go - What is the execution time point of goroutine? -

i run following go code 10 times:

package main  import (     "fmt"     "time" )  func main() {     go fmt.println("hello")     fmt.println("world")     time.sleep(1 * time.millisecond) } 

the output "world" first:

world hello 

does manifest goroutine execute unitl there block in main routine? execution time point of goroutine?

what execution time point of goroutine?

the compiler insert yield points program @ different locations seems adequate. example, in function calls , seemingly tight loops. also, goroutine yield when blocking on syscall. program probably yield execution on second goroutine when first goroutine reaches fmt.println("world") , enters write syscall. after non-determinism ensues because don't know how long syscall take.

this, however, implementation detail , should not concerned it. when talking parallelism, timing guarantees (i.e. "happens before") have provided concurrency primitives standard library's sync/atomic package.

tl;dr: don't rely on yield points program work correctly.