goroutine在打印时间上会互相影响

Question

I'm a freshman for Golang. I know goroutine is an abstract group of cpu and memory to run a piece of code.

So When I run some computing funcs(like sort) in goroutines, I'm hoping they run parallel. But the printed result seems weird, the "paralell" codes print nearly the same timecost.

Why? Is there something I missed about goroutine, or it's because of the func printTime() ?

codes: https://play.golang.org/p/n9DLn57ftM

P.S. codes should be copied to local go file and run. Those run in play.golang has some limitation.

the result is:

MaxProcs: 8

Source : 2.0001ms
Quick sort : 3.0002ms
Merge sort : 8.0004ms
Insertion sort : 929.0532ms
Goroutine num: 1

Source : 2.0001ms
Goroutine num: 4

Insertion sort : 927.0531ms
Quick sort : 930.0532ms
Merge sort : 934.0535ms

Answer 1

Sorry, I don't understand what you want to test. At the first, you code doesn't work for quickSort because you run quickSort with go quickSort(...).

wg.Add(1)
go func(){
    go quickSort(s1, nil)
    wg.Done()
}()

This goroutine will quit immediately. Now, I tested your code. And I notice that you must get total time between start and all of finish.

https://play.golang.org/p/O8Gj-OYIdR