But I build with -gcflags "-N -l" here is gdb code: (gdb) Dump of assembler code for function main.main: 0x0000000000002100 <+0>: mov %gs:0x8a0,%rcx 0x0000000000002109 <+9>: cmp 0x10(%rcx),%rsp 0x000000000000210d <+13>: jbe 0x216c <main.main+108> 0x000000000000210f <+15>: sub $0x18,%rsp 0x0000000000002113 <+19>: mov %rbp,0x10(%rsp) 0x0000000000002118 <+24>: lea 0x10(%rsp),%rbp 0x000000000000211d <+29>: movl $0x0,(%rsp) 0x0000000000002124 <+36>: lea 0x6abfd(%rip),%rax # 0x6cd28 <main.bar.f> 0x000000000000212b <+43>: mov %rax,0x8(%rsp) 0x0000000000002130 <+48>: callq 0x2bf60 <runtime.newproc> 0x0000000000002135 <+53>: callq 0x253c0 <runtime.Gosched> 0x000000000000213a <+58>: callq 0x242d0 <runtime.printlock> 0x000000000000213f <+63>: lea 0x643b1(%rip),%rax # 0x664f7 <go.string.*+967> 0x0000000000002146 <+70>: mov %rax,(%rsp) 0x000000000000214a <+74>: movq $0x8,0x8(%rsp) 0x0000000000002153 <+83>: callq 0x24bf0 <runtime.printstring> 0x0000000000002158 <+88>: callq 0x24550 <runtime.printnl> 0x000000000000215d <+93>: callq 0x24360 <runtime.printunlock> 0x0000000000002162 <+98>: mov 0x10(%rsp),%rbp 0x0000000000002167 <+103>: add $0x18,%rsp 0x000000000000216b <+107>: retq 0x000000000000216c <+108>: callq 0x493c0 <runtime.morestack_noctxt> 0x0000000000002171 <+113>: jmp 0x2100 <main.main> End of assembler dump. (gdb) disas bar No symbol "bar" in current context. (gdb) disas main.bar Dump of assembler code for function main.bar: 0x00000000000020d0 <+0>: mov %gs:0x8a0,%rcx 0x00000000000020d9 <+9>: cmp 0x10(%rcx),%rsp 0x00000000000020dd <+13>: jbe 0x20ec <main.bar+28> 0x00000000000020df <+15>: jmp 0x20e1 <main.bar+17> 0x00000000000020e1 <+17>: jmp 0x20e3 <main.bar+19> 0x00000000000020e3 <+19>: callq 0x2040 <main.add1> 0x00000000000020e8 <+24>: jmp 0x20ea <main.bar+26> 0x00000000000020ea <+26>: jmp 0x20e1 <main.bar+17> 0x00000000000020ec <+28>: callq 0x493c0 <runtime.morestack_noctxt> 0x00000000000020f1 <+33>: jmp 0x20d0 <main.bar>
在 2017年9月4日星期一 UTC+8下午3:54:13，John Souvestre写道： > > 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:* golan...@googlegroups.com <javascript:> [mailto: > golan...@googlegroups.com <javascript:>] *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 [mailto:golan...@googlegroups.com] *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 ? > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts...@googlegroups.com <javascript:>. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
