goroutine stack growth latency
https://eng.uber.com/optimizing-m3/ [eng.uber.com]
2019-04-18 18:35
Instead of using tokens to limit the number of goroutines that can be spawned, we spawn all the goroutines upfront and then use the channel to assign them work. This still limits the concurrency to the specified limit, but prevents us from having to allocate new goroutine stacks over and over again.
source: HN