testing Y.

As a workaround for perf issues like the article, you might choose to reuse the same process more instead, but it's a tradeoff.

Sorry, I thought problem is with thousands parallel processes execution. There problem is with some remainings from previous process runs.

...or with the fact that they're constantly being created and destroyed as some tests/build tasks finish and the new ones are spawned.