time.Sleep() will do the job, but you probably wouldn’t want to use it in a
compute-bound loop.
Perhaps the call to add1() got inlined in bar(). The compiler might have
simplified add1() first, since sum1 wasn’t being used anywhere. Then perhaps
it inlined what was left.
You might want to use sum1 by printing it (not inside the loop!).
John
John Souvestre - New Orleans LA
From: golang-nuts@googlegroups.com [mailto:golang-nuts@googlegroups.com] On
Behalf Of ???
Sent: 2017 September 04, Mon 02:42
To: golang-nuts
Subject: Re: [go-nuts] golang gc stop the world how to stop cpu busy goroutine?
Yes, I just want to let the bar func goroutine run first or replace
runtime.Gosched() with time.Sleep,
But I still doubt why add1 in bar func don't happen preempt schedule ?
在 2017年9月4日星期一 UTC+8下午3:25:04，John Souvestre写道：
I think that you put the call to runtime.Gosched() in the wrong place. You
want to place it in the routine which needs to be pre-empted. In your example,
in add1() inside the “for i” loop or in bar() in the “for” loop.
John
John Souvestre - New Orleans LA
From: golan...@googlegroups.com <javascript:>
[mailto:golan...@googlegroups.com <javascript:> ] On Behalf Of ???
Sent: 2017 September 04, Mon 02:10
To: golang-nuts
Subject: Re: [go-nuts] golang gc stop the world how to stop cpu busy goroutine?
package main
import "runtime"
// GOMAXPROCS=1
var sum1, summain int64
func add1() {
for i := 0; i < 10000; i++ {
for j := 0; j < 10000; j++ {
sum1++
}
}
}
func bar() {
for {
add1()
}
}
func main() {
go bar()
runtime.Gosched()
println("debug>>>")
}
above is my example code,when I set GOMAXPROCS=1 and build with -gcflags "-N
-l" the println("debug>>>") don't execute
I just doubt the go runtime support peempt schedule in call function, it
don't work ??
在 2017年9月4日星期一 UTC+8下午2:20:37，John Souvestre写道：
Although a goroutine isn’t pre-emptible by the Go scheduler, there is an
opportunity whenever it does something which blocks or when it calls a
non-inlined function. So generally the GC’s STW can take place pretty quickly.
But if you are doing something with is totally compute bound then it can be a
problem. An easy solution is to insert a call to runtime.Gosched() every so
often.
I believe that there is an ongoing discussion about a way for Go to plan ahead
and be able to handle even these cases, but it’s something for the future.
John
John Souvestre - New Orleans LA
From: golan...@googlegroups.com [mailto:golan...@googlegroups.com] On Behalf Of
???
Sent: 2017 September 04, Mon 00:47
To: golang-nuts
Subject: [go-nuts] golang gc stop the world how to stop cpu busy goroutine?
when have one or two cpu busy goroutine in my server (example for loop empty),
the gc stop the world how to stop the goroutine ?
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