====== goroutine ======
  * [[https://codeburst.io/why-goroutines-are-not-lightweight-threads-7c460c1f155f|Why goroutines are not lightweight threads? – codeburst]]
  * [[https://devjin-blog.com/golang-errgroup-goroutine/|errgroup으로 goroutine 10배 잘 활용하기 | DevJin-Blog]]