Question on runtime.Gosched

[jameswang2015]

Hi All,

not very clear of runtime.Gosched. below is what go doc showed. so when I execute runtime.Gosched() in goroutine, it will pass the processor to other goroutine for them to run, and meanwhile it will still keep running? Is there a good example that I can try? Thanks

(base) zwang-mac:cmd2 zwang$ go doc runtime.Gosched
func Gosched()
    Gosched yields the processor, allowing other goroutines to run. It does not
    suspend the current goroutine, so execution resumes automatically.

[hollowaykeanho (Holloway)]

@jameswang2015

o when I execute runtime.Gosched() in goroutine, it will pass the processor to other goroutine for them to run

To keep it simple, concurrency is not parallelism. On a multi-core processors (like those i3, i5, etc.), scheduling a goroutine does not simply means you’re having 2 cores running both main and goroutine process (that’s parallelism). Therefore, both main and goroutine share the same (1) processing core, working in a way that looks like they’re working in parallel (that’s concurrency).

Since both main and goroutine shares the same processing core, passing the core between goroutines (note: main is actually a goroutine itself) often happen. This is why runtime.Gosched() is made available.

Note that if your concurrency codes are well planned and executed (e.g. handling channel I/O nicely), you rarely need to call runtime.Gosched().

@jameswang2015

Is there a good example that I can try? Thanks

You can try to re-invent channel feature in Go using mutex locks. It might be waste of time but that’s one case I witnessed its usage before.